Backwards aperture activation

Now I have finally heard the most bizzare way for any manufacturer to handle the way its cameras and lenses operate...Sent by a very long time friend in an on-line small photography oriented group that was formed originally by a nucleus of Nikon film camera owners...

"Yup, the D200 stops down without the battery, and the lens is stopped down all the way when the lens is not mounted. Hard to look for fungus and scratches when you are buying a lens. I remember opening the aperture ring when buying old Nikkor lenses. I wonder why they would design it this way."

Because the camera's autofocus was designed to hold the aperture open during metering and and let it stop down on its own during exposure. It's a purely mechanical thing having to do with the way the autofocus works. Some did it this way, some did it the reverse.

20droger wrote in post #6412913
Because the camera's autofocus was designed to hold the aperture open during metering and and let it stop down on its own during exposure. It's a purely mechanical thing having to do with the way the autofocus works. Some did it this way, some did it the reverse.

But consider the fact that it consumes battery power for every moment you are focusing the lens (wide open) and then the the battery diverts all its energy to activation of the shutter mechanism before it returns to full time opening the aperture...for an all-electronic camera that seems to be uneconomic way to utilize your battery power...you would need to perpetually turn your camera off to conserve power, thereby stopping down the lens and dimming the viewfinder!

Well, the guy who attributed viewfinder darkening with battery removal apparently wrongly associated it with aperture closing down! It seems that there is something going on with an LCD in the viewfinder optical path, that darkens if not energized.

Wilt wrote in post #6412975
But consider the fact that it consumes battery power for every moment you are focusing the lens (wide open) and then the the battery diverts all its energy to activation of the shutter mechanism before it returns to full time opening the aperture...for an all-electronic camera that seems to be uneconomic way to utilize your battery power...you would need to perpetually turn your camera off to conserve power, thereby stopping down the lens and dimming the viewfinder!

Actually, it doesn't use battery power to hold the iris open, only to return it to open after the shot. the holding-open part is purely mechanical. That's why the lens remains open when the camera is powered off.

IIRC, Canon FD lenses worked this way.

Unmounted, they stopped down. Mounting them opened the iris once a small pin was depressed and an aluminum arm on the back of the lens was engaged whlie mounting the lens.

FlyingPhotog wrote in post #6414158
IIRC, Canon FD lenses worked this way.

Unmounted, they stopped down. Mounting them opened the iris once a small pin was depressed and an aluminum arm on the back of the lens was engaged whlie mounting the lens.

Mechanical pins holding open apertures make some sense. If electrical operation of the aperture held it open, and the aperture closed when battery power was removed, that seems very electrically inefficient. But as I posted, it appears that statement which launched the OP was in error. Something appears to energize an LCD which displays focus points, and this apparently is less transparent when not energized.