I specifically didn't say because it depends on whether the spot or
average reading is correct. If neither is correct, it's yet a different
number.
If the average is correct and, as I understood Carlos' post, the spot
mode gives a longer exposure than average mode, one would adjust the
exposure to 2/3 stop less for spot, thus shortening the shutter speed.
I wouldn't read too much about any other camera into Carlos' situation.
His camera is likely not correctly adjusted and it is actually
surprisingly difficult for the human eye to tell if a 'uniformly' lit
subject is actually uniformly lit within a stop or 2, particularly if
the subject is big enough that eye movement is needed to view it all
clearly. Hmmm, maybe that's why the pro repair people use specialized
equipment to measure this stuff. I've been thinking about a solution
similar to what Jan suggested, using a good light table or something
similar. Simply standing the camera/lens on the front of the lens with
the lens focused on infinity might do the trick?
Moose
danrich wrote:
Stupid question, is that 2/3 of a stop more or less?
------------------------------
Date: Thu, 13 Feb 2003 18:30:38 -0800
From: Moose <olymoose@xxxxxxxxxxxxx>
Subject: Re: [OM] Spot-metering madness
That can't be right. I don't know how the spot meter is supposed to be adjusted, but here either spot or average is clearly out of adjustment
if the testing methodology is near correct, i.e. lighting is actually even. The fact that the error is there with 50mm standard lenses
indicates it isn't just the 'angle of incoming rays' effect. The average error over all those lenses from 14-300mm is 2/3 of a stop. If the the
metering that is off were adjusted by 2/3 stop, the average error would be about zero and only 5 lenses would be out by more than about 1/3
stop, certainly a better situation than the current one.
Carlos,
Your comparison is made in such a way that it seems to assume that the spot meter is wrong. I don't see where that is necesarily the case, it
could be either. If you know or can determine through bracketed tests with slide film, which one is off, you could, at least in the short run,
simply adjust the exposure compensation dial by 2/3 stop when switching Modes. That would put you close enough that you would be assured of
acceptable exposures with most of your lenses.
< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >
|