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Thread: Depth of Field - 4x5

  1. #1

    Depth of Field - 4x5

    I currently own a Canham DLC45 with a Rodenstock 210mm lens. Can anyone give me a quick & simple method for figuring depth of field while in the field without having to resort to a slide-rule, laptop computer, abacus or sextant??

    I was taught some quick method many moons ago, but I can't remember it. Please help if you have any suggestions. Thanks!!

    SDM

  2. #2

    Join Date
    Jun 2000
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    Depth of Field - 4x5

    the two quickest and easyiest ways to figure out depth of field are these polaroid, type 55 negs work especially well for these but any polaroid will get you most of the way there. Also if you have a nice heavy darkcloth that you can really wrap yourself up in, simply close down then lens to where you are going to shoot and look. these methods work for me. I don't mean to be flippant but alot of people tend to spend to much time with the math and science of photography rather than the art of it.

    doug

  3. #3

    Depth of Field - 4x5

    Scott,

    I respectfully can't agree with Doug regarding Polaroids. You simply can not tell much about what is or is not in focus with them. They are fine for composition and exposure tests, however. There are a million ways to approach depth of field problems and many are discussed in various places on this site. Take the time to check them out. Probably the the easiest way to get going is to print out the table for your focal length from the Schneider website http://www.schneideroptics.com/large/depth/depthof.htm

    Good Luck Paul

  4. #4

    Join Date
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    Depth of Field - 4x5

    Paul,

    Doug is probably refering to using the negatives from Type 55 polaroid. For over 16 years I have successfully used Polaroid Type 55 negatives to check depth of field in both studio and field work.

    Scott, try this method: You have a scale on the DLC rails. Make note of where your near focus point is and then focus to your far focus point and make note of that. Now refocus two thirds of the way back to the near focus point and close down to f/22, or f/32 if the distance between the two points, as measured on the rail, is great. Now do a visual check with the lens stopped down and then shoot a Type 55 Polaroid and inspect the negative. You can clear it with simple water or although this will take more time than using the sodium sulfite clearing bath. Once again I have found using the Type 55 negative to be an extremely accurate method of judging the focus while I am shooting.

  5. #5

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    Depth of Field - 4x5

    There is no single, universal answer to your questin because what is acceptable depth of field varies depending on enlargement size, viewing distance, personal preferences, and probably other things I'm forgetting. However, if you want something quick and simple, Linhof has a table that works like this. Focus on the near, focus on the far, set the lens midway between the two points. Then measure with a ruler or estimate the difference between the near and far and set the aperture as follows: 1.6 mm difference, F 16, 2.2 mm difference, F 22, 3.2 mm difference, F 32, 4.5 mm difference, F 45, etc. etc. You get the idea. It's easy to remember for obvious reasons. The measurements don't actually have to be down to the tenth of a milimeter, just something close and stop down one more will also work. These numbers assume enlargement of a 4x5 negative to 8x10 or 11x14. Again, they make certain unstated assumptions concerning what is acceptably in focus to most people at some unknown viewing distance but they seem to work pretty well most of the time and the measurement is very easy to do.

    I've personally never been able to tell anything about depth of field from using a Polaroid but obviously some people can.
    Brian Ellis
    Before you criticize someone, walk a mile in their shoes. That way when you do criticize them you'll be
    a mile away and you'll have their shoes.

  6. #6

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    Depth of Field - 4x5

    The easiest and quickest is the Rodenstock Pocket DOF and Scheimpflug circular calculator.

  7. #7

    Depth of Field - 4x5

    I have a the Rodenstock calculator that Bob mentioned. If all you are going to use it for is depth of field and not tilt estimates, than just do what Brian suggests. I have my own table taped to the back of mine, because the Rodenstock f stop estimates are not small enough to get the sharpness I want. I don't have it here with me at work, but I think they are pretty close to Brians. Also, I would be carful about setting the focus at the mid point if the far point is at infinity. If thats the case I would set the focus point about 2/3's of the way to infinity (not sure I worded that right).

  8. #8
    Founder QT Luong's Avatar
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    Depth of Field - 4x5

    Did you read http://www.cs.berkeley.edu/~qtluong/photography/lf/fstop.html While it sounds complicated at first, the method that is described there is actually the easiest and fastest I have found. That's it relies on sound optics doesn't hurt. If you don't have metric scales on your DLC, Keith Canham will upgrade that for a small fee.

  9. #9

    Depth of Field - 4x5

    try this

    1/16" or 2mm = f5.6, 1/8" or 2.8mm = f8, 5/32" or 4mm = f11, 1/4" or 5.6mm = f16, 5/16 or 8mm = f22, 7/16" or 11mm = f32, 5/8" or 16mm = f45, 7/8" or 22mm = f64, 1 1/4" or 32mm = f90, 1 1/2" or 45mm = f128,

    Focus on near object, mark rail. Focus on rear object, mark rail. Measure distance of the two marks and refer to chart. This will give you the minimum aperture needed for both objects to be in focus.

  10. #10

    Depth of Field - 4x5

    reset your focus 1/3 the distance from the front mark.

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