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anyone recommend a good stacker software..

  • 27-08-2020 11:15pm
    #1
    TomSweeney
    Registered Users Posts: 3,192 ✭✭✭


    So I was in a dark sky location , and I was happy with some shots, and tried taking a load of shots of the same scene that I could stack ...


    so first I took shots normally with around 20secs exposure on camera



    50265310422_306f035b3f_z.jpg


    So, I'm thinking great, if I stack a load of images it will look even better if I get the above with just one exposure of 20secs....






    So I stacked a load of images (in same folder) of about 15 seconds each, total exposure time of around 4minutes ....
    Here is an example of one ...
    50276368551_1357431ede_z.jpg







    This is the absolute scutter Deep Sky Stacker live produced :


    50276544572_275d0d1282_z.jpg


    How is this even possible, you would think at worst it would produce something like image #2 ?


Comments

  • #2
    Adyx
    Registered Users Posts: 2,997 ✭✭✭Adyx


    Is it a raw file? And are there calibration frames stacked as well?


  • #3
    TomSweeney
    Registered Users Posts: 3,192 ✭✭✭TomSweeney


    Adyx wrote: »
    Is it a raw file? And are there calibration frames stacked as well?


    They are raw files, hmmm calibration files I only read about after, is that the one you need to include for blacks and brights ?





    I just thought I'd need a load of exposures of the same part of sky ...


  • #4
    Adyx
    Registered Users Posts: 2,997 ✭✭✭Adyx


    TomSweeney wrote: »
    They are raw files, hmmm calibration files I only read about after, is that the one you need to include for blacks and brights ?





    I just thought I'd need a load of exposures of the same part of sky ...

    Yeah darks, flats and bias files. They help reduce the noise built in to the camera as well as dust etc. You'll also need to process the stacked image in Photoshop or GIMP or whatever. It's quite normal for a stacked image to come out looking dark or with very little visble detail but after you stretch it all the detail will be there.

    You only need to do bias frames once and you can reuse the master bias shot for all subsequent imaging.

    Nico from Nebula Photos has great tutorials on this on Youtube. They're quite long but very easy to follow and he explains the process in Photoshop and GIMP.


  • #5
    TomSweeney
    Registered Users Posts: 3,192 ✭✭✭TomSweeney


    OK, after doing some tweaking on LR

    50287509338_4dda4271ed_c.jpg

    The land/trees don't bother me so much but why are the stars around the edges, particularly top left blurred, isn't DSS supposed to keep track of the moving stars ?


  • #6
    Adyx
    Registered Users Posts: 2,997 ✭✭✭Adyx


    There's only so much it can do on untracked exposures. Remember part of its process is effectively rotating the pictures to line them up so you would always lose the edges of an image. Maybe not to that degree though. Although that looks less like star-trailing, maybe field distortion? I'm not an expert by any means.

    Either way, if you're not using a tracking mount, best to keep your exposure time limited. How long depends on the camera and lens. There was an old rule of 500 divided by the focal length of the lens which can give you a rough idea but shouldn't be considered accurate. There's an Android app called Photo Pills which can work it out much more accurately but it costs around €10 I think.

    If you do take shorter exposures, you can always just stack more, just remember to reframe the target occasionally.


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  • #7
    iLikeWaffles
    Registered Users Posts: 4,325 ✭✭✭iLikeWaffles


    I'll be looking to stack in the next few weeks myself just have to get a good light pollution filter, have all the rest of the stuff. Should be fun, tried a couple of times and did not get good results, requires a lot of researching the techniques.

    From researching things the past couple of months, your bias frames would only be good for 2 weeks to 1 month. This is because with use sensor's will introduce a different amount of random noise as they age, it is true you can use the same darks/bias but to a degree. Using the same for a long period of time will introduce unwanted patterns and artefacts in images. If you are to use the same frames it would be good practice to have them for different exposures to match the work put in by the camera (exposure iso etc) but as I said toss them once a month max and take new ones.

    The 500 rule is good but I found the 300 rule is even better! This will be 200 for full frame given the crop factor of about 1.5 (300 / 1.5 = 200 rule full frame)


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