ISO Adjustment - M6

[B-A-C]

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All,

 

When you change the ISO on the back of your film Leica, what happens mechanically within the camera? I am still new to film and do not understand this.

 

Thanks

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[erl]

Changing the ISO dial on the back of the M is simply calibrating the interpretation of light brightness by the light sensor that reads the light reflected from the white spot on the shutter curtain. Remove your lens and you will see the white spot painted on the curtain.

 

Look up to the left of the cam wheel and you can just see the sensor with its black hood to shield it from stray light. This is what controls the Red arrows in your VF.

[B-A-C]

Erl,

 

How does that work with a non metered Leica such as the M3? Thanks

 

BC

[TomB_tx]

The dial on the back of the M2,3,4 is simply to remind what film is loaded. The clip-on MR light meter for these models has it's own ASA (earlier standard than ISO) setting that simply moves the f-stop scale relative to the meter needle that moves by light brightness. On these models you read the recommended f-stop (for the shutter speed selected), and set the lens accordingly.

[Chuck Albertson]

All,

 

When you change the ISO on the back of your film Leica, what happens mechanically within the camera? I am still new to film and do not understand this.

 

Thanks

 

There's a potentiometer (voltage control) in the back flap of the M6, with gold contacts for the specific ISO settings. Even though they're gold, it's a good idea to run the ISO dial through its range when you change film, to scrub off any tarnish or dust on the contacts.