Diopter?

[jwcat]

If I need +2.5 for reading glasses, what diopter lens would I have to buy for the viewfinder of the R-D1?

What is the deal on those 1.3 magnifier lenses that can't be sold in the U.S.? I see they have a +or-3 adjustment.

Thanks

 

[Al Kaplan]

Why don't you look through the finder and see if you can use it without the diopter. My right eye requires a +3.25 diopter for reading but I have no trouble at all focusing an M2 rangefinder. With the M3 the rangefinder image is just a tad away from being crisp but it's still very easy to see when the two images align.

 

[ampguy]

I just use the Nikon diopter equivalent to my R eye rx. Works perfect for me.

 

[andreas.pichler]

In my opinion the assembly of a fixed diopter correction lens would be a disadvantage - you cant give the camera to someone else to take a photo (yes, I wear glasses as well and I give the camera away frequently, for example to my wife, and she is not wearing lenses, but a good photographer).

I would try to learn to use the viewfinder with lenses. Move the camera a bit while holding the finder in front of your eye, and you get an idea conerning the picture. Or better: Practice to hold both eyes open, the 1:1 finder of the RD-1 encourages you to do this. Plus, alignment will be a little bit more easy, you will have the feeling of a "click" when the patches will align and you can see the whole scene with the otehr eye.

Just my two cents...

Cheers,

Andreas

 

[jwcat]

OK, I do not have the camera yet, and I do not have a lot of trouble with an M3. So I will try using stock first. Thanks all

 

[pagpow]

If I need +2.5 for reading glasses, what diopter lens would I have to buy for the viewfinder of the R-D1?

What is the deal on those 1.3 magnifier lenses that can't be sold in the U.S.? I see they have a +or-3 adjustment.

Thanks

Remember that unlike in an SLR, you are not viewing an image at a close distance w. a RF, so you should be looking at your distance prescription not your reading prescription. I have progressives, and I find that a diopter w/in .5 of my distance prescription does fine (in fact even greater deviation might work) -- so I have a -3.5 eyeglass distance prescription and find that a -3 diopter works perfectly, and have fitted both my RD1 and my Leicas with -3's. There was no -3 available when I was looking for my XPAN, so I took a chance on -4 and that also worked well. (I also have some astigmatism, but have found no need to correct for that.)

The Nikon does fit, works fine, but the Bessa (Cameraquest has them) ones have the advantage of rubber/plastic, rather than metal rims, so you don't mangle an eyeglass lens when you forget to flip up your glasses before you bring the camera to your eye.

Finally, if you go the Bessa diopter route, make sure to tighten the diopter well. I did not the first time and simple contact with my face ended up progressively unscrewing it until it fell off unnoticed.

Giorgio

PS It is true that having them on the camera keeps you from handing the camera to someone else for shots, and also calls for flipping up your glasses to focus. i have found that to be the best solution, however.

PPS I also have the 1.3x with variable diopter. Very nice unit, but I have found the simple diopter just fine for shooting, even with a 50.

 

[Rob-F]

The view in a camera finder is generally presented at a "virtual distance," which is different from the actual distance from you the subject. I don't know what that distance is for the Epson, but I believe that for a Leica M camera, it is 2 meters. That may not be exactly right, but good enough for the sake of discussion. I think it is fairly similar for SLRs.

You probably read at a distance of perhaps 16 inches or so--more or less. To correct your vision to that distance requires a stronger correction than will be need at the 2 meter distance in the camera's finder. (Or 1 meter, or whatever it may be.) So the diopter will need to be less strong compared to your reading glasses.

There's another complication. Camera finders generally have a small negative diopter power built into the rearmost lens in the finder. It may look like a clear glass dust cover, but it isn't. It might be about -1/2 to -1 diopter.

Putting that all together, there's only one right answer: you can't figure out what diopter power you need, you have to try it out. If there are ready-made lenses available to try, that would be great. But if not, I think it makes sense to take the camera along the next time you go in for an eye checkup, and have the doctor hold a diopter lens in front of your eye while you look through the camera at the wall chart. If this is not possible, and you have to order a lens, there is a way to figure the change in diopter power as the viewing distance changes. So you could find out the virtual distance for the R-D1 finder, and have somebody (probably your eye doctor, again) figure it out.

