Site Sponsors
Results 1 to 10 of 10

Thread: Long Exposure Banding

  1. #1
    Member
    Join Date
    Mar 2012
    Location
    Victoria, BC, Canada
    Posts
    71
    Post Thanks / Like

    Long Exposure Banding

    Hello,

    I'm working on a project involving long exposure, but in several cases when there is a large portion of the image as sky, I'm getting a banding effect that renders the image unusable.

    I'm using a Nikon D90, with long exposure noise reduction off, and shooting at base ISO. It doesn't look like standard noise or hot pixels, but rather swaths of uneven colour gradient:


    260sec

    Any advice would be greatly appreciated!

  2. #2
    Senior Member
    Join Date
    Aug 2011
    Location
    San Francisco
    Posts
    889
    Post Thanks / Like

    Re: Long Exposure Banding

    I'm not sure what you are describing related to the photo, but any contamination may or may not be caused my the viewfinder not being blocked in long exposures. The Nikon D4 and D800 have a viewfinder shutter I only recently discovered which is exactly for this purpose! Other cameras, including Canon come with a plastic/rubber viewfinder blocker usually found attached to the shoulder/neck strap, which you just slide over the finder.

    I also tend to shoot RAW only, I'm not sure if this helps anyways, since JPEGS are artifacts crazy in my general opinion.

    You didn't mention if you were using a vari-ND filter, so I assume not, but if you were, then somtimes it is best not to use the maximum value, as this too can introduce color contamination. That's all I got, I'm sure others can chime in!
    ___________________
    Po-Ming Chu
    POPHOTO

  3. #3
    Member
    Join Date
    Mar 2012
    Location
    Victoria, BC, Canada
    Posts
    71
    Post Thanks / Like

    Re: Long Exposure Banding

    If you look at the top right of the photo, notice the gradient between the near-white and medium blue - it's not smooth.

    I do shoot RAW, and don't use vari-ND filters because I've heard they produce artifacts and flare.
    I don't think I even used any filters at all for this shot, and I know I've seen this occur in other shots where I didn't use any.

    It may be an issue with the viewfinder - I took off the eyepiece because I have glasses, but wouldn't that produce light leaks rather than artifacts?

  4. #4
    Senior Member
    Join Date
    Aug 2011
    Location
    San Francisco
    Posts
    889
    Post Thanks / Like

    Re: Long Exposure Banding

    Are you shooting lowest native ISO?
    ___________________
    Po-Ming Chu
    POPHOTO

  5. #5
    Member
    Join Date
    Mar 2012
    Location
    Victoria, BC, Canada
    Posts
    71
    Post Thanks / Like

    Re: Long Exposure Banding

    yes

  6. #6
    Senior Member
    Join Date
    Aug 2011
    Location
    San Francisco
    Posts
    889
    Post Thanks / Like

    Re: Long Exposure Banding

    Sorry, not much help here. It could just be your monitor display, obviously a big perhaps here. I don't see the banding issue here on my iPad!
    ___________________
    Po-Ming Chu
    POPHOTO

  7. #7
    Senior Subscriber Member
    Join Date
    Nov 2007
    Location
    San Francisco, CA
    Posts
    1,306
    Post Thanks / Like

    Re: Long Exposure Banding

    My guess would be flare and a subsequent adjustment of the black point to recover a full range. The banding is probably mostly in the red channel. I'd recommend trying a higher contrast lens, remove any UV or protective filter, make sure the lens front and rear are clean, and block the viewfinder. This should reduce flare. To recover the black point, instead of adjusting levels I'd suggest masking off the dark areas (create a mask with a 0 for all pixels below a certain threshold value then feather it) and tone mapping them; this will bring out detail by darkening, given you both increased clarity and real blacks. It can only do so much though...

    You can also blur the red channel to reduce it.

    Finally, the last culprit might be compression, so make sure you're shooting full 14-bit uncompressed raws.

  8. #8
    Senior Subscriber Member Steen's Avatar
    Join Date
    Nov 2007
    Location
    Denmark, CPH
    Posts
    2,500
    Post Thanks / Like
    Images
    12

    Long Exposure Banding


    Quote Originally Posted by Jan Brittenson View Post

    (...) Finally, the last culprit might be compression, so make sure you're shooting full 14-bit uncompressed raws.

    At first I vote for this suggestion, the picture looks heavily over-compressed, perhaps in post-processing, though it's hard to judge from such a small picture size.

    A link to a full size version or a 100 % crop of the relevant part would make it easier to know exactly which part you are talking about and what could be wrong with it.

  9. #9
    Member
    Join Date
    Jan 2013
    Location
    Boston
    Posts
    34
    Post Thanks / Like

    Re: Long Exposure Banding

    I had the same issue on a D700, when I sent sample images to Nikon service (through a contact I had) they pretty much said it was my monitor as they could see nothing. I was never convinced though and showed it to several other photographers, once we even looked at it projected onto a screen from someone else's laptop to show I was ont imagining it. I have never seen it before or since, I moved on and have had several bodies since without issue...I'm still using the same computer screen.

  10. #10
    Administrator, Instructor Guy Mancuso's Avatar
    Join Date
    Oct 2007
    Location
    Arizona
    Posts
    23,623
    Post Thanks / Like
    Images
    2555

    Re: Long Exposure Banding

    You should process these out in 16bit and a adobe RGB color space or Prophoto color space than for web convert to SRGB and 1200 pixels wide. Looks like a color space issue in processing you need full color space for the gradient sky when processing.
    Photography is all about experimentation and without it you will never learn art.

    www.guymancusophotography.com

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •