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m8 built in -0.5 diopter


fursan

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Yes the rangefinder has a -.5 correction built into it and no it is NOT removable. The rangefinder is also set at a fixed distance of 2 meters. Meaning that everything you view through the rangefinder is like looking at something 2 meters (7 feet) from you. This is true most of the time except when you are closer then 2 meters to the subject.

You have to take into account the 2 meter distance when choosing a diopter correction lens.

I normally wear +1.5 reading glasses so if you take into account the -.5 of the viewfinder you would think I need a +2 diopter. Well I tried a +2 and I could barely see anything through the viewfinder.

At 2 meters (7 feet) I really don't need to wear any glasses to see good. So I needed a +1 diopter to bring everything in the viewfinder into focus at normal photo distances.

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Ed,

 

Thank you so much for the explanation. if I might bother you some more. I wear

+2.5 reading glasses. so i bought a +3 diopter coreection lens. Could this be

causing me to miss focus at close distances?

 

really appreciate if you could suggest how I should go about this issue.i too can see

at 2meter distance, but not read.

 

Regards.

 

Yes the rangefinder has a -.5 correction built into it and no it is NOT removable. The rangefinder is also set at a fixed distance of 2 meters. Meaning that everything you view through the rangefinder is like looking at something 2 meters (7 feet) from you. This is true most of the time except when you are closer then 2 meters to the subject.

You have to take into account the 2 meter distance when choosing a diopter correction lens.

I normally wear +1.5 reading glasses so if you take into account the -.5 of the viewfinder you would think I need a +2 diopter. Well I tried a +2 and I could barely see anything through the viewfinder.

At 2 meters (7 feet) I really don't need to wear any glasses to see good. So I needed a +1 diopter to bring everything in the viewfinder into focus at normal photo distances.

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Fahim--

Your glasses should match the projected rangefinder distance. Ed says that's 7 feet, so you use the glasses that let you see sharply at 7 feet.

 

The rangefinder doesn't change its focus distance as far as the eye is concerned, so you don't change glasses to focus more accurately at a different distance.

 

It's like a telescope or a microscope or an SLR viewfinder. All those instruments bring the image to a focus at a comfortable distance for the eye to work with, no matter how close or far the object you're looking at.

 

I'm not sure Ed is right about the 2m apparent distance of the rangefinder. All 35mm SLRs I'm aware of except the SL and SL2 have apparent distances of about 18 inches; and that is about what the -0.5 diopter of the M series calculates out to.

 

But then I use the mid-to-far distance correction of my glasses for the M finder, and that says that my calculations are wrong and Ed's are correct.

 

Ed is definitely correct that you need to take the optical system into account when considering using glasses to use with it; take his word on how to do the math.

 

is the -0.5 correction unremovable? what do folks who do not need correction do?

All optical devices have some kind of basic correction built in, else you wouldn't be able to focus. Consider the focusing screen of an SLR: It's about an inch from your eye, closer than you can focus. And the M finder is the same distance or less. So you need a negative correction to move the image distance further so you can focus on it.

 

--HC

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Howard, thanks for taking the time to explain this to me. I think I will take the

camera plus lens to the optician along with my specs. We will take it from

there.

 

Life was so easy ( but very heavy ) with my nikon!

 

Could it be that a lot of people that might be having focusing problems with their

lenses might be due to this diopter issue?

 

Best.

 

Fahim--

Your glasses should match the projected rangefinder distance. Ed says that's 7 feet, so you use the glasses that let you see sharply at 7 feet.

 

snip

 

. So you need a negative correction to move the image distance further so you can focus on it.

 

--HC

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... I think I will take the camera plus lens to the optician along with my specs.

Good idea. Tell him you want to see clearly what's in the finder and he should be able to direct you. Either he can do the calculation mathematically, or you can hold the M8 up to his instruments and choose the best correction directly while looking through them.

 

Could it be that a lot of people that might be having focusing problems with their lenses might be due to this diopter issue?

Maybe not 'a lot of people,' but definitely some of us. It was when I got the M8 that I realized I need to have my prescription updated.

 

This is definitely not a trivial issue, as you've discovered. I've very often seen it recommended that a person take his camera to his Leica dealer and try various correction lenses. The only problem with that is that in my experience, few dealers have many if any Leica diopters in stock.

 

--HC

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It might be very instructive for someone who has one of the variable diopter magnifiers, to see at what setting they see best through the VF and compare that with what their reading eye-glasses diopter strength is. My impression from using Varifocal lenses, is that the reading distance is not quite right and the mid distance (which in my case is set for a computer screen at about 1.5 meters), is a bit too long. Therefore the the part of the lens I look through for best vision is about halfway between reading and mid-distance. It is a bit hit and miss. My reading eye-glasses are +1.75 for the left eye, so I am guessing that a +1 D might be about right for me.

 

Wilson

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My left eye has 0.0, so i had to install a +0.5 to be able to focus on far distant objects.

Very annoying.

I had very much preferred an adjustable correction, or simply 0.0.

When I install the 1.25 maginifier, first I have to take out the +0.5 correction lens, then install the magnifier, and finally screw the 0.5 into the magnifier!

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You are so right, Howard. But I do appreciate all the help you folks are giving me

in this forum.

 

Re: leica dealers..went to mine,it has a processing lab in the back. asked him

for some ir filters. told me to go to nikon!!

 

they had binoculars in stock though.

 

 

snip

 

This is definitely not a trivial issue, as you've discovered. I've very often seen it recommended that a person take his camera to his Leica dealer and try various correction lenses. The only problem with that is that in my experience, few dealers have many if any Leica diopters in stock.

 

--HC

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I've very often seen it recommended that a person take his camera to his Leica dealer and try various correction lenses. The only problem with that is that in my experience, few dealers have many if any Leica diopters in stock.

