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06-12-2008, 02:00 PM   #1
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Manual lens for trap focus

Hi all,
We finally have some humming birds coming to the feeder so I'm looking for a manual focus "A" lens that I can setup for trap focus. I was thinking 135mm would be a good focal length and found a couple of older Sears 135mm "Macro" lenses on ebay that look interesting (and fairly inexpensive). I know that some of these Sears lenses had that extra pin for the Ricoh mount.

The seller says that is K mount but I thought I'd ask here, also I was wondering if anyone had any exp with this lens, is it decent? I have an old Vivitar 135mm screw mount that does very well so if it is as good as that I'd be happy (see IMGP8852-1pp.jpg photo - palmor photos at pbase.com for an example of this lens).

Thanks in advance
John


Link to auction (it is a by it now so I know I won't be causing a bidding war)
Sears (A)P 135mm 2.8 Camera Lens PENTAX K-Mount MACRO - eBay (item 220244872530 end time Jun-17-08 13:37:25 PDT)

06-12-2008, 02:18 PM   #2
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So why don't you use the Vivitar then? (Feels like it should work with screwmount, never tried it though.)
06-12-2008, 02:20 PM   #3
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QuoteOriginally posted by Gimbal Quote
So why don't you use the Vivitar then? (Feels like it should work with screwmount, never tried it though.)
It doesn't.. I think that it needs to be an 'A' lens for it to work. To verify I tried trap focus with the Vivitar and my Zenitar FE and the trap focus only worked with the Zenitar
06-12-2008, 10:19 PM   #4
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I just tried trap focus with my S-M-C Takumar 135 and it seems to work. My brief test involved a stationary target and moving the camera towards it (a technique I've used handheld with my A 50 Macro), and panning across the target. I don't know if the behavior would be different with a stationary camera and a moving target though.

06-13-2008, 05:39 AM   #5
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QuoteOriginally posted by palmor Quote
It doesn't.. I think that it needs to be an 'A' lens for it to work. To verify I tried trap focus with the Vivitar and my Zenitar FE and the trap focus only worked with the Zenitar
It should. I've used a 135 Takumar fully manual lens and trap focusing works fine without the A setting. What you might be seeing is that the aperture is stopped down enough that AF isn't working.
06-13-2008, 05:50 AM   #6
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QuoteOriginally posted by alohadave Quote
It should. I've used a 135 Takumar fully manual lens and trap focusing works fine without the A setting. What you might be seeing is that the aperture is stopped down enough that AF isn't working.
hmm, when I used the screw mount lens the shutter would fire when-ever I pressed the button no matter how out of focus it was. I put on the Zenitar and it would only fire if it was in focus. I assumed it was because the Zenitar is an "A" lens and the screw mnt Viv isn't... but maybe it is something else (screw mnt vs k mnt)?

I'll give it another try, maybe I'm hallucinating

John
06-13-2008, 06:52 AM   #7
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I actually have 2 of those Sears lenses that I bought new in the late '80s. They were(are) some of my favorite lenses for my film cameras. I have been playing with them on my K200D. Interestingly, one of them works and the other one gives my a flashing F----. I wonder if the one balking is a Ricoh thing or operator eror? I never had any issues on my film bodies.



Edit: here's you a good lens > https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/29809-manual-lens-trap-focus.html

Last edited by Blue; 06-13-2008 at 07:02 AM.
06-13-2008, 10:41 AM   #8
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You need to have a lens that shortcuts the contacts on the camera. If the lens is not doing it because its too thin or got some colour that mess it up, use aluminium foil. It works out of the box on the K100D, I don't know about the K200D or K20D. But the K10D needs the contacts shorted for focustrapping to work.

EDIT: Clarification, you do not have to short the contacts on a K100D.

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