Correction lenses (again)

[ioriw]

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Well I'm still not happy with the sharpness of most of my M8 shots. I quietly went out and got the 1.25x magnifier a few months ago and yes it sure helps with the 90/4... but when I'm SURE I have perfect focus alignment in the viewfinder when shooting the 1.4/50 or the 90/4, when I see the results the right things just aren't sharp at all...

 

Before I even mention the dreaded 'focus shift' I was thinking of trying viewfinder correction lenses. I use the M8 with contact lenses in or with spectacles. I can see the rangefinder patch clearly and can clearly see when there is a perfect alignment there. I think! So will some extra sharpening with a correction lens really do much good? The prescription in my focusing eye is a whopping -4.25. I was thinking of getting a -0.5 correction lens to add on a little strength.. will this help me hit the focus better? Or do I have slight backfocussing problems with the 1.4/50asph?

 

-i

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[carstenw]

The best thing to do is to go to your Leica dealer, and try on various diopters for a while, with different kinds of shots in and around the store. One will seem best. Buy it. It doesn't necessarily match your prescription for glasses. My best diopter was one notch stronger than my prescription.

[gravastar]

One thing to watch out for is the amount of diopter correction needed depends on the camera to subject distance. If you have eyes that have good accomodation then a single diopter may cover all distances. For me though, I need a higher diopter for close work say within 3 to 10 feet. It's a good idea to try the correction lens inside and outside the shop. It's a shame the M8 viewfinder isn't adjustable.

 

Bob.

[jaapv]

Go to the optician, use his correction lenses, holding them in front of the VF, until you have the right one. Leica's correction lenses are not corrected for astigmatism or any other eye problems. One can order a correction lens rim with Leica and the optician (provided he has a machine that can grind down to 10mm) can fit the lens.

[Eoin]

It's funny you should bring this up and mention the 50mm focal length. I used the 1.25x with a +3 diopter and or the life of me could not get consistently sharp results with the Summicron in my case. I removed the 1.25x and left the diopter on the camera and presto I'm now very happy with consistently sharp results. I remember someone here saying there was some form of correction within the 1.25x and perhaps that was throwing things off slightly.

[jaapv]

That is true. With the camera I need +0.50 and with the Leica diopter +0.75. I bought the Megaperls diopter 1.35x and find it very good - with adjustable strength...

[deoman]

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I cannot get my viewfinder lens to unscrew. I saw the earlier post on this subject, but none of that worked and I refused to put a pair of pliers on the viewfinder lens to take it off.

 

Any thoughts?

[gravastar]

I cannot get my viewfinder lens to unscrew. I saw the earlier post on this subject, but none of that worked and I refused to put a pair of pliers on the viewfinder lens to take it off.

 

Any thoughts?

Yes, don't! The diopter correction lens screws into the back of the lens which is already part of the viewfinder, ie. the lens which you can't remove. If you look carefully you will see there's a thread in the metal mount of the eyepiece lens which accepts the correction lens.

 

Bob.

[rvaubel]

I cannot get my viewfinder lens to unscrew. I saw the earlier post on this subject, but none of that worked and I refused to put a pair of pliers on the viewfinder lens to take it off.

 

Any thoughts?

 

What you need here is differential heat. I suggest putting the camera in the oven at say, 450 F and then plunging it into a bucket of cold water. That should do the trick

 

Rex

[glenerrolrd]

Yes, don't! The diopter correction lens screws into the back of the lens which is already part of the viewfinder, ie. the lens which you can't remove. If you look carefully you will see there's a thread in the metal mount of the eyepiece lens which accepts the correction lens.

 

Bob.

DON T USE PLIERS...the original post was my error....the correction lens screws either (1) directly into the viewfinder or (2) into the BACK of the magnifier. I was sure the diopter went on first and then the magnifier ...just before I use pliers on my perfectly working viewfinder ...I was warned by another member . The diopter is very thin so unless you look for it carefully you might not see it. You might also want to try the Megapeals 1.35X magnifier with adjustable diopter. This gives you a lot of flexibilty to fine tune the diopter . Its a good product and very inexpensive ..if I remember right it was $80 including shipping from Japan. This would at least show you whats possible ..the magnification is too high for most wide angle work ..

[ho_co]

One thing to watch out for is the amount of diopter correction needed depends on the camera to subject distance. If you have eyes that have good accomodation then a single diopter may cover all distances. For me though, I need a higher diopter for close work say within 3 to 10 feet. It's a good idea to try the correction lens inside and outside the shop.

Bob--

Are you sure? I've never heard that before. My understanding is that the real image as well as the rangefinder patch and frame lines are at an effective 2 m distance.

 

I know I can't argue with your experience; and my eyes may be deteriorating to the point that I'll agree with you when I get my next eyeglass prescription in another couple weeks!

 

--HC

[ho_co]

Well I'm still not happy with the sharpness of most of my M8 shots....

 

I use the M8 with contact lenses in or with spectacles. I can see the rangefinder patch clearly and can clearly see when there is a perfect alignment there. I think! So will some extra sharpening with a correction lens really do much good?

Iori--

If you see the focusing patch sharply, you should not need any additional eyepiece correction. As others have said, you need either to go to an optician or to do a trial-and-error test with a dealer.

 

Once you're sure you're reading the rangefinder correctly (and it sounds as if you are already sure of that), you may need to start testing the rangefinder and then possibly the lenses.

 

You mentioned the 50/1.4 and the 90/4. Do you have any other lenses that do focus well? Have you tested with a tripod?

 

Or perhaps you should post an example before starting all that?

 

--HC

[jaapv]

..the magnification is too high for most wide angle work ..

 

There is a 1.15 magnifier as well.

 

Btw, Howard, I can tell you from bitter experience that it is quite possible to *think* one sees the RF patch sharply and correctly, and to find out afterwards that the cause for misfocus was indeed the poor correction. With a diopter correction in place the difference between good and excellent vision becomes painfully obvious..