Practical Astrophotography Volume 1 Issue 2 by Practical Astrophotography

PROPERLY TAKING BIAS FRAMES WITH YOUR DSLR

Practical

Astrophotography AUTOGUIDING WITH PHD2 FOR NEWBIES

ASTROPHOTOGRAPHY TOOLS V3.52 FOR THE BEGINNER A BRIEF GUIDE TO CALIBRATION FRAMES IMAGING WITH YOUR SMART-PHONE

ZWO 071 Pro Review & Test

BehindTheShot

Crescent Nebula by Jim Miller

Location: Boulder Colorado Camera: SBIG STT-8300 OTA: Takahashi TOA-150 Mount: Takahashii EM-400 Exposures: 30 OIII - 20 mins each, 1X1 36 HA, 20 mins each, 1X1 Processing: calibrated & combined subs in CCDSoft. Assembled in PS. See more of Jimâ&#x20AC;&#x2122;s work at: www.MillerAstroPix.com

Like us on Facebook: www.facebook.com/ practicalastrophotography Follow us on Twitter: @practastrophoto Visit us on Flickr: www.flickr.com/ groups/practicalastrophotography Visit us Online at: www. practicalastrophotography.com Find us on Instagram: Practical Astrophotography . Email us: info@ practicalastrophotography.com SUBSCRIPTION QUERIES: info@ practicalastrophotography.com Editorial Editor Gene Timothy Editor@practicalastrophotography.com Contributors Juan Ignacio Jimenez Devon Sundle Derek Bill Mike Israel Matthew Green Megan Solusky Chris Berge Jim Miller Ernie Jacobs Graphic Design Jessica Lunk Practical Astrophotography is published on the second Tuesday of every month. Practical Astrophotography is published under license Practical Astrophotography is a registered trademark. © Copyright Yukon Media Group which Practical Astrophotography is a trademark of Yukon Media Group Practical Astrophotography is printed in the USA The publisher makes every effort to ensure the magazine’s content is correct. All material published in Practical Astrophotography is copyright and unauthorized reproduction is forbidden. The editors and publishers of this magazine give no warranties, guarantees or assurances and make no representations regarding any goods or services advertised in this edition. No responsibility can be accepted for images or correspondence lost or damaged in post or transit.

WELCOME Welcome to another great issue of Practical Astrophotograhy. We have received a record number of warm responses fro readers all over the world commending us on what a great publication we have produced and are looking forward to more issues packed full of articles and tutorials on Astrophotograhy. We are continually striving to provide content that your readers want to see, so if you have suggestions please let us know. This is issue is packed full of tutorials and explanations on taking Calibration frames, how to use PHD2 for guiding, Astrophotography Tools and much more. We hope you enjoy reading the magazine! Clear Skies! Gene

Join a growing community OVER 5,000 FOLLOWERS AND GROWING! Get Online and interact with the experts at Practical Astrophotography. You can follow us on Facebook(facebook.com/ PracticalAstrophoto),tweet us on Twitter(@practastrophoto), join us on Flickr (flickr.com/ groups/practicalastrophoto)or Instagram @practicalastrophotography to keep up to date with all that’s going on in astophotography.

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Photographer: Juan Ignacio Jimenez

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IC 1795: The Fishhead Nebula Telescope: RC10 Camera: QHY9M

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Practical

Astrophotography

Contents practicalastrophotography.com

FEATURES

HOW-TO

Smart Phone Astrophotography

Autoguiding with PHD2 for Newbies

Calibration Frames Explained

A Guide to Astrophotography Tools v3.52

Properly Taking BIAS frames with your DSLR

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DEPARTMENTS REVIEWS 6 Astro of the Month 7 Astrophotography Gear 38 ZWO 071 Pro Cooled

8 Destinations 9 Astrophoto Apps

42 Recommended Reads

29 Featured Astrophotography Target

44 AstroShots

ASTROPHOTO OF THE MONTH M8 The Lagoon Nebula by Arthur Maxwell

10” Serrurier Truss Newtonian, QSI 683wsg with Lodestar guider, Astrodon LRGB E-Series Gen 2

For us in Thailand, objects in the Sagittarius Milky Way arrive late in our imaging season. We were fortunate to collect this data before the 2017 rainy season kicked in full gear. This image was shot over two nights a week apart using narrowband filters. 85 individual 5-minute unguided subs were calibrated, stacked and processed in PixInsight

Send Us your Astrophotos if you’d like to see your work published in Practical Astrophotography, here’s how to send us your images: Email a selection of low-res images (up to 2MB of attachments in total) to media@practicalastrophotography.com. Via our Online communities Post your pictures into our Flickr group, Facebook page, Twitter feed, or the gallery on our website.

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Astrophotography Gear Orion starshoot G4 Deep Space Imaging camera Our fourth generation StarShoot Imaging Camera features an impressive CCD chip sensor and highly efficient cooling systems to help you capture amazing astrophotos. StarShoot G4 cameras are some of the “coolest” 16 bit imaging devices available at this price range - literally! Regulated thermoelectric cooling (TEC) keeps each camera at least 20° below ambient temperature to eliminate noise for accurate dark frame acquisition and efficient image capture. Thanks to regulated TEC, StarShoot G4 cameras make it easy to match dark frames night to night, and even hour to hour for impeccable results. Each G4 camera is equipped with a vibration-free fan to further optimize cooling performance. The StarShoot G4 Color is built around the 1/2” format Sony ICX829AKA color CCD sensor, which boasts a 752 x 582 pixel array with sensitive, 8.6 micron by 8.3 micron pixels to detect and capture detailed features of deep space objects. Such large, 1/2” format CCD sensors aren’t usually available in cameras priced as low as the Orion StarShoot G4, and the big chip provides a much larger imaging field of view than cameras equipped with 1/3” format sensors so you can shoot more sky in less time. Specs: Best for imaging Deep sky Meade LPI-G Imaging sensor Sony ICX829AKA Advanced Camera Imaging sensor size 7.4mm x 5.95mm (Color) Pixel array 752 x 582 (437,664 total) This USB 3.0 14-bit Pixel size 8.6 x 8.3 camera allows for Imaging chip increased dynamic Single Shot Color range allowing the Available: Now user to experience the Price; $499 universe like never Orion telescope - www.telescope.com before! The LPI-G Advanced features a large image sensor along with a high pixel count that allows for increased resolution, making it ideal for planets and solar imaging. The LPI-G Advanced has a back illuminated CMOS - SONY IMX178, image sensor with 2.4 x 2.4 micron pixel size and pixel array of 6.3 Megapixels (3072 x 2048). This Imager & Guider is able to take 59 frames per second at full resolution. The camera has a 3.0 connection and ASCOM ST-4 Guider Port for easy connection to the mount. AvaIlable: Now Price: $379 www.meade.com

