Originally posted by Beau Currently with the K10D, and I presume the K20D and K-7, when you are using a manual lens you'll get "F --" and have to use stop-down metering in the M mode.
When the camera does the stop-down metering it could calculate the ratio between wide open and stopped down and thus measure the effective F-stop.
It should therefore be possible to put the camera in Av mode and adjust the shutter speed according to the measured F-stop, only needing a new stop-down metering when you change the aperture on the lens.
It doesn't work like this so maybe I'm missing something?
Cheers,
Beau
the idea is right in concept but wrong in execution for a couple of reasons.
first of all, in all but manual mode the K10D and (I assume) the others, will not operate the aperture lever. the lens shoots wide open all the time.
if you were to add the function you want, the idea would be to have the camera meter when you press the green button without stopping dowe, then stop the lens down meter again, and calculate the change in aperture to know how many stops, and select the shutter accordingly.
You could go one simpler, and add a metering step after stopping down, but before moving the mirror, and set the shutter by this. (but shutter lag will increase since stopping down and moving the mirror are probably done in parallel at present)
In theory it would work, it practice it can't because the K10D and K20D metering are not linear, and need to know maximum aperture to meter correctly.
What would be better, would be to input the max and min aperture and let the camera control the aperture just like with new lenses (except the relatrionship between aperture and lever position is not the same as A series lenses)