31LTD focusing issue...

beaumont · 12-27-2010, 12:15 AM

I have a 31ltd which, when it focus's properly, produces wonderful images. The issue is that most of the AF shots I take with my 10D are out of focus. It seems to focus slightly behind the desired point of focus. (Is this what is refered to a back focusing?)
What are the options to solve this? I'm thinking it should likely be sent in for repair? (I hope to upgrade to a K5 in the new year. Will I have the same problem with it, or will it accomodate the issue?)
Thanks in advance for your feedback.

Last edited by beaumont; 12-27-2010 at 10:12 AM.

buaobao · 12-27-2010, 01:05 AM

Page 126 (K5 pdf manual- Shooting Functions ) Here is what you need to do.
Press Menu, go to C4, select function number 26 - AF Fine Adjustment, there you go.

beaumont · 12-27-2010, 09:27 AM

Thanks for the feedback. Now I know what to look for. It looks like this function may not be available for the 10D though?...

sjwaldron · 12-27-2010, 12:23 PM

The K10D focus can be adjusted, but it's a global setting.

https://www.pentaxforums.com/forums/pentax-dslr-discussion/110320-k10d-focus-...ebug-mode.html

beaumont · 12-27-2010, 01:32 PM

Originally posted by sjwaldron

The K10D focus can be adjusted, but it's a global setting.

https://www.pentaxforums.com/forums/pentax-dslr-discussion/110320-k10d-focus-...ebug-mode.html

Thanks for the heads up. As my other lenses seem ok, I'm thinking my only options are to send the lens in to be "re-calibrated", or wait until I upgrade to a K5...
thx

JeffJS · 12-27-2010, 02:05 PM

Originally posted by beaumont

Thanks for the heads up. As my other lenses seem ok, I'm thinking my only options are to send the lens in to be "re-calibrated", or wait until I upgrade to a K5...
thx

Go to manual focus on the K10d and keep the lens as is. If I'm not mistaken, you have to send both the camera and the lens in for calibration. I had the same issue with my 31 on the K10d. On the K7, it worked beautifully. On the K5, it works beautifully.

beaumont · 12-27-2010, 04:29 PM

Originally posted by JeffJS

Go to manual focus on the K10d and keep the lens as is. If I'm not mistaken, you have to send both the camera and the lens in for calibration. I had the same issue with my 31 on the K10d. On the K7, it worked beautifully. On the K5, it works beautifully.

Thx Jeff, that's what I'll do until I get a K5. (I just wish my eyesight was as good as it used to be for manual focusing. I look forward to the day that this lens once again becomes my favorite!)

taurus9 · 12-28-2010, 06:29 PM

At what aperture are you experiencing the apparent backfocus?

I have a Kx and 31Ltd and had intermittent focus issues, usually with setting it at f2.5 or larger. I thought it was a calibration issue, but after many tests with shooting newspapers and monkeying around debug mode to adjust focus, the end result was no change to the out-of-the factory adjustment value.

I considered sending it the body/lens for calibration but didn't want to lose both for any length of time and it seemed doing such work may worsen the AF performance with other lenses.

Instead I changed the way I focused and began placing the focus point (I'm always on single point AF mode) on areas that are slightly closer to the lens than where I want the sharpest plane of focus to be. This would only matter on certain types of subjects (i.e. people's faces) since that's where I experienced the most problems. With that small change, the focus hit rate increased significantly.

So while you're waiting to get the K5, try experimenting with slightly different AF focus points to see if the issue remains..

beaumont · 12-28-2010, 08:25 PM

Thanks Taurus. We'll give that a shot.

12-27-2010, 12:15 AM	#1
beaumont Veteran Member Join Date: Mar 2008 Posts: 506	HELP! 31LTD focusing issue... I have a 31ltd which, when it focus's properly, produces wonderful images. The issue is that most of the AF shots I take with my 10D are out of focus. It seems to focus slightly behind the desired point of focus. (Is this what is refered to a back focusing?) What are the options to solve this? I'm thinking it should likely be sent in for repair? (I hope to upgrade to a K5 in the new year. Will I have the same problem with it, or will it accomodate the issue?) Thanks in advance for your feedback. Last edited by beaumont; 12-27-2010 at 10:12 AM.

