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  1. #1
    Senior Member

    ISO setting for star trails

    ISO setting for star trails
    Hi,

    I have a request for recommendations on iso setting for star trails photo. I started experimenting night-star photos as shown below. Next, I would like to shoot star trails at the same scene and similar time and lighting (city night sky with heavy light pollution). It will be a single long-exp one for 30min (no way to do multi interval shots with D3500). Ideally, I would like an image with stars trailing in a similar background sky as the 1st photo (15") below. I see there are only two choices for iso left: 200 or 100. I tried calculations and always got < 1. So I would guess 100. It would be a great help if you offer recommendations, tips, or confirmation. (Since this will be one long experiment, about 1.5 hours at least, I would hate to guess wrong and do it over again.) Thanks in advance.

    ISO setting for star trails-2020-05-20-21.15.26-s.jpeg

    ISO setting for star trails-2020-05-20-21.16.58-s.jpeg


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  2. #2
    Senior Member

    Re: ISO setting for star trails

    The images above are the original jpg's (unprocessed).

  3. #3
    Senior Member
    Scott Murray's Avatar

    Re: ISO setting for star trails

    ISO setting for star trails
    Quote Originally Posted by blackstar View Post
    Hi,

    I have a request for recommendations on iso setting for star trails photo. I started experimenting night-star photos as shown below. Next, I would like to shoot star trails at the same scene and similar time and lighting (city night sky with heavy light pollution). It will be a single long-exp one for 30min (no way to do multi interval shots with D3500). Ideally, I would like an image with stars trailing in a similar background sky as the 1st photo (15") below. I see there are only two choices for iso left: 200 or 100. I tried calculations and always got < 1. So I would guess 100. It would be a great help if you offer recommendations, tips, or confirmation. (Since this will be one long experiment, about 1.5 hours at least, I would hate to guess wrong and do it over again.) Thanks in advance.

    ISO setting for star trails-2020-05-20-21.15.26-s.jpeg

    ISO setting for star trails-2020-05-20-21.16.58-s.jpeg
    If you are going to be doing a single exposure star trails, then ISO 100 would be ideal. But honestly combining multiple images would achieve a much better result. Also an aperture of 1.4 - 2.8 would help.

  4. #4
    Senior Member

    Re: ISO setting for star trails

    Thanks, Scott.

    It is more than a confirmation especially from your response. Also, I understand from many's demonstrations and experience that all of the great star trails images come from multiple interval shots and few from single-shot are only slightly comparable. But due to the only camera I use, for now, it is definitely not equipped to achieve this humble task (except manually taking interval shots for 1+ hour...plus not to lose gap control). And unfortune continues f3.5 is the largest I got for now. Thank you for your confirmation and tips and wish me luck with this endeavor.

  5. #5
    Senior Member
    Hobbit's Avatar

    Re: ISO setting for star trails

    Quote Originally Posted by blackstar View Post
    Thanks, Scott.

    It is more than a confirmation especially from your response. Also, I understand from many's demonstrations and experience that all of the great star trails images come from multiple interval shots and few from single-shot are only slightly comparable. But due to the only camera I use, for now, it is definitely not equipped to achieve this humble task (except manually taking interval shots for 1+ hour...plus not to lose gap control). And unfortune continues f3.5 is the largest I got for now. Thank you for your confirmation and tips and wish me luck with this endeavor.
    some where buried deep in the archives of my emails i have details of programs used for star trials, its also the night i launched my D5300 and 10-20 f3.5 across a lecture hall at Jodrell Bank , if i can locate them ill post em up. i do remember practicing in the indoor night sky they have and the f3.5 was spot on for multiple trials and combining

  6. #6
    Senior Member
    Hobbit's Avatar

    Re: ISO setting for star trails

    https://www.startrails.de/?utm_sourc...UT6YA2,NLGJP,1

    DeepSkyStacker - Free

    these were given to me by Dr Holloway at Jodrell bank, hope it helps

  7. #7
    Senior Member

    Re: ISO setting for star trails

    Thanks, Hobbit.

    Unfortunately, Windows pc is now in my computer history. I am all Mac now. But thank you for the help. BTW, I like your stunning star-Milky Way photo (as your Avatar and in which thread?)
    Thanks/Like Hobbit Thanks/liked this post
     

  8. #8
    Senior Member
    Hobbit's Avatar

    Re: ISO setting for star trails

    ISO setting for star trails
    Blackstar, that was one of those where i wasn't out with the camera , id been to the washrooms on campsite and on way back spotted it and was oooooooo run to the tent and grabbed gear, single shot, so happy how it came out , thankfully the area was really dark and minimal LP , its one of the few photos i actually named - Climbing the clouds as the milky way looks like its part of the cloud
    south wales is great for that ISO setting for star trails-climbing-clouds.jpg
    Thanks/Like Needa, blackstar Thanks/liked this post
     

  9. #9
    Senior Member

    Re: ISO setting for star trails

    ISO setting for star trails
    Did the experiment with the result (some diagnose after the images):

    1. original jpg downloaded from the camera
    Attachment 338721

    2. jpg version of RAW exported from Darktable (unprocessed)
    Attachment 338722

    3. processed in DT
    Attachment 338723

    It looks like the original jpg does not fair the one from the RAW file through DT. In any way, it's obvious that the shot is over-exposed for 30', even though iso set as 100. The processed image was done with 2 instances of exp reduction (total about -4.0EV) and others. Couldn't figure out how exactly the exp EV is related to the exp time? Say if exp time cut half to 15', will I get the exp similar to the processed one? And then the star trails length also cut to half? Will anyone say that those farther away star trails look faint compare to the closer ones? Is that because of imaging failure or unclear sky?

    I may learn a tip on how to bring out more of those fainting star trails in DT: First, exposure, shadow & highlight, contrast-brightness-saturation, color reconstruction, and highlight reconstruction all work to improve the problem "a little more or less" but still unsatisfactory to my like. Only the Tone Mapping module surprisingly gave me some very noticeable change and improvement I felt as best as I could get...

    Now it's the point I would like to add my request for your diagnoses and treatments on my experiment. Thanks

  10. #10
    Senior Member

    Re: ISO setting for star trails

    Oh, I know there is still works to do with those foreground trees.





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