MF Lenses and HyperFocal Distance

Discussion in 'General Technical Discussion' started by davewolfs, Jun 7, 2007.

  1. davewolfs

    davewolfs

    633
    May 23, 2006
    Hello everyone,

    I recently purchased a MF lens (have not yet received it). I am curious to know any sort of techniques that you folks use in order to ensure proper focusing. As an aside, I have already purchased a Katz-Eye.

    I read one article that mentions you should attempt to focus at hyperfocal distance.

    The article is found here:

    http://www.dofmaster.com/hyperfocal.html

    This article also mentions that when focusing at hyperfocal distance, near objects will not appear to be in focus unless viewing with DoF preview engaged.

    For those who do focus with MF lenses, I am curious to know how many of you focus using hyperfocal distance and under what conditions do you usually do this.

    Thanks,

    Dave
     
  2. I shoot with MF Ai(S) lenses just about exclusively. I don't shoot at hyperfocal, but focus at the point in the frame that I want. Of course I take DOF into consideration, which will vary quite a bit from one lens to another.

    One consideration where you may want to shoot at hyperfocal would be wide angle street photography. If you were to shoot that with a 20, 24 or 28mm, you could set it at hyperfocal and just snap away for candid shots.
    Personally I see little other use for hyperfocal.
     
  3. gvk

    gvk

    388
    Jun 17, 2005
    Mystic, CT
    Hyperfocal distance is, by definition, the focus distance that maximizes depth of field for a given focal length and aperture combination. If you want objects from some near point to infinity to be acceptably sharp you choose the focal length and aperture combination, as well as, a criteria for "acceptable" (i.e. circle of confusion) that will give you a hyperfocal distance that is 2X the desired near point.

    More usually you focus on your subject directly when it is the most important element in the photo to maximize its sharpness.

    The concept of hyperfocal distance applies equally to both manual focus lenses and to autofocus and zoom lenses. Many older manual focus lenses have DOF markings on the lens barrel to aid in selecting aperture for hyperfocal distance or desired DOF. Simple fixed focus "box" cameras used lenses that were permanently focused at hyperfocal distance to achieve equally blurry pictures everywhere, execpt for close-ups were they were even blurrier. :smile:
     
  4. Artorius

    Artorius

    125
    May 1, 2005
    Tacoma, WA
    I use with most my RF

    I use it with my Leica M's almost exclusively using wides(15-40). With the D2h/x it is mixed, depending on the lens and what I am shooting. I was in Vegas last year and only took my AIs lenses. I never focused once with over 5 GB pics. Not all keepers, but the ones I lost were mostly exposure, WB problems.
     
  5. Hyperfocal Distance is incredibly usefull for Taking IR pics with camera's that aren't modified, Since you can't trust the camera's AF, you just set a Hyperfocal and go nuts

    for me I use my 50mm f1.8 a lot, so I have to really fine tune it (since its at 1.8 all the time) Since i'm lazy and don't carry a tripod with me. The problem is I always bump it and have to reset it!
     
  6. MontyDog

    MontyDog

    Jan 30, 2005
    #1064 - You have an error in your SQL syntax;
     
  7. davewolfs

    davewolfs

    633
    May 23, 2006
    Can you rely on the distance scale for older AIS lenses as an accurate measurement for hyperfocal distance? Or is this value skewed for Nikon digital SLR's because of the 1.5 crop ratio and therefore a different CoC vs Film.
     
  8. gvk

    gvk

    388
    Jun 17, 2005
    Mystic, CT
    The DOF markings on all Nikon MF lenses seem to have been based on a COC of 0.03 mm that traditionally was used for viewing an 8x10 inch print made from a 35 mm film frame. Because the image captured by a DX sensor is 2/3 the size, it must be enlarged 1.5X more to produce the same 8x10 print. Thus the COC generally used to estimate DOF for Nikon digital DSLRs is 0.02 mm.

    Hyperfocal distance is approximately proportional to focal length squared, and inversely proportional to the product of aperture and COC. Strictly speaking, these proportionalities only apply when hyperfocal distance is much larger than lens focal length, but in practice that condition is always satisfied. Therefore, a 1.5X decrease in COC is approximately equivalent to a full stop (1.4X) wider aperture for DOF calculations. Therefore, you can use the DOF markings on a MF lens to estimate DOF and hyperfocal distance even for digital if you remember that you get about 1 stop less DOF when using a DX digital sensor, assuming focal length and distance are the same.

    Since the usual comparison between film and digital is done at equivalent FOV, then the actual focal length used is different by the 1.5X crop factor, and images captured on a digital sensor have about about 1 stop more DOF.
     
  9. gvk

    gvk

    388
    Jun 17, 2005
    Mystic, CT
    Also, as Paul suggested above, I usually use a bit more critical standard of what blur is "acceptable" when estimating DOF, 0.025 mm for 35 mm film and 0.016 mm for a DX DSLR. These COCs result in about 1/2 stop less DOF than the more traditional criteria. Sometimes, particularly if I expect to make large prints from an image, I use a full stop smaller aperture to further reduce blur at the DOF limits.
     
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