Forgot Password
Pentax Camera Forums Home

Show Printable Version Search this Thread
04-17-2017, 03:04 PM   #1
Forum Member

Join Date: Mar 2017
Photos: Gallery
Posts: 76
Testing auto focus accuracy with manual lenses.

So I've determined my new K-1 and DFA 24-70 have a back focus issue. I'm getting the best results at +10 AF adjustment (which imo is beyond accectable tolarences. Hopefully B&H or Ricoh will agree)so I'm thinking either the lens, the body or both have a calibration issue or somthing worse. Before I attempt an exchange I'd like to isolate the issue to either the lens or the body. I don't have access to another AF lens but I do have a manual 50mm 1.4. My question is could a manual lens along with the cameras in focus indicator be used as a guide to determine if there is a AF problem with the body?

04-17-2017, 03:32 PM   #2
Loyal Site Supporter
Loyal Site Supporter
pschlute's Avatar

Join Date: Mar 2007
Location: Surrey, UK
Photos: Gallery
Posts: 4,428
Yes do the same tests with the manual lens.

As I understand it the -10/+10 adjustment range represents the maximum manufacturing tolerances of the camera. So if you need to use +10 that is within tolerance. I have to use somewhere between +6 to +10 on all my lenses with the K1
04-17-2017, 03:39 PM   #3
Site Webmaster
Adam's Avatar

Join Date: Sep 2006
Location: Arizona
Photos: Gallery | Albums
Posts: 49,671
The good news is that AF adjustments are a part of life these days, rather than a defect in the gear, so don't panic just yet

AF adjustments are meant for AF lenses only, so shouldn't use manual lenses if you want to reliably determine global AF adjustments. But you could certainly try catch in focus and see if the photos are usable- this would be a decent indicator that your camera is OK. However, since manual lens AF confirmation has a large tolerance range, a better solution would be to pick up a very cheap AF lens, like the DA L 18-55mm, for testing.

If +10 is yielding sharp photos across the board with the 24-70mm, no further action should be needed as long as the other lens doesn't also need a +10.

Otherwise, I'd recommend sending the combo in for calibration. Precision should be able to figure out to what degree the body/lens is at fault, and apply further corrections if/as needed.

Adam Webmaster (Site Usage Guide | Site Help | My Photography) server and development costs are user-supported. You can help cover these costs by donating. 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:


  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
af, auto focus accuracy, body, camera, focus, issue, lens, pentax help, photography, troubleshooting
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Similar Threads
Thread Thread Starter Forum Replies Last Post
10 Reasons why manual focus primes are better than those new auto focus zoom lenses JoepLX3 Pentax SLR Lens Discussion 188 07-25-2012 03:28 PM
K-30 AF Accuracy Testing for the Pentaxforums Review: Give Us Your Ideas! deadwolfbones Pentax K-30 & K-50 42 07-17-2012 09:50 AM
Focus Indicator Accuracy With Old Manual Lens Siegfried Pentax K-5 24 04-28-2012 06:37 PM
Lense Testing: Aperture reliability/accuracy cps_goodbuy Pentax SLR Lens Discussion 10 08-14-2010 01:16 PM
accuracy of K-x metering manual / M42 lenses? kuuan Pentax DSLR Discussion 7 01-22-2010 01:01 PM

All times are GMT -7. The time now is 02:40 PM. | See also:, part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]