M6 meter LEDs & Film Speed

[TomB_tx]

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I know the M6 meter LED flashing issue has been in several other posts, but I had the issue this week for the first time on my 1985 M6 and found some things that may help others.

This is the first I've used a 3200 speed film in my M6, which makes the issue more obvious because the LEDs flash at higher shutter speeds and normal exposure than at lower ISO films. As reported, the flashing occurs when the meter thinks the light level is below its rated sensitivity as seen by the meter off the shutter curtain. So the smaller the aperture, the less light reaches the meter. With ISO 3200 film and a shutter speed of 1/125 or faster, the LEDs don't flash (on my M6) when the f-stop is set to get normal exposure (equal brightness on both arrows). With 1/60 shutter speed they will flash when the f-stop is closed to get proper exposure. That's because a 3200 film needs very little light, and proper exposure at 1/60 makes the meter think the light is too dim. However, I find it will still meter correctly at least a few stops below the level that the LEDs start flashing - it's just a distraction in the finder. I haven't checked to see if battery voltage affects this, but my batteries are fairly fresh.

Due to changes in the meter circuit board over the production of the M6, this behavior will vary from camera to camera. On an early model like mine, normally the LEDs will just not ight at all if the light level is too low. However, the meter circuit board was replaced on my M6 several years ago after it was damaged by battery leakage (OOPS). 

As I normally use slower films, I hadn't really run into this except in very dark conditions.  

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[Fotoklaus]

Perhaps the meter comes to it's limitations with ISO 3200 Film.

It will flash when it is too bright or too dark.

Don't know the range, maybe EV -1 to 19?

[Shac]

Silicon photodiode - EV -1 to EV 20

[Danner]

I just tested my very early M6 (1985) with its OEM meter.  The metering LEDs go out when there isn't enough light for the photo-diode to detect it.  And, the LEDs never flash.  So, the point at which the LEDs turn off is only dependent on the aperture setting of the lens, and not dependent of the shutter speed setting of the ISO setting at all.  Pointed it at my dark carpet in a room with low light levels, the LEDS are on at f2.0 through f4.0 and go off by f5.6, regardless of what the shutter speed is set at (I tested 1 sec through 1/1000 sec) or what the ISO setting is (tested 50 through 6400).  Of course, if the aperture is at f4.0 or wider, LEDs function in the usual manner.  If I point the camera at a bright source (the shade of a table lamp) the metering LEDs stay on from f2.0 through f16.0, again, regardless of shutter speed or ISO.

Hope this is useful...

 

[TomB_tx]

2 hours ago, Danner said:

I just tested my very early M6 (1985) with its OEM meter.  The metering LEDs go out when there isn't enough light for the photo-diode to detect it.  And, the LEDs never flash.  So, the point at which the LEDs turn off is only dependent on the aperture setting of the lens, and not dependent of the shutter speed setting of the ISO setting at all.  Pointed it at my dark carpet in a room with low light levels, the LEDS are on at f2.0 through f4.0 and go off by f5.6, regardless of what the shutter speed is set at (I tested 1 sec through 1/1000 sec) or what the ISO setting is (tested 50 through 6400).  Of course, if the aperture is at f4.0 or wider, LEDs function in the usual manner.  If I point the camera at a bright source (the shade of a table lamp) the metering LEDs stay on from f2.0 through f16.0, again, regardless of shutter speed or ISO.

Hope this is useful...

 

Yes that is helpful. However, when trying to meter for correct exposure a very high speed film needs a smaller f-stop than a slower film. Indoors with flickering lights you can get banding from some LED bulbs at shutter speeds over 1/60, and I found the lens set for correct exposure at 1/60 (with 3200 ISO) caused my M6 LEDs to flash. (My 1985 had the metering board replaced with a later version - originally it didn't flash like yours.) Curious that the flashing with the revised board seems to happen in brighter light than when the old board went dark. Also, the meter works fine at light levels that cause the LEDs to flash, for at least a couple of stops dimmer, It's just distracting. The 1985 M6 meter sensitivity was rated for 0EV to 20EV. The M7 meter was rated for -2EV to 20EV, so much more sensitive. Now that I have an M7 also, I can see it is much better in dim light.