Catch-in Focus in KA and K lenses

cprobertson1 · 11-16-2018, 02:04 AM

Good morning gentlefolk!

Recently got a K50 (about 6 weeks back) and quickly discovered the Catch-In Focus (CIF) while using a KA-mount Miranda lens that I grabbed on ebay for £5.

The lens has automatic aperture control ("A" setting on the aperture ring) but everything else is manual and works great with CIF.

Emboldened by this discovery, I then purchased a much larger Sigma 75-300mm lens at £10 in an antique store. This lens is entirely manual - (lacks a "A" setting on the aperture ring) - and as such has the barest K-mount imaginable - no contacts whatsoever.

Now, what is interesting about this is that CIF no longer works on it - as soon as I hit the shutter release, it takes a photo (whereas, with CIF enabled and working, it would hold off until focus was achieved).

It actually does this (allows a shot to be taken) even if there is no lens attached to the camera body, and focus-priority is enabled - which makes me wonder if a certain combination of shorted/open contacts may permit the CIF to function?

Incidentally, I can still use this particular lens by waiting for the focus-confirmation on the viewfinder/screen, but, I rather like the convenience of the Catch-In Focus!

So my questions are as follows:

Is there a setting that I am missing that allows CIF to work with this fully manual (PK mount) lens?
If not, can the lens be modified to allow the caamera to use CIF with it?
If not, what is the minimum spec required for CIF to work? Is a KA lens the minimum?

**iheiramo** · 11-16-2018, 02:27 AM

Check AF/MF switch in your camera. If set on AF, CIF works. If set on MF, CIF doesn't work.

I use CIF a lot and, instead of diving into menu, I use this switch to set it on and off.

EDIT: Mount doesn't matter as long as it's not AF lens. AF lenses with AF/MF switch work if set to manual.

photolady95 · 11-16-2018, 02:52 AM

For CIF,, you still have to set it up in the menu next to last option on the custom menu options, and set it on number 2. And then the switch on the body has to be set to AF.S not MF. When you have the all manual lens on, you need to make sure the switch on the body is set to AF.S not MF and the Mode dial set to M.

As an after thought, CIF isn't always accurate either. I used to use it a lot but found just sighting by eye got better in focus than CIF could give me. Especially with prime lenses.

Hope that makes sense to you.

cprobertson1 · 11-16-2018, 03:07 AM

Originally posted by iheiramo

Check AF/MF switch in your camera. If set on AF, CIF works. If set on MF, CIF doesn't work.

I use CIF a lot and, instead of diving into menu, I use this switch to set it on and off.

EDIT: Mount doesn't matter as long as it's not AF lens. AF lenses with AF/MF switch work if set to manual.

Hmm, that's interesting!

Switch is definitely set to AF.S - hmm. Would I be correct in thinking that if CIF (and/or focus-priority shutter release) is engaged then it shouldn't allow a photo to be taken with no lens mounted? Because it does currently permit that!

Come to think of it, I don't think it works on other lenses when using the macro-reversal ring either. Hope there isn't anything wrong with my camera!

Right, so I better outline what's happening:

(Probably) Relevant settings

Mode select == "M" (manual)
Focus Mode lever: == "AF.S"
Rec-Mode 4, Option "AF/AE-L Button" == "AF1" (both the AF/AE-L button and shutter release button are available to perform autofocus)
Custom-menu 2, option 12: "AF.S Setting" == Focus-Priority (the shutter cannot be released until the subject is in focus)
Custom-menu 3, option 20: "Catch-In Focus" == on
Custom-menu 4, option 22: "Using Aperture Ring" == on
Viewfinder in-use (not using live view)

Symptoms:

Allows shutter release with no lens
Allows shutter release with adapter ring (no contacts)
Allows shutter release with fully manual lens
DOES NOT allow shutter release with some manual lenses
DOES NOT allow shutter release with automatic lens with AF linkage disabled (MF set on lens body)

photolady95 · 11-16-2018, 03:24 AM

Did you disable AF.A in Rec, menu 2 Auto focus settings?

cprobertson1 · 11-16-2018, 03:29 AM

Originally posted by photolady95

Did you disable AF.A in Rec, menu 2 Auto focus settings?

