Eyesight dilemma: what to do?

[Dwig]

Found 2 diopters for Nikon F that if I understand right fit fine on the Epson R-D1 one same as my distance prescription +0.5 and another +1.0 & look forwards to seeing how they work out. Meanwhile thanks for all the useful advice that makes me happy I am not the only one in this situation.

Nikon's numbering and your eyeglass prescription are a bit different. While both use diopters as their unit of measure, they are measuring different things.

You prescription measures the strength of the eyeglass lenses. Nikon's diopter number on the attachment lens is a measure of the net total apparent projection distance (the distance at which the VF image appears) of the VF when the add-on lens is attached. Without any additional lens, Nikon VFs of the period are set to +0.5d or a apparent distance of approximately 2m (~6ft). Exactly how these will work with other cameras is a bit of trial-and-terror.

There are several approaches to take. One is to find a diopter that will allow you to shoot without glasses. This gives the best VF view, if a good match is found, but leaves you without good vision otherwise. You may have to put your glasses on to see the camera's controls and/or view the scene.

The other approach is to use a diopter to allow the VF to be used with either the distance portion or the reading portion of your eyeglasses. This is the only practical approach if your eyeglass prescription includes any significant astigmatism correction (the second diopter value that has an associated angle in degrees).

 

[lowep]

which nikon FM diopter for +0.5 eyeglasses?

which nikon FM diopter for +0.5 eyeglasses?

Nikon's numbering and your eyeglass prescription are a bit different. While both use diopters as their unit of measure, they are measuring different things.

Without any additional lens, Nikon VFs of the period are set to +0.5d or a apparent distance of approximately 2m (~6ft). Exactly how these will work with other cameras is a bit of trial-and-terror.

Am a bit confused by this and other posts I have come across that explain the difference between eyeglass prescriptions and Nikon's numbering that if I understand right uses a default value of -1.0 rather than 0?

If this is the case, what nikon fm diopter would you recommend i try out first if my eyeglass prescription is +0.50?

Obviously the trial and error part is my problem but any advice about where to start would be much appreciated, as I have to buy before I can try.

There must be a way to figure this out. Or do other diopter buyers all buy 3 or 4 diopters before they find the right one?

Am also wondering how much margin for error there would be if I bought the wrong diopter. For example if my eyeglass prescription is +0.5 but I put in a +1.0 diopter would that be better than nothing or maybe even worse? How important is it to get exactly the right diopter?

BTW was also interested to read elsewhere that the Fuji X-Pro1 uses the same diopter thread as the Nikon F series cameras and the R-D1. Small world!

 

[peterm1]

This thread really it should be a "sticky" it comes up so frequently as us guys age. If you search this forum you will find other threads on it.

The rangefinder patch is at a virtual distance which in the case of a Leica M is around 2 metres. I do not know what it is for your camera but would be surprised to find its much different - other cameras I know use a similar virtual distance. When I went back to seriously shooting Leica M after a break of a few years I had the same dilemma as you. My eyesight which had been perfect all my life had deteriorated. Its a hell of a hassle. As a virtual distance of 2 metres is shorter than infinity and longer than normal reading distance this means you need correction that is different from either reading glasses or distance glasses (depending on whether you are long sighted or short sighted.) I will give you the same advice I give everyone based on my experience. Go to a chemists store (drug store if you are from USA) and go to the stand where they sell cheap non prescription reading glasses. Try them on one at a time till you find one that gives good vision when looking through the focused viewfinder. Take note of the glasses' diopter - that's the diopter correction you need for your camera. You can either buy the glasses and use them when shooting (a cheap and OK solution if your camera eyepiece has reasonable relief and allows you to view it properly from a little further back than normal.) If it does not, you must buy a diopter adjustment lens that screws in. In my case I went to an online store in Japan (link below) which sells an eyepiece magnifier and bought one with a small magnification. Those magnifiers have the advantage that they also give infinite diopter adjustment from -3 to +1 diopters. But I have no idea if the one for Leica fits your R-D1. You may have to inquire. The advantage of this solution is that if your eyesight changes all you need to do is to screw the adjusting lens of the thing in or out a bit and that should fix the problem. BTW if you are having glasses , made for reading or whatever, explain your problem to your optometrist. They should be able to calculate simply what correction you need for a 2 metre distance based on your eye's correction and simple optical principles.

http://www.japanexposures.com/shop/index.php?cPath=43

 

[Rob-F]

Nikon's numbering and your eyeglass prescription are a bit different. While both use diopters as their unit of measure, they are measuring different things.

I don't think so. The number on a Nikon diopter is the same as your prescription. It is not the same as the true power of the diopter, which is a little different so as to correct for the slight negative power of the prism finder itself. Nikon chose to label their diopters to match your prescription, to avoid confusion! Photographers try to deconstruct Nikon's numbers by insisting on bringing the prism's power into it; resulting in a lot of diopters changing hands on eBay!

 

[john_s]

Peter, reading glasses are all + diopter as far as I know. Fine for those who are far sighted, useless for those of us who are near sighted.

Leica screw-in diopters are marked with their value as an independent piece of glass. Nikon ones are marked differently. See this (it has always confused me, and I'm not convinced that trial and error is not the best way to find the best value for a particular camera, starting with what the optometrist suggests of course)

https://support.nikonusa.com/app/answers/detail/a_id/639/~/viewfinder-diopter-adjustment