12-27-2010, 09:27 AM	#3
beaumont Veteran Member Join Date: Mar 2008 Posts: 506 Original Poster	Thanks for the feedback. Now I know what to look for. It looks like this function may not be available for the 10D though?... Last edited by beaumont; 12-27-2010 at 09:59 AM.

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12-27-2010, 01:05 AM	#2
buaobao Inactive Account Join Date: Oct 2010 Location: des veoux rd west, kennedy town Photos: Gallery \| Albums Posts: 51	Page 126 (K5 pdf manual- Shooting Functions ) Here is what you need to do. Press Menu, go to C4, select function number 26 - AF Fine Adjustment, there you go.

12-27-2010, 12:23 PM	#4
sjwaldron Veteran Member Join Date: Aug 2009 Photos: Gallery Posts: 1,236	The K10D focus can be adjusted, but it's a global setting. https://www.pentaxforums.com/forums/pentax-dslr-discussion/110320-k10d-focus-...ebug-mode.html

12-27-2010, 01:32 PM	#5
beaumont Veteran Member Join Date: Mar 2008 Posts: 506 Original Poster	Originally posted by sjwaldron The K10D focus can be adjusted, but it's a global setting. https://www.pentaxforums.com/forums/pentax-dslr-discussion/110320-k10d-focus-...ebug-mode.html Thanks for the heads up. As my other lenses seem ok, I'm thinking my only options are to send the lens in to be "re-calibrated", or wait until I upgrade to a K5... thx

12-27-2010, 02:05 PM	#6
JeffJS Inactive Account Join Date: Aug 2008 Location: Michigan, USA Photos: Gallery \| Albums Posts: 7,484	Originally posted by beaumont Thanks for the heads up. As my other lenses seem ok, I'm thinking my only options are to send the lens in to be "re-calibrated", or wait until I upgrade to a K5... thx Go to manual focus on the K10d and keep the lens as is. If I'm not mistaken, you have to send both the camera and the lens in for calibration. I had the same issue with my 31 on the K10d. On the K7, it worked beautifully. On the K5, it works beautifully.

12-27-2010, 04:29 PM	#7
beaumont Veteran Member Join Date: Mar 2008 Posts: 506 Original Poster	Originally posted by JeffJS Go to manual focus on the K10d and keep the lens as is. If I'm not mistaken, you have to send both the camera and the lens in for calibration. I had the same issue with my 31 on the K10d. On the K7, it worked beautifully. On the K5, it works beautifully. Thx Jeff, that's what I'll do until I get a K5. (I just wish my eyesight was as good as it used to be for manual focusing. I look forward to the day that this lens once again becomes my favorite!)

12-28-2010, 06:29 PM	#8
taurus9 Senior Member Join Date: Jan 2010 Location: British Columbia Posts: 120	At what aperture are you experiencing the apparent backfocus? I have a Kx and 31Ltd and had intermittent focus issues, usually with setting it at f2.5 or larger. I thought it was a calibration issue, but after many tests with shooting newspapers and monkeying around debug mode to adjust focus, the end result was no change to the out-of-the factory adjustment value. I considered sending it the body/lens for calibration but didn't want to lose both for any length of time and it seemed doing such work may worsen the AF performance with other lenses. Instead I changed the way I focused and began placing the focus point (I'm always on single point AF mode) on areas that are slightly closer to the lens than where I want the sharpest plane of focus to be. This would only matter on certain types of subjects (i.e. people's faces) since that's where I experienced the most problems. With that small change, the focus hit rate increased significantly. So while you're waiting to get the K5, try experimenting with slightly different AF focus points to see if the issue remains..

12-28-2010, 08:25 PM	#9
beaumont Veteran Member Join Date: Mar 2008 Posts: 506 Original Poster	Thanks Taurus. We'll give that a shot.