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How to use Trap-focus or Catch-in focus
Posted By: eurostar, 02-14-2009, 06:21 AM

Any Pentax DSLR allows the user to easily build a photographic trap to shot elusive birds and other animals. No need for infrared sensors and electronic do-it-yourself skills. Just a camera, a manual lens and a cable release with lock, and everyone can create a robot-camera that shot when the subject come on the spot. And the shot will be always in perfect focus.

You need: an AF Pentax reflex camera (a DSRL is preferable), a KA mount manual lens, an electrical cable release with lock and a tripod or similar camera support (pic 1).
Camera must be set on AF-S (pic 2), continuous shooting (pic 3), exposure mode on AV (pic 4). Aperture priority allows the use of a large aperture, with shallow DOF and fast shutter time to freeze movements.
Aim the central focus point to the place where your subject is expected to come, manual focus until focus aid (green hexagon) lit up, recompose to have the central focus point to aim at the point where subject head should be.
Now put viewfinder cap on, to avoid errors in exposure (pic 5)
Plug in the cable release (pic 6), push the release button and block it (pic 7).
Nothing will happens. Go to the place your subject will come, wave you hand in the focus point, and you will hear the shutter working.
Go away and allow subjects to come. After some hours come back and control if pictures counter advanced. If so, you can replay pictures on the LCD to see what species came.

With Pentax K20D, you can use not only the central AF point, but every one, allowing for a better placement of subject in the frame of the picture. This improvemetn has brought Pentax to rename the function catch-in focus.








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10-30-2011, 10:56 PM   #16
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For some reason every time I attempt to use this function, when I press the shutter button on the camera it just ends up taking a picture rather than waiting for a subject to "come into focus".

Could this be because the background is already in focus?

The process seems so simple yet I can't get it to work.

10-31-2011, 12:47 AM   #17
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QuoteOriginally posted by CrazyNuts Quote
For some reason every time I attempt to use this function, when I press the shutter button on the camera it just ends up taking a picture rather than waiting for a subject to "come into focus".
What lens? Does bare metal on the lens base cover the mount's contact pins? CIF depends on Focus Confirmation, which depends on focus points. I don't know which camera you're using, but on my K20D the focus defaults to Center-weighted when using anything other than F|FA|DA lenses. So with CIF, you must keep the subject centered. And are you sure that you've enabled CIF, down towards the end of the [Custom Settings] menu? Tell us what lens on what camera and how the camera is setup, and maybe we can help.
11-22-2011, 10:08 PM   #18
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Great-more stuff to remember!

QuoteOriginally posted by RioRico Quote
What lens? Does bare metal on the lens base cover the mount's contact pins? CIF depends on Focus Confirmation, which depends on focus points. I don't know which camera you're using, but on my K20D the focus defaults to Center-weighted when using anything other than F|FA|DA lenses. So with CIF, you must keep the subject centered. And are you sure that you've enabled CIF, down towards the end of the [Custom Settings] menu? Tell us what lens on what camera and how the camera is setup, and maybe we can help.
This is the first that I've ever even heard of "catch in focus" as I came across the term in the lens reviews. I just ran through my menu quick and couldn't find a "CIF" setting to turn on or off. Does the K10D have this setting or didn't it start until the k20d? I understand the theory and the function, I just can't find the button in the menu
11-23-2011, 02:08 AM   #19
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QuoteOriginally posted by jonhock Quote
This is the first that I've ever even heard of "catch in focus" as I came across the term in the lens reviews. I just ran through my menu quick and couldn't find a "CIF" setting to turn on or off. Does the K10D have this setting or didn't it start until the k20d? I understand the theory and the function, I just can't find the button in the menu
I understand that CIF is in all Pentax AF SLRs, film or digital. (Someone may correct me here.)

The documentation is rather hidden in my K20D manual, with no index entry till I added one. It's in the manual section on Focusing, just after Manual Focus and Using the AF Button. The [C]ustom menu item on the K20D is [34. Catch-In-Focus]; set that On. Set the AF lever to AF.S and use a manual lens whose bare-metal base covers the contacts on the camera mount. Aim and shoot. No problem.

02-12-2012, 09:32 AM   #20
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Original Poster
QuoteOriginally posted by jonhock Quote
This is the first that I've ever even heard of "catch in focus" as I came across the term in the lens reviews. I just ran through my menu quick and couldn't find a "CIF" setting to turn on or off. Does the K10D have this setting or didn't it start until the k20d? I understand the theory and the function, I just can't find the button in the menu
The term "catch-in focus" was introduced with the K20D. Before, since the first AF Pentax camera, was "Trap focus" and it's called that way in the K10D manual.
03-17-2012, 09:08 PM   #21
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Does it matter whether SR (shake resistance) is on or off?
03-17-2012, 09:14 PM   #22
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QuoteOriginally posted by MSL Quote
Does it matter whether SR (shake resistance) is on or off?
Sorry for the quoting, but I couldn't edit the post. I should expand my question (or clarify it). I know for tripod work, SR should be turned off. But I was thinking of trying this in a handheld situation, such as with a child in a swing, where you are trying to catch them at a certain point in the motion. In that sort of situation, would having SR on or off make any difference? I guess I'm also assuming that you can make this work for short hand held situations in general, where you are simply holding down the shutter release.
03-18-2012, 02:42 AM   #23
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QuoteOriginally posted by MSL Quote
I know for tripod work, SR should be turned off. But I was thinking of trying this in a handheld situation, such as with a child in a swing, where you are trying to catch them at a certain point in the motion. In that sort of situation, would having SR on or off make any difference? I guess I'm also assuming that you can make this work for short hand held situations in general, where you are simply holding down the shutter release.
I almost always have SR on for all handheld situations, except some usage of MF zooms. I almost always depend on CIF when using MF lenses, unless I'm going for thick DOF and prefocus. I haven't tested CIF with SR on vs off, but I haven't noticed blurriness in my SR+CIF shots. Note that SR is most effective at slower shutter speeds, and you'll likely be using a fast shutter to snap that swinging kid, so SR shouldn't have a negative impact. Note also that CIF uses the same circuitry as AF, so SR+CIF should have the same effect as SR+AF.

