Tips on taking better night photos

Discussion in 'Digital Photography' started by Gary Hendricks, Oct 19, 2005.

  1. Gary Hendricks

    Ron Hunter Guest

    Point and Shoot users can duplicate this feature by using the shutter
    delay feature.
    Uggggh, why does it matter WHAT you aim the camera at, if the lens cap
    is on? Grin.
    Some DSLR cameras have this feature in the camera. Very nice for ISO
    1600 and above shots. Those of us using P&S cameras can use your
    suggestion, or a variation of it.

    Thanks, Gary, those are useful tips.
     
    Ron Hunter, Oct 21, 2005
    #21
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  2. Ron Hunter wrote:
    []
    All the P&S cameras I've used have dark frame subtraction available. On
    the Panasonic FZ5 it's automatic when you get exposures longer than 2s (or
    so). On the Nikon range you manually enable the function.

    David
     
    David J Taylor, Oct 21, 2005
    #22
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  3. Gary Hendricks

    ASAAR Guest

    A number of P&S cameras also do that and it's called
    (appropriately enough) noise reduction. But it's generally used to
    make the really dark parts of night scenes black, instead of a mushy
    gray. Seems like it should also cancel out hot pixels. But as with
    the "tip", it will at least double the amount of time needed to take
    the pictures. Better would be to have a camera that has a menu
    option to map out hot pixels. This is available not only in DSLRs
    but in some P&S cameras as well.
     
    ASAAR, Oct 21, 2005
    #23
  4. ASAAR wrote:
    []
    There are a number different issues, though.

    - Remapping hot pixels will reduce bright spots in the picture. These
    pixels may be "stuck-at-white" or "stuck-at-black" (in any of the Bayer
    filter colours), and so affect all pictures taken with the camera. Some
    cameras will offer you the option to renew the map of bad pixels, as the
    pixel defects will change over time.

    - Dark frame subtraction. With night-time images, more correctly with
    long exposure times, there may be output from the sensor where there
    should be none caused by the dark current of the sensor. This will tend
    to be constant over a short period (few minutes), so a more accurate
    measurement of the dark parts of the scene may be made by taking two
    exposures, one with the shutter open, and one with the shutter closed. By
    subtracting the shutter-closed image from the shutter-open one, this dark
    current can be largely removed. The elapsed time is doubled.

    - Noise reduction - may refer to software (or in camera firmware
    techniques) to identify noisy (grainy) parts of the image and apply a
    smoothing algorithm to those parts. To be effective, parts of the image
    which carry detail must not be smoothed. Hence the multiplicity of
    programs to do this. This is also available in-camera in many models, and
    may have a number of strength options such as: Noise-reduction none, weak,
    normal, strong. Typically, at higher ISO settings on P&S cameras the
    noise reduction may be applied automatically to reduce the grainy
    appearance. If overdone, the image may have a "plastic" appearance.

    David
     
    David J Taylor, Oct 21, 2005
    #24
  5. My bad, Ed; sorry, don't mean to kopp or nanny you. I try not to do
    either, but sometimes fail. I do try to point a few hints here and there
    that'd help us all, to those who might care to learn, or to others who
    know, such as yourself, and then the reply can illustrate so others can
    learn.
     
    John McWilliams, Oct 21, 2005
    #25
  6. Gary Hendricks

    Mr.Happy Guest

    "set the exposure compensation to +2, use ISO400 or above, "

    let me correct myself.
    Long Term(LT) set to 2secs vs. Exp.Comp. set to +2 & ISO400
    LT wins as the pics were brighter, sharper, and without noise.
    If I were to set LT to 4secs(max on my camera), I bet the pics would be
    even brighter.
    Thus I see no use for Exp. Comp.
     
    Mr.Happy, Oct 22, 2005
    #26
  7. Gary Hendricks

    ASAAR Guest

    It doesn't work that way unless the aperture can't change because
    you're either using Manual Mode or the aperture is already closed
    down as far as it can go. In any of the "auto" modes, if you force
    the shutter to stay open twice as long, the aperture will close one
    stop, giving you the same exposure. Increasing the ISO won't change
    the exposure (brightness) of the images. It will either cause the
    aperture to close a bit or the shutter to close sooner (or both).
    In other words, less light will be captured by the sensor. But the
    increased ISO will cause the camera to compensate by increasing the
    sensor's amplification. This will increase the brightness of the
    JPG image so that it's the same as if a smaller ISO was used, but
    also increase the noise, more or less, depending on the camera.

    Try it both ways, adjusting the ISO and the exposure compensation.
    Then compare the shutter speeds and apertures in the EXIF data and
    you should then see how it works. When you do, feel free to change
    your name to Mr. Happier. :)
     
    ASAAR, Oct 22, 2005
    #27
  8. Gary Hendricks

    Ron Hunter Guest

    You may find this feature on the high end of P&S cameras, but not on the
    low to medium price range. And many users wouldn't know what it was, or
    what it was for.
     
    Ron Hunter, Oct 22, 2005
    #28
  9. .... so I hope my explanation will help such users, and perhaps be added to
    the FAQ.

    If the cameras aren't capable of exposures greater than, let's say, one
    second, there's no need for dark frame subtraction in any case. Perhaps
    the cameras missing the feature also lack long exposure times?

