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03-27-2012, 05:48 PM   #1
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catch in focus

i have 2 of the old MF prime lenses on my KX. I use catch in focus because sometimes I just don't trust my eye completely, esp with shallower DOFs. But, sometimes the Catch in focus doesn't "catch" even if I am focusing reallllly slowly, and my subject isn't moving, and i keep going back and forth on the focus waiting for it to snap, and it takes longer at times than it seems it should take. am i doing something wrong?

03-27-2012, 05:57 PM   #2
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QuoteOriginally posted by jennverr Quote
i have 2 of the old MF prime lenses on my KX. I use catch in focus because sometimes I just don't trust my eye completely, esp with shallower DOFs. But, sometimes the Catch in focus doesn't "catch" even if I am focusing reallllly slowly, and my subject isn't moving, and i keep going back and forth on the focus waiting for it to snap, and it takes longer at times than it seems it should take. am i doing something wrong?
No, you are not. The issue is the "contrast" or lack of contrast break (DOF will affect it somewhat also) - what are the subjects you are shooting?

PS: I to use CIF and mostly on the streets of DC when shooting random people shots...
03-27-2012, 06:00 PM   #3
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This also depends on how shallow to DOF is. Modern cameras don't have very accurate AF for lenses faster than f2.8 so it might be better to just use live-view
03-27-2012, 06:01 PM   #4
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QuoteOriginally posted by joe.penn Quote
No, you are not. The issue is the "contrast" or lack of contrast break (DOF will affect it somewhat also) - what are the subjects you are shooting?

PS: I to use CIF and mostly on the streets of DC when shooting random people shots...
Hi thanks for the reply. That does make sense I guess. I can't remember what other things I've shot specificaly when this happened, but for instance tonight it was when I was trying to get some shots of my dog. Maybe when I was focusing on her dark nose or something.

DC is certainly great for street shooting!

03-27-2012, 06:05 PM   #5
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Is catch in focus affected by whether shake resistance is on or off? If it does affect CIF, then you may be missing shots when there isn't time for the SR to fully engage. I'm not sure how SR would handle you slowly changing the focus as opposed to having a fixed focus point and waiting for the object to arrive in the right place.

(I'm still struggling to get CIF to work under some situations too)
03-27-2012, 06:07 PM   #6
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QuoteOriginally posted by jennverr Quote
Hi thanks for the reply. That does make sense I guess. I can't remember what other things I've shot specificaly when this happened, but for instance tonight it was when I was trying to get some shots of my dog. Maybe when I was focusing on her dark nose or something.

DC is certainly great for street shooting!
Inside lighting makes it a wee harder also, just move center to a break in contrast and it should confirm and fire for you.

And yes, DC is really great, I am actually a native of DC, I live outside of it now but I am down there shooting a couple hundred times per year...
03-27-2012, 06:09 PM   #7
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QuoteOriginally posted by MSL Quote
Is catch in focus affected by whether shake resistance is on or off? If it does affect CIF, then you may be missing shots when there isn't time for the SR to fully engage. I'm not sure how SR would handle you slowly changing the focus as opposed to having a fixed focus point and waiting for the object to arrive in the right place.

(I'm still struggling to get CIF to work under some situations too)
Yea I notice sometimes I have to actually just leave the focus ring alone and actually move my body back and forth before it clicks sometimes.

Not sure about the Shake reduction correlation..
03-27-2012, 06:10 PM   #8
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QuoteOriginally posted by MSL;1885004[B:
]Is catch in focus affected by whether shake resistance is on or off?[/B] If it does affect CIF, then you may be missing shots when there isn't time for the SR to fully engage. I'm not sure how SR would handle you slowly changing the focus as opposed to having a fixed focus point and waiting for the object to arrive in the right place.

(I'm still struggling to get CIF to work under some situations too)
No - the main issue (well, not an issue but the biggest struggle with it) is getting center to cover a break in contrast - gets harder in lower light and also gets harder with fast glass because of the DOF; shooting with a 1.2 wide open in a night club using CIF is pretty challenging, been there done that and won't go back...