But I think "look through it and see" is the best way, if possible.

 

[john_s]

With SLRs it's easier because the ground glass is always the same virtual distance from the eye (often 0.65m or 1m). With a rangefinder, your eye does focus differently for near and far subjects. The correction you need is less than you need for reading, because the virtual image is further away.

I'm short sighted and old (so minimal focusing range) so need less positive (+1.5) for reading than the OP, but -1.5 for most cameras, and -1 for Leica. For one camera, that is used by my wife as well, I have settled on half the correction that I need: it's good enough for me, and my wife finds it ok too. (she needs no correction for distance)

If you use Nikon diopters, note that the value on the diopter is the sum of:
1: its diopter value, and
2: the nominal value of a Nikon SLR viewfinder mechanism, which is -1.

So the Nikon diopter labelled -2 is a -1 piece of glass.

The Leica diopter labelled -1 is really -1.

Nikon have a pdf called Eyepiece Compatibility Chart that explains this.

I agree with everyone who says that trying them is the best way to choose. Take your time, and try near and far subjects, in low light if possible (it's more critical because your eye is operating at full aperture). If you're between two values, I suggest taking the weaker one.

 

[payasam]

Let's assume that the camera's finder is -1D. You need 1.5D less than your near vision prescription, that is, 1.0D correction. Apply what john_s says, you get 0D. See what Rob-F says about "virtual distance". A distance of 1.5M is generally held to be right.

 

[LCT]

If I need +2.5 for reading glasses, what diopter lens would I have to buy for the viewfinder of the R-D1?...

Not sure if the reading distance is relevant here. I need +3.5 to read and +1.5 to view at infinity. I had heard that the R-D1's VF is set to +0.5 when i bought it so i chose +1 for the correction lens and it works fine for me provided the subject distance is not inferior to about 70 centimeters, which is the minimum focusing distance of most M lenses anyway.
BTW i use correction lenses for most of my RF and SLR cameras and i find them more handy than glasses, specially to view the 28mm framelines of the R-D1 viewfinder.

 

[payasam]

It's as I said, LCT: +3.5 minus 1.5 = +2.0 actual = +1.0 labelled. An optician explained the matter to me on Photo.Net.

 

[LCT]

Ah yes sorry i had not seen your post. Interesting thanks. 🙂

 

[jwcat]

I asked this question because my first RF was a Bessa R and I had problems with seeing through it. I eventually gave it to my son. I have since had cataracts removed. I use +1.5 for computer glasses and I do not wear glasses for distance viewing and can see well enough in my M3. So I will just see what happens. Thanks for all the interesting replies.

 

[payasam]

John, after I had my cataracts removed I no longer needed correction for camera view-finders. My computer glasses are about the same strength as yours. If you can use an M3 without trouble, it's likely that you'll be happy with the Epson as you find it.

 

[jwcat]

Sounds good, thank you.

 

[Frankie]

......You probably read at a distance of perhaps 16 inches or so--more or less. To correct your vision to that distance requires a stronger correction than will be need at the 2 meter distance in the camera's finder. (Or 1 meter, or whatever it may be.) So the diopter will need to be less strong compared to your reading glasses.

Diopter is the reciprocal of focal distance in metres.

If your eyesight is perfect at infinity, but need reading glasses at a preferred distance of 0.5m (~20"), then the diopter required is:

1 / 0.5 = +2

Assuming your camera has no built-in VF diopter bias (many SLRs do at -0.5 and often so specified), and if your camera VF virtual view distance is 2m, then the diopter required is:

1 / 2 = +0.5

As I have elsewhere posted, arms-length viewing in digicam LCD sucks, yet bi-focals won't really work because a 10cm viewing distance will require a +10 diopter (1 / 0.1)...coke bottle territory. Even if you settle on 20cm, diopter required is still a +5, unavailable without prescription.