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Diopter saga


rob_w
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Starting some months back I started making enquiries on this forum regarding how effective a diopter (dioptre?) adjustment would be in conjunction with the Leica 1.25 magnifier. Lots of helpful responses, thank you.

 

Now here is what I found:

 

1. Of the 5 or 6 Leica stores I was able to visit while travelling, NO-ONE stocked a range of diopters to try out on the camera

2. Despite cautions on the forum here to the contrary, several stores suggested I get an eye test then come back and order the appropriate diopter

3. One store had a +1.5 diopter in stock, which I knew would be roughly right and, when I tried it, it did seem to help. So since I had one shot at getting something while travelling, I bought it

4. Used it successfully for 3 or 4 weeks and saw a small but definite improvement in focus accuracy

5. Last week I discovered the diopter had come off my camera and disappeared. It must have worked loose and fallen off without my noticing.

 

So I am back to "square one".

 

Clearly this is not a good state of affairs and I would look to Leica to improve it:

 

1. Why not provide a set of trial diopters to all approved re-sellers, without requiring them to pay for stock other than what they sell?

2. There needs to be some safety facility to prevent loss of the unit from the camera

3. More to the point, why not incorporate diopter adjustment into the camera viewfinder itself? Is there any technical reason why this cannot be done, when it is provided in most camera viewfinders?

 

Okay, so this is a saga of a post, but I have to say I am rather hacked off. Do others agree with me and should we be asking Leica to lift their game in this area?

 

Robert

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Do others agree with me and should we be asking Leica to lift their game in this area?

 

Robert

 

You'd have to add this request to the long list of features standard to other cameras which are not on a Leica M-series. I suppose Leica would argue that their cameras are purist tools which allow the user to decide how much effort to put in. Personally, I'd love a diopter adjustment. I use a Megaperls 1.15 magnifier (permanently) which has inbuilt diopter adjustment which with a bit of fiddling does work reasonably well. But still not as easily as on any N or C camera you care to mention.

 

LouisB

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Err...It has been posted in this forum time and time again:

 

1. Try out the diopter strength by using the tryout lenses of your local optician between your eye and the viewfinder.

2. The diopter only works if you make sure you see the rangefinder window and framelines sharply. It does not matter if the viewfinder image itself is slightly soft, that only shows your eyes have a limited acomodation ability. If you go for a sharp viewfinder image you are likely worse off than without diopter.

3. If you cannot find an accomodating optician, use the throw-away reading glasses at any filling station or drugstore to try out which diopter you need.

4.There are online Leica shops that stock the diopters. For instance Meister Camera is worth a try, and a number of other large ones.

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.... More to the point, why not incorporate diopter adjustment into the camera viewfinder itself?....

 

Rob - I enjoy the M8 for certain design advantages that rangefinder cameras provide, most of all; camera compactness and good, very compact lenses. However, there are design aspects to the M8 which were clever solutions for 50 years ago but now represent crap design; the change lens-unscrew dioptre- screw on magnifier-replace dioptre pantomime being one of them. I suspect that the majority of M8 users use dioptre corrections and I find it rather pathetic that the camera does not come with a built in variable dioptre correction. I'm inclined to think that too many Leica customers excuse poor design in the name of Legacy, rather than calling it what it really is.

 

I too know the frustration of shopping for a dioptre correction filter, and not being able to find a Leica 'stockist' who actually stocked them. As to wanting Leica to 'lift their game'; good luck.

 

.............. Chris

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Err...It has been posted in this forum time and time again:

 

 

2. The diopter only works if you make sure you see the rangefinder window and framelines sharply. It does not matter if the viewfinder image itself is slightly soft, that only shows your eyes have a limited acomodation ability. If you go for a sharp viewfinder image you are likely worse off than without diopter.

 

Jaapv you have posted this statement many time and I totally disagree.

In theory the rangefinder patch and the whole viewfinder window, including the frameline, is supposed to be displayed to the users eye at the same theoretical distance, 2 meters (7 feet).

Since the rangefinder patch is a Overlay of what it displayed in the veiwfinder IF the viewfinder window is not clear to the eye then you have the same problem, IE trying to line up, coincide, the image in the RF patch with what is underneath it in the viewfinder which in your statement doesn't need to be that clear. If either are not clear it makes it almost impossible to line them up correctly causing focusing misalignments and out of focus images.