The Atik Horizon is the first Atik CMOS Camera. It houses a 16MP sensor with exceptionally low read noise and incredibly fast read speeds. With our signature Atik blend of form and function, the Atik Horizon provides a sensitive, high megapixel sensor at a competitive price point. This makes it a great option if you’re looking to upgrade from DSLR, or have a system that would benefit from shorter exposure times. Color: $1318 Monochrome: $1686 https://www.atik-cameras.com/product/atik-horizon/ • • • • •

16MP 4/3″ CMOS sensor 256mb DDR3 Image Buffer ~1e- Read Noise Cooling ΔT=>-40°C USB 3.0 Practical Astrophotography 7

Destinations Need a place to stay? There are wonderful options nearby in Mitchell County, Yancey County, and Avery County. Please note that visitors to the Mayland Earth to Sky Park and Bare Dark Sky Observatory, including the Star Park, are here at their own risk, and will hold Mayland Community College harmless in the event of an incident. The road to the ESP is steep and winding, and there may be large trucks on the way to and from the neighboring waste transfer station. You may hear noise from MCC’s firing range which is nearby.

Blue Ridge Star Park and Observatory Spruce Pine, North Carolina Location The Appalachian Mountains of North Carolina have stood as silent witnesses to the uninterrupted, nightly rain of starlight for nearly a half-billion years, but artificial light now threatens this nightly show. In honor of notable local efforts to preserve the natural nighttime landscape of western North Carolina, the International Dark-Sky Association (IDA) designated the Mayland Earth to Sky Park and Bare Dark Sky Observatory as the first IDA-certified Star Park in the southeastern United States. The Blue Ridge Astronomy Group (BRAG), a local amateur astronomy society, was instrumental in supporting MCC’s application to the Dark Sky Places Program. The Mayland Earth to Sky Park and Bare Dark Sky Observatory is the first program participant:

located in the southeastern United States;operated under the auspices of an institution of higher learning; and whose outdoor lighting consists entirely

of fully-shielded, low-color-temperature light emitting diode (LED) fixtures at the time the IDA award is conferred. Want to visit the Star Park? The GPS coordinates are: 35°55′52″N 082°11′03″W The physical address is: 66 Energy Exchange Dr, Burnsville, NC 28714 Camping is not allowed!

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If you visit for star-gazing at night, please remember that lighting is kept to a minimum so that we preserve our dark skies, so bring a flashlight and be prepared to walk on uneven terrain. If gate is closed, please park just outside the gate, without blocking the gate - it must be allowed to open. Walk around/ under the gate on foot, and use caution walking up the hill.

The ESP parking lot is an ideal flat space for setting up telescopes. To find out about Mayland Earth to Sky Park and Bare Dark Sky Observatory events, please call 828-766-1269 for information

ASTROPHOTO APP

Dark Sky Finder By Skidmore Properties, LLC Price: $2.99 Platform: iOS, Android, Windows

Dark Sky Finder Helps Astrophotographers Find the Least Light Polluted Spots For those of you who partake in any sort of nighttime photography, it’s no secret that light pollution can be the bane of your existence. Thankfully, there’s a neat, simple online resource that can help you better prepare to avoid this enemy of great Milky Way photography. It’s called Dark Sky Finder, and it’s an easy-to-use website that gives you an up-to-date, radar-style view of what light pollution across the United States looks like. Even in seemingly small towns, the slightest bit of fallout light can prohibit you from capturing the nighttime photographs you need. In larger cities it can be borderline impossible unless you employ some tricks we’ve mentioned in the past. Dark Sky Finder is meant to ease these pains by providing a simple way to find the nearest location that ensures you’ll get the shot you need — no postprocessing trickery required. Right now, the app is using information from both Google and the NOAA National Geophysical Data Center to display not just light pollution information, but also various crowd-sourced ‘sites’ with information on the location, who owns it, whether there is dedicated parking, whether there are any bathrooms nearby and so on and so forth. Dark Sky Finder is fairly basic in execution, but it gets the job done and the ‘sites’ feature mentioned above makes it particularly useful. So head on over to the website now and give it a run-through to see what conditions are like in your area.

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HOW-TO SMART PHONE ASTROPHOTOGRAPHY

Smart Phone Astrophotography Traditional Astrophotography definitely requires some deep pockets to get started, but this doesnâ&#x20AC;&#x2122;t have to deter those who still want to try their hand at some amazing images taken through a Smart phone.

ver the past several years I have been the witness to visitors at star parties pulling out their smart phones and attempting to take photos through the eyepieces of telescopes. Some of these individuals have been younger kids and teens who are the master of their smart phones and have been practicing taking selfies and the like since they were first introduced to a smart phone. I was truly amazed at the images these young hipsters were getting out of their Smart phones and many riveled the very first images I produced from my Meade 8 inch SCT using an old Canon AE-1 film camera. I set off to find out just 10 Practical Astrophotography

what could be captured and the quality and ease that was it could be done. I found all kinds of forum posts from seasoned imagers that were struggling to get even a mildly aesthetic result. I started to wonder what these youngsters knew that the experienced Astrophotographers did not know or did not implement. The obvious short comings of the common Smart phine was the inability to collect light in low light situations and the inability to capture long exposures. However with the advent of some pretty amazing new Smart phone Applications available this is really not an issue any longer. There are some tips and tricks to getting the images you desire.

