Moose, thanks for sharing the exposure test results. Verrrry in-ter-esting.
The brochure that gives the recommended stops for various OM Zuikos on the
E-1 often eliminates the first and last one or two stops. Olympus'
recommendations seem to correspond with what the people who've noticed the
variable exposure effect have reported. Now, if Oly would only tell us why.
Your results hint at why some people have reported no exposure issues,
whereas others have. It could depend on what metering you use, and what
lenses, and whether you like to play at the extreme apertures or not.
What would happen if you take an incident or brightness range reading with
a hand meter, and expose accordingly, ignoring what the camera says it
wants? Or use the camera's internal manual metering at a medium aperture,
then just go through the EV series. Worth a try, maybe?
I wonder how all this affects cameras that use lenses designed for
film. Does the same thing happen with Canon, Nikon and Pentax lenses on
the same manufacturer's camera, or does the camera know enough to make the
needed compensation? How will this affect the usability of the new Epson
RD-1 (which takes Leica-mount lenses)? That camera has no idea what lens is
mounted, nor what f-stop is set--just as with the manual Zuikos on the E-1
or Canon body.
Film is *so* much simpler. Except that you gotta spend time developing and
scanning it. I guess that these weird exposure effects are just part of
the game with digital, but the needed compensation is programmed in when
you mount a Brand X lens on a Brand X body. Dealing with the effect may
involve trade secrets, hence Oly's reluctance to reveal much besides "OM
lenses are not designed for digital."
BTW, many thanks to Piers and the anonymous OMer who sent me a link and a
copy of the OM compatibility brochure, respectively
--Peter
Moose wrote:
>OK, so I did a test on the 300D with a 50/1.4
><http://www.moosemystic.net/Gallery/300Dexp.jpg>.
>
>Should be pretty self-explanatory.
>
>Top row were taken in Auto Mode, starting with f1.4. I just took a shot,
>moved the aperture one notch and took another, etc. Bottom row the same
>except I adjusted the little arrow to set "match needle" exposure by
>changing the shutter speed. All the speeds are those in the EXIF data
>from the camera.
>
>Subject is a poster of a Van Gogh painting, in case you were wondering
>what would look so odd in the small size.
>
>Looking at the histograms, best exposure is about f2.8@1/80 and
>f2@1/160, iso 800, equivalent exposures found in #3, top row and #2,
>bottom row. Looks like 300D weirdness is in the opposite direction from
>E-1 weirdness, getting darker with smaller apertures. Obviously it is
>not linear, settling at about f2.8-f4 with this lens and light level,
>then staying pretty much the same. Getting an idea of what is going on
>requires a whole set of exposures, particularly at large apertures. The
>first 2 Auto shots are definitely overexposed with some blown out
>highlights.
>
>While Auto uses evaluative exposure on the 300D, Manual Mode uses center
>weighted, with much more stable results. I could just add 1/3 stop plus
>exposure compensation and be good an any aperture.
>
>Light level was moderate, I'll try another lens and/or light level.
>
>Moose
>
>C.H.Ling wrote:
>
> >Just test the E-1 again at center weight average and A mode, with brighter
> >scene (ISO200, F4, 1/250s), both 35/2 and 75-150 (at 75mm) got brighter
> >image at F16 vs F4. When the target light was lower (ISO 200, F4, 1/13s),
> >the images was slightly dimmer at F16 for 75-150 and the 35/2 still gives
> >slightly brighter image at F16. It looks more complicated as I have
> >expected, I didn't know it is light intensity related although I knew
> >different lenses act differently.
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