As I understand the meter field area stays a constant 27% of the total field. Relative to the full viewing frame, the meter field is largest at 28mm and smallest at 135mm.

What I want to know is if it is possible to use the frameline selector to manipulate the meter to give a limited spot reading when a wide angle lens is being used? Will bringing up the 90/28 frame when one is using a 35mm lens work to give a narrow "spot" meter?

Incidentally, if this works how does the meter to bring up the 90mm field and not the 28mm field?

Cheers. Simon Wong

-- Simon Wong (drsimonwong@hotmail.com), June 02, 2001

Answers

I had an old book that stated that you could modify the metering field via the frameline selector, but this is not in fact true. The metering area is solely a function of the light hitting the white dot though the lens, and the lens' angler of view will control the angle of the metering field. A wide lens will have a wider field, the narrow lens will have a more narrow field.

You can however use the frameline selector to estimate the metering field, simply to make sure you are metering a proper tone, excluding subjects that would fool the meter. This is a visual tool for the photographer only... the meter doesn't care which framelines are displayed.

-- Al Smith (smith58@msn.com), June 02, 2001.

Mounting a 135mm lens will permit you to meter the narrowest angle possible, and the exposure value will be valid for whatever lens you make the shot with.

-- Jay (infinitydt@aol.com), June 02, 2001.

One way that might help you understand the metering pattern, is to point the camera at a small light source in a darkened room and watch how the LED's respond. This should give you a pretty good indication of where the meter-pattern area is in relation to the viewfinder.

-- Jack Flesher (jbflesher@msn.com), June 02, 2001.

you can move the frame selector up and down, but it wonīt change the angle of vision you have on the lens mounted, canīt think on any thing else to do, Jackīs observation can be very helpful.

-- r watson (al1231234@hotmail.com), June 02, 2001.

Thanks for all the responses.

I think I've figured it out. Al's comment prompted me to look up my potential source of confusion. Eastland's Leica M Compendium. He stated the meter size would vary with differing focal lengths (true) but I now believed he erronously thought one could bring up the different meter fields with the frameline selector.

Thinking about how the camera actually meters it becomes obvious this isn't possible. Otherwise the meter patterns would be all wrong when you mounted screw to M adapters. Al's comment on the size of the metering being determined by the focal length image from the lens itself is accurate.

What one can use the frameline selector for is to help "visualize" the approximate size of the field measured.

Cheers all.

-- Simon Wong (drsimonwong@hotmail.com), June 02, 2001.

Yes, Eastland does mistakenly say this, on pp. 130-131. First he notes that "The diameter of the measuring field is equal to 2/3 of the short side of the bright-line frame in use." So far, so good. But then he decides that "the bright-line frame in use" can be any frame selected with the lever: " . . . in practice it means that the photographer can accurately measure very small areas of the object to be photographed using the preselector lever.

"For example, when using wide-angle lenses . . By flicking the preselector lever to bring up the 90mm bright-line frame, particular areas of the scene can be measured and interpolated."

WRONG!

Eastland must have outsmarted himself on this. for reasons others explained above, only by changing the lens focal length can the metering field be changed.

-- Bob Fleischman (RFXMAIL@prodigy.net), June 02, 2001.

Yep, spot on Bob. That's the same passage that had me stumped for a few days. Amazing what we believe if it's in print....

Cheers.

-- Simon Wong (drsimonwong@hotmail.com), June 02, 2001.