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HOW-TO SMART PHONE ASTROPHOTOGRAPHY

he key to getting great photos with your Smart Phone is getting the subject in focus and making sure it is well lite. Modern Smart Phones have come a long way in low light photography, but they are still not as good as a DSLR or CCD/CMOS. By using a few tips and essential aids you can get some great images. Here are a few tips to help you started using a popular app called Nightcap. 1. Purchase a well made sturdy phone adapter for use with your telescope. There are numerous Online merchants that sell these. We purchased ours from Orion Telescopes for $89. but you can find cheaper models if you search enough. 2. Use eyepiece filters to help bring out the contrast and colors for Planetary and Moon photos. You will be amazed at how much these can help you when photographing low light objects. 3. If you are going to be doing any long exposure or time lapse astrophotos you will need a sturdy Tripod to hold your camera and prevent any stray movement affecting your shots. We used a Monfrotto. A good tripod can be had for around $50-$130. 4. Also needed for long exposure

wide field photos or time lapse shots is a good tripod phone adapter. We purchased ours from B&H Photo and we paid around $13 for a well made adapter that will fit a 1/4” x 20 threaded hole or ball joint. Wide field imaging Using your tripod and Smart Phone Adapter you can set up your phone to take star trails and capture constellations such as the images below.. Star Trails using NightCap App Capturing star trails is easy, all you need to do is turn on Star Trails Mode, tap the shutter button once to start capturing, then wait at least 15 minutes before tapping the shutter again to save the photo. The longer you wait, the longer the trails will be – you can see them forming on screen. This is a 90 minute photo, pointing north (the star in the center of the circles is Polaris, the Pole Star): It is pretty easy by using the NightCap camera app. We opened the app and chose the Long Exposure setting from the Photo camera options. Constellations To photograph the stars, simply turn on Stars Mode. Stars Mode sets the camera up for you with the best

USEFUL KIT FOR SMARTPHONE ASTROPHOTOGRAPHY SMART PHONE ADAPTER A Smart Phone adapter will hold your phone in place above the eyepiece. The simplest way to take a photo at the telescope is to simply hold your phone’s camera up to the eyepiece EYEPIECE FILTERS While Smart Phone cameras have excellent resolution, they don’t yet have the manual exposure control settings needed to evenly expose the entire lunar disc or to capture subtle planetary features. TRIPOD One item that is essential is a sturdy tripod. You’ll be creating long exposures, so you must ensure your camera doesn’t shake or move at all.

SMART PHONE TRIPOD ADAPTER A good and sturdy Tripod mount for your Smart Phone is essential when photographing the Milky Way and other wide-field Nightscapes. SMART PHONE CAMERA APP A dedicated Smart Phone app for taking photos of the night is very helpful but not necessary. We Use Nightcap Camera

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HOW-TO SMART PHONE ASTROPHOTOGRAPHY settings for stars, so all you need to do is put your device in a tripod or a firm position pointing at the part of the sky you wish to photograph and tap the shutter. After pressing the shutter the app will start a 3 second timer (to avoid blurring if you move the device slightly when tapping the button), then itâ&#x20AC;&#x2122;ll take a 10 second exposure. Wait until you hear the shutter sound or see the shutter button go from red (capturing) to white (ready). Lunar Imaging Probably the easiest target to shoot

Image by Ernie Jacobs

with a Smart Phone is the Moon. The Bright face of the moon makes it an easy snap for Smart Phones, it is evenly and well lite so the camera can easily focus on the surface of the Moon. The best shots are those that are taken of the Terminator and display the contrast between light and Dark areas of the Moon. Planetary Imaging If you have access to a telescope or a nearby astronomy club that has Public Nights you can take some pretty amazing photos of the Planets. You can use the standard camera app your phone comes with or you can try your hand at using a dedicated Smart Phone app for long exposure like Nightcap Camera (https://itunes.apple.com/us/app/ nightcap-camera/id754105884?mt=8 ) NightCap Camera will allow you to better control your exposure with built in focusing aids and exposure. You can try your hand at steadying the phone without a Smart Phone adapter, but it is much easier to use the adapter. Modern Phones like the iPhone8 or the Samsung Galaxy have come a long way in their ability to take images in low light. Most Phones were not designed to take Astrophotography but still do a good

job. By adjusting the settings and focusing on the Planet you can get images like the ones to the right which were taken through a Celestron 14inch SCT using an Iphone7. You will have to adjust the images brightness and contrast a bit after taking them. You can also enlarge the photos and then crop. As you can see the end results are pretty amazing for just using a Smart Phone. Go ahead and give it a try and send us your results for future publishing. CONCLUSION With Modern Smart Phone technology steadily progressing the average person can obtain some pretty spectacular images using some simple accessories and a few tips. We hope that you will go out and experiment a bit and let us know what you were able to photograph. We will feature those images in an upcoming issue.

This shot was taken through a Celestron 14 inch SCT that a local club had open during a Public Night. This was taken by one of the visitors who held the phone up to the eyepiece and snapped the photo. This shows you that you donâ&#x20AC;&#x2122;t have to have own expensive equipment to get a great shot of the moon.

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HOW-TO A Guide to Using Astrophotography Tools v 3.52

A Guide to Using Astrophotography Tools v3.52 Astrophotography Tools has been the go-to choice for many imagers who use both Digital SLR as well as CCD and CMOS cameras.

