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LegOverHead · 01-08-2012, 06:52 PM

Does anyone have this combination?

The auto-focusing on the lens is like not accurate. I point somewhere and it just keeps twitching and sometimes most of my images are blurry, instead of sharp.

bjake · 01-08-2012, 08:39 PM

What light source,low light or ay light?Center focus or splatter focus?
Jake

LegOverHead · 01-08-2012, 11:24 PM

Mainly low light and sometimes a lot of light, on splatter focus.

bjake · 01-09-2012, 11:41 AM

Try it in good light with center focus,it should act better,if not there is a problem someplace.
Jake

yusuf · 01-10-2012, 05:39 AM

Not sure this is the case but Tamron 28-75mm is known to have QC issues, some copies have BF/FF issues. I got my copy right second time.

**pacerr** · 01-10-2012, 10:06 AM

Every lens/body combination has potential issues. Whether those are the result of "known QC" issues is subject to many other factors.

I have had absolutely NO issues with the Tamron SP AF 28-75/2.8 on an *istDS / (2) K100D / K100DS / and (4) K200D bodies.

OTOH, certain of these lens/body pairings, especially those with after market split-screen VF accessories, did require adjustment for precise manual or auto focusing -- however, this was also true for all other lens/body combinations I've used.

H2

LegOverHead · 01-10-2012, 09:25 PM

I'm just guessing that the lens I got has QC issues...

Using the A-Ring focuses a lot better and more accurate.

Last edited by LegOverHead; 01-10-2012 at 09:48 PM.

**pacerr** · 01-10-2012, 10:37 PM

Originally posted by LegOverHead:

I'm just guessing that the lens I got has QC issues...

Using the A-Ring focuses a lot better and more accurate.

Ah, the old "not-using-the-A-ring" fault. Undoubtedly a lens quality control issue for sure.

H2

LegOverHead · 01-11-2012, 03:40 PM

Originally posted by pacerr

Ah, the old "not-using-the-A-ring" fault. Undoubtedly a lens quality control issue for sure.

H2

I really never knew that the A-ring would effect the image quality...

01-08-2012, 06:52 PM	#1
LegOverHead Veteran Member Join Date: Sep 2011 Location: California Photos: Gallery \| Albums Posts: 369	Pentax K100DS w/ Tamron 28-75 f2.8 Does anyone have this combination? The auto-focusing on the lens is like not accurate. I point somewhere and it just keeps twitching and sometimes most of my images are blurry, instead of sharp.

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01-08-2012, 08:39 PM	#2
bjake Veteran Member Join Date: Mar 2011 Location: Eastern Kentucky Posts: 416	What light source,low light or ay light?Center focus or splatter focus? Jake

01-08-2012, 11:24 PM	#3
LegOverHead Veteran Member Join Date: Sep 2011 Location: California Photos: Gallery \| Albums Posts: 369 Original Poster	Mainly low light and sometimes a lot of light, on splatter focus.

01-09-2012, 11:41 AM	#4
bjake Veteran Member Join Date: Mar 2011 Location: Eastern Kentucky Posts: 416	Try it in good light with center focus,it should act better,if not there is a problem someplace. Jake

01-10-2012, 05:39 AM	#5
yusuf Pentaxian Join Date: Nov 2008 Location: Palo Alto, CA Photos: Gallery Posts: 2,497	Not sure this is the case but Tamron 28-75mm is known to have QC issues, some copies have BF/FF issues. I got my copy right second time.

01-10-2012, 10:06 AM	#6
pacerr Loyal Site Supporter Join Date: Jan 2008 Location: Paris, TN Photos: Gallery \| Albums Posts: 3,350	Every lens/body combination has potential issues. Whether those are the result of "known QC" issues is subject to many other factors. I have had absolutely NO issues with the Tamron SP AF 28-75/2.8 on an istDS / (2) K100D / K100DS* / and (4) K200D bodies. OTOH, certain of these lens/body pairings, especially those with after market split-screen VF accessories, did require adjustment for precise manual or auto focusing -- however, this was also true for all other lens/body combinations I've used. H2

01-10-2012, 09:25 PM	#7
LegOverHead Veteran Member Join Date: Sep 2011 Location: California Photos: Gallery \| Albums Posts: 369 Original Poster	I'm just guessing that the lens I got has QC issues... Using the A-Ring focuses a lot better and more accurate. Last edited by LegOverHead; 01-10-2012 at 09:48 PM.

01-10-2012, 10:37 PM	#8
pacerr Loyal Site Supporter Join Date: Jan 2008 Location: Paris, TN Photos: Gallery \| Albums Posts: 3,350	Originally posted by LegOverHead: I'm just guessing that the lens I got has QC issues... Using the A-Ring focuses a lot better and more accurate. Ah, the old "not-using-the-A-ring" fault. Undoubtedly a lens quality control issue for sure. H2

01-11-2012, 03:40 PM	#9
LegOverHead Veteran Member Join Date: Sep 2011 Location: California Photos: Gallery \| Albums Posts: 369 Original Poster	Originally posted by pacerr Ah, the old "not-using-the-A-ring" fault. Undoubtedly a lens quality control issue for sure. H2 I really never knew that the A-ring would effect the image quality...

Pentax K100DS w/ Tamron 28-75 f2.8

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