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02-15-2013, 10:35 PM   #1
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M42 mount auto focus?

Hello everyone! I am a dslr noob and I just purchased an Auto Sears 55mm f/1.4. I should have gotten some info before I even thought about hitting "bid".

I didn't know I needed an adapter as in the auction it stated it was compatible with Pentax. Stupid me I know. I now have a 60 dollar lens sitting and collecting dust. I need to get an adapter, but I am unsure how to go about choosing one.

I am completely unfamiliar with old lenses. There is an M<--- --->A setting with a switch to go back and forth between them - am I correct in assuming this is for switching between manual focus and auto focus?

Are there adapters which allow for the use of auto focus?

I can't seem to find an adapter that is a genuine Pentax for less than 55 dollars. I think that is a tad ridiculous for an adapter. B&H is out of stock in them... is there an acceptable alternative?

Thanks so much everyone - I am so confused right now.

02-15-2013, 10:58 PM   #2
Ole
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Your lens is pure manual focus.

The A/M switch controls how the aperture works. On a modern camera you'll have to set to M (Manual) at all times which means that you manually set the apeture of the lens (the A was to enable yesteryears cameras to stop down the aperture "automatically" for you when you press the shutter button).

The adapter you need is this one which allows for a screw mount lens to be mounted on a K mount bayonet camera.

All this is probably too much trouble and you may be better off looking for an smc Pentax-A 50mm F1.7 or F2.0 lens. They can be had for about $50. These lenses are also manual focus but they don't need an adapter.
02-15-2013, 11:02 PM   #3
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Regrettably, no, it isn't for autofocus. The A setting is for auto aperture setting by the camera when used with an M42 body, and M for manual setting. If you switch it to auto and press the pin sticking out the back of the lens, you'll see the aperture close down to the setting on the aperture control ring on the lens.

The lens will work exceptionally well in a modern Pentax K-mount DSLR (with M42-K Mount adapter) but in manual mode.
02-16-2013, 03:45 AM   #4
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Would be nice if it was auto focus huh.

02-16-2013, 04:30 AM   #5
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Auto-Manual refers to the aperture, not focus. When in "Auto", you have to press the pin on the back to close the aperture, otherwise it stays wide open.
Unfortunately for you, you can't really blame the seller - it is 100% compatible with Pentax, but with Pentax screwmount, or M42. They made some great cameras in this mount in the 60s and 70s.
As to the price of the adapter being ridiculous - if $50 is ridiculous to you, clearly you need to spend more time on this forum.

Last edited by Ash; 02-16-2013 at 03:47 PM. Reason: Unnecessary message.
02-16-2013, 08:50 AM   #6
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Thanks for all the replies guys! Ya'll rock!

QuoteOriginally posted by Ole Quote
Your lens is pure manual focus.

The A/M switch controls how the aperture works. On a modern camera you'll have to set to M (Manual) at all times which means that you manually set the apeture of the lens (the A was to enable yesteryears cameras to stop down the aperture "automatically" for you when you press the shutter button).

The adapter you need is this one which allows for a screw mount lens to be mounted on a K mount bayonet camera.

All this is probably too much trouble and you may be better off looking for an smc Pentax-A 50mm F1.7 or F2.0 lens. They can be had for about $50. These lenses are also manual focus but they don't need an adapter.
Thank you so much for the advice! I'm really considering just cutting my losses and reselling it on Ebay. Your recommendation for the Pentax A would have been super helpful before I bought it. Need to check on forums before I buy anything ever again. Again, thanks a bunch for your reply.

QuoteOriginally posted by kcobain1992 Quote
Huh, you really are new, aren't you.
Auto-Manual refers to the aperture, not focus. When in "Auto", you have to press the pin on the back to close the aperture, otherwise it stays wide open.
Unfortunately for you, you can't really blame the seller - it is 100% compatible with Pentax, but with Pentax screwmount, or M42. They made some great cameras in this mount in the 60s and 70s.
As to the price of the adapter being ridiculous - if $50 is ridiculous to you, clearly you need to spend more time on this forum.
Yes, I have very little experience with equipment. I know people spend thousands of dollars on a single lens, but this is just a hobby to me.
02-17-2013, 06:06 AM   #7
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QuoteOriginally posted by Ripout Quote
Thanks for all the replies guys! Ya'll rock!



Thank you so much for the advice! I'm really considering just cutting my losses and reselling it on Ebay. Your recommendation for the Pentax A would have been super helpful before I bought it. Need to check on forums before I buy anything ever again. Again, thanks a bunch for your reply.



Yes, I have very little experience with equipment. I know people spend thousands of dollars on a single lens, but this is just a hobby to me.
sell it to a forum member. There are those who will want it. Or get a screw mount adaptor, I have a lot of different screw mount lenses they are fun, and cheap. If you want something to really bring you into photography, and get your attention completely an old screw mount lens will do it
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