 

--HC

 

Richard Caplan in London has a great load of them in stock. I have reading glasses with +1.5 so I thought I would try a 2. It was much worse. Then I tried the whole stock all the +s and -s. They were very helpful in the shop but none of correction lenses improved the situation.

 

I am no optician but I cant see how the Leica diopter of -0.5 can be at reading distance. My vision at about 6 feet is excellent so the standard -0.5 works best for me.

 

Jeff

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Wilson, you are introducing another impossible to find item ( variable diopter ) in the

equation. i could barley locate the leica dealer here and the shop ( ! ) is staffed

by a very unhappy attendant. no way i am going there again! i might loose what

eyesight i have remaining.

 

thanks.

 

It might be very instructive for someone who has one of the variable diopter magnifiers, to see at what setting they see best through the VF and compare that with what their reading eye-glasses diopter strength is. My impression from using Varifocal lenses, is that the reading distance is not quite right and the mid distance (which in my case is set for a computer screen at about 1.5 meters), is a bit too long. Therefore the the part of the lens I look through for best vision is about halfway between reading and mid-distance. It is a bit hit and miss. My reading eye-glasses are +1.75 for the left eye, so I am guessing that a +1 D might be about right for me.

 

Wilson

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I am no optician but I cant see how the Leica diopter of -0.5 can be at reading distance. My vision at about 6 feet is excellent so the standard -0.5 works best for me.

I don't understand the whole diopter thing. To my knowledge, the M VF has always been calibrated for two meters, but there are so many opinions expressed by people who may know, that I'm getting unsure. With my glasses, I currently need to use somewhere between 'distance' and 'mid-distance,' and at the moment I'm trying to get a pair made with a new prescription but can't seem to find a competent optician. :mad:

 

i could barley locate the leica dealer here and the shop ( ! ) is staffed by a very unhappy attendant. no way i am going there again! i might loose what eyesight i have remaining.

Unfortunately, fewer and fewer dealerships are interested in learning to sell a technically sophisticated product in a field that is otherwise dominated by merchandise that doesn't take effort.

 

i might loose what eyesight i have remaining.

 

<grin>

 

--HC

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Wilson, you are introducing another impossible to find item ( variable diopter ) in the

equation. i could barley locate the leica dealer here and the shop ( ! ) is staffed

by a very unhappy attendant. no way i am going there again! i might loose what

eyesight i have remaining.

 

thanks.

 

Fahim,

 

Look here Megaperls Webshop - Films and more directly from Japan I wish I had known about these before I bought my Leica 1.25X magnifier. Ignoring the backside covering spiel, these do fit M8's. A number of forum members have them.

 

Wilson

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Is it at all possible to use the built in diopter adjustment mechanism of another camera, or even microscope equipment, to ascertain the correct diopter lens required for an M8. I remember that in the past when I have had a camera, I think the Digilux 2 is one, the built in diopter correction wheel was turned to the point where I believed I had achieved optimum focus but I never paid any attention to the amount of adjustment. Now with the M8 I just make do but suspect I would benefit from an adjustment lens after having recently been told the prescription for my reading glasses by an optometerist.

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Is it at all possible to use the built in diopter adjustment mechanism of another camera, or even microscope equipment, to ascertain the correct diopter lens required for an M8. I remember that in the past when I have had a camera, I think the Digilux 2 is one, the built in diopter correction wheel was turned to the point where I believed I had achieved optimum focus but I never paid any attention to the amount of adjustment. Now with the M8 I just make do but suspect I would benefit from an adjustment lens after having recently been told the prescription for my reading glasses by an optometerist.

 

I think the conclusion we are coming to is that just putting the optometrists correction in for either reading or distance is not the answer. The reading correction is too strong and the distance too weak. I agree with whoever said above that the only way you will probably get this right is to find a Leica dealer with the range of correction lenses and try them out. As you have to mess around with the correction lens when you put on and take off the 1.25x magnifier, I think I have come to the conclusion that I am just going to carry on nodding like a chicken, trying to find the best area of my Varifocals to look through.

 

Wilson

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I think the conclusion we are coming to is that just putting the optometrists correction in for either reading or distance is not the answer.

Wilson

 

I am sure you are right in what you say but using the diopter facility on other equipment might be more useful than the optometerists measurement. I think the point about the optometerist is only that having been given a prescription for for spectacles I am bound to think that I would benefit from having a diopter adjustment on the M8 because a weakness has been measured.

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Guest tummydoc

Your glasses should match the projected rangefinder distance. Ed says that's 7 feet, so you use the glasses that let you see sharply at 7 feet.

 

The rangefinder doesn't change its focus distance as far as the eye is concerned, so you don't change glasses to focus more accurately at a different distance.

 

It's like a telescope or a microscope or an SLR viewfinder. All those instruments bring the image to a focus at a comfortable distance for the eye to work with, no matter how close or far the object you're looking at.

 

Sadly, the facts contradict the foregoing. The Leica M viewfinder is, aside from a reduction in magnification, like looking through a window. You need whatever strength of eyeglasses you need for whatever subject distance as you would if there were no camera before your eye. Those who wear single-vision eyeglasses can abscond with a single corrective diopter, but those who require bi- or multi-focal eyeglasses cannot, moreso the larger the disparity is between near and far-distance Rx. An SLR is completely different. There the entire image is focussed on a single plane (the focussing screen) and one simply need find the diopter that permits seeing a sharp image on the screen. For those with strong multi-focal Rx, the best option is "progressive" eyeglasses and no corrective diopter on the Leica. One then simply adjusts one's view of the finder so that the appropriate area of eyeglasses are used for various subject distances, just as in daily sight.

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