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12-26-2012, 06:14 PM   #1
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Catch in Focus issues?

I have a manual f1.4 50mm lens that I sometimes use on my K5.

I recently read about "catch in focus" so I turned that function on to try it out. Admittedly I was shooting close to the subject. I was maybe 1 foot or 18 inches away. (I can measure exactly if needed).

When the camera beeped indicating focus I was consistently focused about 1 inch in front of exactly where the red square on single point focus was aimed.

When I did it using live view I was able to nail the focus on the spot I was aimed at.

It seems to me that with that one lens it is indicating focus slighting in front on my subject. I don't think my other lenses are doing this.

First question. Will that front focus indication go out exponentially?

Second question. Considering the distances I was shooting at should I try to adjust it?

Last question how would one adjust this but ONLY for that one lens?

12-26-2012, 06:30 PM   #2
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QuoteOriginally posted by alamo5000 Quote
Last question how would one adjust this but ONLY for that one lens?
I do not think you can adjust for different manual lenses.

Try moving toward 'focus' from behind the focus point and then from in front of the focus point. There is a range of 'focus' indicated by the beep. At f/4 it is usually dead on, at f/1.4 the actual focus plain is smaller than the indicator can register. You can check this by coming at it from both directions and seeing if one or the other is better or if they are both off the same amount in different directions. At f/1.4 Liveview or a different focusing screen optimized for manual focus are your best options. I've never had much luck with CIF at really wide apertures.
12-26-2012, 06:54 PM   #3
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That's why I am asking the pros

I don't know how focus actually works but I figured it would need to be very precise with the DOF I am talking about...
12-26-2012, 07:14 PM   #4
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Can you explain in more detail what you are doing? I am assuming you are using a tripod in front of a fixed subject (which should be far enough to be within the lenses min. focusing) in acceptable light conditions.
Now turn AF to AF.S, switch the AF/MF button to AF, go to menu and turn CiF on, hold the shutter and turn the focus ring. The problem here can be if you are turning the ring too quickly or if the AF point if picking up focus on something else (the little red square focus confirmation is much smaller than the actual field the camera is testing for focus). Try focusing toward the subject from the other extreme? Try a different subject?
Also, the manual lens has to short out the contacts for CiF to work, some plastic mount lenses will not do that (and neither will some adapters). I find it odd that a manual lens would be so off. Although my K-r sometimes indicates in-focus when it isn't really, the CiF is pretty consistent, with some occasional misfires. Not sure if you can set AF adjustment for manual lenses, maybe only if you play with the global setting. You can try it and see if that will help at all.

12-26-2012, 07:20 PM   #5
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QuoteOriginally posted by jatrax Quote
I do not think you can adjust for different manual lenses.

Try moving toward 'focus' from behind the focus point and then from in front of the focus point. There is a range of 'focus' indicated by the beep. At f/4 it is usually dead on, at f/1.4 the actual focus plain is smaller than the indicator can register. You can check this by coming at it from both directions and seeing if one or the other is better or if they are both off the same amount in different directions. At f/1.4 Liveview or a different focusing screen optimized for manual focus are your best options. I've never had much luck with CIF at really wide apertures.
This is true . . I find that which direction of rotation is more accurate depends on the lens and circumstances. It varies. Set the camera to burst mode and keep your finger on the shutter button while very slowly rotating the focus ring. You may find that the camera takes up to five or so shots while supposedly within the 'in focus' zone, all slightly different. In practice this is only an issue with fast lenses wide open, with a very shallow DOF.
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