fiftyfive Posted July 20, 2011 Share #1 Posted July 20, 2011 Advertisement (gone after registration) ...my dear Watson. I became an M7 owner first of the year, and recently my son has started down the film path with a Minolta Maxxum 7000i, using my old AF Minolta lenses from the late eighties - I took a lot of great shots with the 28-85 zoom. We were just sitting here indoors under room lighting and compared metering between our two cameras - same film (400), same aperture, same focal length, same center weighted metering. Consistently, the Leica calls out exposure times about twice as fast as the Minolta. Our best deduction is that light transmission through the Leica lens is twice as efficient as the Minolta, all else equal. We'd appreciate your guidance. Thanks Link to post Share on other sites More sharing options...
Advertisement Posted July 20, 2011 Posted July 20, 2011 Hi fiftyfive, Take a look here Elementary question.... I'm sure you'll find what you were looking for!
AlanG Posted July 20, 2011 Share #2 Posted July 20, 2011 ...my dear Watson. I became an M7 owner first of the year, and recently my son has started down the film path with a Minolta Maxxum 7000i, using my old AF Minolta lenses from the late eighties - I took a lot of great shots with the 28-85 zoom. We were just sitting here indoors under room lighting and compared metering between our two cameras - same film (400), same aperture, same focal length, same center weighted metering. Consistently, the Leica calls out exposure times about twice as fast as the Minolta. Our best deduction is that light transmission through the Leica lens is twice as efficient as the Minolta, all else equal. We'd appreciate your guidance. Thanks What the cameras "calls out" is irrelevant as one or both may be inaccurate. If you shoot color slide film with both, is one of them consistently "better"? Link to post Share on other sites More sharing options...
scrubs Posted July 20, 2011 Share #3 Posted July 20, 2011 Different metering modes in both cameras. The minolta as far as I know uses a matrix exposure system default, centre weighted when in manual focus, and option for spot also. M7 uses a large spot, think of it as inbetween center-weighted and a spot-meter. File the whole frame with a flatly lit piece of paper or grey card and you should see more closer matches. Link to post Share on other sites More sharing options...
FiZZ Posted July 20, 2011 Share #4 Posted July 20, 2011 It could be that one calling out 18% gray and the other is 12% gray... You could do the same experiment with something flat outdoors and then compare results. Use sunlight and Sunny 16. Link to post Share on other sites More sharing options...
BobYIL Posted July 20, 2011 Share #5 Posted July 20, 2011 Twice means one f-stop difference which can be quite normal for the different measuring processes employed in these cameras. I would rather recommend you to repeat the same experiments by switching the Maxxum to center-weighted mode and aiming the same portion of a wall homogenously illuminated, for instance. If the difference persists, then check the batteries or one of them needs calibration. Link to post Share on other sites More sharing options...
Michael Geschlecht Posted July 21, 2011 Share #6 Posted July 21, 2011 Hello fiftyfive, Welcome to the Forum. There are a number of other issues you might want to consider in terms of why there might be a difference in the 2 readings: A zoom lens, because of the additional elements, absorbs a greater ammount of light than a single focal length lens. This even though there was multi-coating available @ that time. A zoom lens might therefore require more light for an exposure @ an equivalently marked aperture than a single focal length lens & have a cam to compensate allowing the appropriate exposure. @ that time (1980's) many zoom lenses were variable aperture lenses for a variety of reasons. An actual lens aperture setting @ a longer focal length might be somewhat smaller than what was marked on the barrel which might only be the mathematical F stop @ the shortest focal length. @ that time a number of lenses had actual focal lengths which might be longer or shorter than what they were marked so if you choose a focal length which is the longest or the shortest it may be somewhat inaccurate. Lenses whether zoom or fixed often have less than mathematically defined transmission of light @ certain wider apertures. SLR lenses for cameras w/ BTL meters often have cams which compensate for this light fall off & adjust accordingly so there may be more exposure mathematically given than appears to be called for apparently. & there is more. What to do? I would set the zoom @ the shortest focal length @ a medium aperture for that lens @ a medium distance. Maybe F8 or 11 depending on the range. I would then set the fixed lens @ the same aperture & distance. If the fixed lens is a 1.4 or faster I would not use smaller than F8. I would then photograph the SAME center spot on an evenly lit WHITE wall. I would make sure the white wall was evenly lit for a distance beyond the angle of the wider lens. I would use either meter to check the evenness for both. Whichever you choose. Not 2 meters for 2 lenses. Then I would begin by choosing the same ISO for both cameras & photographing the white wall @ what each camera says for its own exposure individually + 2 stops MORE exposure. Then both cameras should photograph the spot on the wall w/ what 1 camera says +2 stops MORE exposure. Then both w/ what the other camera says +2 stops MORE exposure. Compare all the photos & tell us here what you get. The +2 stops exposure is because you want all of the photos of the white walls to be reasonably white. Best Regards, Michael Link to post Share on other sites More sharing options...
garygsandhu Posted July 21, 2011 Share #7 Posted July 21, 2011 Advertisement (gone after registration) The OP did say the minolta was on center metering (it helps to read the post!). The Leica and the minolta have different center metering patterns (google it for diagrams). You'll notice that when you point at a lit lamp in the dark and move your camera around how the exposure changes differently in both cameras. The light transmission of different lenses may account for a 20% difference (especially between a complex zoom and a prime) Link to post Share on other sites More sharing options...
Guest Randle P. McMurphy Posted July 26, 2011 Share #8 Posted July 26, 2011 ...........elementary outcome ? What system was right ? Link to post Share on other sites More sharing options...
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