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04-02-2014, 07:10 PM   #1
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Astrophotography Attempt
Lens: F 50 f/1.7 Camera: K-01 full spectrum Photo Location: my balcony in TN ISO: 400 Aperture: F2 

Okay, here's a couple my latest astrophotography attempt taken with my full spectrum converted K-01. The first attachment is a stack of 93 images using Deep Sky Stacker, and the second is one of the images by itself, processed in photoshop. I would think that the stacking would REALLY make the images pop with more detail, but... well. So, anyway, I am posting it in this section for advice. What am I doing wrong? How can I fix it? The shutter speed was 2.5 seconds, so the stacked image should be over 3 minutes worth of exposure. Help me become better! Thanks.

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04-02-2014, 07:30 PM   #2
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OK, I don't know much about optics, but I don't see how stacking could provide more detail. Virtually everything is an infinite distance away, so everything should be within the depth of field for your image. I can see how stacking might give an improvement in dynamic range - but since the stars are all pretty much infinitely bright, that would - I guess - only help for those dim stars or on observation days when the sky is cloudy. Again, not likely to be a big help, IMO.
What am I missing here, please?
Thanks for sharing.
04-02-2014, 09:06 PM   #3
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You are one experiment ahead of me if you are using deep sky stacker which I downloaded but haven't gotten to yet.
You should be able to reproduce my fumbling with the equipment you listed.
https://www.pentaxforums.com/forums/58-pentax-beginners-corner-q/252668-basic...-peasants.html

From the looks of your photos you are doing something wrong with the software or giving it the wrong exposures to stack since even with one exposure I was able to get far more stars to show up. I don't think there is a patch of sky that is truly that empty.
I also have no idea what full spectrum conversions do or why one would need it for astrophotography.
With deep sky stacker the picture I took would be much better because you could get the flame nebula which is just barely visible as a faint red smudge around Orions left most belt star to show up. The Orion nebula (m42?) is very visible in my photo.
You should also consider building a simple barn door tracker since anything longer than the exposures I was taking had visibly elongated stars when zoomed way in.
Also you should be stacking raw images if it allows that, I forget, I really need to look into that software.

EDIT: And to answer jfords question you stack to increase exposure because everything is so faint so you have to build up an image. Its supposed to make all the faint stars and nebula and whatnot show up without using crazy high ISO or several minute exposures and allow much smaller apertures to clarify the incoming light.

Last edited by PPPPPP42; 04-02-2014 at 09:21 PM.
04-03-2014, 10:55 AM   #4
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Here is what I would suggest. Shoot raw and expose to the right (ETTR technique, you can google for tutorials) and then use PP to darken the photo. On the camera, keep the "Slow shutter NR" enabled. And don't be afraid to raise ISO to 1600 or even above.
The other problem is that you seem to be taking photos near your home. There might be light pollution and unclear sky which lowers the contrast of the sky. What you want is to go someplace with as little light as possible. This makes the stars stand out more.

Stacking frames is a great idea, but it is very difficult to do. You would need a tripod which moves along as the Earth rotates. Buying the OGPS accessory might be the cheapest, best option. But! I think it doesn't work with the K-01..

04-03-2014, 07:15 PM   #5
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I think the OGPS unit would be awesome, and I want to find one used for that for my K5. I am not worried about light where I live. It is very dark skies at my place. I will try some of those settings, and the stacked image was stacked in RAW. I really want to get this down.
04-16-2014, 07:27 PM   #6
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QuoteOriginally posted by VoiceOfReason Quote
I think the OGPS unit would be awesome, and I want to find one used for that for my K5. I am not worried about light where I live. It is very dark skies at my place. I will try some of those settings, and the stacked image was stacked in RAW. I really want to get this down.
I have tried getting a used OPGS unit for quite a while but couldn't find any. I have a new one now and really like it.
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