I believe it is set to "off" as I prefer manual switching - but will double-check just to be sure!

Will need to get back to you in a few hours though - just discovered I never picked up the camera this morning - whoops! =/

**iheiramo** · 11-16-2018, 03:35 AM

Originally posted by cprobertson1

hmm. Would I be correct in thinking that if CIF (and/or focus-priority shutter release) is engaged then it shouldn't allow a photo to be taken with no lens mounted? Because it does currently permit that!

Had to test it. Assumption is incorrect. Without lens CIF is off and camera takes shots. With M series lens on CIF works as supposed to. Even with lens cap on.

Could the problem be that for some reason with your Sigma the camera doesn't regognize that the lens is attached?

cprobertson1 · 11-16-2018, 04:04 AM

Originally posted by iheiramo

Had to test it. Assumption is incorrect. Without lens CIF is off and camera takes shots. With M series lens on CIF works as supposed to. Even with lens cap on.

Could the problem be that for some reason with your Sigma the camera doesn't recognize that the lens is attached?

Now that is an interesting question!

How would it usually detect an attached lens (with original K mount)? Is there pin on the camera body that detects it? Perhaps the shorting of contacts across the metal body of the lens?

I can test this of course by using a suitable thin feeler gauge and/or sheet of paper to short/open the contacts with both the working and the non-working lens to test whether CIF still functions - but if I know in advance, it saves me faffing around with feeler gauges and paper sheets!

photolady95 · 11-16-2018, 04:16 AM

Try cleaning the body contacts, and the mount with a soft dry cloth. Light buffing could make the body see the lens. Is the lens clicking into place fully?

**iheiramo** · 11-16-2018, 04:31 AM

Originally posted by cprobertson1

How would it usually detect an attached lens (with original K mount)?

I have no idea. I hope someone else is able to help you.

photolady95 · 11-16-2018, 04:39 AM

Is the lens mount silver or black?

**twilhelm** · 11-16-2018, 05:05 AM

If the lens mount is painted, it will not make an “electrical” contact with the body and the camera will not know that a lens is mounted.

cprobertson1 · 11-16-2018, 06:26 AM

Originally posted by twilhelm

If the lens mount is painted, it will not make an “electrical” contact with the body and the camera will not know that a lens is mounted.

Originally posted by photolady95

Is the lens mount silver or black?

This lens has a silver (machined stainless steel, I believe) mount - BUT - it may have an oxide layer that is giving poor, intermittent or even breaking electrical contact!

Originally posted by iheiramo

I have no idea. I hope someone else is able to help you.

Not to worry! Should be easy to test - as I said, by deliberately blanking or shorting out the contacts on both the working and non-working lens, one should be able to work out if it tests for a lens using either electrical or mechanical means, or whether it uses both (electrical AND mechanical) - the final option (electrical OR mechanical) is little harder to test: as I would need to disable any possible mechanical linkage to test it.

I'm including this mainly for my own reference! xD
These all make the assumption that the non-working lens (the sigma) has a slightly different mount to the working lens - and will not trigger a physical switch if installed in the camera.

Electrical-only: detection relies on non-physical means - simply wiring it correctly should enable it. Blanking or shorting the contacts should enable CIF regardless of lens used.
Mechanical-only: a mechanical linkage (pin, lever, tab or similar) enables CIF - shorting or blanking the electrical contacts should have no effect on CIF - the working lens will always work regardless, and the non-working lens will never work (without modification)
Electrical AND Mechanical: both electrical contact and a button/pin/tab must be engaged to confirm the presence of a lens. Shorting/Blanking the contacts on the working lens should disable it: but have no effect on the non-working lens (which won't work at any time)
Electrical OR mechanical: either electrical contact OR a mechanical linkage tells the camera a lens is present - shorting or blanking the electrical contacts should have no effect on the working lens, but should enable or disable the non-working lens.

