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02-28-2019, 12:42 PM - 1 Like   #1
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First Astro Attempts

So I took the plunge and decided to attempt to photograph the Pleiades star cluster with my K3. I took 30 unguided 4 second shots with my 55-300 and then used sequator to stack them and Photoshop CC with Annies tools to process the stacked image. The result is shown below, any useful comments and tips would be very welcome.

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02-28-2019, 03:27 PM   #2
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Wow! Good work!
02-28-2019, 05:00 PM   #3
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Great shot.

Readers might find some interest in your exposure info (f-stop, ISO, and aperture) if you kept it. Also what focal length did you use and did you use any cropping?

Your stacking is spot on! Many other good subjects ahead.

Last edited by Bob 256; 02-28-2019 at 05:06 PM.
02-28-2019, 05:27 PM - 1 Like   #4
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Out of total curiosity I wondered if a plate solver would have success. It did.... took like 30 seconds.

* Astrometry.net




02-28-2019, 11:01 PM   #5
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QuoteOriginally posted by interested_observer Quote
Out of total curiosity I wondered if a plate solver would have success. It did.... took like 30 seconds.

* Astrometry.net


Thanks for this. How do I use a plate solver?
02-28-2019, 11:01 PM   #6
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QuoteOriginally posted by MarkJerling Quote
Wow! Good work!
Thank you Mark

---------- Post added 02-28-19 at 11:09 PM ----------

QuoteOriginally posted by Bob 256 Quote
Great shot.

Readers might find some interest in your exposure info (f-stop, ISO, and aperture) if you kept it. Also what focal length did you use and did you use any cropping?

Your stacking is spot on! Many other good subjects ahead.
Hi Bob. I used an ISO of 2000 and had the aperture wide open. I also forgot to mention that I used a 2x converter on the lens and cropped after stacking to remove some vignetting and stacking artifacts.
03-01-2019, 12:32 AM - 2 Likes   #7
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QuoteOriginally posted by dworme Quote
Thanks for this. How do I use a plate solver?
Using the Plate Solver at Astrometry.net is easy. Just upload your jpg image to it and it does the rest. You can use the url to the image (web image), or upload an image from your own system, and it just takes it from there....
03-01-2019, 06:23 AM   #8
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So, first off, congrats on getting started with astrophotography. It's not easy, and there's a steep learning curve.

Next time you go out, spend more time driving to darker skies if possible.


Perhaps you could post a single original, unprocessed image so we can see what you did.
When you try again, a few suggestions:
- if you can, zoom in more, to make the Pleaides fill more of the field. They're tiny, so maybe this is the limit of what you can do with your lens/camera.

- change the white balance - eg Use "Sun" white balance, or adjust for a G2V star (yellowish star like our sun).

- The magenta-pinkness suggests incorrect colour processing or AWB in use.
- there seem to be some serious vignetting or challenges stacking - the background should be the same brightness across the field. Either crop the edges or do some flat fielding.
- ditch the teleconverter, it may be contributing to the vignetting and lack of sharpness.
- make sure the lens wasn't dewing over and no high cirrus clouds - it could explain some of the issues.


I hope you didn't spend more time stacking than you did getting the original images.;-)
Anyway, a good first effort - keep going, the more you do, the better the results.

03-01-2019, 11:18 AM   #9
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Stacking and focus look pretty good.

Magenta background means you pushed the image too much. You're brightening the noise and it dominates your image. Things to try in Photoshop include reducing the black slider, reducing the shadow slider, and/or playing with the contrast curve. There are many different ways to approach it.

Maybe a setting in Sequator or Annie's Tools led to the overprocessing. I dabbled in the former and never used the latter, so can't offer more specific advice on those.


QuoteOriginally posted by dworme:
... 30 unguided 4 second shots ... aperture wide open. I also forgot to mention that I used a 2x converter ...
I suggest not using the teleconverter because it eats a lot of light. You need 4 times as much exposure time because it's a square function. I assume you were at the 300mm end of the 55-300 (or else you wouldn't have needed the convertor). That lens is f/5.8 wide open and the convertor makes it effectively f/11.8.
03-01-2019, 12:40 PM - 1 Like   #10
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I would suggest forgetting about the 2x converter and instead use the zoom of the lens. I would assume that you were shooting at 55mm or some where around there given how small the Pleiades is in the frame. ISO 2000 seems awfully high for something that bright with that length of exposure. I use to shoot object like this without tracking at f/4 - f/5.6, .6s or 1s depending on the lens, and ISO3200 or ISO 1600. Even then I would have a stack of 200-300 high ISO images to work with to drive down the noise. I'm not sure if the blown highlights are from editing or because they were over exposed so seeing an unedited image would help. I would see if stacking in something else would work better. Deep Sky Stacker (DSS) has lots of knobs and isn't super beginner friendly but may provide better results. A piece of advise when stacking in DSS is to use median-kappa-sigma stacking with a sigma of three and 5 iterations instead of using just the regular average method. Of all the stacking options in DSS the default average method produces the worst results and I have found that piece of advice I got from Pete_XL to have worked wonders. I have stacked deep sky objects in sequator before and never like the results which is why I suggest trying something else. Never bother doing any image editing in DSS as it is really only good for stacking.

The magenta may likely be just a levels issue. To correct it in photoshop go to adjust levels and select the eyedropper to set the grey level and click around some to see if you can remove the cast. Don't click on the Pleiades or the area around them as they are actually blue.

Also to help get you pointed in the right direction here is a beginners guide I pounded out a while ago to help get people off and running while avoiding a bunch of beginner mistakes. It isn't comprehensive and there is lots more to learn but it should help you get out and get better results than I and others had gotten when first starting.
03-02-2019, 12:49 AM   #11
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Some great advice, thanks everyone for taking the time to help me learn.
03-02-2019, 03:17 PM - 1 Like   #12
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QuoteOriginally posted by MossyRocks Quote
A piece of advise when stacking in DSS is to use median-kappa-sigma stacking with a sigma of three and 5 iterations instead of using just the regular average method. Of all the stacking options in DSS the default average method produces the worst results and I have found that piece of advice I got from Pete_XL to have worked wonders
I just wanted to say thanks for this heads up. I've tried DSS a few times and never got a good result. I'll try it again with your settings
03-04-2019, 06:16 PM - 2 Likes   #13
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I finally remembered when I got home to provide a link to some astro image processing tutorials. I got these from Pete_XL when I first was starting. Basically keep in mind that you want to do small changes many times, and adjustment layers are your friend.
A bunch of intro astro processing video tutorials they are quiet some times.
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