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View Poll Results: Do you want to be able to use trap-AF with all lenses?
Yes 4488.00%
No 612.00%
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10-29-2009, 10:50 AM   #16
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QuoteOriginally posted by flyer Quote
Trap focus has it's good points. It comes real handy when you want to get a picture of the finish line. You set the camera on a tripod, prefocus, and use a cable release with a lock to have a picture of the winner without having to actually hold the camera. That way, I can use a second camera with a long lens to get facial expressions of the runners.
Great point. My crowning achievement using snap-in-focus (SF1 name for it) was to take three pictures of hummingbirds at a feeder while I was eating supper. Continuous drive, AF single, tripod, cable release locked down, tripod.

10-29-2009, 01:52 PM   #17
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If you can prefocus in MF mode onto something at or close to where the subject will pass through, then trap focus is not all that necessary.

Nevertheless, trap focus does have its applications, even for AF lenses (I'm not arguing that point).
10-29-2009, 01:59 PM   #18
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QuoteOriginally posted by Ash Quote
If you can prefocus in MF mode onto something at or close to where the subject will pass through, then trap focus is not all that necessary.

Nevertheless, trap focus does have its applications, even for AF lenses (I'm not arguing that point).
Well, with trap-AF I can focus on focusing and not timing on when to trip the shutter, since in burst mode it will just take a bunch.
10-29-2009, 02:14 PM   #19
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Trap focus lets you do things like thishttp://www.youtube.com/watch?v=b7ZQxJ874uM

10-29-2009, 11:03 PM   #20
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I have found that this works good in the K-7, but not so good in the K20
10-30-2009, 05:38 AM   #21
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I have just recently began playing with this setting on my K20D. I have been using it combined with AF.C mode and am not sure yet, but I seem to be getting more keepers when not using it in AF.C, at least on my numpty around the house practice shots.

Nice to read it seems even better on the K7.

EDIT: Thought I would add, I have also been doing this in spray-n-pray more as well...it slows the the FPS but still, more of what I am getting are keepers. Since i have AF decoupled from the shutter button I just hold the AF button down while also holding the shutter down in order to keep AR spun up and activated. Of course for tripod shots no need for SR as a rule.

Last edited by brecklundin; 10-30-2009 at 07:18 AM.
10-30-2009, 06:39 AM   #22
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I agree with Eruditass. I would find this feature quite useful. The K7 is much faster focusing than the K100d I was using previously; however, even using the DA70 which is no AF slouch, I find that AFC is wanting. Why not use the AF system to trigger the shutter when it gets a lock? Then the lens focus is no longer trying to catch up with the subject and you get at least one good shot rather than a series of shots that are out of focus. As far as the delay between the subject coming into focus, the AF system sensing this, and the shutter firing, I don't think it is an issue. Photons and electrons move pretty darn fast, much faster than the subject you are trying to capture.

Last edited by al_undy; 10-30-2009 at 06:40 AM. Reason: spelling
10-30-2009, 08:48 AM   #23
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QuoteOriginally posted by brecklundin Quote
I have just recently began playing with this setting on my K20D. I have been using it combined with AF.C mode and am not sure yet, but I seem to be getting more keepers when not using it in AF.C, at least on my numpty around the house practice shots.

Nice to read it seems even better on the K7.

EDIT: Thought I would add, I have also been doing this in spray-n-pray more as well...it slows the the FPS but still, more of what I am getting are keepers. Since i have AF decoupled from the shutter button I just hold the AF button down while also holding the shutter down in order to keep AR spun up and activated. Of course for tripod shots no need for SR as a rule.
Catch-in-focus requires the body to be in AF single. In AF continuous, the camera will simply take the image whenever you push the shutter button down all the way. The system dates back to the SF.1, when Pentax thoughtfully left the focus circuitry engaged with a manual focus lens.

The K10 does not recognize the AF/MF switch on the lens, so I only use it with manual focus lenses. It is extremely useful with the M 100 macro, chasing butterflies around. Set the magnification, set the camera body to AF.S and simply move to and fro with the shutter release held down. It is less useful with the 400 for all the reasons that AF doesn't work with birds in the bushes. I have used it for waterfowl on lakes, etc. with some success.

01-09-2010, 08:24 AM   #24
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Well, I've just sent the following proposal to pentax, via all the available contacts (hoping they will include it in the next firmware release, or in a future model) :

In MF mode (the physical lever), if you press the AF button and then the shutter (with the AF button still pressed), then the camera should wait for focus confirmation to take the pic...
02-01-2010, 04:49 PM   #25
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You CAN use Focus Trap with AF lenses. . .

Hi,

You can use an AF lens with Trap Focusing by shorting out the Data pin on the lens. The Data pin is the one farthest from the lens lock notch or closest to the screw drive port. This allows full aperture and exposure automation just like an "A" lens (which doesn't have the Data pin), but you must short the pin as opposed to insulating it (like with tape, unless it's a conductive metal tape).

Scott
02-01-2010, 05:14 PM   #26
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kinda sucks that the k-x is limited to center point focus only with old manual focus lenses. would've been great if i can use its 11 focus points on old manual lenses, then use trap focus.

on an AF lens, i find trap focus useless though.
02-02-2010, 09:56 AM   #27
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QuoteOriginally posted by buliwyf Quote
kinda sucks that the k-x is limited to center point focus only with old manual focus lenses. would've been great if i can use its 11 focus points on old manual lenses, then use trap focus.

on an AF lens, i find trap focus useless though.
It is not the K-X that is limited to the centre point only for manual focus lens catch-in-focus (snap-in-focus for SF-1 users like me), it is all Pentax AF cameras.
02-06-2010, 10:39 PM   #28
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Best workaround I've found, as brecklundin said, for AF lenses is to remap the AF to the 'OK' button. You prefocus to a set area, then fire burst shots.

QuoteOriginally posted by Canada_Rockies Quote
It is not the K-X that is limited to the centre point only for manual focus lens catch-in-focus (snap-in-focus for SF-1 users like me), it is all Pentax AF cameras.
This is true in normal operation, however debug mode allows other focus points, see here

Last edited by rmtschanz; 02-06-2010 at 11:01 PM.
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