Originally posted by PentaxPilot Hello, and thanks for the great site!
3. I have an old screwmount Takumar 1.4 lens. It is in great condition. It has an "auto/manual" select...what is this?
4. Will this lens interface well, and is it worth keeping...or is it reduntant with the Tamron 28-80 which was included.
Thanks for the time, and consideration...
I assume that the Takumar 1.4 lens is a 50mm, so-called "normal" lens. That is a very good lens and it will work on any Pentax dslr, with a relatively inexpensive adapter.
The Auto/Manual switch on the lens refers to the aperture operation. These lenses were "automatic" in that the camera pushed the little silver pin on the lens mount to stop the aperture down to the selected f-stop. Otherwise the lens remains wide open for focusing. The camera stops it down for exposure and then lets if open again. With the switch in the Manual position, the aperture stops down immediately as you turn the ring.
Try it. Put the lens in Auto and turn the aperture ring while watching through the lens. Nothing should happen. With the aperture set at 16, push the silver pin. The aperture will close.
Now put the lens in Manual mode and turn the ring. The aperture should close and open as you turn the ring.
Back in the day, this was used when the lens was on an extension tube or bellows, which did not have the linkage to let the camera operate the aperture. On a dslr, it is important, because no Pentax dslr has the necessary linkage to push the pin, so the lens MUST be used in manual mode. This is not as bad as it seems. I use that very lens on my K10D. I put the lens in M mode, the camera in aperture-priority mode and fire away. I set the aperture on the lens and the camera picks the necessary shutter speed.
While the 50mm focal length is duplicated by the Tamron 28-80 zoom, the f/1.4 aperture can be very useful for low-light situations. I believe that the maximum aperture of the Tamron is f/3.5. That's over two stops.