This older M42 lens does't come with a A/M switch. It has a long pin sticking out with the aperture wide open and my K20D body won't depress it to the close down the blades according to aperture stops
I am planning to do some modification to make the lens manual permanently. I researched on various discussions with questions to all my buddies such as Mis, Peter, Frank, and few others from another forums, here is the summary of possible remedies:
- Use some way to jam the pin with cotton swap
- Converting Auto-Aperture M42 Lens to Manual Aperture on Flickr - Photo Sharing!
- Crazy clue to press down the pin in position
- Peter reported success with Helios-44M
- Unfortunately, my pin is long and the spring seems very strong underneath
- Subject to glue used, possible to undo the change
- Use of Kindai M42 to K mount adapter
- Helios 44m-5 is good for k10d?
- thanks to Frank for the suggestion