For proper use you need to find the happest medium where both the RF patch and the whole VF are clear to your eye. If you can't then something is screwy with the viewfinder or the rangefinder.

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Ed, this is incorrect. The image that coincides with the RF (the moving part) patch is a projected image, which is focussed at 2m too. In an ideal world you are right, both should be in focus. However, many users are over fifty, which means their eye simply cannot accomodate enough to reach this happy state. Then the best compromise is to have the RF patch in perfect focus.

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Ed, this is incorrect. The image that coincides with the RF (the moving part) patch is a projected image, which is focussed at 2m too. In an ideal world you are right, both should be in focus. However, many users are over fifty, which means their eye simply cannot accomodate enough to reach this happy state. Then the best compromise is to have the RF patch in perfect focus.

 

 

I think you are not understanding something correctly.

The whole viewfinder is a projection, IE it is NOT straight though front to back. It goes through at least one if not more prisms and mirrors and when that happens the framelines and rangefinder patch are added to that projection.

 

If you had ever broken a M range/viewfinder, like I did on one of my M3's and then toke it apart because it was unfixable, you would/could see all the work that goes into building one of them.

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If you had ever broken a M range/viewfinder, like I did on one of my M3's and then toke it apart because it was unfixable, you would/could see all the work that goes into building one of them.

Most of us do actually understand this. The finder proper is a reverse Galilean telescope, while the rangefinder optics constitute a Keplerian one (though with a prism to turn the image right way up). But it is a fact that all visual components are not at exactly the same apparent distance.

 

The situation then is somewhat reminiscent of the one when you shoot a rifle or pistol with iron sights: You have to decide where to focus, because you cannot focus on everything -- rear sight, front sight, target -- simultaneously. So you have to put your focus where a deficit is most destructive, sending you off the target, or causing misfocusing, respectively. In the first case, it is the front sight. In the Leica case, it is the rangefinder.

 

By the way, no matter how good your visual accommodation is, you cannot focus on several things simultaneously, if they are at different (optical) distances. I could not focus on the rear sight, front sight and target simultaneously even when I was twenty, and could actually see the planet Venus as a minuscule gibbous moon during good conditions. I did encounter some naive souls that did imagine that they could. But this is a physical impossibility, and I used to tell them to go see an optometrist!

 

The old man from the Age of Max Berek

Edited by lars_bergquist
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I think you are not understanding something correctly.

The whole viewfinder is a projection, IE it is NOT straight though front to back. It goes through at least one if not more prisms and mirrors and when that happens the framelines and rangefinder patch are added to that projection.

 

If you had ever broken a M range/viewfinder, like I did on one of my M3's and then toke it apart because it was unfixable, you would/could see all the work that goes into building one of them.

Well, having lived near Odin and having sat nattering with the technicians there for many hours, I guess I have not seen under a few hundred disassembled Leicas of all kinds. But that has nothing to do with the fact that you focus with the rangefinder, and in order to achieve perfect focus you must be able to see the rangefinder perfectly sharp, no matter what the rest of the viewfinder looks like.

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3. More to the point, why not incorporate diopter adjustment into the camera viewfinder itself? Is there any technical reason why this cannot be done, when it is provided in most camera viewfinders?

 

My old IIIg had the diopter adjustment (and the other III-series bodies as well?).

 

Is this something that wouldn't fit when they designed the M-series bodies?

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Well, having lived near Odin and having sat nattering with the technicians there for many hours, I guess I have not seen under a few hundred disassembled Leicas of all kinds. But that has nothing to do with the fact that you focus with the rangefinder, and in order to achieve perfect focus you must be able to see the rangefinder perfectly sharp, no matter what the rest of the viewfinder looks like.

Having the rangefinder patch crystal clear and the viewfinder blurry is the same as having both blurry. Just how can you properly overlay the RF image on the blurry part of the VF the RF patch covers. The RF patch is just that, a patch that overlays the image seen in the VF.

The RF patch is not a entity all by itself, IE there is not 2 images produced by the RF patch that you align.

 

We agree to disagree, I guess.

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My old IIIg had the diopter adjustment (and the other III-series bodies as well?).

 

Is this something that wouldn't fit when they designed the M-series bodies?

 

Actually from what Lars has said that is not a diopter adjustment on the old III cameras.

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Having the rangefinder patch crystal clear and the viewfinder blurry is the same as having both blurry. Just how can you properly overlay the RF image on the blurry part of the VF the RF patch covers. The RF patch is just that, a patch that overlays the image seen in the VF.

