Adjustable Diopter for Leica M

[LouK]

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I require different glasses for seeing near versus far. So I have to change glasses to shoot portraits. I have a temporary solution using a Leica diopter of +1.5 in the eyepiece with the 1.25 magnifier but that is not that good. What would be ideal is an adjustable diopter as on DSLRs. Is there one made for the Leica?

[ayewing]

Would varifocals provide a solution?

[Printmaker]

I use a Megapearls 1.33 adjustable diopter magnifier. I think the name has changed to Japanexposures MS-Mag. Good for 50 - 135 lenses. However, taking glasses off to shoot and then back on to see clearly can be a real PIA. And, since I shoot mainly with a 35 mm lens, the magnifier sits in my bag most of the time. Others report being able to use this with a 35 mm lens but I find it uncomfortable.

[lars_bergquist]

Varifocals ('progressive lenses') are my solution. I am so oversighted that I cannot even see the horizon sharply, but my varifocals let me use the same specs always, including when reading – and focusing my M9 with excellent precision.

 

The objects in the Leica finder that are at the closest apparent distance, the framelines, the LED display and the patch edges, are at 2 meters. The actual subject image (including those in the rangefinder) is at varying and mostly slighter longer apparent distances, though not at infinity! Now a spec set that does not allow you to see sharply at two meters seems to me dysfunctional. I used to switch between distance and reading glasses, but I would have needed two meter glasses too!

 

The trick with varifocals is to learn what part of the lens you press against the eyepiece, and then to subconsciously do it. This is easier than learning to ride a bicycle. I never have to think of it. And the everyday convenience is the best there is (except 20 years old eyes ... )

 

The old man with the fix-focus eyeballs

[jaapv]

It would be too elaborate to try and adjust your ocular for each subject distance, although LTM bodies had a little lever for the purpose. But then, they had separate RF and VF systems.

If you can see the RF patch sharply, that suffices. As it is set to a virtual distance of two meters, that is the distance you should optimize your ocular for.

[lars_bergquist]

Those finder items are at a virtual distance of two meters, and can be that, because the things themselves – the finder mask, in fact – are at a fixed distance in the camera.

 

But our subjects are 'out there' at varying distances. They are imaged in the finder by two different telescopic systems, a reverse Galilean for the large finder image, and a Kepler or astronomical telescope (with image-reversing prisms) for the rangefinder.

 

All telescopes or binoculars, except the simplest, have and must have a focusing system. In the Leica III, of 1935) the rangefinder telescope's magnification was raised from unit to 1.5x. So all following Leica III models had to have that focusing lever, around the eyepiece (III, IIIa) or under the rewind knob (IIIb to g).

 

The M3 did not need that focusing because its finder magnification was even less than unit (0.93x). And subsequent Leicas have even less magnification. So the subject image in the finder, though actually at varying apparent distances, can be seen sharply as long as we can see the frame lines sharply, because the apparent subject distances are not that longer than two meters. So they fall within the depth of field!

 

Bit it is in fact possible to select the eyepiece focus so that you see only the frames, or only the subject sharply! If so, the things that must be seen clearly are not the frames, but the superimposed two images in the rangefinder patch – and note that this is NOT the same thing as the edge of the patch! This is by definition always at the same distance as the framelines, because both are really holes in the flat finder mask.

 

The old man from the Age of the Brilliant Finder

[LouK]

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First, thank you all for you help. I guess there is no variable diopter adjustment made for Leica M. I do wear progressive lenses but cannot get them to work in this situation. Lars, you are fortunate. If I understand what Lars and Jaapv are saying, the correct eye prescription for focusing is one that is sharp at 6 meters, which is why my computer glasses work so well. I am off to the optometrist with my camera to get a more exact prescription for a diopter adjustment. Since Leica rangefinder lens is -0.5 diopter I will need to take that into account.

[Falstaff]

I use a Megapearls 1.33 adjustable diopter magnifier. I think the name has changed to Japanexposures MS-Mag. Good for 50 - 135 lenses. However, taking glasses off to shoot and then back on to see clearly can be a real PIA. And, since I shoot mainly with a 35 mm lens, the magnifier sits in my bag most of the time. Others report being able to use this with a 35 mm lens but I find it uncomfortable.

 

I have two of the Megapearls ones but cannot remember which one.

Use them all the time from lenses 28mm - 75mm. Wouldn't be without them.

The only problem is that once you've adjusted them to your eye, they have a habit of rotating around ie useless. However, the trick is to unscrew the bit you use for focusing and re-screw it in with a washer in place. That holds it in place. As your eye deteriorates, just tighten it.

Falstaff

[jaapv]

First, thank you all for you help. I guess there is no variable diopter adjustment made for Leica M. I do wear progressive lenses but cannot get them to work in this situation. Lars, you are fortunate. If I understand what Lars and Jaapv are saying, the correct eye prescription for focusing is one that is sharp at 6 meters, which is why my computer glasses work so well. I am off to the optometrist with my camera to get a more exact prescription for a diopter adjustment. Since Leica rangefinder lens is -0.5 diopter I will need to take that into account.

Make life simple on yourself. The Optometrist has a box full of testing lenses. Just hold them between your eye and the viewfinder until you find the correct strength. Take astigmatism into account as well. If you have that you will need a WalterXeyepiece.

[LouK]

I have two of the Megapearls ones but cannot remember which one.

Use them all the time from lenses 28mm - 75mm. Wouldn't be without them.

The only problem is that once you've adjusted them to your eye, they have a habit of rotating around ie useless. However, the trick is to unscrew the bit you use for focusing and re-screw it in with a washer in place. That holds it in place. As your eye deteriorates, just tighten it.

Falstaff

 

Found the MS-MAG x1.35 adjustable diopter on the Japan Exposures website and ordered it. This is what I was looking to try. I mostly shoot portraits with 50mm and 75mm lens so this may work well. This company reliably converted my Contax 90mm f2.8 Sonnar lens to a Leica M mount last year. Thanks everyone you are very helpful and i appreciate the time you take.