Win a Pentax Limited Lens: Raffle Now Live!

Saul · 03-22-2009, 02:50 PM

Hi.
I have tested my lens on AF adjustment chart. The lens is Pentax 31 mm. F/1,8.
After number of tests I am confused. In the left side of a chart I see perfect results with exact focus on -00-, while in the right side it performs about 3 mm. front focus. Adjustment in my K20D does not help as one side of the lens shows perfect results. The lens is still in the warranty time period. Should I send it back? How to react on this?

Thanks.
Saulius

Wheatfield · 03-22-2009, 04:37 PM

Either jump up and down and scream like a baby, or just get out and take pictures.
Odds are, there is a problem with your testing procedure, not with the lens, but either way, you don't want to open up a lens for something that insignificant.

roentarre · 03-22-2009, 06:49 PM

I would not bother the fine tuning of the autofocus on k20d. You would have to fine tune everytime a different lens is used.

Back focusing does happen from time to time. Just test it in the field instead of doing these tests that are not indicative of true applications of this lens.

k100d · 03-22-2009, 06:50 PM

3mm doesn't sound like much. but if one side is sharper than the other and might be worth sending it back for decentering issues.
do you have any samples?

03-22-2009, 02:50 PM	#1
Saul New Member Join Date: Nov 2007 Location: Lithuania Photos: Gallery Posts: 13	AF adjustment problem. Different corners, different focus results. Hi. I have tested my lens on AF adjustment chart. The lens is Pentax 31 mm. F/1,8. After number of tests I am confused. In the left side of a chart I see perfect results with exact focus on -00-, while in the right side it performs about 3 mm. front focus. Adjustment in my K20D does not help as one side of the lens shows perfect results. The lens is still in the warranty time period. Should I send it back? How to react on this? Thanks. Saulius

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Wow, a +8 Focus Adjustment?	iocchelli	Pentax DSLR Discussion	22	07-15-2010 09:55 AM
focus adjustment on k20d - beyond -10	bortao	Pentax DSLR Discussion	4	05-10-2010 07:27 AM
FA 50 Focus Adjustment	dazman	Pentax SLR Lens Discussion	13	08-20-2009 10:05 PM
K20D Focus Adjustment	Mallee Boy	Pentax DSLR Discussion	3	07-21-2009 02:57 PM
Focus adjustment on K100D	sawtooth235	Pentax DSLR Discussion	0	12-11-2008 01:04 PM

03-22-2009, 04:37 PM	#2
Wheatfield Moderator Join Date: Apr 2008 Location: The wheatfields of Canada Posts: 15,987	Either jump up and down and scream like a baby, or just get out and take pictures. Odds are, there is a problem with your testing procedure, not with the lens, but either way, you don't want to open up a lens for something that insignificant.

03-22-2009, 06:49 PM	#3
roentarre Veteran Member Join Date: Oct 2006 Location: Melbourne, Australia Posts: 11,783	I would not bother the fine tuning of the autofocus on k20d. You would have to fine tune everytime a different lens is used. Back focusing does happen from time to time. Just test it in the field instead of doing these tests that are not indicative of true applications of this lens.

03-22-2009, 06:50 PM	#4
k100d Veteran Member Join Date: Feb 2008 Location: Toronto Posts: 3,911	3mm doesn't sound like much. but if one side is sharper than the other and might be worth sending it back for decentering issues. do you have any samples?

AF adjustment problem. Different corners, different focus results.

Win a Pentax Limited Lens: Raffle Now Live!