Stacking Images of Mars Retrograde

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hricci
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Joined: Fri May 27, 2016 10:12 am

Stacking Images of Mars Retrograde

Unread post by hricci »

Hi,
I am a new member and have been trying to capture the last turn of the Mars retrograde motion. I have been taking shots and stacking in layers in Photoshop Elements and manually aligning the stars (see image). It is difficult to do and I have been trying to find some way to automatically align the stars. Have tried Registax and Deep Sky Stacker with strange results. Does anyone know of an easy, accurate and automated method of aligning the stars?

Thanks,

Hank Ricci, Falmouth
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marsresize.jpg
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Apollo XX
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Re: Stacking Images of Mars Retrograde

Unread post by Apollo XX »

Hi Hank,

Cool project! I hope you're able to successfully trace the path of Mars. That would be a very interesting image in the end.

I'm not sure, but I suspect your problem has to do with the framing of the images and the repeatability of it. In order for the stacking programs to work the star field has to be reasonably close from frame to frame. One thing I've done in the past is I've tried rotating and cropping the frames using bright stars as reference points to get the star fields as close as possible to each other. I've had mixed results.

There are people on here who are more qualified to talk about this. I know Andy, Ron and Steve are all veterans of multiple night imaging of the same area of sky, which involves getting the scope and camera aimed at the exact same point in the sky over however many nights (or years sometimes) it takes to get the imaging done. They're making heavy use of software to accomplish it, but before plate solving programs and camera rotators is was done manually and I'm sure they can explain it.
"The purpose of life is the investigation of the Sun, the Moon, and the heavens." - Anaxagoras
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rjbokleman
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Re: Stacking Images of Mars Retrograde

Unread post by rjbokleman »

Hank,

Welcome!

There are several tools in the market for stacking and everyone has their own preferences mostly derived from either success or failure with a particular toolset.

I found DSS to be frustrating. However, others love it. Stacking manually with things like Photoshop are do-able, but as you've discovered very, very tedious and time consuming.

You might want to take a look at a trial version of Nebulosity for either Windows or OS X. There's a Batch tool called Align and Combine Images that can be used to make this easier.

I'm assuming these were DSLR images?

There is one of the best tutorials I've ever seen for Nebulosity here on YouTube: https://www.youtube.com/watch?v=OMhLYg-xPuc

Ignore all the chatter in this video about Bias, Darks, Flats (for now) and just watch the section where stacking occurs and see if you can get your frames aligned.
Ron B.
T5i/700D, ASI1600MM-C, ASI120MM, ASI174MM, XAGYL 7x36mm FW
Astronomik Deep-Sky(RGB), CLS, Ha, OIII, SII
SV60EDS 60mm f/5.5 APO
AT65EDQ 65mm f/6.5 ED Quadruplet
SW ProED 100mm f/9.0 Doublet APO
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AVX, iEQ45 Pro

http://www.astrobin.com/users/rjbokleman/
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rjbokleman
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Re: Stacking Images of Mars Retrograde

Unread post by rjbokleman »

Funny, I was posting at the same time Mike was and read his reply afterward. :lol:

Keeping your camera pointed in the same spot, with the same angle, and focal length certainly can affect the final outcome as Mike mentions.

You should be able to align the images non-the-less on the stars provided that the focal length didn't change. So if you were using a fixed 50mm or 135mm lens, then that shouldn't be an issue for you. If you are using a zoom that can be problematic getting it back to the correct setting.

The edges of the final image when stacked might not be perfectly square or overlapped, but that's ok that happens to the best of us over multiple nights as well since it's nearly impossible to get the camera/scope in the EXACT position it was in the night before.

Getting to within <50 pixels is probably close enough in this situation. You want to be close enough though that you can simple crop off the outmost edge to clean things up once their stacked.

Let us know how you make out!
Ron B.
T5i/700D, ASI1600MM-C, ASI120MM, ASI174MM, XAGYL 7x36mm FW
Astronomik Deep-Sky(RGB), CLS, Ha, OIII, SII
SV60EDS 60mm f/5.5 APO
AT65EDQ 65mm f/6.5 ED Quadruplet
SW ProED 100mm f/9.0 Doublet APO
C8 EdgeHD, AT130EDT
AVX, iEQ45 Pro

http://www.astrobin.com/users/rjbokleman/
hricci
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Re: Stacking Images of Mars Retrograde

Unread post by hricci »

Thank you Mike and Ron,
Very informative posts. I should have mentioned that I'm doing this with a Pentax K-X DSLR with 50mm fixed fl lens piggybacked on an Alt-Az GOTO scope centered on Mars. Will try to take some shots that are more closely framed. Watched the Nebulosity video and downloaded the trial of version 4. Will report back on results.

Thanks Again,

Hank
Henry R.
hricci
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Re: Stacking Images of Mars Retrograde

Unread post by hricci »

Nebulosity is THE solution for aligning stars. Thanks so much for the help.

Hank
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stack 1-- 4 Mars files croppedresize.jpg
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Henry R.
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AndyG
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Re: Stacking Images of Mars Retrograde

Unread post by AndyG »

Hi Hank, Welcome to the club!
I'm glad to see you got the results you were looking for with Nebulosity. It's very cool seeing the retrograde motion stacked like that.
Andy
Bruce D
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Re: Stacking Images of Mars Retrograde

Unread post by Bruce D »

Nice work Hank! Thanks for posting your image
Bruce D
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rjbokleman
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Re: Stacking Images of Mars Retrograde

Unread post by rjbokleman »

Hank,

Congrats! Glad Nebulosity worked out for you.

As Bill L. mentioned field rotation can also be an issue with Alt-Az mounts over longer periods of imaging time. In this particular case, probably not an issue, but if it does happen you'll see a 'spin' affect in the image (like a Star trails image) where things just don't line up right. Nebulosity has the ability to handle this issue as well. Instead of selecting a single star for alignment you can select two. Preferably one toward the center and the other at the edge of the image and the alignment process will compensate.

I used Nebulosity for many months while I was coming up to speed on DSLR processing. Found it a great way to get some good results while learning the in's and out's.
Ron B.
T5i/700D, ASI1600MM-C, ASI120MM, ASI174MM, XAGYL 7x36mm FW
Astronomik Deep-Sky(RGB), CLS, Ha, OIII, SII
SV60EDS 60mm f/5.5 APO
AT65EDQ 65mm f/6.5 ED Quadruplet
SW ProED 100mm f/9.0 Doublet APO
C8 EdgeHD, AT130EDT
AVX, iEQ45 Pro

http://www.astrobin.com/users/rjbokleman/
hricci
Posts: 30
Joined: Fri May 27, 2016 10:12 am

Re: Stacking Images of Mars Retrograde

Unread post by hricci »

Just want to thank everyone for their help and encouragement. This Board is a great asset with all the knowledge, enthusiasm and willingness to share.

Hank
Henry R.
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