APT

stands for “Astrophotography Tool” and it is like Swiss army knife for your astro imaging sessions. No matter what you are imaging with - Canon EOS, Nikon, CCD or CMOS astro camera, APT has the right tool for planning, collimating, aligning, focusing, framing, controlling, imaging, synchronizing, scheduling, analyzing and monitoring. All its features are packed in an easy and comfortable to use interface with design that had no alternative back in 2009 when it was released. Since then APT is constantly being improved and refined by the real experience of many astrophotographers from all over the world including one of the APT authors. Currently APT works on MS Windows XP, Vista, 7, 8, 8.1 and 10. This excerpt taken directly from the Developers

01 Check List Screen

This is the main screen presented to the user when the program is started. Here you are given various “Check Lists” to help make life easier when setting up to image. You can change these and add new “Check Lists” as you like. You choose to see this screen every time you start the program of dismiss it by choosing to no longer see it on startup at the lower left side of the tip screen. Click Ok and this screen will close.

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website is a pretty good description of exactly what you will find when using APT. There are numerous seasoned Astrophotographers whom use APT rather than other expensive packages such as Sequence Generator Pro or Software Bisque’s The Sky X, not saying those are any less capable but APT’s simplicity is definitely a major factor when using a image acquisition software. The cost 18.70 Euro, of APT is another factor beginners consider when choosing a software like this to start with. The; developer Ivo is very responsiveness to feature suggestions and has put in place a number of changes in each successive version update. APT is truly an All-inOne software package for Astrophotographers.

HOW-TO A Guide to Using Astrophotography Tools v3.52

02 Camera Connect

This is the camera connect screen you will see after clicking on the camera tab in the upper left corner. You can connect a DSLR, CCD or CMOS camera. The CCD and CMOS cameras are under the same bullet. You can also set your Bayer preview here. Once you connect your camera the software will remember your choice the next time you start the program making it easier and one less step to complete at the beginning of each imaging session.

03 Settings Screen

One of the first screens you should set up is the settings screen. Here you will find the ability to change the screen color from Grey to Red for Night vision. You can also find your locations settings, accessories settings such as a focuser, filter wheels and sound. You can set your own sounds if you do not care for the male or female voice calling out events. You can also mute the sounds by clicking on the speaker icon just right of the time readout.

04 Live View

APT has a great Preview feature that allows you to see your target, use it to frame the shot and to also focus real time. In order to see what you are imaging and to start focusing your image, you can click on the â&#x20AC;&#x2DC;Live viewâ&#x20AC;? button. This will bring up a Live View of what your scope is viewing and refresh the images based on what your exposure is set at. To change the exposure you can click the drop down in the lower right hand corner and choose an appropriate setting.

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HOW-TO The Beginners Guide to Using Astrophotography Tools v3.52

05 Focusing

Under the Tools tab you will find a host of tools that can aid you in your imaging session. Among them is a Focus Aid, Bahtinov Aid, Auto-Focus Aid and Pixel Aid. The most useful for manual focusing is the Focusing Aid tool. By clicking on the button you are given a screen which you place the preview box over the star you want to focus. This will display a readout of your FWHM current and Best readout with an option to reset values. You can also use the Magnifier tool to help make sure it is in focus

06 Adding/Editing Plans

Once you have your stars in focus you can start imaging with your setup. Once you choose the Camera tab you will need to setup an exposure plan. Click on the drop down and choose “test” underneath the Light Plans and then click Edit. Here you can set the Plan name, exposure bin, pause and # of each exposure by “adding as new” or “update the current” plan line. We recommend that you create several plans for later use so that you can maximize your imaging time. See Appendix Image

07 Imaging

Once you have your Plan setup and saved you will see it on the right side of the screen. To start imaging click on the “Start” button and your plan will run through its course. You can pause the plan by using the Pause button Depending on the plan you have setup you will hear audio alerts based on when an exposure has started or ended. This is a nice feature if you like to walk away from your computer during long imaging sessions. If this becomes too much of a distraction you can go back into your settings screen and change the sounds.

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HOW-TO The Beginners Guide to Using Astrophotography Tools v3.52

08 Image/Plan Status

After starting your plan you can see the status of your plan and the exposure progression in the upper left corner of the screen. Unlike other programs it counts up rather than down. You will see the exposure you are currently on as well as the remaining time left to completion. Note: in version 3.52 you can move the Status window to a horizontal position if you feel that is a better way to view.

09 Image Preview

During your imaging session you will see the latest image you have taken under the “Img” tab. If you Double Click the image it will be displayed full size in the main Preview Window. If you go back into the Tools tab you can click on the “histograms” button and you will be presented with the screen from which you can adjust the image your currently viewing. Here you can adjust the histogram to stretch the image if you so choose.

10 Gear Tab

If you want to take control of your focuser, filter wheel or telescope You can do so from this screen. It is easier to control all of your peripherals and your scope from within APT then it is to other software programs open. Most seasoned imagers know that time is a commodity when the skies are clear and any wasted time is wasted imaging. From this screen you can also plate solve your images when your scope is connected.

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HOW-TO The Beginners Guide to Using Astrophotography Tools v3.52 Plan Editor (CCD Mode)

Tools Tab

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HOW-TO The Beginners Guide to Using Astrophotography Tools v3.52 Img Tab

Gear Tab

Camera Tab

CONCLUSION This is only a small sampling of the many features of APT and does not cover all of its features or functionality. In upcoming issues we will take deeper dives into more specific operation and use of APT. It definitely deserves a closer look into its many features. APT lives up to its claims as being the â&#x20AC;&#x153;swiss army knifeâ&#x20AC;? for your astro imaging sessions. Visit https://ideiki.com/astro/Default.aspx to download a trial and for more information. Practical Astrophotography 19

HOW-TO The Beginners Guide to Using Astrophotography Tools v3.50

Main

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HOW-TO The Beginners Guide to Using Astrophotography Tools v3.50

Screen

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A Brief Guide to Calibration Frames

A Brief Guide to Calibration Frames: Bias, Dark, Flats and Dark Flats Many Budding Astrophotographers are often confused on exactly what Calibration frames are and if they even need to use them since they do take quite a bit of effort to acquire. I’ve seen this come up on here numerous times in comments and descriptions of images, and in replies, so I wanted to put some info on here about what calibration frames are for, why we take them, and some suggestions for how to get the most out of them. I’m not an expert; I’m not going to get into the math. This is not intended towards experienced astrophotographers, this is meant for the new imagers to help steer them in the right direction...

