NikonGear'23
Gear Talk => Camera Talk => Topic started by: Frank Fremerey on July 25, 2016, 12:43:29
-
OK. I now want to buy or have made the diopter correction for my FM2. My fathers knows some online shops where they sell these prefabricated for cheap.
I will just have to buy one, use one of the original nikon screw in lenses as a donor for the 19mm-ring and done.
But now: how do I find which strength I really need?
My idea:
I could count the clicks on the D600/D3/D500 until I get the best result with the builtin correction.
Can I use this value(s) to deduct the best coorrection for the FM2 screw in diopter???
Please help.
Thank you!
-
I got 16 clicks on the D600. If I turn the knob completely to the left and click clockwise I am best at click #9
I got 6 clicks on the D500. If I turn the knob completely to the left and click clockwise I am best at click #3
I got 12 clicks on the D3. If I turn the knob completely to the left and click clockwise I am best at click #6
what is the range and what are the steps?
Sitting in front of my computer screen I need a chapo correction of +1.5 will do
Reading a book or on a smartphone my expensive custom glasses +2.25 are much better
-
OK. I now want to buy or have made the diopter correction for my FM2. My fathers knows some online shops where they sell these prefabricated for cheap.
I will just have to buy one, use one of the original nikon screw in lenses as a donor for the 19mm-ring and done.
But now: how do I find which strength I really need?
My idea:
I could count the clicks on the D600/D3/D500 until I get the best result with the builtin correction.
Can I use this value(s) to deduct the best coorrection for the FM2 screw in diopter???
There is a table at https://support.nikonusa.com/app/answers/detail/a_id/639/~/viewfinder-diopter-adjustment
From the table, if your prescription is +2-ish you need the +1 correction lens. If you have a lot of astigmatism that will only correct the centre of the field - but that should be fine for focusing.
-
I bough the
0 and the +1
They do not work.
I need a custom made glass.
-
Any idea of how to deduct the value from tze clicks?
How much correction per click???
-
The camera manual provides the dioptre range. Assuming a linear relationship, just divide by the total clicks to get an estimate of delta dioptre per click.
-
You could bring the camera to an optometrist. Explain/demonstrate your needs and the 'apparent distance' idea. I have seen Optos that have small handheld test lenses that could be held between the finder and your eye.
-
Hi Frank,
I really hope you'll soon find the right diopter. Bringing it to the optometrist could be worth a try.
Cheers Daniel
-
Thank you Bjørn. I assumed a linear relationship, but...
Trouble is the lenses are glued to the screw in aluminium...
-
Frank,
You need a correction lens for an optical viewing distance of 1.0 meter (39.37") for a Nikon or Nikkormat from the Nikon F to the Nikon F5 and FM/FE family to the FM3a. The F and F2 and FM/FE to the FM3a all use the same size. The finders on all of these are without a correction lens -1. If you needed a custom made 0.0 diopter correction you would add a +1.0 diopter (not Nikon's +1) as -1 +1 = 0.
If your ophthalmologist or optometrist told you that you need a +1.5 diopter correction to view an object at 1.0 meter you would need a generic +2.5 diopter eyepiece (+2.5 -1 = +1.5) not Nikon's 1.0 or 2.0. Nikon's eyepieces are marked with the combined diopter as in -1 (body) +1 eyepiece is marked 0.
If you call your ophthalmologist or optometrist he/she can calculate the correction you need for 1 meter. Then you factor in the standard Nikon -1 diopter if having a custom eyepiece made or ignore it if buying a Nikon eyepiece. The fly in the ointment is astigmatism. If your persecution includes astigmatism it will include cylinder if I remember correctly. If it's slight it can probably be ignored. If it's strong it's a problem. The astigmatism corrected eyepiece will have to be aligned correctly and it will need to swivel 90 degree for horizontal and vertical. Marty Forscher did a modification for a Nikon F2 or F3 for a swiveling eyepiece for astigmatism. I think there is a link here at NikonGeard.net showing a camera with this modification.
I have a Hasselblad 500CM with NC-2 Prism and a custom eyepiece ordered and delivered by my ophthalmologist with astigmatism correction. The Hasselblad 500CM has a mind controlled rotating back so the camera is never turned. With that eyepiece and an Acute-matte D screen the viewfinder is as pleasant to view and focus as my Nikon F3. I couldn't focus it with the standard eyepiece in the NC-2. I had to take the NC-2 off to focus.
