Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
11-18-2016, 11:18 PM   #1
Veteran Member




Join Date: Sep 2013
Location: Pasadena, CA
Photos: Albums
Posts: 1,125
16-50 gross AF inaccuracy in PDAF - only in some AF points?

Hi,

I am having trouble with the accuracy of the vertically distributed AF points on the AF 16-50 / K-3. Everything in the horizontal center line is fine (see below; green - ok, red - grossly off).
The contrast AF turns out fine, so it's not the optics.

The inaccuracy is very severe, beyond what could be corrected with microadjustments.

Any thoughts on what could be causing this?

Attached Images
 
11-18-2016, 11:21 PM   #2
Loyal Site Supporter
Loyal Site Supporter
UncleVanya's Avatar

Join Date: Jul 2014
Photos: Gallery | Albums
Posts: 15,229
Other lenses work ok?
11-18-2016, 11:22 PM   #3
Veteran Member




Join Date: Sep 2013
Location: Pasadena, CA
Photos: Albums
Posts: 1,125
Original Poster
QuoteOriginally posted by UncleVanya Quote
Other lenses work ok?
They do.
11-18-2016, 11:29 PM   #4
Loyal Site Supporter
Loyal Site Supporter
UncleVanya's Avatar

Join Date: Jul 2014
Photos: Gallery | Albums
Posts: 15,229
The AF points are in the camera. But calibration data is in the lens. Did you ever back up your lensrom file?

Do you have access to pull the lensrom file? You do it the same way you convert to screw drive. If damaged it can screw up focusing from what I have seen people post. Each is unique to your lens. A few people have used others files when desperate.

11-18-2016, 11:40 PM   #5
Veteran Member




Join Date: Sep 2013
Location: Pasadena, CA
Photos: Albums
Posts: 1,125
Original Poster
QuoteOriginally posted by UncleVanya Quote
The AF points are in the camera. But calibration data is in the lens. Did you ever back up your lensrom file?

Do you have access to pull the lensrom file? You do it the same way you convert to screw drive. If damaged it can screw up focusing from what I have seen people post. Each is unique to your lens. A few people have used others files when desperate.
Thanks. I will look into the rom file. The error is consistent, so maybe I can recalibrate it.
Hell, maybe I will even contact Ricoh tech support. My first instinct was to come here...
11-18-2016, 11:52 PM   #6
Site Supporter
Site Supporter




Join Date: Nov 2014
Location: Edmonton
Posts: 600
how good is the lighting during your tests? are you outside in good light? or indoors with a screen
11-18-2016, 11:56 PM   #7
Veteran Member




Join Date: Sep 2013
Location: Pasadena, CA
Photos: Albums
Posts: 1,125
Original Poster
QuoteOriginally posted by wibbly Quote
how good is the lighting during your tests? are you outside in good light? or indoors with a screen
Happens in both cases. I have some outdoors shots that were grossly off. They are off enough that even at f8, the shots aren't sharp. All fine with the center focus.
I have a feeling occasionally they turn out fine, but it's almost as if that's because AF missed in those cases, just in the correct direction.
11-19-2016, 08:15 AM   #8
Loyal Site Supporter
Loyal Site Supporter
UncleVanya's Avatar

Join Date: Jul 2014
Photos: Gallery | Albums
Posts: 15,229
The few cases of damaged files I have heard of gave focus problems at various focal lengths and distances. I don't recall the problem involving the focus point used. I could be sending you down the wrong path.

11-19-2016, 10:58 AM   #9
Site Supporter
Site Supporter




Join Date: Nov 2014
Location: Edmonton
Posts: 600
if i were in your position i'd convert to screw drive and re-test.
11-19-2016, 11:29 AM   #10
Loyal Site Supporter
Loyal Site Supporter
UncleVanya's Avatar

Join Date: Jul 2014
Photos: Gallery | Albums
Posts: 15,229
QuoteOriginally posted by wibbly Quote
if i were in your position i'd convert to screw drive and re-test.
That is certainly a doable thing. I don't know that I've ever heard of this type of behavior from failing SDM however. I'd love to see the lens tested on another camera myself.
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!
af, af inaccuracy, inaccuracy, inaccuracy in pdaf, k-mount, pentax lens, slr lens
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
K-1 - number of AF points shown in A-33 mode acoufap Pentax K-1 3 09-19-2016 10:12 AM
Sony a6300 Boasts the World’s Fastest AF and Highest Number of AF Points osv Non-Pentax Cameras: Canon, Nikon, etc. 23 02-27-2016 11:12 AM
K50 no visible AF points in viewfinder telum Visitors' Center 10 12-12-2014 06:57 PM
Focal Plane In Relation To AF Lighted Points JimC1101 Pentax DSLR Discussion 2 12-08-2013 09:47 AM
Is K5 really only 11 AF points ? kinkindoll Pentax News and Rumors 72 09-19-2010 09:19 PM



All times are GMT -7. The time now is 10:05 PM. | See also: NikonForums.com, CanonForums.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