Help needed for a newbie

[lensman57]

Hi,

I captured this on the 8th just as an exercise for guiding, it is a heavy crop of the whole image. I have processed it to the best of my abilty but the background is clipped. The stars are also a funny shape due to bad focusing I guess but I would appreciate any advice or help with thanks.

It was taken on a StarWave Ed80 with 0.8 reducer , Canon 1000d (modded), no filter of anysort. 30 subs out of 39 were used. Exposure was 180 sec at iso 800, the Canon is very noisy. Darks, Flats and Bias frames.

Many thanks and Regards,

A.G

[steppenwolf]

The focus does indeed look out on this image and that will have had a bad effect on the two galaxies as well as the stars, of course. We can sort the focus issue easily enough. When I image with a DSLR camera, I use a Bahtinov mask and this clever piece of software to get my focus right at the start of the imaging session. Simply download this free software and use it at 5x zoom while pointing at a bright star - with a Bahtinov mask in place, achieving accurate focus is a doddle and if the test star is in focus other deep sky objects will also be in focus.

Never aim for a truly inky black background as this is not how you will ever see these objects except under most unusual desert skies! Every bit of clipping at the dark end is valuable data lost.

[lensman57]

The focus does indeed look out on this image and that will have had a bad effect on the two galaxies as well as the stars, of course. We can sort the focus issue easily enough. When I image with a DSLR camera, I use a Bahtinov mask and this clever piece of software to get my focus right at the start of the imaging session. Simply download this free software and use it at 5x zoom while pointing at a bright star - with a Bahtinov mask in place, achieving accurate focus is a doddle and if the test star is in focus other deep sky objects will also be in focus.

Never aim for a truly inky black background as this is not how you will ever see these objects except under most unusual desert skies! Every bit of clipping at the dark end is valuable data lost.

Many Thanks Steve for your help. I am always in a rush to get things done quickly and that is when I mess up. Need to slow down a bit but then again the weather here is not much help. I have APT and I think that I will use the focus aid next time. If I kept the value of the background to about 21~25 I think that would lift it a bit but as for the noise I really am at a loss.

Regards,

A.G

[andyo]

Many Thanks Steve for your help. I am always in a rush to get things done quickly and that is when I mess up. Need to slow down a bit but then again the weather here is not much help. I have APT and I think that I will use the focus aid next time. If I kept the value of the background to about 21~25 I think that would lift it a bit but as for the noise I really am at a loss.

Regards,

A.G

I am not an expert at processing images there are others on here who could give you far better advice than me.I believe the best way to reduce noise is more subs as this will give you a better signal to noise ratio.There are various bits of software out there to help with noise control.Imagenomic do one called noiseware I think the free version is only 8 bit though.However you try to control noise with software,care should be taken not to overdo it.

I think the idea is to get a balance between how much you can stretch the image and extract data before it becomes to noisy,this is why a good signal to noise ratio is important.

[steppenwolf]

Noise is always an issue especially with a DSLR as it doesn't have any sensor cooling. However as Andy says, more subs will certainly help although to be honest, 30 subs = plenty of subs as far as I am concerned!

Again, as Andy has said, Imagenomic Noiseware is pretty good as is NeatImage but be careful how you use these two plugins as they can leave your images looking 'over-processed'. A technique that I use, if I am low on sub-count but need a complete image, is to duplicate my top layer, apply the noise reduction then reduce the opacity of the new smoothed layer until the background noise just starts to re-appear. This tends to give a more realistic yet smoother appearance to the image and as a final touch, use the eraser and a small brush to cut back the transition edges to reveal the more important detail (albeit in a noisy form).