07-22-2010, 03:56 PM
[quote name='Yakim' date='22 July 2010 - 05:28 PM' timestamp='1279812483' post='1240']
No, but I don't think it'll make any difference. In my previous experience I get the same exposure in the pic itself, regardless of the lens mounted.
[/quote]
Hi Yakim,
I really do think you need to. I honestly do reckon that wide open the Mamiya underexposes by about a stop, if the brightness levels were exactly the same when either lens was mounted.
I also think you need to test more rigorously to see what is really at play, which means you really have to create a setup indoors with controllable fixed lighting or flashes.
The Canon may be slightly optimistic when stopped down a little, and the Mamiya probably underexposes by a full stop, especially wide open, and likely suffers from both reflections and light loss due to lesser coatings. And that if the light levels realy stayed the same throughout yoru test.
If you take that first stop away, it is only 2.5 stops, and that is quite reasonable. Light measurement generally is no more acurate than about 1/3 of a stop anyway. I also think you need to compare all metering modes, not just spot metering; it is more easily misled than more integral metering modes.
Finally, you should also try this at different f-stops, not just F/4, i.e., wide open for the Mamiya. I think that is the only way to find out how the Mamiya behaves, and find possible causes. And you have to take pictures, of course, and check and compare those.
Kind regards, Wim
No, but I don't think it'll make any difference. In my previous experience I get the same exposure in the pic itself, regardless of the lens mounted.
[/quote]
Hi Yakim,
I really do think you need to. I honestly do reckon that wide open the Mamiya underexposes by about a stop, if the brightness levels were exactly the same when either lens was mounted.
I also think you need to test more rigorously to see what is really at play, which means you really have to create a setup indoors with controllable fixed lighting or flashes.
The Canon may be slightly optimistic when stopped down a little, and the Mamiya probably underexposes by a full stop, especially wide open, and likely suffers from both reflections and light loss due to lesser coatings. And that if the light levels realy stayed the same throughout yoru test.
If you take that first stop away, it is only 2.5 stops, and that is quite reasonable. Light measurement generally is no more acurate than about 1/3 of a stop anyway. I also think you need to compare all metering modes, not just spot metering; it is more easily misled than more integral metering modes.
Finally, you should also try this at different f-stops, not just F/4, i.e., wide open for the Mamiya. I think that is the only way to find out how the Mamiya behaves, and find possible causes. And you have to take pictures, of course, and check and compare those.
Kind regards, Wim
Gear: Canon EOS R with 3 primes and 2 zooms, 4 EF-R adapters, Canon EOS 5 (analog), 9 Canon EF primes, a lone Canon EF zoom, 2 extenders, 2 converters, tubes; Olympus OM-D 1 Mk II & Pen F with 12 primes, 6 zooms, and 3 Metabones EF-MFT adapters ....