rpavich wrote:
Hi,
I need a +1 diopter for my Nikkormat FTn and the FM2 diopter that I have for my other camera certainly isn't correct in size, thread type.
I "think" that F2 and F3 diopters work for a Nikkormat but I want to make sure with someone who knows for certain.
Anyone here know if that's the case?
I stumbled upon this as you got me curious. It may help or even complicate the issue more. Your eye doctor might find it informative too.
"[Kelly Flanigan, Jan 10, 2009; 11:59 a.m.]
Here I have used Nikkormats since 1965; FS; FT; FTn; FTn-K etc.
A "stock eyepiece" of the Nikkormat has a plain piece of glass as the eyepiece window; BUT the screen is made to appear 1 meter away by the camera's built in -1 diopter system; as to the eye's focus. This means if you peer into the eyepiece with another slr's lens; it would be in focus at a 1 meter setting on the lens.
Thus to use a Nikkormat with the stock eyepiece your eyes need to be able to focus on objects 1 meter away.
The Pickle or confusion to some folks and eyedoctors arises because of the built in -1 diopter of the camera; it is common that a custom made lens is off by 1 diopter; the cameras internal -1 was ignored.
The NAMING of the stock Nikon removeable eyepiece lens is BASED on the combo of camera and eyepiece;
thus the stock parallel actual 0 power eyepiece lens is a CALLED a -1 diopter; when it is on a Nikkormat the SYSTEM is -1; ie the screen appears 1000mm away to ones eye.
A boxed -2 Nikon eyepiece makes the camera a -2 system; the screen appears to be 500mm away; ie about 19 inches; the eyepiece is really a -1 diopter lens to an eyedoctor; its -1 + -1 = -2 when on the camera. One adds the diopters; -1 for the camera; -1 for the eyepiece ITS CALLED A -2 when one buys it from Nikon; one would ask an eye doctor for a -1; since he doesnt know about cameras
For a nearsided old chap with -5 diopter glasses and no focusing ability with ones eyes anymore; they may need only -4 diopter glasses for watching a TV that is 1 meter away; or -4 glasses for using a NIkkormat whos screen appears 1 meter away. He could buy a Nikon -4 labeled eyepiece on ebay; or could have his eyedoctor make a -3 diopter lens; which adds to the -1 built in with the camera.
If ones eyes only focus on infinity objects; one could buy a 0 diopter Nikon eyepiece. One places in on the Nikkormat and now the screens image is like it is at infinity as for focus. IF one asked an eyedoctor for a 0 diopter eyepiece; he could make one out of a microscope slide; except when its is on the Nikkormat one would have a -1 system; ie wrong . The 0 diopter Nikon eyepiece; labeled as a NIKON 0 diopter eyepiece; is really a +1 diopter lens; ie a 1000mm positive focal length lens that will form a real image; ie burn ants; start fires; expose film:) One adds the +1 to the -1 and gets a 0 diopter camera.
IF you are getting a eyedoctor to custom make an eyepiece for you Nearsided right eye thats -4.5 for infinity; a swag is that its only -3.5 for watching TV; -3.5 for the Nikkormat. He would make a -2.5 diopter custom lens; ie a -400mm negative focal length lens. The one's Nikkormat with the custom -2.5 lens plus -1 in the Nikkormat add to -3.5.
If one does not mention to ones eye doctor that one's camera has this built in already -1 diopter; you will get a lens that wrong; off by 1 diopter. With young eyes with alot of adaptability one still gets focus; with ancient eyes one just threw money away.
On photo.net it pops up time to time that folks had an eyedoctor custom make these eyepiece; and "they were made wrong" the real wrong is the duffus photographer; who gave the eye doctor faultly inputs; thus they got the wrong lens made,
I haved repeated the -1 diopter built in bias of the Nikkormat many times here ; in the hope some brain cells get activated,:)
With other brands of slrs; the image of the screen may not be at 1 meter away; in cheap brands the readouts ie shutter speeds and F stops; leds; whatever may EACH be a weird different distance; OK for a teenager; pure hell for an old chap.
In a pro camera like a Nikon or Nikkormat the "stuff" in the slr viewfinder is made to mostly appear at one distance; so ones eyes are not refocusing. In a goober slr the screen might be at 2 meters; the fstops at 1/2 meter; the shutter at infinity; they often just make the text bigger instead of adding cost to get them all at one focus distance.