Lenses with quarter click stops?

Discussion in 'Casual Photo Conversations' started by stuart_pratt, Mar 20, 2019.

  1. I’ve been reading an old copy of Amateur Photographer from 1997, containing a review of the Leica R8 by a photographer who found the Leica lenses annoying because they only had a half stop aperture control, whereas he wanted quarter stop detents. Maybe I don’t move in the right photographic circles, but as far as I can recall, no lens I have ever owned had quarter stop detents, so my question is, which ones do ( or at least did in 1997). TIA
     
  2. William Michael

    William Michael Moderator Staff Member

    Interesting question.

    My first thought is the reviewer was acting the goat.

    I have never seen nor heard of any format lens with 1/4 Click Stops, but am forever interested in learning something new, especially an oddment.

    I guess that if the throw of the aperture ring on (for example) a large Cine Lens was relatively long, then you could make a reasonable estimate of 1/4 Stops, but they're not clicked.

    WW
     
  3. Maybe not quarter stops, but plenty of lenses had continuous stops.
     
  4. AJG

    AJG

    Several of my large format lenses have 1/3 stop markings but no click stops for any settings. I think that other issues (consistent shutter speeds, slight changes in flash output, etc,) would render this a minor concern.
     
    William Michael likes this.
  5. I must admit that fairly obvious possibility was one I had overlooked, somewhat to my embarrassment. The review is quite dry and literal, but the reviewer was a long standing Contax user, and you know what those guys are like!
     
    William Michael likes this.
  6. Zeiss lenses for Sony and Leica typically have 1/3rd stop clicks. That is also an option for Sony cameras and lenses which have no aperture ring (also for shutter speeds). AFIK, diaphragm settings on manual lenses could always be split between stops. You could do that with shutter speeds on Leica M cameras throughout most of the range. LF aperture settings were continuous too, but non-linear, making them harder to interpolate.
     
  7. William Michael

    William Michael Moderator Staff Member

    Haha! That made me smile...

    Probably you were reading the article about film cameras with your 'romantic' hat on, however simply had brief and cold facts presented to me - easier for me to have my 'circumspect' hat on.

    WW
     
  8. Actually, after I posted this, I looked back at the article, and it goes on beyond that, to the effect that ' I can assure you that many cameras do have this function' with no hint of irony at all. Odd. All I can think is that rather than referring to lens stops, he was referring to shutter speeds giving the same option (i.e quarter stops). This is much more common nowadays with digital cameras but back then, I think the R8 had full stop shutter speed scale.
     
  9. As a veteran photofinisher, I can attest to the fact that it is daunting task to maintain 1/6 f-stop limits on a film processor. Such tight control requires due diligence few labs are willing to exert such effort. As to film manufacturing, maintaining the ISO from batch to batch to 1/6 f-top is equally daunting. Now let’s look at the precision needed to adjust the iris of a camera and maintain 1/3 f-stop correctness.

    Now let’s examine the iris diameter setting for a 50mm lens. Set the 50mm to f/8, the working diameter is 50÷ 8 = 6.25mm. Stop down 1/3 f-stop, the f-number is f/9 = 50 ÷ 9 = 5.55mm, 1/3 more stopped down = f/10.1 = 50 ÷ 10.1 = 4.95mm, 1/3 more stopped down = f/11 = 50 ÷ 11 = 4.55mm.

    Let’s list these working diameters: 6.25mm --- 5.55mm --- 4.95mm --- 4.55mm. Now consider the gear train precision needed to make these diameter changes. Again, the mechanical precision to do this in 1/3 f-stop increments is formidable. If you make the increment 1/4 of an f-stop, the task becomes problematic.
     
  10. 0.110 mm range is not exactly a challenge for a reasonably precise mechanism like aperture control. Accuracy within 0.02 mm is reasonable, even sloppy by machine tool standards.
     
  11. If someone said an old copy of a photography magazine, I would think 1960's or so. DSLRs that I know of have 1/2 or 1/3 stop, usually selectable, for the electronic aperture wheel. I think I can count to two or three, or four or six, to change by one or two stops. Four or eight sounds harder.
     

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