Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
09-11-2015, 07:05 AM   #1
Forum Member




Join Date: Feb 2011
Location: Connecticut
Posts: 90
AF Micro-Adjustment Confusion

Maybe someone can shed some light on this for me. On my K3, I need varying levels of adjustment for all of my lenses. I use a SpyderLensCal to calibrate. +5 on my 18-135, +2 on my 35 Limited, 0 on my 55-300, -2 on my 50 1.4, and +10 (!!) on my 16-50. My K7 requires very similar levels of adjustment. Until recently, I just accepted this as sample variation with the lens manufacturing process.

My dilemma is that I recently discovered that each of these lenses miraculously works perfectly without ANY AF adjustment on my mother's K50. How is this even possible? Does this indicate a problem with my K3 and K7? Or with her K50? Is it voodoo?

I just don't get it. I understand sample variation between bodies, but I would expect a similar spread between the lenses regardless of the body. i.e. how can my 55-300 and 16-50 have an 8-10 point spread between each other on my other bodies but neither requires any adjustment on the K50?

Any insight you can share would be tremendously helpful.

Thanks!

09-11-2015, 08:00 AM   #2
Site Supporter
jatrax's Avatar

Join Date: May 2010
Location: Oregon
Photos: Gallery | Albums
Posts: 10,289
Not sure I can explain why but it is not unusual. My k-5 required various adjustments on almost all lenses. My k-3 required no adjustments on any lens.
09-11-2015, 08:17 AM   #3
Forum Member




Join Date: Feb 2011
Location: Connecticut
Posts: 90
Original Poster
QuoteOriginally posted by jatrax Quote
Not sure I can explain why but it is not unusual. My k-5 required various adjustments on almost all lenses. My k-3 required no adjustments on any lens.
Thanks jatrax, at least I know I'm not the only one who sees this type of behavior.

FWIW I must say, I've really liked using this K-50. I'm a bit of a snob and have always owned "prosumer" DSLRs, but now I wonder if I haven't wasted a bit of $$$ over the years
09-11-2015, 11:20 AM - 1 Like   #4
Forum Member




Join Date: Oct 2011
Posts: 78
QuoteOriginally posted by sweendiggs Quote
Maybe someone can shed some light on this for me. On my K3, I need varying levels of adjustment for all of my lenses. I use a SpyderLensCal to calibrate. +5 on my 18-135, +2 on my 35 Limited, 0 on my 55-300, -2 on my 50 1.4, and +10 (!!) on my 16-50. My K7 requires very similar levels of adjustment. Until recently, I just accepted this as sample variation with the lens manufacturing process.

My dilemma is that I recently discovered that each of these lenses miraculously works perfectly without ANY AF adjustment on my mother's K50. How is this even possible? Does this indicate a problem with my K3 and K7? Or with her K50? Is it voodoo?

I just don't get it. I understand sample variation between bodies, but I would expect a similar spread between the lenses regardless of the body. i.e. how can my 55-300 and 16-50 have an 8-10 point spread between each other on my other bodies but neither requires any adjustment on the K50?

Any insight you can share would be tremendously helpful.

Thanks!
Fairly simple answer - one of the major variables is the AF subsystem itself. The AF sensor, logic and design is different between those cameras. The AF performance, for example the sensor and its loop parameters can also interact with the lens characteristics (poles and zeros in the control equations/solution) and cause differences in performance between lenses on the same camera. This is also why, in part ( there are other reasons) that zooms lenses focus differently at either ends of the zoom range. Also the lower resolution is a bit more forgiving. As the megapixels climb the mis focusing can become a bit more evident.

09-11-2015, 04:42 PM   #5
Forum Member




Join Date: Feb 2011
Location: Connecticut
Posts: 90
Original Poster
QuoteOriginally posted by Fauxton Quote
Fairly simple answer - one of the major variables is the AF subsystem itself. The AF sensor, logic and design is different between those cameras. The AF performance, for example the sensor and its loop parameters can also interact with the lens characteristics (poles and zeros in the control equations/solution) and cause differences in performance between lenses on the same camera. This is also why, in part ( there are other reasons) that zooms lenses focus differently at either ends of the zoom range. Also the lower resolution is a bit more forgiving. As the megapixels climb the mis focusing can become a bit more evident.
Good info, thank you!
Reply

Bookmarks
  • 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!
adjustment, af, bodies, dslr, k-3, k3, k7, lenses, levels, pentax k-3, spread, variation
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
K3 AF Micro Adjustment Problems candgpics Pentax K-3 23 02-15-2015 02:01 PM
Micro AF adjustment IchabodCrane Pentax K-30 & K-50 6 08-11-2014 07:13 PM
Sigma lenses AF micro adjustment Greyser Pentax SLR Lens Discussion 8 01-07-2013 06:57 AM
K30 AF micro-adjustment Roberts Pentax K-30 & K-50 8 05-22-2012 05:06 PM
AF micro-adjustment MacKay Pentax DSLR Discussion 10 05-07-2010 01:51 PM



All times are GMT -7. The time now is 04:07 PM. | See also: NikonForums.com, 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?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top