The RF patch is not a entity all by itself, IE there is not 2 images produced by the RF patch that you align.

 

We agree to disagree, I guess.

Oh yes, we know one another long enough to disagree in peace. But, if it is not possible to have both in focus at the same time? how would you solve that problem?

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Oh yes, we know one another long enough to disagree in peace. But, if it is not possible to have both in focus at the same time? how would you solve that problem?

 

 

Well that's just it. IF "I" could not get both in focus to my eye at the same time I'd have to stop using a Leica M camera.

I have thought about this at great length and don't like the option. But if my eyes start to fail to that point then that's just what I'll have to do. Hopefully that won't be for some time.

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Guest Chris M

Maybe we could contact Leica in reguards to this thread and get the manufactures opinion of how and what is it and does? just a peacefull request:eek:

 

chris m.

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Well that's just it. IF "I" could not get both in focus to my eye at the same time I'd have to stop using a Leica M camera.

I have thought about this at great length and don't like the option. But if my eyes start to fail to that point then that's just what I'll have to do. Hopefully that won't be for some time.

I can set your mind at rest, fortunately that is not the case. There are two reasons for that. The first is Lars' gunsight analogy. The sight nearest to the eye must be in focus. The second is that the coincidence of images is just an approximation of focus. Exact focus is only reached when the RF patch snaps into maximum contrast - and that does not depend on the optimal focus of the rear image. So, as time moves on for all of us we need only concentrate on the sharpness of the RF patch :)

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Guest Chris M

Jaapv,

Thank once again for your anoligy, I now understand how this hole complex veiw,range finder mechanism works with a diopter.(off subject) Jaapv, can I contact u inreguards to Capture one and how to use it? I have the current 4.8 on my macbook pro, and am completly lost, are you a mac guy and if so do you use ichat video?

 

thanks again,

 

chris m.

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I can set your mind at rest, fortunately that is not the case. There are two reasons for that. The first is Lars' gunsight analogy. The sight nearest to the eye must be in focus. The second is that the coincidence of images is just an approximation of focus. Exact focus is only reached when the RF patch snaps into maximum contrast - and that does not depend on the optimal focus of the rear image. So, as time moves on for all of us we need only concentrate on the sharpness of the RF patch :)

 

Well then all the books and the manuals written on the M rangefinder are wrong.

In the manual for the M8/.2 on page126 is talks about lining up split images until they come together. There is no talk of greater/greatest contrast.

If the back, viewfinder, image isn't clear you can't line up anything. It desn't matter how sharp the RF patch is.

Like I said in a earlier post. IF YOU can NOT get both the whole viewfinder and the rangefinder patch to be crystal clear at the same time then there is something wrong with the View/Rangerfinder in your camera.

The image you are looking at through ther viewfinder and rangefinder window are at the exact same distance from your eye looking through the M eye piece.

 

Maybe I'm not expressing myself correctly.

When you look through a M eye piece what you are seeing is a projection of what is in front of the camera. Whether the scene/object your are looking at is 1 meter away or 40000000 meters away it is always project to your eye as being 2 meters in front of you. Otherwise you would need to change the diopter correction, even the base built in diopter correction, depending on how far away the scene/object is you are trying to focus on.

Your eye always see what is in front of the camer AT the same distance

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Actually from what Lars has said that is not a diopter adjustment on the old III cameras.

Correct. Eye problems were corrected by pairs of lenses screwed into the viewfinder and rangefinder eyepieces. The lever is for focusing the rangefinder telescope (magnification 1.5 X) for far and near subjects. It could do absolutely nothing about the finder.

 

The old man from the Age of the IIIa

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... When you look through a M eye piece what you are seeing is a projection of what is in front of the camera. Whether the scene/object your are looking at is 1 meter away or 40000000 meters away it is always project to your eye as being 2 meters in front of you. Otherwise you would need to change the diopter correction, even the base built in diopter correction, depending on how far away the scene/object is you are trying to focus on.

Your eye always see what is in front of the camer AT the same distance

 

No. It's 2 meters for subjects at infinity. The negative magnification of the finder optics does however increase the depth of field of the combined finder-eye optical system so that everything looks reasonably sharp. What we need extra correction for is gross defects of the eye lens. You would find a 1:1 finder more problematical in this respect.

 

The old man from (of?) the Age of Repetitiveness

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