Am I barking up the wrong tree here?

[Andrew-77]

Forgive another noob, cluttering up the forum but I need a spot of advice.

I took 152, 8 second subs of Andromeda the other week (ISO 800) with a view to having a stab at producing something with DSS and Photoshop. Once the subs are aligned and stacked though, there is so much 'mid-tone' that it's drowning everything out. Now, I know that I'm not going to achieve a great deal with 20mins total exposure using an unguided 200p, but I thought I might be able to draw out some detail, however grainy.

Here's one of the subs.

And here's the eventual stack.

I can tease out a little detail using curves and level in P'shop, but the grey mush makes anything else impossible (for me, right now). All I can think to do is perhaps use a lower ISO, and gather more subs.

I suppose my question is am I on the right track, but with rotten data, or am I missing something more fundamental?

Any advice gratefully received.

Andy

[Earl]

It would be worth looking at 30 seconds as a minimum exposure time, nailing Polar alignment is job number one.

[Ewan]

Hi Andrew, thats still a good shot Andrew, you can see see dust lanes, nice dark band too.

Light Pollution filter maybe ? judging by the orangy pinky glow, I have the same camera as you, i have had good results using iso 1600 but turn 'in camera noise reduction' off as it just lengthens imaging time (i expect you know that anyway).

I am looking at doing the same DSO tonight but with the moon out i dont think ill get much but i want to practice on my aligning anyway.

PS Earl we gotta stop meeting like this :-)

[Steve Ward]

Have a play with the adjustments in DSS , there's a lot that can be done before you need to go photoshoppin'

[Ant]

There is a certain length of exposure that is too short - regardless of how many you get.

I would agree with Earl that 20 - 30 second exposures are the minimum really... But with full moon M31 is going to be hard. To be honest M31 is a hard target at the best of time.

I've had a little play with your image - the tif would get better results. But there it's not a bad amount of data for 8 second subs...

Ant

[steppenwolf]

Hi Andy, you're certainly not barking up the wrong tree. Your exposure lengths are extremely short and I agree with the other comments that you should be trying for longer. However, the 'grey mush' can be attacked in post processing. The following quick 'n dirty work on your images shows that there is some good detail in there. I removed the light pollution by aligning the intensity of the red, green and blue by adjusting them in PhotoShop to match. I then used several iterations of curves to tease out some more detail.

[Andrew-77]

Awesome, thanks chaps.

I'd managed similar results with the software, perhaps not quite as good. At least I know I'm on the right track.

Practice and perseverance, I think.

[ollypenrice]

Have a play with the adjustments in DSS , there's a lot that can be done before you need to go photoshoppin'

I disagree here. I wouldn't make any changes in DSS if you have Ps. What Steve did is nicely explained on Rob's website. http://www.middlehil... and curves.htm

This Levels and Curves routine lies at the very heart of image processing. As you advance you may learn to use different 'stretches' for different parts of the image and use Layers to blend them.

You are not barking and you are in very much the right tree!!!

Olly