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03-10-2010, 10:07 PM   #16
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QuoteOriginally posted by jmbradd Quote
I have never been able to get this to work even with manual lenses like the takumar 135mm 2.5

(and yes i've enable it in the custom shooting menu )
Cameras before the K20 (such as my K10) will not use catch-in-focus on any AF lens, even with the lens switch in MF. Any Pentax AF camera will snap-in-focus (SF-1 terminology) with any manual K mount lens, provided the camera is in AF.S mode.

You have to do some mount tricks to get an M42 (screw mount) lens to snap-in-focus.

03-11-2010, 12:38 AM   #17
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QuoteOriginally posted by Canada_Rockies Quote
You have to do some mount tricks to get an M42 (screw mount) lens to snap-in-focus.
An what are those tricks, please? Have you worked them?

ANSWER: Aha, now I see! It's the old short-out-the-contacts-with-tinfoil trick! And a flanged not-infinity-focus adapter will short the contacts, whilst an Official Pentax or Bowers-type won't.

Last edited by RioRico; 03-11-2010 at 01:57 AM. Reason: answering myself
03-11-2010, 09:59 PM   #18
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QuoteOriginally posted by RioRico Quote
An what are those tricks, please? Have you worked them?

ANSWER: Aha, now I see! It's the old short-out-the-contacts-with-tinfoil trick! And a flanged not-infinity-focus adapter will short the contacts, whilst an Official Pentax or Bowers-type won't.
BINGO! You have just won the prize! Yup, that's the trick. I have just been given a 55/1.8 SMC Tak, and it is one with the painted mount, so I have to figure out if I want to have snap-in-focus or not.
03-12-2010, 12:18 AM   #19
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QuoteOriginally posted by Canada_Rockies Quote
BINGO! You have just won the prize! Yup, that's the trick. I have just been given a 55/1.8 SMC Tak, and it is one with the painted mount, so I have to figure out if I want to have snap-in-focus or not.
And when I complained about maybe losing bits of tinfoil, flying away in the wind whilst changing lenses, newarts said:
The hardware store has sticky back aluminum tape used to repair heating ducts. Put a bit on the base of your m42 lens to short out the data pin (closest to 6 o'clock.) Or scrape some paint off the lens base to short the contact.
So today at not-the-cheapest-hardware-store-at-Lake-Tahoe I bought a 48mmX9.1m roll of Nashua 322 Foil Tape (made in USA) for US$2.99+tax. Let's see, ten yards, cut pieces 9mmX24mm, that's enough for 2000 lenses -- hey, almost a lifetime supply! And I stick bits on some lenses, and VOILA! Most are CIF-enabled!

Exceptions: M42 macro tubes, and many German and Russian lenses with VERY narrow bases, and some lenses where the base extrudes strangely, just don't push the foil tape against the contacts. So for those I still need the flanged adapter.

03-12-2010, 04:03 AM   #20
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QuoteOriginally posted by bullwhip Quote
Do you have a closeup shot of how to short the pin? Can this hurt the camera? Can this hurt the lens? Always wanted to try catch in focus, but I only have the 2 kit lenses (18-55 and 55-300) and no extra $$ to buy another lens with.
Thanks

Shorting the pins cannot do any harm as the mount is designed for old K mount lenses which always short the pins.

If you use sticky-backed aluminum tape there is no change to the lens.

Dave in Iowa
03-12-2010, 10:01 AM   #21
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QuoteOriginally posted by newarts Quote
Shorting the pins cannot do any harm as the mount is designed for old K mount lenses which always short the pins.

If you use sticky-backed aluminum tape there is no change to the lens.

Dave in Iowa
Thanks, Dave! I never thought of sticky metal tape. I am a bit slow at times.
03-12-2010, 10:51 AM   #22
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QuoteOriginally posted by RioRico Quote
Let's see, ten yards, cut pieces 9mmX24mm, that's enough for 2000 lenses -- hey, almost a lifetime supply!

Can you mail me a foot?

But seriously folks--glad this thread made it to the top of the pile again:

She wasn't working with my Taks and the manual is saying it SHOULD. Now I know why.

Milk, butter, eggs, aluminum tape...
03-12-2010, 01:39 PM   #23
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Just one more trick

I mentioned that (with M42) macro tubes, certain lenses with narrow bases, and lenses with oddly-shaped (step-pyramid) mounts, won't hold down the sticky tape against the contacts. So sometimes a bit of tinfoil is still needed, or a flanged adapter (with which you lose infinity focus). Ah, but there's also a hybrid situation: lenses that don't focus close enough.

In another thread I brought up my M42 Suntar 135/2.8, which actually shoots rather nicely. BUT its minimum focus is around 2m, 6 1/2 feet. And I had a 5-inch tall Mexican piggy bank to test-shoot, hand-held. What to do? Go *slightly* macro. I used the flanged adapter and a 12mm tube. For shake reduction, the rule-of-thumb is focal length + extension, which here is 135 (lens) + 12 (tube) + 1 (flange) = 148; for SR, 150mm is close enough. Now I could close in to 3 feet or so, trap-focus, and get a nice clear shot. Maybe I'll post it when I have time. Gotta go now, I'm being summoned.

03-12-2010, 02:45 PM   #24
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I'm not interested in shorting anything out. But I would like to figure out how to use catch in focus, if I'm able. Never used it before.

As far as I can tell none of my Pentax lenses have an AF/MF switch on them. So I've mounted the Sigma 28 f/1.8 EX DC on my K20D. Pulled the barrel sleeve in to the MF position. Put the camera into MF, too, so I could rotate the lens to set the focus distance. Returned the camera to AF.S. Plugged in the remote cable release. I'd set the focus for a distance of 5 ft. Covered the lens hood with my hand and clicked the shutter release. The camera tried to auto-focus, then took a picture. In other words, it didn't work.

