Pentax 24-70 Focusing Issues?

danperezphotography · 02-24-2019, 03:26 PM

Hello, all. New to the group and new to the Pentax K-1 (just purchased one and a few good lenses). I'm not a total amateur but I'm coming from Micro 4/3. Took the camera out yesterday to a city fair and noticed some irregular focus with my 24-70 2.8. Focus was much softer on the left side of the images than the right. I've uploaded some examples.
The daylight photo with the three girls was shot at f/4.5, the Hawaiian dancers was shot at f/4 and the group of young dancers was shot at f/2.8. In each of these photos you'll see far better sharpness on right side, Is this something I'm doing wrong or is my camera/lens in need of repair (bought on ebay).
Thanks, in advance...
PS - I've had far better image sharpness with my Tamron 70-200.

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Adam · 02-24-2019, 03:32 PM

Looks like the lens may be de-centered. You can test it using this procedure to verify:
How to Check Your Lens for Decentering - Articles and Tips | PentaxForums.com

If the ebay seller was an authorized dealer, you can get the lens repaired under warranty. Otherwise, if it turns out to be de-centered, I would return the lens and buy another elsewhere.

danperezphotography · 02-24-2019, 04:33 PM

Just lined up three cans outside. Stood a bit to the left in front of the first one and tried to spot focus on each one (closest to farthest). 24-70 consistently stumbled to focus on any can. Tried it with the Tamron 70-200 and it had no problem with focusing on each can.
Safe to say this is a lens issue and not a camera issue?

Dericali · 02-25-2019, 05:27 AM

in my experience the 24-70 is very poor at focusing on subjects that are not high contrast, in dim light, and meanwhile it also seems to struggle to make minor focus adjustments (e.g. if you want it to adjust its focus on one object 30cms behind where the focus it, it often can't manage this).

It's potentially the weakest lens in the DFA line up, insofar as its main weakness (focusing ability) impacts precisely what you want to use the 24-70 for (e.g. events, photo journalism). Compare this lens with the DFA* 50mm or 70-200mm and it massively underperforms, even the 28-105mm seems to do better.

Your lens looks like it may have decentering on the left side, but you should do a systematic test to be sure - either as in the link that Adam provided, or shooting something like a brick wall etc.

danperezphotography · 02-25-2019, 10:40 AM

Originally posted by Dericali

in my experience the 24-70 is very poor at focusing on subjects that are not high contrast, in dim light, and meanwhile it also seems to struggle to make minor focus adjustments (e.g. if you want it to adjust its focus on one object 30cms behind where the focus it, it often can't manage this).

It's potentially the weakest lens in the DFA line up, insofar as its main weakness (focusing ability) impacts precisely what you want to use the 24-70 for (e.g. events, photo journalism). Compare this lens with the DFA* 50mm or 70-200mm and it massively underperforms, even the 28-105mm seems to do better.

Your lens looks like it may have decentering on the left side, but you should do a systematic test to be sure - either as in the link that Adam provided, or shooting something like a brick wall etc.

It had trouble focusing from the very first time I used it. Thought it was strange that a lens at that cost could be outperformed in focusing by a comparable micro 4/3 zoom lens. It will be returned and a new lens purchased. Hope the new lens works better :-)

**Crooski** · 02-25-2019, 10:51 AM

f / 2.8 is not the ideal aperture for a group photo, But it is certainly decentering.

02-24-2019, 03:32 PM	#2
Adam Administrator Site Webmaster Join Date: Sep 2006 Location: Arizona Photos: Gallery \| Albums Posts: 51,608	Looks like the lens may be de-centered. You can test it using this procedure to verify: How to Check Your Lens for Decentering - Articles and Tips \| PentaxForums.com If the ebay seller was an authorized dealer, you can get the lens repaired under warranty. Otherwise, if it turns out to be de-centered, I would return the lens and buy another elsewhere. 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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02-24-2019, 04:33 PM	#3
danperezphotography New Member Join Date: Feb 2019 Location: South Florida Posts: 10 Original Poster	Just lined up three cans outside. Stood a bit to the left in front of the first one and tried to spot focus on each one (closest to farthest). 24-70 consistently stumbled to focus on any can. Tried it with the Tamron 70-200 and it had no problem with focusing on each can. Safe to say this is a lens issue and not a camera issue?

02-25-2019, 05:27 AM	#4
Dericali Senior Member Join Date: Jul 2016 Location: Berlin Posts: 298	in my experience the 24-70 is very poor at focusing on subjects that are not high contrast, in dim light, and meanwhile it also seems to struggle to make minor focus adjustments (e.g. if you want it to adjust its focus on one object 30cms behind where the focus it, it often can't manage this). It's potentially the weakest lens in the DFA line up, insofar as its main weakness (focusing ability) impacts precisely what you want to use the 24-70 for (e.g. events, photo journalism). Compare this lens with the DFA* 50mm or 70-200mm and it massively underperforms, even the 28-105mm seems to do better. Your lens looks like it may have decentering on the left side, but you should do a systematic test to be sure - either as in the link that Adam provided, or shooting something like a brick wall etc.

02-25-2019, 10:40 AM	#5
danperezphotography New Member Join Date: Feb 2019 Location: South Florida Posts: 10 Original Poster	Originally posted by Dericali in my experience the 24-70 is very poor at focusing on subjects that are not high contrast, in dim light, and meanwhile it also seems to struggle to make minor focus adjustments (e.g. if you want it to adjust its focus on one object 30cms behind where the focus it, it often can't manage this). It's potentially the weakest lens in the DFA line up, insofar as its main weakness (focusing ability) impacts precisely what you want to use the 24-70 for (e.g. events, photo journalism). Compare this lens with the DFA* 50mm or 70-200mm and it massively underperforms, even the 28-105mm seems to do better. Your lens looks like it may have decentering on the left side, but you should do a systematic test to be sure - either as in the link that Adam provided, or shooting something like a brick wall etc. It had trouble focusing from the very first time I used it. Thought it was strange that a lens at that cost could be outperformed in focusing by a comparable micro 4/3 zoom lens. It will be returned and a new lens purchased. Hope the new lens works better :-)

02-25-2019, 10:51 AM	#6
Crooski Loyal Site Supporter Join Date: Feb 2013 Location: Rozenburg , Zuid-Holland Photos: Gallery Posts: 3,683	f / 2.8 is not the ideal aperture for a group photo, But it is certainly decentering.