Nikon F Diopter

Discussion in 'Nikon' started by brian_donaldson|3, Jan 2, 2018.

  1. This question is not about the weird way Nikon's corrective lenses work. I already did the reading glasses trick and found the right diopter for me. This is about the Nikon F Eye Level finder and getting the correct sized frame.

    I have seen three different examples of the eye level finder. One, might be newer, uses the round frame. One, uses the rectangular frame. And one uses an almost square frame. My eye level finder uses a rectangular frame. However, my Photomic FTn uses a rectangular frame with round threads. So the diopter I have for my F2 fits fine in the FTn. But it will not work on the eye level finder.

    Does anyone here have the F eye level finder with rectangular frame and using a corrective lens (not eye glasses). The frame size is .975" x .75" (24.73mm x 19.05mm). Or have a Nikon camera that has that size frame for the eye piece?

  2. There is a very hard to find adaptor that slides over the rectangular viewfinder and will allow you to use the 19mm diopter. Use the link to see.

    Eyecup Adapters for Nikon F
    Last edited: Jan 3, 2018
  3. Sandy Vongries

    Sandy Vongries Moderator Staff Member

    The F, F2, and Nikkormats up to the ELW take a round threaded diopter with a 19mm diameter. A rubber eyecup will fit over the rim of the diopter. I physically checked Nikons in hand. The Nikon / Nikkormat Handbook says that diopters were available from -5 to +3. The F3, F4, F5 and DF share a similar larger eyepiece which comes with a rubber cover, though all are adjustable for photographer vision.
  4. Sandy, like I said above, not all the F eye level finders had round windows. There are three examples that I have seen like I mentioned. My F2 and my Photomic FTn all have round viewers, but my F prism does not.

    Graham, thanks for that info. So something does exist for the F with the rectangular frames. The search is on!
  5. The eye level I have has two grooves down the side, and I'd hoped that a cup from a "standard" rectangular finder(as used on cameras as old as the EM to as new as the D750) would fit. If it would, that would make life very easy as Nikon also makes diopters that fit those finders directly.

    Unfortunately, both the eye level and Photomic(also rectangular) that I checked are too wide for that.

    With that said, it seems CLOSE to the size finder used for a lot of Canon cameras including the A-series and T-series. Unfortunately, I don't have a cup for one of those readily at hand to check. I'll try some measurements tomorrow. If it does fit, diopters are also available for those cameras. They aren't as easy to find as the Nikons, but are out there.
  6. False alarm-sort of.

    I found a Canon cup and it doesn't QUITE fit, but it's closer than a standard Nikon. It MIGHT be possible to modify a cup/diopter to fit.

    I got excited for a moment as I found an aftermarket cup I never really liked, but it's on a metal frame and can take a screw-in eyepiece inside the cup. Since round eyepieces are nearly synonymous with Nikon, I thought it MIGHT take a standard Nikon screw in. It's too big for a non-HP screw in(F, F2, F3 non-HP, FM series, FE series) and too small for an HP screw-in(every pro camera F3HP and newer). Instead it takes-big surprise-the screw-ins for the Canon F-1. The metal base of the cup would probably be easier to modify, and F-1 screw-in diopters are also available.
  7. The best solution is to obtain an F finder with the round threaded ocular. Shouldn't be terribly expensive.
  8. Unfortunately, the metered finders haven't necessarily held up that well. The Photomic, IMO, is the least desirable for use as it lacks TTL metering(although I have used one sucessfully) and only gives you basically 35mm or 85mm equivalent coverage. The T and TN are a pain since you have to manual set the maximum aperture. The FTN is the best user, but it is functionally identical to the DP-1(F2 Photomic) and suffers from the same problems like "jumpy" needles and lost sensitivity. All of them were designed for one or two mercury batteries, which brings its own problems.

    This combined has driven up the value of eye level finders quite a bit as folks prefer the "clean look" to the camera and completely undistracted view. They tend to be less expensive bought as a complete camera, but short of oddball Fs and the desirable collectible ones(low SNs, red dots, high condition black) they tend to be the most expensive.

    I'm not EXACTLY sure when the eye level switched over to a round eyepiece, but I'd guess it's right around the time the metered finders did also. That means the Photomic T. Regardless, though, from my observation the round eyepiece eyelevel is the least common. A guess would be that, by that point, the metered finders had become good enough and inexpensive enough that most buyers opted for them over the plain eye level.
  9. I gave up looking for an adapter. I thought about the DK-22 but didn't want to waste anymore money.

