PHOT-ALL Lens

Just recently picked up a lens titled PHOT-ALL F2.8 135mm The lens is can be unscrewed apart. It has 2 f stop dials that from F2.8 to F22, the lower dial closest to the camera body seems to work the apateur, the other ?. The lens has a M42 thread mount and a 55mm filter thread, No220360E on the outer side. Anyone know about or any links to explain this unusual lens?

galelegg wrote in post #18994958
Just recently picked up a lens titled PHOT-ALL F2.8 135mm The lens is can be unscrewed apart. It has 2 f stop dials that from F2.8 to F22, the lower dial closest to the camera body seems to work the apateur, the other ?. The lens has a M42 thread mount and a 55mm filter thread, No220360E on the outer side. Anyone know about or any links to explain this unusual lens?

Those lenses used to be pretty common. They're called preset lenses.

One of the rings should have detents, the other should operate smoothly with no detents. The idea is you set the detent ring to your desired f-stop, then open the iris fully to focus. When you're ready to press the shutter you close the iris to the preset detent setting.

This was because many lenses, especially long telephotos, couldn't be focused accurately at smaller apertures.

So-called automatic lenses (not autofocus, just automatic stop-down before shutter activation) became common and preset lenses pretty much disappeared.

-js

Thanks number 6. I removed the aperture ring closest to the outer ring of the lens and it still worked. Attached it to my Canon 6d with Eos to m42 converter and took some photos of my granddaughter at the pool and park. Also swapped it over with a Consinon lens same focal length and aperture, could not tell the difference in the photos. These old F2.8 135mm lenses work great probably because they allow so much light to the sensor easy to hear focus beep from camera. Phot_All cost $10AUD. Consinon about $25AUD.