Talk this over with your ophthalmologist or optometrist. I hope this helps...
Dave
-
I bough the
0 and the +1
They do not work.
I need a custom made glass.
Can you try a Nikon +2 at a camera dealer? You may need a +1.5 or maybe something like a +1.25 with astigmatism correction. As suggested above you might take the camera with you to your eye specialist.
Dave
-
Dave. Thank you. Ok. And if I get the right lens, how do I mount it?
My father says it is 80 Euros machine setup cost to manufacture the 19mm screw in ring without without the lens.
It is much easier and cheaper for me (20 Euros) to get the Nikon +2 and try it.
-
The old F diopters I have appear to have the glass elements swaged in. In other words, the inside edge of the brass shell is crimped over the edge of the glass to hold it in. If it costs that much to machine a new ring, I suspect you'd be better off buying one even if it comes out wrong. If it does not work, punch the glass out and use the frame. If you can't swage it again, glue it.
-
May be there is a half way house approach - take an old Nikon eye piece and have the machinist / lathe operator carefully machine away the swaged area of the eye piece and prepare a seat for the new prescription lens, which can then be glued in. Alternatively the machinist could cut a groove for a retention ring or circlip. Since no fine thread cutting is involved with this approach, machining costs should be significantly reduced.
In my case, my left eye is significantly better than my right eye, and sometimes I use it instead of the right eye when I am trying to achieve critical focus. It is awkward, but doable. Might be worth trying if that is also true in your case - at least it might give you an indication of whether it is an eye issue or a camera issue that you are dealing with.
Good luck.
-
Excellent, technically coherent suggestions in the preceding posts.
There is one ultimate alternative: Get a film cam that is HP finder equipped and shoot with your glasses on.
-
Thank you all. It would help to know which glue Nikon uses in these 19 mm screw in diopters.
Then it should be easy to find a solution dissolving the glue in a non destructive way.
if I then know the exact diameter of the lens I can order a prefabricated one and glue it in.
-
Feank,
I shoot through my glasses for several reasons. I have astigmatism in both eyes. The left is better than the right. I get astigmatism correction through the distance area of my glasses. At 65 I can no longer read the LCD on the top of a dSLR. I must use the bifocal area to view the LCD and other controls. I used to have no problems focusing an FE2, FM2n, F3 or F5. I may need a correction eyepiece now. I use the built in diopter correct in my D800 and D300s.
Have you tried shooting through glasses? It might help. Also check the standard eyepiece as I believe the glass is held in with a steel "C" ring (not sure what to call it). I believe it can be fetched out with the eye end of a fine needle. If I used a diopter with my glasses I'd have to replace the clear glass in the standard eyepiece with the diopter lens. You might do the same. It's something you might try.
Best,
Dave
-
Frank,
You need a correction lens for an optical viewing distance of 1.0 meter (39.37") for a Nikon or Nikkormat from the Nikon F to the Nikon F5 and FM/FE family to the FM3a. The F and F2 and FM/FE to the FM3a all use the same size. The finders on all of these are without a correction lens -1. If you needed a custom made 0.0 diopter correction you would add a +1.0 diopter (not Nikon's +1) as -1 +1 = 0.
If your ophthalmologist or optometrist told you that you need a +1.5 diopter correction to view an object at 1.0 meter you would need a generic +2.5 diopter eyepiece (+2.5 -1 = +1.5) not Nikon's 1.0 or 2.0. Nikon's eyepieces are marked with the combined diopter as in -1 (body) +1 eyepiece is marked 0.
If you call your ophthalmologist or optometrist he/she can calculate the correction you need for 1 meter. Then you factor in the standard Nikon -1 diopter if having a custom eyepiece made or ignore it if buying a Nikon eyepiece. The fly in the ointment is astigmatism. If your persecution includes astigmatism it will include cylinder if I remember correctly. If it's slight it can probably be ignored. If it's strong it's a problem. The astigmatism corrected eyepiece will have to be aligned correctly and it will need to swivel 90 degree for horizontal and vertical. Marty Forscher did a modification for a Nikon F2 or F3 for a swiveling eyepiece for astigmatism. I think there is a link here at NikonGeard.net showing a camera with this modification.
