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M7 intermittent optical DX reading


cbretteville

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My M7 had it's DX reader changed to the optical type last year. I'm now seeing intermittent values returned and am not sure I can trust it.

 

Last roll in the camera was Porta 160, it would some times when the camera was switched on return and display "320". Very annoying.

 

The DX coding for 160 and 320 are WBWBWW and WWWBWW respectively. I inspected the DX coding on the canister after I took it out of the camera and there were two tiny dots of black paint missing from the first black field. Thus it might be possible that the reader gets a return from those tiny specs causing it to beleive it has a 320ISO film inserted.

 

I'm beginning to think the camera has to go back to CS again (for the third time since i bought it), but thought I'd check the collective's experience:

 

Has anyone else experienced this with their M7?

 

Carl

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I used to get odd readings occasionally, but most of the time it was loaded with b&w film, rated differently from the DX anyway, so the problem didn't occur.

 

It's a pity it has to go back again.

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It sounds rather like the (numerous) problems I had with my M7. Even after it had had the DX reader replaced there were periodic misreadings. It turned out that in addition to the DX reader there was also a faulty circuit board that was *not* investigated when the DX reader was swapped.

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I have similar issues, with 160 film I get occasional 2500 iso. Turning the camera on and off and a light tap fixes it, but it is annoying as heck. But so far my annoyance was not big enough for a without doubt ridiculously expensive return to Leica.

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Hello Carl,

 

Because it is an "optical reader" you might try blacking out the DX patch on the film cannister w/ a black permanent marker before sending in your camera. You might even experiment w/ a different roll of film or 2.

 

Whiting out that 1st black patch changes the configuation to ISO 320.

 

Whiting out the 2d black patch instead of the 1st on a film cannister configured for ISO 160 gives you ISO 2500.

 

If I had a camera w/ a DX reader I would have a DX code explainer like the 1 on page 8 of the June 1983 edition of Modern Photography. If I was more capable w/ computers I would put a copy in the computer.

 

Best Regards,

 

Michael

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Are you sure it is the DX reader and not the ISO dial on the back-plate? My camera has the optical DX reader (the camera was factory refurbished and upgraded with optical DX reader / MP type VF) but shows occasional erratic ISO values when switching ON and / or the blinking red dot. This happens after slightly pressing the ISO dial on the back-side and a slight turn brings it back to normal function. My camera was a couple of times in for service but this problem was never solved.

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I too have had DX setting issues, but haven't yet sent it off. I have set the iso manually ( as I do with MP) now for the past two years. I also notice the bottom LED dot also flashes (suggesting I have EV compensation set but I don't). Rotating the EV compensation outer ring used to turn this LED off but it doesn't seem to any more. I guess I wait until I mess up a film because of bad exposure, which will be noticable on my slide films, then get a fix for the DX and meter electronics.

 

The MP meter doesn't have these issues, but does have trouble in sub 5C temperatures if I'm out for more than an hour or so in cold temps. But the battery will recover again when warmed up.

 

The AE and electronic shutter control are nice to have but not so if we are worried about wrong exposure as that disturbs our creativity.

 

Perhaps newer M7 have a different meter/DX circuit board and don't have these issues? For 3K you'd hope so.

Lincoln

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