Diopter correction, a note.

Discussion in 'Medium Format' started by celasun, Aug 26, 2010.

  1. This is in fact a note, not a question.
    The information below is present buried in the forums and elsewhere; I just wanted to make it easily reachable.
    I have replaced the viewfinder lens on my Pentax 67 with another one made by an optical technician (within minutes).
    The lens is just a circular piece of glass held in place by two rings. It has nothing integral to it.
    The price of diopter correction lenses (of original equipment manufacturers) is rather too high and they may be difficult to find especially for older cameras. Mine was not available, for example, at the auction site.
    You loose absolutely nothing by replacing them with a locally available source. The price for mine was less than USD15. If you require a coated one that may be slightly pricier! However, I do not really think the coating is critical for viewfinder lenses.
    Focusing is so easy now :)
     
  2. That is a BRILLIANT post.
    Been struggling focussing my 67 and now realise that getting a diopter was almost impossible. Although I did hear that a Nikon viewfinder diopter may fit. Unsure from which body though.
    Thanks for passing that on Bulent
     
  3. Good tip indeed, Bulent.
    I have done the same with my prism finders (other brand camera): have an optician order and grind to size correction lenses to suit my eyesight.
    A well-staffed shop selling eye-glasses/spectacles will be able to measure the diopter power of the lens in the eyepiece (it has to come out, of course) and then it is easy to add or subtract the correction you need (which they can measure too), get the catalogue, and order a suitable lens. When it arrives, all they have to do is grind it to the correct diameter.
    It all takes less time then trying to find the correction lenses camera makers once offered.
    Cheap. Matched to your needs. Yet the same quality as the more expensive eyepiece lenses camera makers sell.
     
  4. Rollei 6000 series: round diopter for waist level finder
    I'll add my bit to Bulent's post. The diopter itself press-fits into a plastic holder, the holder in-turn fits into the finder. Removing the dipoter out of the holder simply requires gently working the plastic ring loose using your fingers. Make small movements to separate diopter/ring: reverse procedure to replace.
    Follow Bulent's advise to correct the dipopter, an alternative to finding an original, Rollei diopter.
    Joe
     
  5. Clive, the eyepiece lenses from Nikon will not fit the Pentax 67. I have plenty of round Nikon eyepieces, and they come in several sizes. None fit the Pentax. Some are close, but the threads are too shallow to mesh with the threads in the prism. They may even be the wrong pitch, but that hardly matters.
     
  6. A pair of discarded plastic-lens, reading glasses with the desired diopter effect and patience has fixed the needed correction on a number of my old film bodies.
    A very fine toothed saw and a small file or finger nail sanding board can be used to shape the center of the lens to a press fit in the view finder frame. A little rubber cement or silicon sealer helps to ensure the insert 'stays inserted'.
    After a little trial-and-error, I can get two 'inserts' from each plastic lens and the cost is nil.
    H2
     
  7. I applaud all these clever alternative solutions for dioptre corrections.
    But as a glasses wearer (moderately short-sighted), I've never gone down the dioptre correction route on my camera viewfinders. Sure, I could add a correction lens to my Mamiya(s) and this would free me from needing to wear my specs when looking in the viewfinder; but then I wouldn't be able to see anything around me except through the camera viewfinder! That, to me, would be too debilitating. So I have to ask, out of curiosity: why do you folks choose it?
     
  8. One the internet one can order a custom set of glasses for 39 dollars. That is the frames; 2 lenses and case. One can just cut the plastic lens out of the eyeglass lens.
     
  9. Ray,
    >but then I wouldn't be able to see anything around me except through the camera viewfinder!
    I wear glasses as well. However, I can see things relatively clearly without them as long as the objects are not "close".
    So, without glasses, I can hardly read a book or look at a PC monitor. Viewfinder images seem to be at an arm's reach distance, where my eyes fail to focus (that is why I need diopter correction). Anything farther, I see -almost- normally...
    With my multifocals, I simply can not focus.
    This may have something to do with the differences in our -sightedness, I believe.
     
  10. Yes, wearing "old man glasses" I did exactly the same thing on my pentax 6x7 prism, because with this camera :
    1/ the metalic eyepiece tended to scratch my spectacles
    2/ looking through them (spectacles) I could not approach enough to see the full frame in the viewfinder
    Once by curiosity, I measured where the eyepieces of my 35mm SLR cameras located the image of the groundglass : more or less around 80cm (any brand). This is all right with young eyes accomodating down to a couple of decimeters, but not for my old man "fix-focus" eyes. I did not correct the eyepiece of all my cameras, so most of the time I have to "viewfind" through my reading variglasses. But with my Pentax 6x7, as I said, I had to take the other way.
    Paul
     
  11. I'm so longsighted now that my near point is in the next county, so this is a really useful tip. Finding correction lenses for my Canons is impossible.
     

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