    As mentioned above, the best course of action is to just get a complete F that has the eyelevel round frame. That is what I am doing. I have an eyelevel with a rectangular frame and it is in superb condition. I plan on listing it on eBay when the other F arrives. So that will make it 2xF and 2xF2. Whoot. LOL
  10. Its a good thing you did not waste any more money on a DK adapter, because they are not quite the same size, though they look close. The appearance is quite similar to the ones shown on the Destoutz link above, but not the size.

    Measuring the width of the recessed portion of the rectangular finder, onto which the adapter must slide, I find the following:

    The DK 22 and its ilk that fit the D7100, FM10, D3200, etc. have a slot that is just about an even 22 mm. wide.

    That in an early F is 23.7 mm. wide. A DK adapter will not fit. The outer edge of both these is about 25 mm wide, but the groove in the old F is quite shallow, and also looks to be a little narrower, and I suspect it would work best with a metal adapter. It's possible one could file down a DK-22 but I have not tried it, and suspect it would never be a really comfortable fit.

    That for a Yashica or Contax, which also fits a Minolta and at least some Pentaxes, is 19 mm. wide. The outer edge of a Minolta is about 24 mm. I no longer have a Pentax to measure, but I do recall that the Contax magnifier which fits that Minolta also fit whichever Pentax it was that had a square finder. It's a handy interchange if ou have one of those cameras, but not much use for Nikons.

    I don't have a Canon camera, but for some reason I seem to have a Canon eye cup, and that is a bit over 18 mm. wide. That cup fits nothing I have.

    Though Minoltas used a slide-on magnifier and other attachments, the diopters were rectangular and snapped into the inside of the eyepiece. While it looks as if such a diopter might fit in the eyepiece of an old F it does not, though if you had one around you might find it possible to file it down and jam or glue it in, but likely not a good solution either.
  11. Info
    Here's a 2004 Nikon reference on the eyepiece diopters:
  12. Note in the above that the square eyepiece F is not listed. Also that, although designs changed and some have rubber rings or locks and some do not, there are actually only two different sizes of threads. The smaller ones, 19 mm., for the Photomic F, Nikkormat, and through the F3, and the larger ones that fit the F3HP and later models with high eyepoint finders. Some later models such as the FM-3a used the smaller thread. So, for example, you can actually use the diopters from an F3HP on an F100. The DK-22 adapts later square eyepieces to the smaller thread. The far right column in blue is for the later square eye pieces, which will fit unlisted later digitals such as the D7100 as well. Not shown here is the FM-10 which has a square eyepiece unlike other FM's

    Here's another link that looks as if it does a good job of sorting all this out:

    through the Nikon F-Mount - Viewfinder accessories
  13. As Matthew said, the above probably covers a lot more detail than necessary.

    I essentially there to be three "classes" of screw in eyepieces-the low eyepoint ones used on the F Photomic T-F3 along with Nikkormats, ELs, and FM/FE/FA cameras, the "HP" type used on the F3HP, subsequent single digit Fs, and D1 series cameras. The third, which really is a minor distinction, is the "locking" HP ring used on the F6, D2 series, and all subsequent round eyepiece DSLRs. The non-locking rings will fit on locking cameras, although I've never tried the reverse.

    I've never really played with the eyepiece on my N8008s or N90s, but I always thought they seemed the "small" size. I know the F100 is the HP size, so I guess it's indeed the HP size.

    In any case, I have a cheesy eyecup I bought for my T90, and I think this is the same

    Hoodman Glasses Model Hoodeye Eyecup for Canon 18mm HEYEC18G B&H

    It has a metal frame, and is close enough to eyepiece on my F that it could probably be modified. The cup can be pulled off, and the one I have will take screw in eypieces for the Canon F-1(all versions). Diopters for F-1 aren't as plentiful as the Nikon ones, but are out there.
  14. I think for the FM10/FE10, the reason it is odd man out is that they were not made by Nikon. But made for Nikon by Contax.
  15. Made by Cosina; Contax is not a manufacturer but a brand name.
    brian_donaldson|3 likes this.
  16. LOL I knew that. Just checking to see if you were paying attention. (I also knew I had the wrong name but couldn't remember Cosina... thanks for the correction).

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