Julian wrote:
>>
Max frame rate for OM2 is 4fps. This according to the first version of the
MD manual and Pangerl (plus my and now your measurements) . The assumption
that 5 is available is down to clever wording in version 2 onwards of the MD
manual. 5 is for an OM1 with the mirror locked up.
Experiments with later bodies indicates that none is significantly faster
than the OM2, so the 5fps claim for the motors is true only for OM1. Try it
and lock the mirror up while winding. The difference is VERY obvious, and
from a winding / releasing point of view, it's the same camera as an OM2.
Pretty much the same as a 2S, 3(Ti) 4(Ti) as well, come to that.
<<
The service manual for the MD2 is pretty explicit it says 5FPS can be had when
using the MMS-B3,
which is the house code for the M15V. It does not specify OM1 or to use mirror
lockup. The MD2 is
aimed at the OM4 with rewind functions,reset on back open etc, so it would be
interesting if it is
such a weasel spec., implying only the oldest model with mirror up! The MD
manual you refer to,
which one is that? for the MD1 or MD2.
The OM2S you mention as being the similar is of course by design **slower**
because of the stop
down delay they added for PGM mode.
Wayne wrote:
>>How much different would the behaviour (peak current, average current, frame
>>rate) be with film
in the body ? What would you predict the behaviour to be with the M18V with
alkalines ?
<<
I have not measured what difference it would make, but it seems likely the film
is a relatively
small load. The 250 roll back however is something else, anybody know whether
this slows things
down?
Mark D. feels that the 18V grip runs faster than the M15V but has not done the
back to back
comparison. I would guess the peak current would be less because the short cct
current of the
Alkalines is only 5~6A (a bit lower than the NiCd's). This implies at the ~3A
peak that I measured
the cell voltage would drop to ~9V and equivalently the cell peak currents
would be lower. This
means peak currents are likely below 3A with 18V grip. But this does not
necessarily mean it runs
slower because over the ~0.6A end of the wind cycle the voltage may run a
little bit higher than
the 15V NiCd pack . Given the vintage of most M15V packs it is a little
difficult to be definitive
in comparison as the cells get higher internal resistance as they age. Maybe
someone with new
(replaced ) cells in an M15V pack and a OM4T recently CLA'd could do a test?
To get an average
rate I ran the 36 frame countdown of the MD2. On the scope it is pretty clear
that polarization
causes the rate to drop a bit over the 36Frames. Make sure you charge the M15V
for at least
14hours before you run the test. Aside: Given the high peak currents you will
probably do less
damage to the cells by overcharging which tends to equalize capacity than you
will by deep
discharging where cell reversal occurs with the very high current peaks (very
bad).
It would be interesting to run the 18V grip with Nicd's, but my guess is it
would be very similar
to the test I ran with the M15V+regulated supply in parallel.
It would also be interesting to compare the current draw of the MD1 versus the
MD2 as the MD1 uses
a single motor. The MD2 may use rare earth magnet motors to cut size so again
this may help
current a bit despite the two motors.
Regards,
Tim Hughes
TimHughes@xxxxxxxx
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