M6 Metering

[Guest]

Hi y'all. I've been using my M6 (ttl) for some time. It is a great tool and I get great results. Still, I can't seem to pinpoint some of the quirkiness of the metering. Specifically, sometimes it will have significant meter swings (maybe 4-5 stops) when I'm framing the same subject area.

For instance, the little arrow will tell me to stop down, and I'll do it. Then it will tell me to go back to where I started. Is there some amount of time you need to wait for the meter to settle down (I like to make my aperture/exposure changes very fast).

Is this a battery issue, or something I'm doing wrong? I still feel like my camera can't always decide on how it wants to meter a composition.

 

[Guest]

The M6TTL uses a silicon photo diode, which has a very rapid reaction to changing light levels and there is no settling-down period.

What you could be experiencing is the effect of vignetting, noticeable particularly in the 50mm Noctilux and Summilux lenses at full aperture. It's most pronounced in dim light. This can cause the light meter to give unexpected readings because the brightness is not evenly distributed across the area measured by the meter but is concentrated in the middle. As you reduce the aperture, the vignetting is reduced and the light is spread more evenly, which fools the light meter. I notice it with my 50 Summilux, e.g. when changing from f/1.4 to f/2 (1 whole stop): the required shutter speed according to the meter does not change by a whole stop. However, this would make a difference of only 1 to 2 stops, not the 4-5 stops that you mention.

Another possible cause is dirty contacts between the camera back and the body, causing variable resistance in the metering circuit and erratic light readings. It can even change if you slacken or tighten your grip on the camera! These contacts can get greasy/dusty and need to be wiped clean with a soft cloth every so often. Don't use anything abrasive: these are gold contacts and do not corrode, they just get dirty occasionally.

 

[Guest]

Re: erratic meter readings.

This sounds like it may be a dirty contact(s) problem. Use a cotton swab and some denatured alcohol or electrical cleaner ( NOT TV TUNER CLEANER ! ) and carefully clean the contacts in the battery compartment and also the contacts at the film door. DO NOT use a pencil eraser. Although this is a "time honored tradition", it is also a short term fix and can cause more corrosion over time.

 

[Guest]

Thanks for the help, Ray. I'll see if the "problem" is any different at smaller apertures. I tend to shoot with wide apertures in low light, which sound alot like what you described.