**UncleVanya** · 11-16-2018, 06:53 AM

I thought I remembered something about back button auto focus interaction with CIF. But I can't find it right now. You might try disabling that and see if it behaves as expected after disabling back button af.

cprobertson1 · 11-16-2018, 07:02 AM

Originally posted by UncleVanya

I thought I remembered something about back button auto focus interaction with CIF. But I can't find it right now. You might try disabling that and see if it behaves as expected after disabling back button af.

I know that CIF doesn't work if using only back-button focus (Rec Mode 4, AF/AE-L == "Enable AF2") - it's currently set to AF1 - which allows the shutter-button-half-press OR the back-button to focus - and that definitely works with the KA lens.

The other options for that button are "Cancel-AF" and "AE Lock" - I'll try them out with the Sigma lens and get back to you with the results! I'll have a look for that thread you mentioned as well!

11-16-2018, 02:04 AM	#1
cprobertson1 Veteran Member Join Date: Nov 2018 Location: Irvine, Ayrshire Posts: 386	Catch-in Focus in KA and K lenses Good morning gentlefolk! Recently got a K50 (about 6 weeks back) and quickly discovered the Catch-In Focus (CIF) while using a KA-mount Miranda lens that I grabbed on ebay for £5. The lens has automatic aperture control ("A" setting on the aperture ring) but everything else is manual and works great with CIF. Emboldened by this discovery, I then purchased a much larger Sigma 75-300mm lens at £10 in an antique store. This lens is entirely manual - (lacks a "A" setting on the aperture ring) - and as such has the barest K-mount imaginable - no contacts whatsoever. Now, what is interesting about this is that CIF no longer works on it - as soon as I hit the shutter release, it takes a photo (whereas, with CIF enabled and working, it would hold off until focus was achieved). It actually does this (allows a shot to be taken) even if there is no lens attached to the camera body, and focus-priority is enabled - which makes me wonder if a certain combination of shorted/open contacts may permit the CIF to function? Incidentally, I can still use this particular lens by waiting for the focus-confirmation on the viewfinder/screen, but, I rather like the convenience of the Catch-In Focus! So my questions are as follows: Is there a setting that I am missing that allows CIF to work with this fully manual (PK mount) lens? If not, can the lens be modified to allow the caamera to use CIF with it? If not, what is the minimum spec required for CIF to work? Is a KA lens the minimum?

11-16-2018, 02:27 AM	#2
iheiramo Unoriginal Poster Join Date: Nov 2016 Location: Espoo Photos: Albums Posts: 3,182	Check AF/MF switch in your camera. If set on AF, CIF works. If set on MF, CIF doesn't work. I use CIF a lot and, instead of diving into menu, I use this switch to set it on and off. EDIT: Mount doesn't matter as long as it's not AF lens. AF lenses with AF/MF switch work if set to manual. Last edited by photolady95; 11-16-2018 at 02:45 AM. Reason: fixed typo

11-16-2018, 03:07 AM	#4
cprobertson1 Veteran Member Join Date: Nov 2018 Location: Irvine, Ayrshire Posts: 386 Original Poster	Originally posted by iheiramo Check AF/MF switch in your camera. If set on AF, CIF works. If set on MF, CIF doesn't work. I use CIF a lot and, instead of diving into menu, I use this switch to set it on and off. EDIT: Mount doesn't matter as long as it's not AF lens. AF lenses with AF/MF switch work if set to manual. Hmm, that's interesting! Switch is definitely set to AF.S - hmm. Would I be correct in thinking that if CIF (and/or focus-priority shutter release) is engaged then it shouldn't allow a photo to be taken with no lens mounted? Because it does currently permit that! Come to think of it, I don't think it works on other lenses when using the macro-reversal ring either. Hope there isn't anything wrong with my camera! Right, so I better outline what's happening: (Probably) Relevant settings Mode select == "M" (manual) Focus Mode lever: == "AF.S" Rec-Mode 4, Option "AF/AE-L Button" == "AF1" (both the AF/AE-L button and shutter release button are available to perform autofocus) Custom-menu 2, option 12: "AF.S Setting" == Focus-Priority (the shutter cannot be released until the subject is in focus) Custom-menu 3, option 20: "Catch-In Focus" == on Custom-menu 4, option 22: "Using Aperture Ring" == on Viewfinder in-use (not using live view) Symptoms: Allows shutter release with no lens Allows shutter release with adapter ring (no contacts) Allows shutter release with fully manual lens DOES NOT allow shutter release with some manual lenses DOES NOT allow shutter release with automatic lens with AF linkage disabled (MF set on lens body)