There is a -1 lens in the viewfinder that creates an enlarged virtual image of the ground glass screen which appears to be at 1m. If you can focus at 1m, the virtual image is in focus.
The piece of glass you can take off and replace is not the -1 lens, although, colloquially, we call it the viewfinder (and Nikon's description is confusing, which will surprise no one who has ever read a Nikon manual). In the case of the FM2/3 that piece you can take off and replace is plain glass. In most Nikons the piece you can take off and replace includes adjustable elements, but that makes no difference in this context.
You do not subtract -1 from your prescription to get the corrective lens power.
Spectacle prescriptions for "close" focus use reading distance - 0.3m or so. Two diopters long-sightedness means the closest the person can focus is 2m, so a +2 lens enables them to focus at zero distance. A +1 lens enables them to focus at 1m. Nikon's table is correct, and they do not mis-describe their corrective lenses.
Astigmatism should not be the problem, because Frank is complaining about focusing, which is done in the centre of the image. Astigmatism would affect the sharpness of the metering indicators at the periphery, but reading the +/0/- indicator on the FM2 does not require it to be sharp.
-
I cannot see anything with glasses except for the very near field.
My right eye is too bad to use for photography so I had to switch to left eye shooting.
I can see anything beyond one meter sharp and clear.
So shooting with glasses seems impractical. I need to get a feel of the scene before I decide how to frame.
That means glasses off. Then I would have to put the glasses on, take the camera, shoot, get rid of the glaases
again. No. Better adapt the camera. The F6 might be better for me than the FM2 though.
-
The retaining "thing" is probably best called a retaining spring. It not really a "C" but almost a complete circle. The FM/FE family of cameras use a retaining spring in the standard eyepiece with rubber protection for glasses. The Nikon F3HP (DE-3) and F5 (DP-30) standard eye piece also use a retaining spring. The F3 (DE-2) does not use a retaining spring. I'm not sure who the glass is held in. The rubber eye glass protector could be use with a diopter eyepiece on the DE-2. It would simply slip over.
For the way I focus, anywhere on the ground glass of a B/E type focus screen astigmatism is an issue.
Dave
-
You do not subtract -1 from your prescription to get the corrective lens power.
If I can think at this hour this is correct if buying a Nikon diopter eyepiece. I'd have to search and don't know if I'd find it but my father used a "0" diopter eyepiece which if you looked through it one could see it as a slightly positive diopter, i.e. +1. I don't think I've ever owned a corrective eyepiece as I never needed one in the past. I remember filling down an edge on my father's eyepiece so it would fit a Nikkormat FTn. Later he owned a Nikon FE2. I might find a "0" diopter eyepiece for his FE2.
OK, I'm going to make a hot drink and go to bed. It's 2:01 AM here in California.
Best,
Dave
-
Yes, you are right, the standard eyepiece has a retaining spring. Very good. Wee can use that as a screw in frame.
The ZERO is +1 (see link above) and I got it, the PLUS ONE is +2. Both do not work for me, neither does the standard eye piece.
SOOOOO ... now I still have to find the strength I need.
-
Nikon D3 Diopter Adjustment range -3 to +1
12 clicks over 4 diopter values means 1/3 split (best in red)
-3 -2,66 -2,33
-2 -1,66 -1,33
-1 -0,66 -0,33
0 +0,33 +0,66
+1
-
Nikon D600 Diopter Adjustment range -3 to +1
16 clicks over 4 diopter values means 1/4 split (best in red)
-3 -2,75 -2,5 -2,25
-2 -1,75 -1,5 -1,25
-1 -0,75 -0,5 -0,25
0 +0,25 +0,5 +0,75
+1
-
Nikon D500 Diopter Adjustment range -2 to +1
6 clicks over 3 diopter values means 1/2 split (best in red)
-2 -1,5 -1 -0,5 0 +0,5 1
-
OK. Now we got -1 as the right value, and that fits well together with the fact that -1 is the FM-2n diopter setting without correction (better without the standard eyepiece) and that is the best for me, while still not good as in: "I can easily and safely acquire focus"
What next?
-
For me the right diopter setting is often fuzzy, something that changes from day to day and I cannot tell to a one click precision where the best setting is. Is it more accurate for you?
-
For me the right diopter setting is often fuzzy, something that changes from day to day and I cannot tell to a one click precision where the best setting is. Is it more accurate for you?
