Bracketing... what is it?

Discussion in 'Digital Photography' started by lamina, Jul 24, 2007.

  1. lamina macrumors 68000

    lamina

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    #1
    What is bracketing and how is it of use to me?

    Well, I know what bracketing is.. taking several shots of the same subject with different focus, exposure, etc... but I have a bracketing setting on my D50 and when I'm using it, it doesn't take several pictures, just one. Is it just exposure bracketing that it computes after the photo is taken?
     
  2. Father Jack macrumors 68020

    Father Jack

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    #2
    Bracketing is not about focusing .... It's about exposure.:eek:
     
  3. compuwar macrumors 601

    compuwar

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    #3
    You can focus bracket, and some folks are doing it for composite landscape shots. It gets around one of the limitations of the small format, fixed focal-plane, non-bellows camera- lack of the Sheimpflug principle.
     
  4. Father Jack macrumors 68020

    Father Jack

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    #4
    Bracketing has been around long before digital and the thought of composite images. We used to use Depth of field to ensure all part of a picture were sharp.
     
  5. compuwar macrumors 601

    compuwar

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    #5
    The bracketing setting on the D50 should give you multiple exposures bracketed by the exposure value you've dialed in, but you have to set it up first. If you don't get multiple exposures, you're not set up correctly.

    Exposure bracketing gives you the advantage of getting light and dark tonal values outside of the dynamic range of the sensor or film exposed well. You can then blend the images digitally, or sandwich the negatives to expose a picture that looks more like your eye sees due to your built-in exposure compensation and dynamic range.

    Focus bracketing allows you to get multiple points of interest in focus, and blend the resultant images so that you have more than your depth-of-focus in sharp focus. This is a newer digital technique. It allows you to mirror the results you get with a large format bellows camera, where tilts of the lens and film plane allow the photographer to alter the plane of focus so it's not just perpendicular to the ground, but more of a wedge from foreground to background without every element in the picture being in focus. This wedge of focus is created by something called the Scheimpflug principle, and it's one of the things that makes large format landscapes work so well. As far as I know, focus bracketing has to be done manually on any digital camera.
     
  6. Father Jack macrumors 68020

    Father Jack

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    #6
    Could this possibly be "Depth of Field" mode? Where you focus first on the nearest distance you want sharp and then on the furtherest point you want sharp. The camera uses these two points of focus to choose an aperture to everything between these two points sharp.

    Depth of Field and Depth of Focus are two completely different things.
     
  7. compuwar macrumors 601

    compuwar

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    #7
    Exposure bracketing has- though even on an enlarger you're doing a composite image. As far as I can tell, focus bracketing is new with digital.

    Depth of Field only goes so far, especially in landscapes where you want a foreground and background image in focus. We've been using Scheimpflug for longer than I've been photographing- and that's significantly longer than digital has existed. If you've not shot large format gear, you've likely not heard of it, as most small format and medium format photographers tend to think the only advantage to camera movements is to control perspective in architecture and monolith shots.

    You may wish to Google "Focus bracketing" with the quote marks to bring yourself up to date with this technique, the software available to assist in creating such shots, and think some about how it's advantageous to have near, middle and far subjects in focus without having every element in the picture in focus.
     
  8. atari1356 macrumors 68000

    atari1356

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    #8
    I'm not sure how it is exactly on the D50, but on my Canon 350D it doesn't automatically take 3 shots in succession... you still have to press the shutter button 3 times if you're bracketing for 3 different exposures.

    I haven't had a need to use the feature much... but I'd probably use a remote shutter or cable release, to avoid moving the camera in between the shots.
     
  9. compuwar macrumors 601

    compuwar

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    #9
    Optically, only a given point will be "in focus," so "Depth of Focus" is a misnomer, thought the two are popularly used interchangeably it's true that depth of focus is technically accepted to be depth of field on the other side of the lens from the subject.

