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09-04-2010, 01:23 PM   #1
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Found some old lenses...compatible?

Hi! Very new here, excuse my confusion! I just ordered my K-x and have yet to receive it. I've had an old camera bag full of film SLR goodies for many years now (given to me), never knowing the condition of the camera and lenses inside. I finally decided to poke around a little and think I might be able to use one or more of these on my K-x, but need advice. I'm confused by the info I've found so far.
Here is what I have:
Auto Sears 50mm 1:2.0 (I've read that this is a K mount, but do I need to watch for ricoh pins? Where/what would those be? Can I put this lens straight on my camera?

Olympus (OM-System) Auto-W 28mm 1:3.5

Olympus (OM-System) Auto-S 50mm 1:1.8 Are either of these usable with an adapter? Which adapter would that be?

(The latter two are from an OM-1 SLR that is in my posession.)

Any info at all would be greatly appreciated...or even just steer me in the right direction to where I can find answers. Thank you so much!

09-04-2010, 01:34 PM   #2
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No adapter for the Oly lenses; they're really nice though. You can modify the mount (you can find threads in this forum), but I don't know if you will find the effort worth it, since you can buy Pentax/Super Takumar counterparts for those lenses for relatively cheap.
09-04-2010, 01:40 PM   #3
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If the Sears has a P (A) setting on the aperture ring, it has the Ricoh pin and could get stuck.

Here is how to find the Ricoh pin.



If it is an older lens, based on the XR, it will not have the Ricoh pin.
09-04-2010, 03:17 PM   #4
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Thank you! That pictures helps a ton. I do not see a Ricoh pin (or anything for that matter) on the base of the lens.

Will probably end up selling the Oly lenses...if anyone has suggestions as to how much I could get for them, feel free to let me know!

09-04-2010, 03:27 PM   #5
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Then the lens is probably based on the Ricoh XR Rikenon 50mm F2. It will only work in M mode. You will have to set Use aperture ring to enabled in Custom menu 4. You set the exposure by pressing the Av+- button.

Ricoh XR Rikenon 50mm f/2.0 Lens Reviews - Pentax Third-Party Lens Review Database
09-04-2010, 09:38 PM   #6
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Thank you for that! I will have to play with it once my camera arrives!
09-05-2010, 05:44 AM   #7
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As mentioned, you can't use the Oly lenses as-is. They are easily adapted (somewhat) to PK and would still be usable on OM cams, but would probably lose whatever resale value they have, which honestly ain't much right now. A scan of COMPLETED LISTINGS on eBay should discourage you.

The mod: I have adapted an OM-mount Vivitar 35/2.8. It mounted (somewhat) unmodified on my ZX-M (polycarbonate/plastic mount) but not my K20D (metal mount). I use a cheap PK macro ring to check mountability, because I can watch the action from the inside. With the OM-mount, I saw that the OM bayonet lugs didn't quite fit under the corresponding PK mount blades. So I used a thin Dremel metal-grinding blade to taper the underside of the leading edges of those OM bayonet lugs.

Unaltered on the ZX-M, or altered on the K20D, the OM lens twists just a few mm, enough for a firm-feeling press-fit, but by no means rock-solid locked-on. I take care anyway not to subject the K20D to physical shock and stress, but I'm extra careful with non-locked lenses. I have an OM TC and I tested the lens on it -- it locked in solidly, so it would be usable on OM cameras. Whether shaving your lenses is worthwhile is up to you to decide. Have fun!
09-05-2010, 07:49 AM   #8
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You could also get a reversing ring and use the Olympus lenses for macro work.

09-05-2010, 09:21 AM   #9
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boris - where would I find a reversing ring? I would love to have a cheap macro option, but have no idea how to use the OM lenses for that purpose. Is it pretty easy?
09-05-2010, 09:28 AM   #10
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I wouldn't necessarily do it for either of those lenses, but Leitax makes mounts for converting Oly to K for ~ 60 Euro. Just use them with your OM-1 and film.

Olympus OM lens for Pentax cameras
09-05-2010, 09:45 AM   #11
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QuoteOriginally posted by cristylo Quote
boris - where would I find a reversing ring? I would love to have a cheap macro option, but have no idea how to use the OM lenses for that purpose. Is it pretty easy?
You would need something like this.

MACRO REVERSING RING 49mm FOR PENTAX K NEW IN BOX - eBay (item 160356122639 end time Sep-09-10 19:28:10 PDT)

I don't use a reversing ring myself, I have a 1:1 macro lens and a 2x macro converter, check out the macro photography social group.

Macro Photography - PentaxForums.com
09-05-2010, 04:29 PM   #12
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QuoteOriginally posted by cristylo Quote
boris - where would I find a reversing ring? I would love to have a cheap macro option, but have no idea how to use the OM lenses for that purpose. Is it pretty easy?
Thread- and mount-reversing rings are widely available CHEAP on eBay. I have all the mount-reversers I need, but I'm about to spring for more thread-reversers.

OK, there are several ways to do macro with what you have: simple mount reversal, extended mount reversal, and thread-reversed stacking. In each case, you need to know what the front thread diameter of each lens is. Many Pentax/Takumar lenses have 49mm threads.

A Pentax-compatible mount-reversal ring will have a PK mount on one side, and male threads on the other. Screw the threaded side onto the lens, then put the reversed lens on the camera mount. Nice and easy, and the brand of lens doesn't matter. BUT... you only get magnification *IF* the lens front is recessed a bit. And with any lens reversal, your working distance (lens to subject) is rather small, under 2 inches with PK and OM lenses. So why reverse? Because standard lenses often give better images reversed, when working very very close.

For more magnification, you need extension -- macro tubes or bellows. Simple tubes are real cheap, like under US$10 on eBay. Bellows should cost under US$50 and give you a lot more flexibility. Sometimes, you need both together. Reversing a single lens doesn't magnify -- only extension provides magnification. The more extension, the more magnification.

You can also put extension on a standard lens. Shorter lenses let you work closer, longer lenses let you work further from a subject. The closest a non-reversed lens can focus, no matter how much extension, is its focal length. That's why we like 100-200mm macro lenses for outdoors, 'cause we don't have to work 2 inches from whatever. With a 150mm lens on any amount of extension, I'll be at least 6 inches from a subject -- hopefully the bugs won't run off, eh?

Thread-reversal rings, and stacking lenses, are different. Put a longer lens (the primary) on the camera, screw a thread-reversal ring into it, and screw a shorter manual prime lens (the secondary) reversed onto that. If I use a 150mm primary and a 25mm secondary, magnification is 150/25 = 6x, which is A LOT!!

That's an overview. Are close-up and macro work easy? Well, they can be, and they're lots of fun. The easiest way to start is with tubes and your 50mm Sears lens, then a mount-reversal ring for your OM's if you keep them. Have fun!
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