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Any tips please

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Hi this is the first image ive taken of M13. Any tips on improving this with the kit i have please.

I don't know how to reduce or remove the grainy noise, i just end up loosing stars in Photoshop.

Nexstar 6SE alt/az
F6.3 reducer
10x 3 seconds light
5 x 3 seconds dark
Canon 450D ISO 800
Deep sky stacker



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Much more data. You will be limited in sub length because of the alt-az. But you still want an integrated time of 60 minutes plus. You would also need more dark subs. That would dramatically reduced the noise.

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Yup, more subs. Lots and lots more. Personally I'd be surprised if darks did much good. I'd be inclined to use a master bias made from 50 or more indivdual bias. Dither will occur naturally via the alt az. Check focus very regularly.

In Ps I would use the colour select tool to pick up the background sky but not the stars. With this selected there are various things you can do, the most obvious being to reduce colour saturation. You could also try noise reduction with a heavy dose of 'reduce colour noise.' Never  run processes like noise reduction, colour saturation or  sharpening on the whole image. Different parts of the image need entirely contradictory processing. This is a key insight into post processing.


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My thinking behind the more darks comment was that 5 is not enough if you are using them. But I will not (dare!) argue with Olly's assessment.

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All of the above, but also ISO800 is above the limit I would be comfortable with on an old Canon. My 400s are instantly noisy at this ISO especially with a dark plain background.

Try going down to ISO400 and below if possible.

Oh, you don't say, but shoot RAW, and you will have a much better chance of dealing with noise in PP before converting to TIF or JPEG.

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