Why so much noise in my pictures???

[Owzat]

Hello all. 
I need help with my imaging. The photo of the whirlpool galaxy is 30,90s iso 800 subs. 50 darks at the same iso, same temp and same exposure, 50 bias and 50 flats. Why am I getting so much noise? All the pictures I take are the same. Excuse the two finger marked on bodes galaxy didn’t realize I had touched my scope until after my imaging session. Bodes photo was 40, 60s 800 iso subs, same flats,darks,bias. 
can anyone help?

[knobby]

What camera ? I'm guessing a DSLR as you say ISO 800. Maybe try dithering or look at which ISO is optimum for your camera.

[Tommohawk]

They both look really good apart from the noise - I just checked my best effort with a DSLR and I was using 8 minute subs, so probably you need more and/or longer subs.

Wondering what scope youre using, and what camera? 

[Owzat]

Thanks for the reply. 
I’m using a un modded cannon 700d dslr with my Celestron advance gt  8” schmidt cassegrain scope. Camara control using AstroDSLR, Stacking with Siril and editing on gimp. Only last night I ordered the ZWO ASI 120MM Mini USB 2.0 Mono Camera so that I can start guiding and hopefully take longer exposures, I will be using Astroguiding that are software only for Mac but great to use. I’m not sure if it is dithering because the noise is not really lines but stationary noise. I don’t know that’s why I’m here. Thanks again for your comments

[Phillyo]

What stacking software and algorithm are you using to combine the subs together?

[SteveNickolls]

Local light pollution level, atmospheric conditions and the waxing Moon phase won't help. Last night if you are in the UK we had the Jet Stream over part of the country. All will help degrade your image.

Cheers,

Steve

[Gerr]

Hi Owzat,

Welcome to astrophotography!!! So many things effect this hobby as we all continue to learn.

Main things are signal to noise ratio - more subs will improve this.  Cooled cameras seem to have very little inherent noise.

Use of flats, bias and dark frames (or dither after each exposure).

Perfect focusing and PHD guiding for longer subs (Bahtinov mask and guide camera).

Use filters to reduce light pollution (or image in Bortle 2/3 skies).

Image on moonless nights and when your object is close to the zenith (less atmospheric effect).

Become an expert in astroprocessing techniques where you can learn about 'background extraction' and further noise reduction and image sharpening processes.

Optimise your equipment for the DSO you want to image. 

Know your equipment limits or buy more expensive stuff (can help).

This hobby can be very expensive, frustrating and so dependent on the weather. But when it comes together you'll be amazed by what you can achieve!!

Good Luck,

Gerr

 

M42 and Running Man Nebula

 

 

 

 

 

 

 

[Tommohawk]

5 hours ago, Owzat said:

Thanks for the reply. 
I’m using a un modded cannon 700d dslr with my Celestron advance gt  8” schmidt cassegrain scope. Camara control using AstroDSLR, Stacking with Siril and editing on gimp. Only last night I ordered the ZWO ASI 120MM Mini USB 2.0 Mono Camera so that I can start guiding and hopefully take longer exposures, I will be using Astroguiding that are software only for Mac but great to use. I’m not sure if it is dithering because the noise is not really lines but stationary noise. I don’t know that’s why I’m here. Thanks again for your comments

Well you're off to a good start - TBH I'm amazed you got such a nice result with just 90s subs. The SCT is a great scope but its F10 or F6 ish with reducer so you will need longer subs to get a nice result. Once you get guiding sorted you should be good for longer subs, though guiding at F10 can be challenging.

[Owzat]

4 hours ago, Tommohawk said:

Well you're off to a good start - TBH I'm amazed you got such a nice result with just 90s subs. The SCT is a great scope but its F10 or F6 ish with reducer so you will need longer subs to get a nice result. Once you get guiding sorted you should be good for longer subs, though guiding at F10 can be challenging.

Why is guiding with a f10( I haven’t got a reducer) difficult? I wouldn’t  be putting the guide cam into that it will be in my 6x30 finder scope. 

[Owzat]

Thanks for all the great reply’s.  all the info I get from people is so helpful and appreciate it so much!

[Owzat]

11 hours ago, Phillyo said:

What stacking software and algorithm are you using to combine the subs together?

I’m using siril for stacking and gimp for editing the stacked image.  I have a Mac so Mac software is useful and easier than messing about trying to use windows programs. I’m using cloudmakers software for my camara and guiding settings

[Tommohawk]

47 minutes ago, Owzat said:

Why is guiding with a f10( I haven’t got a reducer) difficult? I wouldn’t  be putting the guide cam into that it will be in my 6x30 finder scope. 

It's only that guiding is much more challenging with longer focal lengths. Your imaging scope has a 2000mm focal length, and so will be very sensitive to small deviations. You definitely want to guide for longer subs, I'm just pointing out that learning to guide is tougher with that imaging scale. But do go for it! 

[Budgie1]

You could also try stacking again, only this time leave out the darks and only stack the lights, flats & bias.

Sometimes the darks can increase the noise on an image with DSLRs, rather then help reduce it, so it maybe worth a try to see if it changes anything on yours.

[Gerr]

With regards to guiding it is not the guiding scope that takes your image but your f10 scope with that long focal length and the camera attached to it. Small adjustments made by your guiding system can translate to large deviations in your imaging scope which will reduce the image accuracy.  The longer the focal length the more risk of potential error. This makes long exposure subs a challenge and your guiding will need to be spot on.

Gerr.