What kinds of calibration frames are there, and what is the purpose of each? First things first- all calibration is about is increasing the signal to noise ratio. Think of when you take an image with your cell phone in the house without a flash- the image looks grainy. If you do a video, you see the “noise“ flickering in the images as you play the video. When you do it in day light the images look great because of the high signal to noise ratio. When dark, you have a low signal to noise ratio. Calibration and stacking is all about increasing the signal to noise ratio. Note the light signal from what you are imaging is constant, the noise is NOT and varies randomly. Thus with math we can take a lot of Light, Bias, Dark, Dark Flat frames and figure out what is noise and what is signal and make amazing pictures out of a noisy mess. Keep in mind if you have a camera with 12 million pixels it is impossible to have all the pixels act the same. Calibration allows us to mathematically calibrate each pixel to react the same way to each photon it sees. •

Bias Frames - Your Camera inherently has a base level of read out noise as it reads the values of each pixel of the sensor, called bias. When averaged out, basically it’s an inherent gradient to the sensor. BIAS frames are meant to capture this so it can be removed.

•

Dark Frames – When taking a long exposure, the chip will introduce “thermal” noise. Its level is magnified by three things - temperature, exposure time, and ISO. Dark frames are used to subtract this sensor noise from your image, and mitigate “hot or cold” pixels. (Some modern sensors automatically calculate dark levels and don’t need dark frames). Dark Frames also will calibrate the chip so all pixels give the same value when not exposed to light.

•

Flat Frames - I’ve seen people say flats help for light pollution. NOT TRUE AT ALL. Flat frames allow you to calculate the correction factor for each pixel so they all give the same value when exposed to the same quantity of light for a given optical path. Things like dust motes, lens vignetting consistently reduce the light to a given pixel, flat frames allow you to mathematically remove them to give a smooth evenly illuminated image.

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A Brief Guide to Calibration Frames •

Dark Flat Frames- These are just like dark frames for your lights, but are for your flats. (May not be needed depending on what software & process you’re using)

Bias Frame

Dark Frame

Flat Frame

How do I take each type of calibration frame? •

Bias - Make sure it’s dark (or put your camera in a box, etc), and put the lens cap on. Set your camera to the shortest exposure time possible. Take a bunch of pictures. Stack those.

•

Dark - As above, darks are temperature and exposure time dependent, as well as ISO. You want your camera in the dark, with the cap on. To match the temperature, it’s easiest to simply have your camera outside when the ambient temp is the same as when you image. (either do these after you’re done for the night, or on another night the temp is the same) Set the exposure time to match your lights. Take a bunch of images.

•

Flat Frames - There are lots of ways to do flat frames. My favorite is currently to put a white t-shirt over the end of my scope, and point it at a laptop screen. On a DSLR the exposure time should be so your histogram is between 1/2 and 2/3 on the back of the camera. Once you have it right, take a bunch. Since you’re trying to capture how the dust, etc. was, this should be done right after you’re done imaging for the night. You don’t want your focus, rotation, etc. To change before you get your flats since doing so will change your optical path to each pixel.

•

Dark Flats - Since these will be short to match your flats, they’re quick. Just pop the lens cap on when you’re done with your flats, and take a bunch of darks at the same exposure time.

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Practical Astrophotography 23

A Brief Guide to Calibration Frames How many of each calibration frame should I take? •

The general answer is “As many as possible, more is better”. Keep in mind that the reduction in noise goes by the inverse square law. Going from 1 exposure to 2 exposures will reduce the noise by a factor of ½, going from 2 frames to 4 frames will again reduce it by a factor of ½. Then you need to go to 8 frames, then 16, then 32, then 64 then 128, then 256. As you can see it gets out of hand quickly. More realistically; however, I go by the following.

•

Bias - I take 50 - 100. They’re fast, and you can take them any time.

•

Darks - Depending on your exposure time, these can be a chore. I go for at least 20, and up to 50. Though for really long exposures, I’ve used as few as 5.

•

Flats - I have varied between 25 - 50, but really see no improvement over 25, so have stuck with that of late.

•

Dark Flats - Match your number of flats

•

Notice that these quantities don’t change at all based on your number of lights

General tips •

Need to take Light , Dark, and Bias frames at the same temperature. The Flat and Flat Darks need to be taken at the same temperature, preferably the same temperature at the Light, Dark, and Bias.

•

ISO Matters for all of these. You need a bias for each ISO you want. You need a dark that matches the ISO of your light. Your flat ISO must match your light ISO, and your dark flat must match your flat.

•

Bias Frames last a long time. Take a bunch, use your stacking software (pixinsight or DSS) to make a master Bias, and just re-use that. Can easily be re-used for 6 months. I never saw a change in mine.

•

Darks - Some modern sensors don’t need dark frames, they do dark subtraction via a function in the camera firmware. The best thing to do is test an image by processing it with and without darks, and evaluate the difference they made.

•

Darks - Build a dark library. This is made easier if you can settle on one (or two) standard exposure times & ISO Combinations (for me it was ISO 800 x 300s), and take darks at different temperature points. Create Master darks and label them. (i.e., Master_Dark_ISO800_300s_25c, Master_Dark_ISO8300_300s_20c) These masters will last as long as your Bias Masters.

•

Take darks on cloudy nights! You can just put your camera outside and let them click away. Even if you haven’t imaged, if you don’t have darks at that temp, take some!

•

Flats are a pain, but don’t skip them! Dust is very hard to remove later without them

•

For my DSLR images, I just stuck with ISO 800. This meant I only ever had to worry about calibration frames for a single ISO.

CONCLUSION Calibration Frames are essential for eye-catching images, although it can be time consuming to acquire them you will notice a difference in your images when you do take the time.

