[OldChE]

I'm interested in adding one of the original "Pentax" models (those first cameras with an eye level pentaprism finder, after the Asahiflex models) to my collection. I'm considering either the original Pentax "AP" model of 1957, or the third model in this line, the Pentax "K" model of 1958. Both have two shutter speed dials (one for fast, one for slow speeds). The "K" model introduced the little push plate behind the lens that actuates the pin on the lens to close down the aperture when the shutter is fired. It was sold with the "Auto Takumar" lenses that introduced the pin on the lens. The K also has shutter speeds going to 1/1000s, while the AP goes to 1/500s.

My question is: since the model K has that push plate, how will it work with the later Super Takumar lenses with fully automatic diaphragms? Would I be able to use those lenses pretty much the way I use them on my Spotmatic, which also has that push plate? What I'm hoping is that, if I mount say my 35mm F3.5 Super Takumar to the Asahi Pentax K, and leave the lens auto/manual switch on auto, then I can focus with the lens wide open, set the aperture ring to the desired setting, and when the shutter is fired the push plate will move forward, stop down the lens for the exposure, then after the shutter closes the lens will open back up (which is the "fully automatic aperture" feature of the lens). Is that how it will work?

Please excuse me if this has already been answered in the threads. I did try to search for "Pentax K" and "Asahi Pentax K" but you can imagine that turned up almost every post in the entire forum.

Thanks - Richard.

[arnold]

I'm interested in adding one of the original "Pentax" models (those first cameras with an eye level pentaprism finder, after the Asahiflex models) to my collection. I'm considering either the original Pentax "AP" model of 1957, or the third model in this line, the Pentax "K" model of 1958. Both have two shutter speed dials (one for fast, one for slow speeds). The "K" model introduced the little push plate behind the lens that actuates the pin on the lens to close down the aperture when the shutter is fired. It was sold with the "Auto Takumar" lenses that introduced the pin on the lens. The K also has shutter speeds going to 1/1000s, while the AP goes to 1/500s.

My question is: since the model K has that push plate, how will it work with the later Super Takumar lenses with fully automatic diaphragms? Would I be able to use those lenses pretty much the way I use them on my Spotmatic, which also has that push plate? What I'm hoping is that, if I mount say my 35mm F3.5 Super Takumar to the Asahi Pentax K, and leave the lens auto/manual switch on auto, then I can focus with the lens wide open, set the aperture ring to the desired setting, and when the shutter is fired the push plate will move forward, stop down the lens for the exposure, then after the shutter closes the lens will open back up (which is the "fully automatic aperture" feature of the lens). Is that how it will work?

Please excuse me if this has already been answered in the threads. I did try to search for "Pentax K" and "Asahi Pentax K" but you can imagine that turned up almost every post in the entire forum.

Thanks - Richard.

I have found that the models like the K and H2, had push plates to trip the earlier pre set lenses. They most likely won't move far enough to proportionately close the later lenses. You can try and see how well it works. By the way, I have several of these earlier S model cameras. They are old and on three of them the old shutter tapes let go. Age just dries things out and they can only take so many shots before the curtains fail.

[OldChE]

I have found that the models like the K and H2, had push plates to trip the earlier pre set lenses. They most likely won't move far enough to proportionately close the later lenses. You can try and see how well it works. By the way, I have several of these earlier S model cameras. They are old and on three of them the old shutter tapes let go. Age just dries things out and they can only take so many shots before the curtains fail.

Thanks for your comment. When you say the plates won't likely move far enough, is that based on your experience trying them with later Super Takumar lenses? Or are you commenting more from observation of how the plate usually moves? Someone recently told me that the plate should allow operation of modern lenses. But, it is good to be forewarned that this might be an issue.

Yes, I understand about the shutters. I would like one that works, but we'll see. I am just as old (born in 1957), so I know well how this kind of age can affect things!

Thanks - Richard.

[arnold]

Thanks for your comment. When you say the plates won't likely move far enough, is that based on your experience trying them with later Super Takumar lenses? Or are you commenting more from observation of how the plate usually moves? Someone recently told me that the plate should allow operation of modern lenses. But, it is good to be forewarned that this might be an issue.

Yes, I understand about the shutters. I would like one that works, but we'll see. I am just as old (born in 1957), so I know well how this kind of age can affect things!

Thanks - Richard.

I discovered this when I used a later lens. It did not close fully due to the limited throw of the push plate. However, this is not to say there won't be exceptions in some cases.