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  1. #1

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    Eye glasses and manual focusing

    I wonder if I'm seeing things or if this is really the way it is....

    I have been having problems with manual focusing. It's not that it's impossible but it's harder. I don't see the images in view finder as crisply as I'd like making the split prism image more difficult to match exactly.

    I wear bi-focal eye glasses. I have several. I also have single vision eye glasses. They are made to the same power. (the distance part anyway)

    It seems single vision glasses offer more crisp view of the view finder, and more importantly, the split prism part. I can focus little easier than when I'm using bi-focals.

    Do others have the similar experience?

    I'm thinking, since bi-focal are two lens with varying focal length in one, and mine is progressive, which makes the transition part continuously variable. Wouldn't it make this glass more less have aberration characteristic where not all rays focus at the same point?

    Anyone else notice this?
    Develop, stop, fix.... wait.... where's my film?

  2. #2
    Sirius Glass's Avatar
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    Contact lenses work well except when I am working with the LF ground glass. Then I slip on much stronger than usual reading glasses.
    Warning!! Handling a Hasselblad can be harmful to your financial well being!

    Nothing beats a great piece of glass!

    I leave the digital work for the urologists and proctologists.

  3. #3

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    Really? Contact lens actually have softer image than glasses. My optometrist have been telling me this and I can confirm it too. My problem isn't the magnification of the images. It's really an issue with crispness, sharpness, and clear edge contrast.
    Last edited by tkamiya; 07-08-2011 at 07:57 PM. Click to view previous post history. Reason: clarified description of the problem
    Develop, stop, fix.... wait.... where's my film?

  4. #4

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    Ok, I have bifocals, old style lined ones. To see the viewfinder clearly, I made a +1.25 diopter lens from a pair of dollar store reading glasses and put the lens in a normal diopter lens carrier. Did this for both the F3 and the F's and Nikkormats. Works like a charm.

    I just stood 1 meter away from the glasses stand and looked thru various reading glasses while wearing my regular ones to see what power was needed for a nice sharp view of the test block of text on the stand.


    Most distance parts of bifocals are not set for infinity, but a much closer distance.
    Bob

  5. #5
    Neanderman's Avatar
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    For MF, I have to focus using the built-in magnifier; for LF, I use reading glasses. It's 35mm that I don't have a good solution for. I'd buy some diopters, but they don't make them for my cameras anymore and they are pretty much impossible to find used. :-(

    Ed
    "I only wanted Uncle Vern standing by his new car (a Hudson) on a clear day. I got him and the car. I also got a bit of Aunt Mary's laundry, and Beau Jack, the dog, peeing on a fence, and a row of potted tuberous begonias on the porch and 78 trees and a million pebbles in the driveway and more. It's a generous medium, photography." -- Lee Friedlander

  6. #6
    Sirius Glass's Avatar
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    I see much better with my soft contact lenses that my bifocals or trifocals; distance, contrast, crispness, sharpness ... With the right reading glasses, reading is no problem. With 35mm and MF I do not need reading glasses. I do not need reading glasses with the Graflex [SLR] and the Speed Graphic. I only need strong magnifiers for the critical focus with the Speed Graphic when I am using the ground glass for focusing and shifts, raises and tilts.

    Steve
    Warning!! Handling a Hasselblad can be harmful to your financial well being!

    Nothing beats a great piece of glass!

    I leave the digital work for the urologists and proctologists.

  7. #7

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    Steve,
    Do you have no-line progressive or lined ones?
    Develop, stop, fix.... wait.... where's my film?

  8. #8
    Sirius Glass's Avatar
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    Quote Originally Posted by tkamiya View Post
    Steve,
    Do you have no-line progressive or lined ones?
    Both. I prefer the progressives but I do not have a problem using lined glasses.
    Warning!! Handling a Hasselblad can be harmful to your financial well being!

    Nothing beats a great piece of glass!

    I leave the digital work for the urologists and proctologists.

  9. #9

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    Well, just having gone through this same problem, I will attempt to give you an answer. After age 40, or so, the lens of your eye loses its elasticity and, therefore, loses its ability to focus closely. That is called "Old-age Farsightedness" or Presbyopia. There is no way to tell just how farsighted one will end up, but it may be a while before it settles down to the final stage.

    Camera manufacturers usually build SLR viewers with an apparent distance of 1 meter. That works fine for normal eyes that can adjust, but works poorly for eyes that are farsighted and cannot adjust/acomodate.

    If you are not too farsighted, you can sometimes get cameras with adjustable dioptric correction in the viewfinder. If you are further out, or your camera is not adjustable, you can get add-on viewfinder diopters.

    Another way is to go down to the Five-and-Dime or bargain store, or drugstore and buy a cheap pair of reading glasses. Take your camer with you and keep trying different corrections until you like the picture and can focus correctly. I needed to use about a +2.50 for an SLR and about a +1.50 for my Hasselblad waist-level finder. Your numbers may very well differ, but the correction will always be +, unless you are nearsighted. In addition, bifocals and continuous-change glasses suck, in my opinion.

    My real break came when I had to have cataract surgery. At that time, one is expected to state how they want the final view to look. Since I had been extremely nearsighted, they offered to let me return to that since I had been so for so many years --or-- they offered to correct my vision for normal distance visions, for which I would wear reading glasses for close work. I elected to be farsighted; they installed the lenses, and I ended up very slightly closer than that. I am about 1 Diopter nearsighted and that works well on SLRs and I can use +1.50 reading glasses for my waist-level viewfinders.

    My optometrist was very good in helping me find the right correction for my cameras when I went there. I dragged my cameras with me to the eye exam and explained what I wanted. She understoon perfectly and, in short order, had me happy.
    Geo.

  10. #10

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    Geo,

    Thank you very much for your detailed response. Much appreciated. My problem is little different. I'm near sighted but recently, I acquired some far sightedness. The latter part isn't that bad yet. With diopter corrections I can bring the view finder in focus, as well as those little indicators in the view finder. I can also bring the split prism in focus.

    The real problem starts after that. Although those things in view finders are in focus, they lack clearly defined edges. When I bring two parts of split prism together to get it to focus, rather than looking like two crisp images matching, they look like two Twinkies coming together. (well, not nearly that bad, but I hope you get the idea...) Edges are soft - fuzzy - not-clearly-defined.... which makes it difficult to attain exact focus.

    I was thinking for a while, and I thought - well - this looks like soft focus lens! So I started to think some more. Someone explained to me how soft focus lens actually work. Not all rays come together at a point. Well, that's exactly what bi-focal glasses do, and mine is progressive.

    Then, I switched my glasses to a single focal one. It's a little better....

    I was wondering if others experience the same.
    Develop, stop, fix.... wait.... where's my film?

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