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How-To: Properly taking Bias Frames with your DSLR

Properly Taking Bias Frames with your DSLR by Chris Berge When you want to use flat frames and/or dark frames, you will have to create a Master-Bias as well and use this on the flats/darks. Shooting bias frames is pretty easy, but still many different things are said about them and how to take them. To make sense of this it’s good to understand what a bias frame is and what it’s role is in the calibration process. What is a Bias frame and what does it do? Any imaging sensor will have noise that is produced by the electrical system itself. By this we don’t mean the dark current, but just the sensor picking up electrons from the processes of the electrical system itself. Most of the time this will have a fixed pattern, and therefor can be calibrated. When combining many bias frames you will create a masterbias that will be a capture of this fixed noise pattern. You need to subtract this from flats and dark frames, because those frames have this pattern as well as a basis, and on top of that need to correct either the artifacts of the imaging train (the flats) or the dark current/thermo noise (darks). You can imagine that this is best done without the fixed noise pattern that is already there, so this is where darks come in to subtract that and make sure we are correcting the right signals. How to take bias frames with a DSLR Reading the above explanation on what a bias frame is and what it’s purpose is, you probably can guess a few things already what to do when taking bias frames;

• Use the fastest shutter speed your camera offers. Since we are interested in the fixed noise pattern of the electronics, we don’t want other noise creeping up (like dark current) so keep the exposure as short as possible • Cover the camera and viewfinder Again, we don’t want any signal spoiling our bias frames, so make sure you cover the camera to avoid any light falling in. • Use the same ISO as your lights. I’m not sure on this one, but since I shoot at a fixed ISO setting and I need to pick an ISO value anyway, best to keep it at the same setting. • Temperature doesn’t really matter. I’m pretty sure theoretically it will matter, but in reality you won’t notice any difference because of the short exposure time. Don’t worry about shooting the bias frames indoor at room temperature while you image outdoors with way lower temperatures. • Don’t debayer your bias frames. The whole calibration process should be done with ‘un-debayered’ frames; undebayered bias is used with undebayered flats on undebayered lights. After calibration you debayer the corrected lights, and start the registration/integration process. • Shoot a lot of frames! This seems to be overlooked and misguided statements are given often. Taking 5 frames is NOT enough. Nor is 10 or 20 probably. I would say you will need AT LEAST 30+ frames. But you are better off taking more frames. The acquisition of these bias frames is easy, so why wouldn’t you? Let’s have a closer look why it is important to use many frames: How many bias frames should I take? Like mentioned before, 10, 20 or 30 frames won’t be sufficient. You are trying to capture the fixed noise pattern as so you need a lot of frames to get it clearly showing. See below the difference between a master bias of 50 frames and that of 250 frames: Please note that the images are stretched to show the difference. CONCLUSION The importance of Bias Frames cannot be overstated if you choose to use dark and Flat frames. A good Bias frame will make a noticeable difference in your stacked images. Its very easy to obtain these frames so you should never have an excuse to not use them.

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Featured Astrophotography Target NGC 281: The Pacman Nebula

Magnitude: 7.4 Constellation: Cassiopeia Type: Diffuse Nebula in Cassiopeia Constellation The Pacman Nebula, 9,200 light years from Earth, is found in the Cassiopeia constellation, part of the Perseus Spiral Arm of our Milky Way. It was discovered in August 1883 by EE Barnard and, since then, it has been imaged in a variety of new and wonderful ways as NASA has endeavoured to find out more about this stellar nursery. NGC 281 is actually a cluster of stars found about 1,000 light years above the plane of the Milky Way. Thanks to its positioning it is not obscured by much dust or gas in X-ray and infrared images, so it gives astronomers an almost unhindered view of the star formation within. In visible light a portion of the nebula is hidden by dust and gas, forming a gap like a mouth. This led NASA to dub NGC 281 the â&#x20AC;&#x2DC;Pacman Nebulaâ&#x20AC;&#x2122; Practical Astrophotography 29

A Beginners Guide to Using PHD2 Guiding

PHD2 Guiding for Beginners - PART 1

PHD2 is the most widely used software for auto guiding originally designed and developed by Craig Stark. INTRODUCTION

PHD2 Boast the following: • Easy-to-use, “push here dummy” guiding for beginners • Sophisticated guiding and analysis tools for experienced users • Extensive support for commonlyused equipment • Easy upgrade/co-installation with PHD1, including many new features • Available for Windows, Mac, and Linux • Extensive Online help and responsive product support 30 Practical Astrophotography

What is Auto-guiding? An Auto-guider is an automatic electronic guidance tool used in astrophotography to keep a telescope pointed precisely at an object being photographed. This prevents the object from drifting across the field of view during long-exposures which would create a blurred or elongated image resulting in star trails. The Open PHD Guiding project began in 2009 when Craig Stark of Stark Labs, the author of PHD Guiding and Nebulosity, released the source code of his popular PHD Guiding application. In 2012 the project was picked up by Bret McKee who did a major refactoring of the code, reworking much of the internal infrastructure and introducing the multi-threaded architecture in

A Beginners Guide to Using PHD2 Guiding use by the application today. In 2013 the project maintenance role transitioned to the current maintainers, Andy Galasso and Bruce Waddington, who have overseen the development of the application since then. The application today is the result of contributions from more than 40 developers and translators. See Help – About in the PHD2 menu for the full list of contributors. PHD2 is the second generation of Craig Starks original PHD application. PHD has become fixture of the amateur astronomy community with more than a

quarter of a million downloads. From its inception it has been successfully embraced three seemingly conflicting objectives. 1. For the beginning and casual imager, to deliver ease of use and good guiding performance “out of the box“ 2. For the experienced imager, to deliver sophisticated guiding algorithms, extensive options for tuning, and broad support for imaging equipment. 3. For all users, to consistently exhibit a commercial level of quality while being available

free of charge. PHD2 is the standard among Astrophotographers who enjoy FREE software. But it is not only liked by Astrophotographers because of its price it is probably the easiest to use, which is conveyed in its name of “Push Here Dummy”. PHD2 is very simple to operate and has a small learning curve for beginners to get started. After a few wizards and calibration runs you can be up and running within minutes.

