Forgot Password
Pentax Camera Forums Home

Show Printable Version Search this Thread
02-23-2009, 10:01 PM   #1
Inactive Account

Join Date: Feb 2009
Location: Lincoln, Nebraska, USA
Posts: 65
Looking for input on what to do about a new lens.

I just got a used tammy 17-50 from B&H for $369 USD. I would have sworn they sent me a brand new lens -- it's perfectly immaculate.

It's incredibly sharp, from corner-to-corner, at all focal lengths, and doesn't seem to have the underexposure issue I've heard about. My friend's 16-50 doesn't compare (and he's got a decent copy).

HOWEVER (...and we all know there's ALWAYS a "however"), it backfocuses quite a bit on my K10D. I went into the debug menu and adjusted it to correct it. It's the only current AF lens I have (I've been shuffling around lenses quite a bit recently). Oddly enough, the AF confirm for my Pentax-A 50/1.4 seems to work just as good as ever.

I've never really believed a lens could front-focus or back-focus (since all the AF functions are in the camera -- i.e., the body spins the motor until it thinks it's in focus, so any back-focus / front-focus issue would be a result of the body -- not the lens).

Right now, everything's fine -- but when I get my student loans paid off and start buying more AF lenses, am I going to regret going this route? Am I going to have to leave the camera in debug mode and shift back and fourth between AF adjustments?

Or am I right about the AF front-focus/back-focus being a in-camera issue? (I'm right... RIGHT?)

I've read everything I can about the K-Mount and SAFOX and everything -- so it seems like my body just needed to be calibrated. But if I should exchange the lens and try to get one that doesn't have this "problem" (again, that's if it's actually the lens's fault), then I'd like to know ASAP.

Any input would be greatly appreciated.


  • 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, back-focus, bit, body, camera, debug, dslr, front-focus, input, issue, lens, photography
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Similar Threads
Thread Thread Starter Forum Replies Last Post
First lens ? Input apreciated jolinjo Pentax SLR Lens Discussion 22 09-19-2009 02:54 PM
What do I input when using old manual focus lens? lurchlarson Pentax SLR Lens Discussion 10 02-23-2009 02:57 PM
Input focal length for a manual lens jpzk Photographic Technique 11 01-14-2009 08:50 PM
Pentax DA 55-300mm lens Input Requested rw2mlt Pentax DSLR Discussion 14 10-09-2008 11:32 AM
Interesting lens and photos...input please! Fireball Post Your Photos! 5 01-24-2008 06:38 PM

All times are GMT -7. The time now is 11:54 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]