How often do you calculate the depth of field

  • 39 votes.
  • Started by TomAxford on June 14, 2023.
Often
3 votes, 8% of total.
  • 3 votes, 8% of total.
Sometimes
8 votes, 21% of total.
  • 8 votes, 21% of total.
Never (I rely on experience, or depth of field preview, or trial and error, ...)
28 votes, 72% of total.
  • 28 votes, 72% of total.
  • Members 562 posts
    June 15, 2023, 8:36 a.m.

    Thank you to everyone who has voted in the poll or contributed to this thread.

    What strikes me most forcefully is the distinct impression that both the understanding and use of depth of field has markedly decreased since the days of purely manual focus lenses with accurate distance scales and depth of field markings on the lens.

    I remember in the 1990s my favourite cameras were medium format rangefinders with fully manual prime lenses. It was so easy to check the depth of field from the marks on the lens. I never used the standard CoC that was used to compute those DoF marks, but instead I often used a CoC of half the standard size (and sometimes less than that). It was trivially simple to do that: if the lens was set to f/16, then I used f/8 DoF marks; and if the lens was set to f/8, I used the f/4 marks.

    It is a great pity that modern cameras so far have been unable to give us focus distance and DoF scales as accurate and easy to use as on those old manual lenses. I guess it's the price we pay for cheap and easy autofocus.

  • Members 457 posts
    June 15, 2023, 9:02 a.m.

    In my book, calculating DOF using lens marking or a hyperfocal approach should involve distance metering (e.g., laser distance meter). However, guestimating is likely the most common approach.
    Focusing at infinity is probably a better approach, even for film:
    www.trenholm.org/hmmerk/DOFR.html
    "What bothers me even more is the old story about maximizing depth-of-field by focusing at the hyperfocal distance. If you follow that advice you will be guaranteed that scenes in the distance will never be resolved any better than mediocre. You will have sealed in that "minimum acceptable standard".

    My question: is lack of precise lens markings really a bad thing?

  • Members 562 posts
    June 15, 2023, 10:06 a.m.

    It is only very basic cameras that do not have a distance metering facility in the camera. Every single-lens reflex camera, every twin-lens reflex, every rangefinder camera has the ability to determine the focus distance when using a manual focus lens with a distance scale.

    With SLRs and TLRs, you simply focus on your subject in the viewfinder and read the distance from the scale on the lens. With rangefinder cameras such as most Leicas, you focus on your subject in the rangefinder and read the distance from the scale on the lens.

  • Members 457 posts
    June 15, 2023, 10:20 a.m.

    Yes. Calculating the DOF would involve reading the near and far DOF distances as well. Most of times that is not done, at least I do not.

  • Members 457 posts
    June 15, 2023, 10:21 a.m.

    Yes. Calculating the DOF would involve reading the near and far DOF distances as well. Most of times that is not done, at least I do not.

  • Members 128 posts
    June 15, 2023, 11:07 a.m.

    You think either of these were accurate?? Did you test them for accuracy?

    DoF depends on print size, as well as other factors unrelated to the lens, and is somewhat subjective. Also, the scales on manual lenses are crude.

    It's not that the cameras are unable (lack the capability or lack necessary information). It's that manufacturers choose not to implement it.

  • Members 562 posts
    June 15, 2023, 11:25 a.m.

    Yes, I often checked the infinity position for accuracy and in most of my lenses it was accurate to my ability to test the accuracy, which is all that really matters for a lens distance scale.

    I only occasionally checked the close focus distances for accuracy and they were usually reasonably accurate as well.

    Why do you think they would not be accurate?

  • Members 128 posts
    June 15, 2023, 12:26 p.m.

    The problem is precision, as well as accuracy.

    I have a 135mm f/2 fully manual lens.

    At 3m (10') at f/2, the depth-of-field is a few cm (an inch or two). Even if I lined up the focus on the lens to the 3m mark, and used a tape measure or laser rangefinder to make sure that the subject is 3.00m from the image plane, I'm not going to guarantee focus. If I stopped down to f/8, I'd probably be OK.

    To assure focus, I need tools in the camera to help me, whether they are digital contrast enhancement, or an old skool split-prism focussing screen.

    The Astro folk are a bit obsessive about accurate infinity focus.

  • Members 243 posts
    June 15, 2023, 1:08 p.m.

    These days its so easy to bracket and pick your favorite.

  • Members 128 posts
    June 15, 2023, 1:18 p.m.

    If you're real picky about focus, at short to moderate distances, then putting the camera on a macro rail, and racking the macro rail with the lens focus fixed, is the way to go.

  • Members 457 posts
    June 15, 2023, 2:23 p.m.

    Aperture or focus point bracketing?

  • Members 457 posts
    June 15, 2023, 2:39 p.m.

    In-camera focus stacking (assembly) can produce pleasing results but is not for serious application. The number of images that can be stacked is small, and the result is JPEG only. Also, artifacts cannot be handled as they can be in the post (e.g., using the Helicon brush).

  • Members 300 posts
    June 15, 2023, 3:23 p.m.

    In-camera focus bracketing is more advanced thing. You can work with those raw shots in post.

  • Members 243 posts
    June 15, 2023, 6:18 p.m.

    I was thinking aperture

  • Removed user
    June 15, 2023, 6:39 p.m.

    I got interested in that long ago when I was fixing wristwatches for sale. Back then, there was some controversy as to which was "better" - by focus or by rail?

    Is there a consensus these days?

  • Members 1738 posts
    June 15, 2023, 7:20 p.m.

    Depends on the magnification.

  • Removed user
    June 15, 2023, 7:38 p.m.

    Terse and, no doubt, to the point - which I didn't get.