In the early morning it is a bit fuzzy sometimes, quite stable during the day. With the finer diopter settings it is not perfect to say wich is the best. Sometimes it can be one click more or less.
-
The FM2n and FE2 have a 0.86x finder magnification with a 50mm lens focused to infinity. This is as easy as it gets to see to focus. One can use the standard K2, B2 or E2 screen or the darker FE series or brighter FM3a series of focus screens. Exposure compensation is needed to switch between the K/B/E series and the K2/B2/E2 series. I don't know about the FM3a screens.
The FM3a offers 0.83x and K3, B3 and E3 screens.
The F3 (DE-2) offers 0.80x with more eye relief (higher eyepoint thought not "HP") and the advantage of the older F/F2 type darker screens or the F3 Red Dot screens which are brighter.
The Nikon F3HP (DE-3) offers a 0.75x finder magnification with higher eyepoint than the F3. Critical focus is a bit harder for me because of the lower finder magnification. I prefer the F3 (DE-2) even though I ware glasses.
I believe the eyepoint is in the same order as the magnification with the highest magnification offering the lowest eyepoint.
---
If one can't tell which of two clicks on a dSLR is best this may be because the best diopter is something in between.
---
Changing visual ability from day to day? I'd see an ophthalmologist to find out if there is an underlying problem with the eye that needs medical treatment. I would not worry about the first few minutes after waking up.
Dave
-
I can see the red LEDs are unsharp. Always.
-
I can read red digital alarm clocks at night without my glasses but I had to return one that was blue because it fuzzed out and was totally useless for me. As I remember my mother could read a blue alarm clock but not a red one, just the reverse. I'm not sure of the reason but I think it's something specific to one's eyes.
Dave
-
Dave. I guess the click-correction in my other cameras do not correct for astignatism.
The information in the VF is displayed in white for the D500 and green for the D3 and D600.
my current guess is that I am 0.5 dioptrien off from -1, the base setting.
which could it be?
+0.5 or -0.5???
-
Dave. I guess the click-correction in my other cameras do not correct for astignatism.
The information in the VF is displayed in white for the D500 and green for the D3 and D600.
my current guess is that I am 0.5 dioptrien off from -1, the base setting.
which could it be?
+0.5 or -0.5???
-
I can read red digital alarm clocks at night without my glasses but I had to return one that was blue because it fuzzed out and was totally useless for me. As I remember my mother could read a blue alarm clock but not a red one, just the reverse. I'm not sure of the reason but I think it's something specific to one's eyes.
Dave
I noticed the same phenomenon with the "blacklights" (long wave UV lights) we played with way back in the 1960's.
Deep red or deep blue come to focus at different distances from the same lens. Yellow/green or white light should sit in the middle. I was/am farsighted(shorter lens-to-retina distance), so I could focus on the deep blue light, but it didn't happen with deep red.
-
Dave. I guess the click-correction in my other cameras do not correct for astignatism.
The information in the VF is displayed in white for the D500 and green for the D3 and D600.
my current guess is that I am 0.5 dioptrien off from -1, the base setting.
which could it be?
+0.5 or -0.5???
I advise against guesswork, and for empirical discovery.
Find an optician that has small hand lenses in 0.25 diopter values, or order some cheap plastic lenses from a science supply house.
The optician is better because they can deal with astigmatism and intelligently advise you. Your 1.00 astigmatic value(as I recall) is serious enough to annoyingly blur your vision if it isn't brought into the calculations.
-
I have been to and mortar optician today. We measured and tested.
Result: focussing on objects less tan 2 meter from the camera +0.5 helps. But: focussing on anything beyond
the correction disturbs my focussing.
So: for near objects I should get a chepo +0.5. For far object I do not need anything.
Diagnosis: The ability of my eye to compensate the light trouble in the near field is limited. A static diopter cannot work.
-
Frank, commiserations my friend.
Does the issue just apply to your preferred eye, or to both?
-
My preferred eye is kaputt.
I had to switch to the left a while ago.
There is not problem with DSLRs so no trouble at work.
The VF and esp the ground glass of the FM2 are not up to the task.
Best MF camera I own is the D500. Good diopter adjustment and
a great ground glass.
I guess that if I get the F6 ground glass to work in my FM2 or
D600 that focussing might be just as precise and snappy.