First attempt using a mount, M42

I picked up a tracking mount this weekend and had a go at M42 I have very little experience stacking with DSS & using curves in Photoshop so I'm sure the final result could be better. But for a first attempt I am very happy with the result.

Final image is a stack of about 32ish light frames 30 dark frames and 20 bias. All 30 seconds shot with a 100-400 @ 400mm f8

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Why f/8 instead of f/5.6 with that lens?
Unlike daylight photography where aperture has a significant effect on the DOF, you want that aperture opened up for night sky DSO astrophotography. You're not going to notice the DOF or Bokeh imaging DSO's It will make things easier on you. Additionally, using a larger aperture will help reduce those diffraction spikes caused by the shutter blades.

What ISO?

Your histogram is only showing a mean value of 11.73 and a median value of 8. Your median value should be closer to 25 or 30 for each channel. You don't have "Image Editing OK" so I won't re-post your image. But just a minor tweak and I revealed much more nebulosity. However, there isn't much I can do with it already saved as a jpeg to correct for the clipped image data.
I can however tell there is some good image data there. If you had used a larger aperture setting with ISO 800 you would have even more image data revealing even more faint nebulosity. Which there is a lot of in that area.

When you make adjustments with Curves and/or levels you want a little room between the far left and the beginning of the histogram graph. If you slam that all the way to the left and start cutting into the graph you're clipping/cutting away and destroying image data. Data that is most of your faint detail.

awesome. which mount did you get

I used f5.6 and 8 throughout the night (I was fiddling with several settings and focus). The series shot at f8 seemed the best so those are the ones that got used.

ISO was 1600, highest my XS can do.

Turned on Image Editing. I'm not too familiar with the photoshop histogram but will look up the settings you mentioned and see if I can improve things.

04yellowf150 wrote in post #11566827
awesome. which mount did you get

Picked up a CGEM used locally. It's embarrassing because I really don't know how to work it yet :P Still learning. Going to try and polar align tonight weather permitting.

Great first attempt! I'd agree with tkerr, give it another whack and see how much detail you can pull out of it, because there is definitely a lot more there.

Good job. Suggest you work on polar alignment. Learn drift alignment method. Also suggest you read "Astrophotography for Amateurs" by Michael Covington.

BKATX wrote in post #11566853
I used f5.6 and 8 throughout the night (I was fiddling with several settings and focus). The series shot at f8 seemed the best so those are the ones that got used.

ISO was 1600, highest my XS can do.

Turned on Image Editing. I'm not too familiar with the photoshop histogram but will look up the settings you mentioned and see if I can improve things.

ISO 1600 may have been producing too much noise, Both from the High ISO as well as any sky glow in the area, and is probably why it looked better using a smaller aperture. Try reducing the ISO to 800, open that aperture up to f/5.6 and bump up your exposure to 45 or 60 seconds and see what your results are. You should even get good 90s exposures at ISO 800 f/5.6. However, that also depends on whether or not you have good polar alignment and are guiding as well.
You would get more light grasp if you use f/5.6 which would equate to more of that fainter detail. More light grasp does not equate to increasing the effects of any light pollution/sky glow.
Either way more exposures will increase your SNR helping overcome that high ISO Noise as well as pretty much of that sky glow noise. If your individual exposure look close to but not quite washed out and noisy don't worry about it. If you can get a lot of them the SNR will increase overcoming it. The appearance of them will change once stacked.


See if this will help with your post processing.
http://www.astropix.co​m/HTML/J_DIGIT/DIGTECH​S.HTM

I tried to pull some more detail out of the image. Was running into banding problems and had to stop. Still trying to get a handle on the histogram as well as setting the black point. I think there could be some more color in the image as well.

Second attempt:

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Very nice first attempt!

BKATX wrote in post #11569622
I tried to pull some more detail out of the image. Was running into banding problems and had to stop. Still trying to get a handle on the histogram as well as setting the black point. I think there could be some more color in the image as well.

Second attempt:

Looks like you brightened it up some in this one, and it does look good.
But please allow me to tell you this: There is nothing black about the space in and around the Orion Constellation, and especially in that area.

From what I can see just by looking at the Orion and Running man in this image, I can see that you have got some good image data in your original Un-Edited Stack. If you got that much in those two areas you also got much more throughout the entire image.

Looking at the blackness in your image, and looking at the histogram tells me that all that black is void of data. Any image data that was there is now gone.
You Got Image Editing Ok now, but there isn't really anything anyone can do when the image data is no longer there to work with.

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I have to say that this is much better than my first attempt!

foxtrot01 wrote in post #11579911
I have to say that this is much better than my first attempt!

Definitely better than mine too back when I was shooting with film. It is much better than a lot of first attempts I have seen.

I think he's captures some very nice image data there, but then that's not all there is to astroimaging, and the area that gets most of us is the PP.

Thanks all. It seem processing is "where the magic happens" with astrophography. I'm having to learn a completely different set of photoshop skills compared to the my other work (wildlife and macro).

I attempted M42 again, this time using Tim's advice. 60 sec subs, turned the ISO down to 800 and set the lens wide open. The results were disappointing and worse than my first attempt. There was a giant "hot spot" around the nebula (a big unnatural bright area). I was not happy with the final image.

I'm not sure if something went wrong with the stack (don't think so, I restacked several times). Maybe the weather was just bad (we had some clouds move in for a while). Orion was setting, so there was probably more light pollution. Or maybe 60 seconds was too long of an exposure.

I was getting tired and frustrated with photoshop and had to quit (had a business trip the next day) Here is what I ended up with. I'm sure I clipped the black again, will have another go at again when I get back home tomorrow evening.

Thanks again for all the help.

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BKATX wrote in post #11585767
Thanks all. It seem processing is "where the magic happens" with astrophography. I'm having to learn a completely different set of photoshop skills compared to the my other work (wildlife and macro).

I attempted M42 again, this time using Tim's advice. 60 sec subs, turned the ISO down to 800 and set the lens wide open. The results were disappointing and worse than my first attempt. There was a giant "hot spot" around the nebula (a big unnatural bright area). I was not happy with the final image.

I'm not sure if something went wrong with the stack (don't think so, I restacked several times). Maybe the weather was just bad (we had some clouds move in for a while). Orion was setting, so there was probably more light pollution. Or maybe 60 seconds was too long of an exposure.

If you can get good exposures, and lots of them, using a higher ISO then by all means go for it. ISO 800 is what I found to be the optimal ISO for astrophotography with my DSLR's under my sky conditions, i.e sky-glow. Most people that I know of have similar results while others can use higher and some have to use lower.

Uneven field illumination (Hot spot (vignetting)) is quite common and is just one reason why we need to use flat frames. Less noticeable with short exposures, but then your not getting as much image data when you shoot shorter exposures than you can.

The weather will have significant effect/impact on your results. E.g. "Astronomical seeing" !

60 seconds isn't too long under good circumstances. However, looking at your latest results you are showing more Declination drift than in your previous results. This tells me your tracking isn't good and that you need to work on that polar alignment more, and use guiding if you want to use longer exposure times.
Polar alignment will help extend your exposures. Unfortunately that's often not enough and we have to use some method of guiding, either manually with a guide-scope and reticle eyepiece, and you watch for and make corrections as soon as you see any drift, or autoguiding which makes life much easier.

Astrophotography is much more complicated than regular general photography and people soon find they are in deeper waters than they expected. There is so much more involved with it that you don't even have to consider otherwise. And then there is the huge difference in post processing. It's not as simple as a little brightness and contrast adjustment or color correction.
There are all kinds of great tutorials throughout the web, you just have to find the ones that work best for you.