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06-01-2013, 07:42 AM   #1
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f/2.8 Focus Point with manual lenses

Does it work? Or does it work only with lenses which relay the aperture? I'm asking this because my K-5II focuses in ultra low light with the 18-135 at 135, which is f/5.6 (or even less due to light loss), it will not confirm with my 135/2.8 or 50/1.8, or will not confirm reliably.

06-01-2013, 09:41 AM   #2
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Does the catch in focus menu setting have to be on for confirmation to occur?
06-01-2013, 10:19 AM   #3
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I do not believe the F2.8 focus point has anything specifically to do with the low-light focusing abilities of the k-5II.
06-01-2013, 10:25 AM   #4
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QuoteOriginally posted by Giklab Quote
Does it work? Or does it work only with lenses which relay the aperture? I'm asking this because my K-5II focuses in ultra low light with the 18-135 at 135, which is f/5.6 (or even less due to light loss), it will not confirm with my 135/2.8 or 50/1.8, or will not confirm reliably.
There's a bit of tolerance involved when using manual lenses. Also, IDK why, but sometimes I've seen the K-5 II just decide not to even try focusing if it thinks it can't do it.


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06-01-2013, 11:56 AM   #5
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QuoteOriginally posted by crewl1 Quote
Does the catch in focus menu setting have to be on for confirmation to occur?
No idea. In good light focus is confirmed whether the setting is on or off, with AF on S, C or M.

Thanks Adam. Better than nothing I guess. Although I have not yet run into a situation where the camera would flat-out not focus.

PS I think I merged two problems into one question. I'd like to know whether the 2.8 focus point is active at all with manual lenses, and why my K-5 II reliably focuses with a T5.6< lens in near darkness (about -2EV) and why it gives up with a manual T~2 lens at around 3EV.
06-01-2013, 12:09 PM   #6
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There is a settings in the menu, something related to C4-27. using aperture ring to enable focus confirmation on manual lenses, I don't know why it depends on that setting but for me it starts confirming the focus with the f7.3 telescope. Also I hink this enables SR and input focal length for manual lenses.

Last edited by valy; 06-01-2013 at 12:17 PM.
06-01-2013, 01:36 PM   #7
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QuoteOriginally posted by valy Quote
There is a settings in the menu, something related to C4-27. using aperture ring to enable focus confirmation on manual lenses
These are two different settings:
C25 Catch-in focus (is this spelled correctly?)
and C27 Using Aperture Ring.
06-01-2013, 01:47 PM   #8
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Try playing with "C27 Using Aperture Ring." and see if it works, put in ON. I found this looking to enable SR and input focal length for manual lenses, after this I found by accident that the red square is live and kicking after giving up and believing that K5 loose the focus confirmation due to it's "f2.8 focus system".

C25 Catch-in focus is OFF and C27 Using aperture ring is PERMITTED on mine.


Last edited by valy; 06-01-2013 at 02:23 PM.
06-01-2013, 11:57 PM   #9
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QuoteOriginally posted by valy Quote
C25 Catch-in focus is OFF and C27 Using aperture ring is PERMITTED on mine.
I have both of these set to ON. I'll play around.
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