I normally have autofocus detached from the shutter button; I use the AF button instead. I relinked autofocus and shutter, as it seems necessary, although the K20D operating manual doesn't say that. Still no go.

What am I doing wrong? Won't work with this lens? Something else?

Will
03-12-2010, 03:00 PM   #25
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QuoteOriginally posted by WMBP Quote
I'm not interested in shorting anything out. But I would like to figure out how to use catch in focus, if I'm able. Never used it before.

As far as I can tell none of my Pentax lenses have an AF/MF switch on them. So I've mounted the Sigma 28 f/1.8 EX DC on my K20D. Pulled the barrel sleeve in to the MF position. Put the camera into MF, too, so I could rotate the lens to set the focus distance. Returned the camera to AF.S. Plugged in the remote cable release. I'd set the focus for a distance of 5 ft. Covered the lens hood with my hand and clicked the shutter release. The camera tried to auto-focus, then took a picture. In other words, it didn't work.

I normally have autofocus detached from the shutter button; I use the AF button instead. I relinked autofocus and shutter, as it seems necessary, although the K20D operating manual doesn't say that. Still no go.

What am I doing wrong? Won't work with this lens? Something else?

Will
Did you enable catch in focus in the menu?
03-12-2010, 03:24 PM   #26
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QuoteOriginally posted by Rense Quote
Did you enable catch in focus in the menu?
Yep.

Will
03-12-2010, 03:34 PM   #27
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QuoteOriginally posted by WMBP Quote
As far as I can tell none of my Pentax lenses have an AF/MF switch on them. So I've mounted the Sigma 28 f/1.8 EX DC on my K20D. Pulled the barrel sleeve in to the MF position. Put the camera into MF, too, so I could rotate the lens to set the focus distance. Returned the camera to AF.S. Plugged in the remote cable release. I'd set the focus for a distance of 5 ft. Covered the lens hood with my hand and clicked the shutter release. The camera tried to auto-focus, then took a picture. In other words, it didn't work.
If you have the lens set to MF and it still tried to auto-focus. there's something wrong on that end.
03-12-2010, 04:12 PM   #28
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QuoteOriginally posted by GoremanX Quote
If you have the lens set to MF and it still tried to auto-focus. there's something wrong on that end.
QuoteOriginally posted by WMBP Quote
I'm not interested in shorting anything out. But I would like to figure out how to use catch in focus, if I'm able. Never used it before.

As far as I can tell none of my Pentax lenses have an AF/MF switch on them. So I've mounted the Sigma 28 f/1.8 EX DC on my K20D. Pulled the barrel sleeve in to the MF position. Put the camera into MF, too, so I could rotate the lens to set the focus distance. Returned the camera to AF.S. Plugged in the remote cable release. I'd set the focus for a distance of 5 ft. Covered the lens hood with my hand and clicked the shutter release. The camera tried to auto-focus, then took a picture. In other words, it didn't work.

I normally have autofocus detached from the shutter button; I use the AF button instead. I relinked autofocus and shutter, as it seems necessary, although the K20D operating manual doesn't say that. Still no go.

What am I doing wrong? Won't work with this lens? Something else?

Will
I think you are mis-understanding CIF (Focus Trap). You should not have to go through all that to use it. The camera see's focus whether you use the shutter release or the AF button. Even in MF, you still get a focus confirmation. The difference is, with the camera in one of the AF modes, the camera will Not fire (AF-S) until it sees the confirmation. With MF, it will fire regardless.

The way to use it is put a MF lens on your camera. OR a lens that can be Made MF (AF/MF switch or similar). Look through the viewfinder at your subject, Hold the shutter release COMPLETELY down, while turning the focus ring (AF-S only). With some lenses you have to do this slowly. When the camera sees the focus confirmation, it should fire the shutter. Going through all the BS of switching the camera back and fourth and using a remote release, is pointless and destroys the entire advantage of Focus Trap.

If your sigma does not disable AF when you move the collar, I agree with GoremanX, Something wrong with the lens.

03-12-2010, 04:58 PM   #29
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QuoteOriginally posted by GoremanX Quote
If you have the lens set to MF and it still tried to auto-focus. there's something wrong on that end.
Thanks. Perhaps you're right but I'm not sure. I think this particular lens simply has a sort of "clutch" on the barrel. When the "clutch" is set to MF, turning the barrel focuses. When it's set to AF, turning the barrel does nothing. But I don't think it's doing or supposed to do anything more than that. I think the lens expects you to put the camera into MF mode if you want to use the MF clutch on the lens.

That being the case, it looks like I don't have a lens that will work with catch in focus. Doesn't look like any of my Pentax lenses can be set to MF (35, 40, 50, 70, 16-45, 18-250). Sigh.

<sourgrapes>I didn't really want to do this anyway.</sourgrapes>

Will
03-12-2010, 05:35 PM   #30
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a quick experiment

I place a bit of unsticky aluminium foil over the K20D's contacts and mount the DA18-55 kit lens, which has no switches of any sort. SR is ON, focus on body is AF-S, mode is Av. Turn on K20D's power. SR asks for input of a focal length, which I provide. I aim at a meaningless subject, very out of focus, press shutter. No activation. I slowly bring subject into focus. Green hex of confirmation flashes on, shutter trips. I have successfully used Catch-In-Focus on an otherwise autofocus-only lens.

Again, shorting the contacts does no damage. It's not like shorting a car battery or a power main. It merely blocks communication between body and lens.
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