DA 35mm f2.4 focus issues

de1937 · 04-20-2014, 02:46 PM

After a week of shooting, i find the "plastic fantastic" to be awful in terms of focusing. Paired with my k-5, it spends most of it's time hunting for focus. And with screwdrive AF, that gets pretty noisy. Today as I was shooting out in harsh sunlight at noon, I found that it kept back focusing, which was never an issue before. It says focus is locked on the subject 2m away from me, but instead was actually at infinity. Do i just have a bad copy? should i try to calibrate the lens or just send it in and get a replacement from amazon?

Adam · 04-20-2014, 02:49 PM

Which focus point(s) are you using? I would recommend trying to calibrate the lens before returning.

de1937 · 04-20-2014, 02:51 PM

I've been using the center focus point.

Na Horuk · 04-20-2014, 03:55 PM

Try live view? My DA 35mm f2.4 focuses pretty quickly, even on the K-01. Only time it hunted is when I tried to focus on something too close (closer than the lens' minimum focus distance) or on something with no contrast (white plastic door)
With the focus points, remember that the AF point is much larger than the actual little red overlay in the viewfinder. So maybe the camera is finding focus on something behind the intended object. This especially happens when the background is more contrasty or has sharper edges.
Thing is, I don't know how the DA 35mm's AF could be.. broken. Its possible you got a bad copy. But I would recommend you print out a focus chart and do a test in Av mode at f2.4, with the camera on tripod and using 2 sec timer. There are threads and blog posts about AF charts and focus calibration.

tl:dr; DA 35mm f2.4 is good at AF, provided the subject isn't closer than its MFD. Fast, accurate. Live view should focus perfectly every time, regular (phase detect AF) should focus reasonably well and can be improved with AF adjustment.

de1937 · 04-20-2014, 04:11 PM

Oh god haha, live view with the k-5 is a nightmare. My copy also has the tendency to hunt when trying to focus to infinity. whenever i want shots of the sky, it would hunt and never obtain focus. I don't think that the camera focused on something behind the subjects - mainly because it happened to all of my photos that i took in harsh noon time light.
I've also noticed that my copy can't focus on anything white. walls, statue, shirt, it never works, even in a variety of other lighting situations. My 18-135mm never had these issues with the k-5 , so i'm sure it must be attributed to the lens.

Na Horuk · 04-20-2014, 04:29 PM

Originally posted by de1937

whenever i want shots of the sky,

Well okay, that is not too strange. The sky is an odd thing to AF on. But white clothes should be okay, unless its very dark.

Can you focus to infinity manually? Does the lens focus much past infinity?

Oh and btw, does your K-5 have the latest firmware update? It might improve CD AF a little.

de1937 · 04-20-2014, 06:04 PM

I'm going to go out tomorrow and take some tests with it again

may be user error haha.
Focus to infinity manually is fine - in fact manual focus is perfect. the lens doesn't focus past infinity.
OOPs. Firmware update. right. i'll get to that tonight :P Thanks Na Horuk!

04-20-2014, 02:46 PM	#1
de1937 New Member Join Date: Jul 2013 Posts: 25	DA 35mm f2.4 focus issues After a week of shooting, i find the "plastic fantastic" to be awful in terms of focusing. Paired with my k-5, it spends most of it's time hunting for focus. And with screwdrive AF, that gets pretty noisy. Today as I was shooting out in harsh sunlight at noon, I found that it kept back focusing, which was never an issue before. It says focus is locked on the subject 2m away from me, but instead was actually at infinity. Do i just have a bad copy? should i try to calibrate the lens or just send it in and get a replacement from amazon?

04-20-2014, 02:49 PM	#2
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,595	Which focus point(s) are you using? I would recommend trying to calibrate the lens before returning. 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:

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04-20-2014, 02:51 PM	#3
de1937 New Member Join Date: Jul 2013 Posts: 25 Original Poster	I've been using the center focus point.

04-20-2014, 03:55 PM	#4
Na Horuk Veteran Member Join Date: Feb 2012 Location: Slovenia, probably Photos: Gallery \| Albums Posts: 11,186	Try live view? My DA 35mm f2.4 focuses pretty quickly, even on the K-01. Only time it hunted is when I tried to focus on something too close (closer than the lens' minimum focus distance) or on something with no contrast (white plastic door) With the focus points, remember that the AF point is much larger than the actual little red overlay in the viewfinder. So maybe the camera is finding focus on something behind the intended object. This especially happens when the background is more contrasty or has sharper edges. Thing is, I don't know how the DA 35mm's AF could be.. broken. Its possible you got a bad copy. But I would recommend you print out a focus chart and do a test in Av mode at f2.4, with the camera on tripod and using 2 sec timer. There are threads and blog posts about AF charts and focus calibration. tl:dr; DA 35mm f2.4 is good at AF, provided the subject isn't closer than its MFD. Fast, accurate. Live view should focus perfectly every time, regular (phase detect AF) should focus reasonably well and can be improved with AF adjustment.

04-20-2014, 04:11 PM	#5
de1937 New Member Join Date: Jul 2013 Posts: 25 Original Poster	Oh god haha, live view with the k-5 is a nightmare. My copy also has the tendency to hunt when trying to focus to infinity. whenever i want shots of the sky, it would hunt and never obtain focus. I don't think that the camera focused on something behind the subjects - mainly because it happened to all of my photos that i took in harsh noon time light. I've also noticed that my copy can't focus on anything white. walls, statue, shirt, it never works, even in a variety of other lighting situations. My 18-135mm never had these issues with the k-5 , so i'm sure it must be attributed to the lens.

04-20-2014, 04:29 PM	#6
Na Horuk Veteran Member Join Date: Feb 2012 Location: Slovenia, probably Photos: Gallery \| Albums Posts: 11,186	Originally posted by de1937 whenever i want shots of the sky, Well okay, that is not too strange. The sky is an odd thing to AF on. But white clothes should be okay, unless its very dark. Can you focus to infinity manually? Does the lens focus much past infinity? Oh and btw, does your K-5 have the latest firmware update? It might improve CD AF a little.

04-20-2014, 06:04 PM	#7
de1937 New Member Join Date: Jul 2013 Posts: 25 Original Poster	I'm going to go out tomorrow and take some tests with it again may be user error haha. Focus to infinity manually is fine - in fact manual focus is perfect. the lens doesn't focus past infinity. OOPs. Firmware update. right. i'll get to that tonight :P Thanks Na Horuk!