My first attempt with a modified DSLR - North American Nebula

[osbourne one-nil]

Here are a couple of shots taken last night with my modified Canon 1100D.

I'm quite pleased with them. I think I must have aligned my Astrotrac pretty perfectly as the shots were a 3min exposure at 50mm and 2min at 200mm focal length respectively - not too shabby in terms of tracking. 

I've read lots about taking multiple images and stacking them but what would I have gained if I'd done that? Would it have been marginal?

Also, any processing tips gratefully received as I simply opened the images in Photoshop, adjusted the levels to remove any blank stuff either end (I know what I mean) and that was pretty much it. The unprocessed images are below. 

[PeterCPC]

There would be a huge gain by taking multiple images and stacking them. You have only 3 min exposure but faint objects like this really need WAY more exposure and you get that by taking many exposures. Great start though.

Peter

[michael.h.f.wilkinson]

Very good start. As said, stacking multiple images in Deep Sky Stacker (freeware) or the like improves matters a lot

[MarsG76]

That's not bad for single shots.. stack them, and move the frames a few pixels either way at random a little between exposures to dither your subs...  when you stack them you will reveal more nebulosity.

[osbourne one-nil]

Sorted - I'll try again tonight (hopefully). Hadn't heard of moving the frames by a pixel or two but that makes sense to me. Would lots of three minute shots be better than twice as many 90 second shots or should I combine different exposure lengths?

I just hope I can align as well as I did last night because as much as I like the Astrotrac its alignment scope is a sod!

[Knight of Clear Skies]

Those are excellent for single exposures, well processed too. Here's the difference that stacking can make on the NA & Pelican, a 40 minute image I also took the other night with a 200mm lens:

The exposure details are in this thread if you are interested. Stacking improves the signal to noise ratio making it possible to bring out much fainter detail. The NA is very bright so it's possible to get a decent image very quickly, but stacking will bring a huge number of targets into range.

[wxsatuser]

Stacking improves the SNR and allows better processing.

SNR increases by the square root of the number of exposures.

If you do 4 subs your SNR increases by 2.......9  subs SNR increases by 3......16 increases by 4 etc etc.

[osbourne one-nil]

Thank you.

A 40 min exposure?! Was it guided? That's amazing and good to see what you can do with the same camera as me. 

I have been offered a chance to have a bit of pasture out of the village where I could build an observatory - I'm drooling. Last night's photo was taken in my garden which is surrounded by trees, in the middle of the best lit tiny village in Cumbria and adjacent to a beck and its population of 18 trillion midges. If I went ahead, I could take my time very nicely!

[osbourne one-nil]

Stacking improves the SNR and allows better processing.

SNR increases by the square root of the number of exposures.

If you do 4 subs your SNR increases by 2.......9  subs SNR increases by 3......16 increases by 4 etc etc.

Ah! I had read about the SNR before but couldn't get my head round it until now. 

I've also got a Canon 6D but it's not modified so I guess that wouldn't give me any advantage over the modified 1100D?

[Knight of Clear Skies]

A 40 min exposure?! Was it guided? That's amazing and good to see what you can do with the same camera as me. 

That's 40 minutes in total, I took 75 second subs, unguided. There are a few more details in the thread I linked to.

Looking at your single exposures it looks like you're in a great location for imaging, I'm not seeing a gradient or any orange in the 50mm shot.

[geordie85]

It's not a 40 minute single exposure. It's many shorter exposures that equal to 40 minutes when stacked

[osbourne one-nil]

Cheers - I did think that was well nigh impossible. I'll take a good look at the link over lunch.

[symesie04]

Sorted - I'll try again tonight (hopefully). Hadn't heard of moving the frames by a pixel or two but that makes sense to me. Would lots of three minute shots be better than twice as many 90 second shots or should I combine different exposure lengths?

I just hope I can align as well as I did last night because as much as I like the Astrotrac its alignment scope is a sod!

Have to agree. The Astrotrac is a great tool in itself however the Polor scope is rather disappointing i have to say. Just out of interested have you collimated the scope. Although to be fair you have round stars with 2min subs at 200mm so thats a great start.

[wxsatuser]

Ah! I had read about the SNR before but couldn't get my head round it until now. 

I've also got a Canon 6D but it's not modified so I guess that wouldn't give me any advantage over the modified 1100D?

The 6D is vry good low light/noise with biggish pixels and a nice QE.

If you have low light polution it should give good results, worth a try even unmodded.

[osbourne one-nil]

Just out of interested have you collimated the scope. Although to be fair you have round stars with 2min subs at 200mm so thats a great start.

No, and it's dropped every 5 mins or so! I think I must just be lucky. 

The 6D is vry good low light/noise with biggish pixels and a nice QE.

If you have low light polution it should give good results, worth a try even unmodded.

I'll try that too - perhaps on something like the Andromeda Galaxy where I'm not trying to get anything too nebulous.