11-30-2013, 11:38 PM   #24
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Please could somebody help me to get CIF to work on my K5-II and Pentax DA 55-300mm ED lens.

Here are the steps I followed:
- Taped a piece of foil over the Data (gold) pin on the lens mount
- Mounted the camera onto a tripod
- Switched off the image stabilisation setting on the camera
- Set the camera to AF-S
- Set the camera to AV mode
- Confirmed that MF mode was on by looking in the view finder
- Enabled the CIF setting on the camera
- Plugged in the remote cable shutter release
- Set the focus setting to auto focus points (not spot or select)
- Aimed the camera at a test subject and manually focused on the subject until I heard a confirmation beep and saw the green focus icon
- Pressed the remote shutter release and locked it
- Waved my hand immediately in front of the subject
- The shutter did not go off, as expected, but I heard the camera beep continuously

What am I doing wrong?
12-01-2013, 01:31 AM   #25
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CIF only works with manual lenses, or AF lenses that have the option to engage or disengage AF/MF, on the lens itself. As far as I know the lens you're talking about, don't have that option.





12-01-2013, 10:47 PM   #26
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I can't get this to work with my K5II. It works fine when I operate the shutter with my finger ie it won't take the picture until the center spot is in focus as expected. But with the remote cord it takes the photo whether it is in focus or not. I have an A lens attached, the camera in AV mode, the AF set to AF.S, CF 25 Catch-in Focus set to 2 (on), continuous shooting.

Anyone got an idea what's wrong?

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12-03-2013, 03:28 PM   #27
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@ kiwibiologist: It should work, the way you describe it and it certainly does on my K-5. But maybe - just maybe - there could be an explanation here:

In the custom menu for AF.S Setting (pos. 15 on my K-5), the setting should be '1: Focus Priority' rather than '2: Release Priorityand

In the custom menu for AF with Remote Control (pos. 18 on my K-5) the setting should be '2: On' rather than '1: Off'.

Off-hand, I would suspect that that you have AF with Remote Control set to 'Off' (because I believe this is the default setting).
12-03-2013, 10:39 PM - 1 Like   #28
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QuoteOriginally posted by Stone G. Quote
@ kiwibiologist: It should work, the way you describe it and it certainly does on my K-5. But maybe - just maybe - there could be an explanation here:

In the custom menu for AF.S Setting (pos. 15 on my K-5), the setting should be '1: Focus Priority' rather than '2: Release Priorityand

In the custom menu for AF with Remote Control (pos. 18 on my K-5) the setting should be '2: On' rather than '1: Off'.

Off-hand, I would suspect that that you have AF with Remote Control set to 'Off' (because I believe this is the default setting).
Thanks for your suggestions - I had tried that AF with remote control set to off and focus priority is already set on the AF.S setting, and it made no difference. Trap focus works with the shutter but not with the remote cable. Is there anyone else with a K5II, a manual lens (or an AF lens with an AF/MF switch), and a cable release that could test whether they can get trap focus with the cable. Could Pentax have broken this function in the K5II or perhaps there is something wrong with my cable release?

Alastair
04-18-2014, 03:10 PM   #29
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QuoteOriginally posted by kiwibiologist Quote
Thanks for your suggestions - I had tried that AF with remote control set to off and focus priority is already set on the AF.S setting, and it made no difference. Trap focus works with the shutter but not with the remote cable. Is there anyone else with a K5II, a manual lens (or an AF lens with an AF/MF switch), and a cable release that could test whether they can get trap focus with the cable. Could Pentax have broken this function in the K5II or perhaps there is something wrong with my cable release?
Bumping this thread to answer kiwibiologist’s question, as I was having the same problem using my K-5II and a KA lens. Followed the instructions above (and in the Pentax manual), and still couldn’t get CIF to work with a cable release. It just fired away like a monkey with a machine gun, no matter what was in the focus point. I too thought it may have been a firmware bug, or my cheap Chinese cable...then I remembered I had my autofocus “delinked” from my shutter release button (i.e., Record Menu--Button Customization--Shutter Button Half Press set to “OFF”) per the technique recommended in the following thread:

https://www.pentaxforums.com/forums/38-photographic-technique/236970-perfect-...everytime.html

So I decided to try setting that back to the default setting to see if it made a difference. It did. Now CIF is working as advertised for me. (Though hastily posted, this hummy picture was one of today’s results.)

I’ll add that those trying this CIF feature had better bring a mugful of patience—it’s temperamental.
Cheers

04-29-2014, 01:16 AM   #30
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I finally tried out the "Catch in Focus" on my K5IIs. Most of the shots were taken with a SP 60-300 that I got a few days ago; I also used the DA* 50-130. This is with the SP.

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