11-16-2018, 06:26 AM	#13
cprobertson1 Veteran Member Join Date: Nov 2018 Location: Irvine, Ayrshire Posts: 386 Original Poster	Originally posted by twilhelm If the lens mount is painted, it will not make an “electrical” contact with the body and the camera will not know that a lens is mounted. Originally posted by photolady95 Is the lens mount silver or black? This lens has a silver (machined stainless steel, I believe) mount - BUT - it may have an oxide layer that is giving poor, intermittent or even breaking electrical contact! Originally posted by iheiramo I have no idea. I hope someone else is able to help you. Not to worry! Should be easy to test - as I said, by deliberately blanking or shorting out the contacts on both the working and non-working lens, one should be able to work out if it tests for a lens using either electrical or mechanical means, or whether it uses both (electrical AND mechanical) - the final option (electrical OR mechanical) is little harder to test: as I would need to disable any possible mechanical linkage to test it. I'm including this mainly for my own reference! xD These all make the assumption that the non-working lens (the sigma) has a slightly different mount to the working lens - and will not trigger a physical switch if installed in the camera. Electrical-only: detection relies on non-physical means - simply wiring it correctly should enable it. Blanking or shorting the contacts should enable CIF regardless of lens used. Mechanical-only: a mechanical linkage (pin, lever, tab or similar) enables CIF - shorting or blanking the electrical contacts should have no effect on CIF - the working lens will always work regardless, and the non-working lens will never work (without modification) *Electrical AND* Mechanical*: both electrical contact and* a button/pin/tab must be engaged to confirm the presence of a lens. Shorting/Blanking the contacts on the working lens should disable it: but have no effect on the non-working lens (which won't work at any time) Electrical OR mechanical: either electrical contact OR a mechanical linkage tells the camera a lens is present - shorting or blanking the electrical contacts should have no effect on the working lens, but should enable or disable the non-working lens.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Manual focus K (or KA) zoom lenses with non-rotating front elements?	ChrisR	Pentax SLR Lens Discussion	13	04-05-2018 08:05 AM
Catch In Focus on AF lenses, is it ok to do?	BruceBanner	Pentax SLR Lens Discussion	19	09-02-2017 04:48 PM
How to use Trap-focus or Catch-in focus	eurostar	Pentax DSLR and Camera Articles	34	07-22-2017 08:29 PM
Focus Trapping (aka Catch-In Focus)	regor	Pentax K-01	7	01-05-2013 11:32 PM

11-16-2018, 02:52 AM	#3
photolady95 Otis Memorial Pentaxian Join Date: May 2009 Location: Cruising the forum watching his back Photos: Gallery \| Albums Posts: 12,712	For CIF,, you still have to set it up in the menu next to last option on the custom menu options, and set it on number 2. And then the switch on the body has to be set to AF.S not MF. When you have the all manual lens on, you need to make sure the switch on the body is set to AF.S not MF and the Mode dial set to M. As an after thought, CIF isn't always accurate either. I used to use it a lot but found just sighting by eye got better in focus than CIF could give me. Especially with prime lenses. Hope that makes sense to you.

11-16-2018, 03:24 AM	#5
photolady95 Otis Memorial Pentaxian Join Date: May 2009 Location: Cruising the forum watching his back Photos: Gallery \| Albums Posts: 12,712	Did you disable AF.A in Rec, menu 2 Auto focus settings?

