I know you weren't here for the complete thread, but before we run the risk
of branding the PROGRAM mode cameras as "not being able to work with all
lenses", OR that "Even Zuiko lenses don't work on al Olympus OMs" ..... Are
we now talking about the "warning" Olympus gave with reference to third-party
lenses, or are we talking about motor-drive capability? The discussion of
PROGRAM limits was originally with regard to the reduced (3.5 fps as opposed
to 5.0 fps) motor drive capability in PROGRAM mode due to the extended
metering time lag. Now it seems we're discussing the possible problems of
using the PROGRAM mode with some lenses. I'd just about disregard the
3rd-party lens "warning" as all manufacturers put a similar warning into
their owner's manuals. I think it's more for idiots who may try to mount an
incompatible lens on to an OM, and hence damage the camera mount and/or
electronics.
I may be wrong, it wouldn't be the first time,
George S.
HI100@xxxxxxx writes:
> Hi all,
> Excuse me if I repeat what others have said, I have been away and
> may
> have missed some of this thread.
>
> Hans writes:
>
> << The manuals of the OM-2S and OM-40 say regarding program mode under
> 'other
> cautions':
>
> "When the OM-2S [OM-40] Program is used with other brand lenses, Olympus
> can
> not
> assume any responsibility for poor image quality or other problems. This is
> particularly true when other brand lenses are used in PROGRAM mode."
>
> I'm not sure how serious one must take this warning. I think it only
> applies
> if
> the aperture mechanism including the levers of the lens does not operate as
> smoothly as Zuiko's.
>
> Wether Cosina zooms are included in this warning is unsure ;)
> >>
>
> Actually, even some of Olympus's own lenses don't all work as advertised in
> Program mode due to differences in diaphragm construction. The exposure
> time
> is meant to be fine adjusted (regular OTF method) after stop down to make
> up
> for diaphragm stop down setting errors but, probably due to long bounce
> times
> for some lenses, this is less than perfect affecting overall accuracy.
>
> Olympus specifically mentions the following aspects (my abreviated version)
> of their bad actors using Olympus house codes (my translations are guesses
> marked ?) :
>
> MZ3510K : aperture mechanism different so program setting not as described
> but overall exposure still ok.
>
> MT1820 (180mm F2.0?).MT2520 (250mm F2.0?), MT3528 (350mm F2.8?), MT6065
> (600mm F6.5?), MT1011 ( 1000mm F11?): Large apertures cause problems in
> stabilizing aperture blades in a short enough time. This causes inaccurate
> high speed exposures.
>
> MZ3570AF (35-70mm Auto focus zoom?) Use only in SINGLE AF mode when in
> low
> light 9because of the focusing delaying stop down?).
>
> "Certain lenses" with "early operation-start timing" are slightly stopped
> down at low luminance so they are not fully open used in PGM mode. Overall
> exposures are still correct. Third party lenses with different timing
> might
> be a problem here as well?
>
> M8FE (8mm Fisheye) can be used if the aperture is set to F22. The
> description
> is a bit unclear.
>
> Even with a standard lens Aperture accuracy is specified loosely:
>
> Olympus specifies an **overall** exposure accuracy of +/-0.4EV in PGM mode
> (specified test conditions,50/1.8/ASA 100,BV6-15)
> but an accuracy of **aperture** setting (with a 50mm F1.8 lens) of:
>
> F8: +0.7 to -1.2 EV
> F3.7 +0.8 to -1.0 EV
> F1.8 +0.8 to -1.0 EV
> The last value makes no sense but maybe it is an "early operation start"
> type
> see above.....
>
> Of course the program mode does not know the lens maximum aperture so the
> program setting depends on the lens maximum aperture. So in a sense there
> is
> no fixed program for a fixed light value since it depends on the particular
> lens's max aperture. With slower lenses of F3.5 F4 etc there are fewer
> program steps available too.
>
> Warren wrote:
> >> I suppose the design specs for Zuiko lens set forth that xx mm. of
> lever movement corresponded with yy aperture stop down.
> <<
>
> The stop down mechanism does not rely on the position of the aperrture stop
> lever because the camera actually measures the light during stoping down
> and
> halts the lever movement at the predetermined light value for the
> predetermined program setting. ( that it decided on just prior to
> performing
> stop down. )
>
>
>
|