    Depth of Field is the point before and after the point of focus which *appears* to be in focus. The hyperfocal distance for a lens is the largest value of that, or the point at which a particular lens focuses from it's nearest point to infinity (that is the largest depth of field, which is called that because focus is a point target and depth of field is an area effect.)

    You may find the following helpful:

    http://en.wikipedia.org/wiki/Depth_of_field
    http://www.heliconsoft.com/heliconfocus.html
    http://en.wikipedia.org/wiki/Scheimpflug_principle

    Also, lest we forget, simply moving to a smaller aperture will at some point produce diffraction artifacts. Especially on digital, where the size of a sensor site has a profound effect. For instance, while you might get away with f/22 on a 6MP APS-C sensor, on a 12MP APS-C sensor, diffraction starts to rear its ugly head after f/11. Obviously then, even if we had lenses that routinely went to f/128, we'd be hard-pressed to take advantage of that, whereas we could focus bracket (sometimes called focus stacking) to our heart's content, and end up with a usable image.
     
  10. Father Jack macrumors 68020

    Father Jack

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    #10
    Remember there are more factors controlling depth of field than aperture.

    Aperture
    Focal length of lens
    Distance the lens is focused at.
    Maximum permissible size of the circles of confusion
     
  11. compuwar macrumors 601

    compuwar

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    #11
    Clearly, all of which are covered in the Wikipedia article I cited. However, none of that changes the fact that folks are focus bracketing- which is your original misstatement that I took issue with.
     
  12. lamina thread starter macrumors 68000

    lamina

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    #12
    Thanks everyone for your replies... I'm at work right now but I will definitely look through them on my lunch.
     
  13. redrabbit macrumors 6502

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    Aug 8, 2006
    #13
    Question on bracketing: My Canon Digital XT Rebel supports exposure bracketing of three shots, I believe. Would this, in combination with a tripod, before sufficient to produce HDR photos? Or would I need to take more shots at more exposure increments?
     
  14. Father Jack macrumors 68020

    Father Jack

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    #14
    Can you tell me which cameras have this new technology? I would be extremely interested to check them out. I taught photography and graphics for over 20 years in one of the largest Higher Education colleges in Europe.

    As for large format cameras, I have two 5" x 4" Sinar cameras and a box full of lenses sitting here. They haven't been used for quite a few years and probably never will. I retired just over a year ago.
     
  15. compuwar macrumors 601

    compuwar

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    #15
    Again, as I stated earlier in the thread- it's not done in the camera, it's done in post-processing. One of the links I provided previously is to one of the preferred packages- Helicon Focus. Here it is again:

    http://www.heliconsoft.com/heliconfocus.html

    It's Mac & Windows, and I've been considering it because I'm diffraction-challenged past f/11 on my primary body.

    As I said, a quick Google will give you more information, since we really couldn't blend focus on an enlarger, this is simply one of the advantages of digital that doesn't really have a film analog.
     
  16. Father Jack macrumors 68020

    Father Jack

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    #16
    Thanks for the info ... I will check it out.

    FJ
     
  17. compuwar macrumors 601

    compuwar

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    #17
    While the real answer is "it depends," where the size of the bracket and the tonal range of what you're shooting are the deciding factors, generally most folks who're serious about HDR want 5-7 images at the low end. Since you're on a tripod, you can vary the exposure manually so long as the camera is locked down well, so you're not limited to in-body bracketing.
     
  18. IscariotJ macrumors 6502a

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    UK
    #18
    Continuous Mode Helps

    According to the D80 manual, it recommends setting the required number of exposures, and then turning on continuous mode; that way, you can hold the shutter down. After the camera has taken the specified number of shots, it pauses, and you can release the shutter.

    Must admit, when I first started shooting with the D80, I tried exposure bracketing, and couldn't understand why it only took one shot.....
     
  19. BigJimSlade macrumors member

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    Dec 16, 2005
    #19
    I haven't really looked at HDR that much to be honest, but the first thing I read about it said that the typical exposure range when you bracket isn't anything like enough. You need to stop down in much larger values to get the benefits.
     

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