Paul Repacholi wrote:
MedF has an advantage over 35: well capacity of the CCD. You can put
just as many pixels (or even more) but they are *bigger*. As you
probably don't want to cart liquid N2 or an peltier cooler and fridge
with you, the read out noise plus dark current is stuck at 20-30
electrons/sec. Simular for the CMOS one. So to get the brightness
range you need a *HUGE* well capacity. This is why the scanning
MedF backs still hold their market. A MedF lens is a good match
for CCDs, as on top line 35 lenses you must reduce the resolution
to prevent aliasing. MedF lenses are about right for 2 pixels
per line, the limit. But larger one with a higher capacity.
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Paul,
I disagree with what you are saying. The reason we do not have larger CCDs
is not heat, but the fact that doing so causes more defects in manufacture.
Larger CCDs are also more expensive to make with limited defects. Larger
CCDs typically have more defective pixels it will have. As manufacturing
improves (new techniques/equipment) this gets better.
CMOS is a different technology, uses less electric and generates less heat.
The reason Scanning MF backs may remain around is for the studio where you
need the absolute maximum resolution but they too are smaller than the film
area. Even the studios these days are using one-shot more and more because
they can do more than just still life. One-shot (or single shot) backs also
allow for flash/studio strobe whereas scanning backs need continuous
lighting.
Just my 3 cents.
Peter K
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