    David
     
    David J Taylor, Oct 22, 2005
    #29
  10. You're going to run into problems with long exposures. Forget about
    hand-held photos at long exposures. Even if you have a tripod, only a
    "still life" will be possible without motion-blurs. The worst-case
    scenario is an image where part of the photo is properly exposed and the
    rest is underexposed. Not many people can afford to spring for a camera
    that's noise-free at ISO 3200 and/or get a super-powerful flash. I'd
    suggest selecting shutter-priority and set an exposure length that won't
    allow blurs. Then enhance the image after-the-fact on your computer.

    By sheer co-incidence, I've just gotten a "proof-of-concept"
    enhancement program functioning, for salvaging under-exposed photos.
    See http://www.pbase.com/waltdnes/enhancements for a worst-case scenario
    and what I could salvage out of it. I used Image-Magick and FreeBasic,
    compiling a program I wrote, to do it. If you've followed this group
    recently, you'll probably be aware of my unhappiness with my FZ5's
    low-light "performance" (or lack thereof). I got pissed-off enough that
    I went and did something about it.

    If anybody is interested, my code works on linux and should also work
    on Windows. For further details download my discussion notes at
    http://www.waltdnes.org/photostuff/pmod.txt and the (FreeBasic) source
    code at http://www.waltdnes.org/photostuff/pmod.bas

    I realize that my approach is clumsy and heavy-handed, but it's at the
    limits of my programming ability as it is. I've posted on the gimp
    newsgroup and the ImageMagick mailing list and pointed people at the
    code. Hopefully, someone who's a better programmer than me will
    implement these algorithms in one or both of these programs.
     
    Walter Dnes (delete the 'z' to get my real address, Oct 23, 2005
    #30
  11. Thanks Cathy. I will try to post some new tips whenever possible - the
    thing is, I'm not sure if its appropriate. Some forums don't really
    like this sorta things.


    *****************************************************************
    Sincerely,
    Gary Hendricks, Basic-Digital-Photography.com
    The best digital photography tutorials and how-to guides:
    http://www.basic-digital-photography.com
    *****************************************************************
     
    Gary Hendricks, Oct 23, 2005
    #31
  12. Hi Walter

    Thanks for the comments. I do realize that the FZ5 has problems too - I
    read it several times off the net about its bad low light performance.
    That's an interesting little piece of programming there - I do know
    some Perl - I wonder if I can take it and try it out for ya.

    *****************************************************************
    Sincerely,
    Gary Hendricks, Basic-Digital-Photography.com
    The best digital photography tutorials and how-to guides:
    http://www.basic-digital-photography.com
    *****************************************************************
     
    Gary Hendricks, Oct 23, 2005
    #32
  13. Gary Hendricks

    Cathy Guest

    I haven't been on this NG for a long period of time as many others have,
    but I don't see how it could hurt. You could even just give your website
    URL. Its nice that you at least ask if its appropriate. Just my
    obvservations of this NG, since I came here which is 8 months or so, I
    see more off topic messages and flareups here than any other newsgroup
    I go to every day. I
    download about 12 or 13 newsgroups daily and have done so for 8 or 9
    years.I also filter more threads and people from this NG than any other
    NG's I frequent. But we all do that to some degree, especially with busy
    NG's like this one. On the other hand, there are lots of nice people
    here who I like and who have a genuine desire to help and I've learned
    a lot. My two cents which probably doesn't count much :).

    Cathy
     
    Cathy, Oct 23, 2005
    #33
  14. Thanks Cathy, for the kind words.

    I really just wish to share some knowledge with the folks here. Here's
    to better photography for all!

    *****************************************************************
    Sincerely,
    Gary Hendricks, Basic-Digital-Photography.com
    The best digital photography tutorials and how-to guides:
    http://www.basic-digital-photography.com/tutorials
    *****************************************************************
     
    Gary Hendricks, Oct 24, 2005
    #34
  15. Gary Hendricks

    Cathy Guest

    You are welcome Gary.
    I hope you will share your knowledge here. I am always grateful for any
    knowledge involving how to take better pictures, and other useful
    information about digital cameras and I am sure I am not the only one.
    There is a lot to learn. Bring it on :)

    Cathy
     
    Cathy, Oct 24, 2005
    #35
  16. You have my permission. BTW, after having gone to all that trouble,
    I discovered that ImageMagick can do similar stuff. E.g...

    convert -depth 8 original.tif -fx 'u^0.30' output.tif

    ....will do the same as my painful manual method. That command is
    actually a shortcut, and you can modify individual channels separately
    like so...
    ImageMagick has libraries (perl, python, C, etc) and also command line
    utilies with "convert" being the one I use most often. It'll convert
    between formats, resize, rotate, and generally slice+dice in a alot of
    very useful ways. Being able to run it from the command line means that
    I can use linux shell scripts (or DOS .BAT files) for batch mode
    processing. It's free; it's Open Source; there are versions for DOS,
    Windows, linux, etc, etc. I've only begun to scratch the surface, but I
    already see that it is one seriously powerful toolset. I noticed on one
    of their "about" pages that pbase.com mentions they use ImageMagick.
    The home page is http://www.imagemagick.org/script/index.php
     
    Walter Dnes (delete the 'z' to get my real address, Oct 26, 2005
    #36
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