A typical Auto-Guiding setup displaying how to connect your equipment to your computer for use with PHD2

Equipment Connection Screen

When first opening PHD2 you will be presented with this screen, if you click in the lower left corner on the USB plug button you will get the equipment connection screen. Here you can connect to your guiding equipment to start your session. If you are new to the software the first task is to setup a new equipment profile by clicking the drop down in the upper right corner. Here you will be able to choose the equipment you are using. We recommend using the Wizard which will guide you through the task much easier.

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A Beginners Guide to Using PHD2 Guiding

New Profile Wizard - Choose a Guide camera

When using the wizard you are taken through several steps to help you configure and setup your chosen equipment for auto-guiding. The choose camera screen allows you to select the guide camera you are using and set the focal length of the guide scope you are using. if you are not sure what settings to use for the pixel-size you can consult your cameras manual or if your scope is properly connected you can use the “detect” button. We are using the Orion Starshoot for this article so we are using the specs from the Orion product page Online.

New Profile Wizard - Choose a Mount Connection

The next step in the wizard is the set what mount you are using. .For most users they will choose the ASCOM option and then set their desired mount guide speed, although we have found that the per-populated value is usually the best. Other users can simply use the option “On Camera” as their mount will be controlled directly through the connection from the Auto-guiding camera to the mount.

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A Beginners Guide to Using PHD2 Guiding

New Profile Wizard - Choose Adaptive Optics Device (optional)

This step is optional and most will not use it, however for those that do use an Adaptive Optics Device you can set it here. As the screen explains this is used for high speed, small guiding corrections while the mount is used for the larger corrections needed.

New Profile Wizard - Finish Creating Your New Profile

The Final step in the Wizard is to give the newly created Profile a name so that you can load this for each session from this point forward. You can optional choose to start the process of creating a Dark Library.

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A Beginners Guide to Using PHD2 Guiding

New Profile Wizard -Dark Library

After successfully creating your new equipment Profile you have the option to create a Dark Library. This screen will allow you to take a series of darks to remove any dust or foreign objects on your auto guider sensor. You can take darks from 1 second all the way up to 30 seconds, we recommend you take a series between 1 second and 6 seconds which is sufficient for most users. When ready simply click on the Start Button and you will be prompted to cover your guide scope and the program will automatically take your darks and store them for future use.

Connect Equipment

Once you have finished the new Profile wizard and setup your Dark Library you can connect your equipment and allow PHD to start calibrating your setup. Click on the “Connect All” button and you will see the “Connect” buttons status change to “Disconnect” you can then close this window and return to the Main screen.

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A Beginners Guide to Using PHD2 Guiding

Exposure Time and Guide Star Selection

You will need to start the looping of the guide camera in order to pick up stars. To do so click on the Green circular arrow Icon. This will start your camera in a continuous looping session. A typical exposure time is around 2 seconds. However if you are not seeing enough stars in your image you can change the exposure to 4 seconds . You can let PHD2 auto select the appropriate guide star based on your seeing by using the ALT and S keys. This will highlight the star PHD thinks should be used as seen in the image to the left.

Automatic Calibration

09a

When you have the appropriate guide star chosen you need to start a Calibration run to allow PHD2 to measure some things in order to calibrate your setup. including in those measures are the angle of your guide camera in relation to your telescope axes and the length of guide pulse need to move the telescope by a certain amount.

09b

To start the calibration run hold down the Shift key and click on the Green Cross hairs icon. This will start a calibration run. If everything is in order this should not take more than a few minutes. This can be one of the more frustrating parts of using PHD2 when it returns a vague error dialog.

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A Beginners Guide to Using PHD2 Guiding

Guiding

When the calibration run is successful you will see the doted yellow cross-hairs will change to solid green verifying your calibration run was successful and that you are currently guiding. .You will also be presented with the tracking and corrections history chart or what the help contents call guiding performance screen which is seen in the upper left corner. You can also use this to monitor your guiding accuracy.

PHD2 Overlays and Screens

Guidance Performance Screen

Star Profile Screen

CONCLUSION PHD2 has become one of the most widely used auto-guiding solutions if not the most used. Its simplicity, even though at times it can be frustrating to get your settings dialed in, it is rather easy to use. In Part 2 of this article we will go beyond the basics of setting up your equipment ans will tackle some of the most common errors and mistakes the beginner will make and how to overcome and fix them to get your guiding setup locked in and guiding for hours of hassle free imaging sessions.

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Photo Contest Snap a photo of your astrophotography setup via Instagram for your chance to win an Exclusive feature in Practical Astrophotography as well as a License to the latest version of Astrophotography Tools. Tag your photo with #practicalastrophotography Submissions must include: • hashtag: #practicalastrophotography • Photo of your Imaging Setup Rules & Regulations • follow @practicalastrophotography • photos must be submitted between March 3rd and March 15th, 2018 Our latest winner of an APT license

Jack Walker @astrojack

Check out his instagram page! his setup includes:

Telescope: SkyWatcher Evostar 80ED Pro Guide Scope: Astromania 50mm Mount: SkyWatcher EQ6-R Cameras: Canon 6D unmodified ZWO ASI 120mm guide camera

A proud supporter and partner of Practical Astrophotography Magazine.

Vist Us at NEAF2018 on April 21 and 22 in Suffern, NY

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REVIEW: ZWO ASI 071 PRO COLOR CAMERA - COOLED

ZWO ASI 071 MC PRO COLOR CAMERA COOLED SPECIFICATIONS Sensor: SONY IMX071 CMOS Resolution: 16 Mega Pixels 4944 x 3284 Pixel Size: 4.78µm Sensor Size: 23.6mm x 15.6mm Diagonal: 28.4mm Exposure Range: 64µs-2000s ROI: Supported Read Noise: 2.3e @24db gain Full well: 46ke he ASI 071 Pro is an excellent Interface: USB3.0/USB2.0 full-color CMOS astronomy Bit rate: 14 bit output (14 bit ADC) camera for the discerning DDRIII Buffer: 256MB astronomer who seeks a high Adaptor: M42 x 0.75 power camera optimal for deep sky Dimensions: 86 mm Diameter imaging. The sensor is an impressive Weight: 640g and respectable 28.4mm diagonal Back Focus Distance: 17.5mm and provides a pixel array of 4944 x Cooling: Regulated Two Stage TEC 3284. It’s a great choice for any kind Delta T: 35-40 degrees of imaging, and works especially well C below ambient for deep sky imaging. The sensor is Cooler Power a Sony IMX 071, which is a high-level Supply Required: 12V at 3A Max APS-C format sensor. The size per Price: $ 1379 pixel is 4.78 microns.

The Pro version has been upgraded with a 256MB DDR3 memory buffer

to render data transfer more stable and correct the amp-glow issue that the original had. This increases the speed and stability of data transfer between your camera and the computer, providing a boost in performance. One of this cameras greatest features is its incredibly low read noise and gain, averaging 2.3e at 24db gain. What this means is that it accrues interference very slowly, and can be active for long periods of time with minimal worry about trash data. This is compounded by the high power cooling system that lets the camera stay active for long periods of time without overheating. It is these features that make this camera excellent for deep sky imaging; it can take as long as it needs to capture as much data as you want.

DDR Memory Buffer ASI071MC Pro camera includes a 256MB DDR3 memory buffer to help improve data transfer reliability. Additionally, the use of a memory buffer minimizes amp38 Practical Astrophotography

REVIEW: ZWO ASI 071 PRO COLOR CAMERA - COOLED glow, which is caused by the slow transfer speeds when the camera is used with a USB 2.0 port. ASI071MC Pro offers very good performance for astrophotography. Low read noise, high dynamic range.

USB 3.0 Port & USB2.0 HUB USB 3.0 Port: Provide 5Gb bandwidth to make it possible for ASI071MC Pro to run at 10 fps (14bit, normal mode) at full resolution(16Mega). We recommend using a 12V/3-5A or more DC adapter for cooler power supply (2.1×5.5, center positive). Using a battery with 9-15V is also suitable for the cooler power supply. USB 2.0 HUB: Can connect with various accessories, including a filter wheel, guide camera or electronic focuser, allowing you to manage your cables better. There are two short 0.5m USB2.0 cables included with the ASI071 Pro. The hub is powered by the external power supply if you connect one.

Unique Tilt Adapter ASI071 Pro includes unique tilt adapter. Say goodbye to tilt problems forever !

Anti-dew and cooling system ASI071MC Pro has a two-stage TEC cooling system that allows deep cooling (35°C-40°C below ambient). You will need an external power supply to power the cooler. An ACDC power adapter is not included in this package, however you can order one from here. The anti-dew heater will heat the AR protect window to avoid any dew problems. The heat anti-dew heater power is around 3.6W and can be turn off in software to save power.

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he first impressions were excellent. Stylish red finish, as every other ASI camera. It comes well boxed and is bundled in a soft protective carrying case.

The camera looks solid and well built, but a bit heavier than the previous models it was built to replace. I did have some reservations as to whether this would cause issues with my 2 inch focuser being able to hold the additional weight. On the camera back there is an USB3.0 port to connect the camera to the computer but it can be connected to USB2.0 ports too. It has two USB2.0 ports for additional devices like focuser, filter wheel etc. This feature is very useful because this can reduce the number of dangling wires from the telescope to the computer. There is also 12V/2A power inlet for the cooling system. However these things are not new. They exist on many other ASI cameras but they are worth to be mentioned. 40 Practical Astrophotography

Compared to the ASI071MC-Cool there is almost nothing in common besides the sensor. Both cameras use IMX071 CMOS sensor from Sony and both are color only, which may be a setback for some users. However the Pro version comes with a complete mechanics and electronics redesign and the most notable is that ASI071MC-Pro has 256MB DDR3 internal storage buffer. In my opinion this is a huge improvement in several aspects. First because it can run smoothly connected to a slow computer hardware and single board computers like Raspberry Pi. So no more occasional broken frames on a slow hardware. And second, because the sensor readout speed does not depend on the USB transfer speed, the readout is always optimal, which means to you and me that the Ampglow ASI071MC-Cool shows connected to USB2.0 port is eliminated and my tests confirm that. According to the specification cooling is supposed to cool down the sensor to 35 - 40 degrees Centigrade below ambient. However my copy can only do -35. I kind of missed the 45 degrees of ASI1600, but comparing the dark current of the two cameras proved that there is no reason to worry about the higher sensor temperature of the ASI071MC Pro. Another mechanical feature of this camera I find valuable is the built in tilter. This will allow you to keep your sensor parallel to the focal plane at no additional cost. Some of the features include: • Sony IMX071 APS-C(1.8″) CMOS sensor • Regulated Two-stage TecCooling 35-40 degree below ambient temperature • Read noise is 2.3e @24db gain 3.3e @lowest gain • 14bit ADC • Electronic Shutter • USB3.0 Port (backwards

compatible with USB2.0) and built in 2 port USB2.0 hub • Frame rate of 10fps@4944X3284 • 256MB DDR3 internal buffer for images • Controllable Anti-Dew protect window heater • Built in tilt adapter • Supported platforms: Windows / Mac OS / Linux Pros • Very little noise • 256mb DDR3 memory buffer (allows slower computer and single board PC use) Cons • Cooling doesn’t work as well as ASI1600, doesn’t hold the temperature • Camera is heavier than previous models • Larger diameter housing

CONCLUSION The camera is a large advancement from earlier models and the low noise makes this camera a great performer.

Unprocessed Image taken with ZWO 071 MC PRO on a Stellarvue 80 by Dennis Bartkowiak

Telvue NP101 refractor at f/5.4 and a ZWO 071 Pro OSC camera. Exposures were 34 x 300s. Imaged by Mike Israel Practical Astrophotography 41

Recommended Reads: The 100 Best Astrophotography Targets