11-16-2018, 03:29 AM	#6
cprobertson1 Veteran Member Join Date: Nov 2018 Location: Irvine, Ayrshire Posts: 386 Original Poster	Originally posted by photolady95 Did you disable AF.A in Rec, menu 2 Auto focus settings? I believe it is set to "off" as I prefer manual switching - but will double-check just to be sure! Will need to get back to you in a few hours though - just discovered I never picked up the camera this morning - whoops! =/

11-16-2018, 03:35 AM	#7
iheiramo Unoriginal Poster Join Date: Nov 2016 Location: Espoo Photos: Albums Posts: 3,182	Originally posted by cprobertson1 hmm. Would I be correct in thinking that if CIF (and/or focus-priority shutter release) is engaged then it shouldn't allow a photo to be taken with no lens mounted? Because it does currently permit that! Had to test it. Assumption is incorrect. Without lens CIF is off and camera takes shots. With M series lens on CIF works as supposed to. Even with lens cap on. Could the problem be that for some reason with your Sigma the camera doesn't regognize that the lens is attached?

11-16-2018, 04:04 AM	#8
cprobertson1 Veteran Member Join Date: Nov 2018 Location: Irvine, Ayrshire Posts: 386 Original Poster	Originally posted by iheiramo Had to test it. Assumption is incorrect. Without lens CIF is off and camera takes shots. With M series lens on CIF works as supposed to. Even with lens cap on. Could the problem be that for some reason with your Sigma the camera doesn't recognize that the lens is attached? Now that is an interesting question! How would it usually detect an attached lens (with original K mount)? Is there pin on the camera body that detects it? Perhaps the shorting of contacts across the metal body of the lens? I can test this of course by using a suitable thin feeler gauge and/or sheet of paper to short/open the contacts with both the working and the non-working lens to test whether CIF still functions - but if I know in advance, it saves me faffing around with feeler gauges and paper sheets!

11-16-2018, 04:16 AM	#9
photolady95 Otis Memorial Pentaxian Join Date: May 2009 Location: Cruising the forum watching his back Photos: Gallery \| Albums Posts: 12,712	Try cleaning the body contacts, and the mount with a soft dry cloth. Light buffing could make the body see the lens. Is the lens clicking into place fully?

11-16-2018, 04:31 AM	#10
iheiramo Unoriginal Poster Join Date: Nov 2016 Location: Espoo Photos: Albums Posts: 3,182	Originally posted by cprobertson1 How would it usually detect an attached lens (with original K mount)? I have no idea. I hope someone else is able to help you.

11-16-2018, 04:39 AM	#11
photolady95 Otis Memorial Pentaxian Join Date: May 2009 Location: Cruising the forum watching his back Photos: Gallery \| Albums Posts: 12,712	Is the lens mount silver or black?

11-16-2018, 05:05 AM	#12
twilhelm Loyal Site Supporter Join Date: Feb 2009 Location: Florida Photos: Gallery \| Albums Posts: 2,369	If the lens mount is painted, it will not make an “electrical” contact with the body and the camera will not know that a lens is mounted.

11-16-2018, 06:53 AM	#14
UncleVanya Loyal Site Supporter Join Date: Jul 2014 Photos: Gallery \| Albums Posts: 28,446	I thought I remembered something about back button auto focus interaction with CIF. But I can't find it right now. You might try disabling that and see if it behaves as expected after disabling back button af.

11-16-2018, 07:02 AM	#15
cprobertson1 Veteran Member Join Date: Nov 2018 Location: Irvine, Ayrshire Posts: 386 Original Poster	Originally posted by UncleVanya I thought I remembered something about back button auto focus interaction with CIF. But I can't find it right now. You might try disabling that and see if it behaves as expected after disabling back button af. I know that CIF doesn't work if using only back-button focus (Rec Mode 4, AF/AE-L == "Enable AF2") - it's currently set to AF1 - which allows the shutter-button-half-press OR the back-button to focus - and that definitely works with the KA lens. The other options for that button are "Cancel-AF" and "AE Lock" - I'll try them out with the Sigma lens and get back to you with the results! I'll have a look for that thread you mentioned as well!