DSStacker help

[jasperuk]

Would it be correct to say that 10 x 2 minutes exposures of the sky will give to more detail in the intended DSO than 20 x 1 minute exposures of the same area ?????

What would be the advantage if any (Assuming EQ3-2 that was tracking perfectly for arguments sake) of doing shorter exposures over the longer exposures ?????

If i have 30x30 second exp M42 all the same no filters or anything what exactly is DSS going to do to improve the image, logically putting one on top of the other you would presume would do nothing, do i not need to put together colour filtered images of different exposure lengths to get the best pictures ????

[roundycat]

Only sometimes! Exposure depth is reliant on several factors; Time, f-ratio, sky background, read noise etc. Not to mention filter factors and spectral sensitivity of the camera so I won't.

In general longer exposures are better but in astrophotography you cannot generalise, there are too many variables.

To avoid the pitfalls and agony of contrast stretching you should give each target about 100 hours exposure. That way a fully 'developed' image will come out of the stack. We only stretch the image because everything is grossly under exposed.

There is an advantage to doing shorter exposures if by shorter you mean 5-10 minutes rather than 20-30 minutes. You have more frames in the stack so an outlier rejection algorithm will have a better chance of getting rid of the sat trails, cosmic rays, aircraft nav lights and so on.

I would let the non-linear region of your camera be the final arbiter on exposure.

Any stacking software is taking advantage of two things. The noise in each frame is random so tends to cancel out. The signal in each frame is the same so tends to re-inforce. There are different ways of doing this particular job, some better than others. I'm not allowed to comment on DSS here but in theory it should stack images the same as any other software.

Dennis