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12-06-2010, 06:42 AM   #1
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Catch-in-Focus defect on K-x

Heyho,

i recently discovered that my Catch-in-Focus option stopped working on my k-x. With a MF Lens attached the camera does not bother wether CiF is activr or not.

Any suggestions what is wrong or how to fix this?

greez,
Marlboroman


Last edited by Marlboroman; 12-06-2010 at 06:50 AM.
12-06-2010, 07:18 AM   #2
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QuoteOriginally posted by Marlboroman Quote
Heyho,

i recently discovered that my Catch-in-Focus option stopped working on my k-x. With a MF Lens attached the camera does not bother wether CiF is activr or not.

Any suggestions what is wrong or how to fix this?

greez,
Marlboroman
Check all your settings.

Make certain at least some of the camera mount pins are short-circuited.

Dave
12-06-2010, 08:45 AM   #3
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Also make sure you are still set for AF-S.

12-06-2010, 10:30 AM   #4
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There have been some third party lenses through the years that were almost all plastic and I have seen some metal mounts that were painted. A plastic or painted surface won't short the pins to allow catch in focus to work. If the mount is metal, the paint can be sanded off (carefully!) or you could slide a strip of alumunium foil between the lens and mount to short the pins. I keep some foil in my bag to use with my Taks which won't short the pins.

12-13-2010, 05:23 AM   #5
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reeftool is correct on this.

But I am wondering why this must be so.
Is there any need for the camera to have the pins shortened?
It asks for the focal length so it should know that a lens is attached.
Perhaps we could persuade Pentax to change this?
I mean this aluminum foil trick isn't exactly ideal.
12-13-2010, 06:22 AM   #6
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QuoteOriginally posted by blende8 Quote
reeftool is correct on this.

But I am wondering why this must be so.
Is there any need for the camera to have the pins shortened?
It asks for the focal length so it should know that a lens is attached.
Perhaps we could persuade Pentax to change this?
I mean this aluminum foil trick isn't exactly ideal.
Aluminum duct tape is a good alternative until Pentax fixes the firmware (if ever.)

QuoteQuote:
It asks for the focal length so it should know that a lens is attached.
K-x asks for focal length even with no lens.

Dave
12-13-2010, 07:27 AM   #7
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The camera gets lens information through the pin connections. It will ask for lens info if it doesn't receive it regardless whether the pins are shorted or open which is the case with most Takumars. There have been discussions in the past as to whether or not catch in focus was a planned feature or an accidental benefit of the design of the auto focus system. I never remembered reading anything about it in the K10D manual and first heard about it from other users here in the forum a few years ago. Newer camera bodies document it in their manuals.
12-13-2010, 07:50 AM   #8
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QuoteOriginally posted by reeftool Quote
There have been discussions in the past as to whether or not catch in focus was a planned feature or an accidental benefit of the design of the auto focus system.
Interesting note.
Accidental benefit is plausible enough.

When Pentax moved the AF in LV from the AF button to the shutter button (in some K-7 firmware release), all of a sudden the mirror flipped in LV when touching the shutter button even in manual focus mode, provided LV focus was set to phase AF. So, the mirror action flag wasn't unset by AF manual mode. It is unset by LV focus set to contrast/face AF.

That's a sign that the firmware uses a bunch of flags (or logical expressions) which are rather independent and a manual focus lens probably disables one flag (lens AF motor) while not disabling another (autotrigger when in focus). The AF mode switch would set both modes, but again forgot the mirror action flag ...

So, the firmware design lacks a flag state chart or state matrix diagram.

You get the idea ...


Last edited by falconeye; 12-13-2010 at 07:55 AM.
12-13-2010, 11:14 AM   #9
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QuoteOriginally posted by newarts Quote
Aluminum duct tape is a good alternative until Pentax fixes the firmware (if ever.)
Is that working stable? Will it not become loose from the bajonet locking pin and the AF Pin?

It seems that one has to shorten just one pin, any pin, to get it to work.
12-13-2010, 12:52 PM   #10
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QuoteOriginally posted by blende8 Quote
Is that working stable? Will it not become loose from the bajonet locking pin and the AF Pin?

It seems that one has to shorten just one pin, any pin, to get it to work.
In my experience aluminum duct tape lasts well. I typically have used it only in the region of the pins to be shorted. At least once I covered an entire m42 base and held up well.
12-13-2010, 01:16 PM   #11
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CIF is not the only difference when no pins are shorted, on green button press in M-mode the k-x releases the aperture lever and flips the mirror with an M-lens (chromed base, some pin(s) shorted), but leaves both alone with no lens (no pins shorted as with a coated base M42). Again, no obvious reason for the difference in operation.
12-13-2010, 01:26 PM   #12
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I don't want to derail this thread, but I don't think I should start another.

What are the conditions needed to make catch-in work? This is what I'm trying:

•A K7 with an old Asahi 50mm F1.4, a Rokinon 85mm f1.4 and my 50-135 (just to see how different an autofocus lens behaves.)

•I have my camera set to center point and AFS. And I turned on the catch-in focus option in the menu.

BUT It doesn't matter if I'm 40 feet out of focus, the camera takes the picture if I press the shutter; it doesn't wait for focus.

What am I doing wrong?

EDIT: OK, thanks for the help everyone :P . I phoned Pentax support and we found out that you must have the shutter button activate focus. You can not use the thumb AF button.

Last edited by Dubious Drewski; 12-13-2010 at 02:49 PM.
12-13-2010, 06:14 PM   #13
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I think I know what's wrong, I had this problem and posted in another thread.

Like someone mentioned, it is not set in AF.S

Basically, what happens is when you put on an AF lens on, it lets you choose between AF.S/AF.C/AF.A on a K-x. But, when you take off the AF lens, and put on a manual lens, you cannot change this mode anymore. When you stick a manual focus lens on, it is stuck no whatever mode you last set it to.

So, if you want CIF to work again, you will have to mount the AF lens back on, switch the mode back to AF.S, then put your manual lens back on, and voila it will work again.

This is a lame software error, but for the higher end bodies, switching between AF.S/AF.C is done with a dedicated button, and not a menu, so it was probably thought few users with an entry level dslr would be dabbling with MF lenses and switching AF modes at the same time.

Cheers!
03-02-2011, 10:17 PM   #14
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I cannot get the CIF to work on my K-x. I have tried all the above and it will not automatically fire. I will focus on something, press the shutter release, move into the area that I focused and nothing happens. If I focus on my hand and hold down the shutter release, it will fire when my hand comes back into focus, but it will not fire again unless I release the shutter and press it again, hold it, and move my hand back into focus.

This sounds like a feature that I would like to use........
03-02-2011, 11:22 PM   #15
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@tdannar
It is working as designed, the problem is the K-x does not have the ability to enable constant shutter press since it does not have a wired remote facility. This is where building a mechanical device to do what you are doing with your finger is required.
You also need to set drive mode to continuous if you want it to repeatedly take pictures once something comes into focus.
See https://www.pentaxforums.com/forums/pentax-camera-field-accessories/132847-d-...lease-k-x.html
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