03-27-2012, 06:13 PM   #9
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QuoteOriginally posted by joe.penn Quote
No - the main issue (well, not an issue but the biggest struggle with it) is getting center to cover a break in contrast - gets harder in lower light and also gets harder with fast glass because of the DOF; shooting with a 1.2 wide open in a night club using CIF is pretty challenging, been there done that and won't go back...
I think you'd be better to sit with your finger half pressed on the trigger and shoot when your eye told you to, or just operate in burst mode under those conditions and hope for the best
03-27-2012, 06:28 PM   #10
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I've noticed no CIF+SR problems.

One real CIF problem is light. The subject must be adequately lit, and contrasty. I use CIF with many non-A-type non-auto lenses and I see a cut-off around f/8-11. In almost all situations, CIF works if the lens is at f/8 or wider, and CIF doesn't work if at f/11 or tighter. CIF does work with some lenses at f/14 in bright light, and does fail with others at f/7 in fairly dim light. No problem with A- or M-type glass, as the lens stays wide-open till the exposure. But I stay at f/5.6 or wider if CIF is vital with non-A's non-auto's.

EDIT: For "non-A-type" substitute "non-auto" where 'auto' means there's some camera-to-aperture linkage, like with M-type lenses. That ~f/8 cutoff applies to lenses that won't auto-stop-down.

How to exploit CIF in action shots? Set the aperture tight enough for sufficient DOF; set the ISO high enough for fast enough exposures; and set the shutter fast enough to freeze the image. High-ISO noise can be fixed in PP; motion blur can't. If curbside-shooting a street cycling race or soapbox derby with an A-type 28/2.8 lens on my K20D, I might use TAv mode set to f/4 @ 1/250 second, and let ISO float up to 2000. (Too bad I'll miss the annual bike and staircase races here in Bisbee.)

Anyway, I prefocus on a point where I know the action will be, hold the shutter down, and wait for the photo to snap itself. Same with people-shots on the street: prefocus to 1m-2m and shoot stealthily. Piece of pie! Easy as cake! Just be sure you have the right DOF and exposure. Nail the subject and everything else can be fixed.

Last edited by RioRico; 03-29-2012 at 02:30 AM.
03-27-2012, 06:30 PM   #11
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Good to know - I've only been shooting A type lenses so as usual the problem is with me and not the equipment...
03-27-2012, 06:51 PM   #12
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I never could get catch in focus to work. I press the shutter and it auto focuses and fires. I would expect it to not autofocus and fire when a subject breaks the focus plane. Im using manual, catch in focus on, af on remote off, af-s and MF. Im using the wired remote and its not working.
03-27-2012, 06:57 PM   #13
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Not all lenses can utilize CIF (well, straight out of the box anyways). If the lens you are using is an autofocus lens, the lens "MUST" be capable of sending the "IN MANUAL FOCUS" signal back to the body or CIF can not work with these lenses. Some examples are DA* lenses and Sigma HSM lenses, these lenses send the signal to the body that tells the body the lens is in MF, lenses like the Tamron do not...
03-27-2012, 11:09 PM   #14
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QuoteOriginally posted by jennverr Quote
i have 2 of the old MF prime lenses on my KX. I use catch in focus because sometimes I just don't trust my eye completely, esp with shallower DOFs. But, sometimes the Catch in focus doesn't "catch" even if I am focusing reallllly slowly, and my subject isn't moving, and i keep going back and forth on the focus waiting for it to snap, and it takes longer at times than it seems it should take. am i doing something wrong?
Focus Confirmation = you can see this in your VF - it is the little green hexagon. When lit it shows you that the subject is in focus. Note however that there is a 'range' (also with AF) so it depends on whether you are focusing from Infinity DOWN to your subject or from minimum focus distance UP to your subject. For each lens one direction will always give sharper shots (and it does vary from lens to lens though for most of mine it is Infinity DOWN to the subject). This is easy to check on the K7/K5 by taking one shot from each direction and then using the side-by-side review mode and zooming in to see which is sharper, do this a few times and you will now be certain which direction it is for each lens (write it down so you can remember) - it makes a big difference. This of course is important when using MF but also when using CIF.
03-28-2012, 05:48 AM   #15
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I had a really crappy lens once that CIF just plain didn't work on. It was a $10 lens, never produced sharp photos and I quickly unloaded it. All of my Pentax/Tamron primes always worked well with CIF.
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