f/2.8 Focus Point with manual lenses

Giklab · 06-01-2013, 07:42 AM

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.

**crewl1** · 06-01-2013, 09:41 AM

Does the catch in focus menu setting have to be on for confirmation to occur?

JinDesu · 06-01-2013, 10:19 AM

I do not believe the F2.8 focus point has anything specifically to do with the low-light focusing abilities of the k-5II.

Adam · 06-01-2013, 10:25 AM

Originally posted by Giklab

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.

Adam
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Giklab · 06-01-2013, 11:56 AM

Originally posted by crewl1

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.

valy · 06-01-2013, 12:09 PM

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.

Giklab · 06-01-2013, 01:36 PM

Originally posted by valy

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.

valy · 06-01-2013, 01:47 PM

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.

Giklab · 06-01-2013, 11:57 PM

Originally posted by valy

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.

06-01-2013, 07:42 AM	#1
Giklab Veteran Member Join Date: Jan 2012 Location: Slovenia Photos: Gallery Posts: 2,182	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, 12:09 PM	#6
valy Senior Member Join Date: Jun 2011 Location: Bucharest Posts: 120	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, 01:47 PM	#8
valy Senior Member Join Date: Jun 2011 Location: Bucharest Posts: 120	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.

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06-01-2013, 09:41 AM	#2
crewl1 Site Supporter Join Date: Jul 2010 Location: Los Angeles, CA Photos: Gallery \| Albums Posts: 9,807	Does the catch in focus menu setting have to be on for confirmation to occur?

06-01-2013, 10:19 AM	#3
JinDesu Veteran Member Join Date: Jun 2011 Location: New York City Photos: Gallery Posts: 5,638	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
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,594	Originally posted by Giklab 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. Adam PentaxForums.com Webmaster (Site Usage Guide \| Site Help \| My Photography) PentaxForums.com server and development costs are user-supported. You can help cover these costs by donating or purchasing one of our Pentax eBooks. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, KEH, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

06-01-2013, 11:56 AM	#5
Giklab Veteran Member Join Date: Jan 2012 Location: Slovenia Photos: Gallery Posts: 2,182 Original Poster	Originally posted by crewl1 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, 01:36 PM	#7
Giklab Veteran Member Join Date: Jan 2012 Location: Slovenia Photos: Gallery Posts: 2,182 Original Poster	Originally posted by valy 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, 11:57 PM	#9
Giklab Veteran Member Join Date: Jan 2012 Location: Slovenia Photos: Gallery Posts: 2,182 Original Poster	Originally posted by valy 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.