Originally posted by jase036 Hmmm, I did not know that, but sure, it makes sense, with no A setting it can't do P-TTL metering... Thanks, learned something new!
Actually you CAN do P-TTL flash with a manual lens or A lens set at a specific f-stop. This is just the opposite of what the original poster wanted, but it can be done.
If you look at the K-r lens mount, you will see that the 3rd contact from the left (lens locking pin) side is indented rather than sticking out. Look at the mount of a K-A lens with it set on A versus any fixed f-stop value. You will see the matching contact retracts when not on A. So we can force the K-r to think it always has an automatic aperture on any lens by shorting this indented pin.
The slickest way to do this (not my idea by the way) is to remove the lens mount from the camera and place a thin strip of several layers of aluminum foil (2-4 depending on the foil) over the pin. Reinstall the mount (it will work like a paper hole punch) and trim any excess. It takes less than 5 minutes and a jeweler's screwdriver. (okay it took me 10 minutes the first time)
What happens is really useful.
- First, you can manually set a lens aperature and because the camera thinks every lens has an automated aperature, flash will be P-TTL.
- Second, if you manually set a f-stop, manual metering will normally just show "F _ _ _", except with the pin shorted, your camera will display a f-stop and shutter speed ... the operator's chore is now to make sure what the camera says will be the f-stop and where the lens is manually set are the same. Now program the green button to stop down the lens so you can see depth of field in the viewfinder. WOW! it's almost like shooting with a K-1000 and match needle metering.
What to return to how Pentax programmed your K-r? (can't imagine why, but...) Just remove the foil you installed.