Sorting out a front-focussing Tamron 17-50:

Kiwigeezer · 11-13-2018, 03:07 PM

Newly purchased Tammy 17-50 appears to be front focussing on my K5 IIs. Have made up a focus-checking rig (as per 'Andy's Handy Focussing Checker'). REALLY dumb question -presume I'd set focus select to spot/middle focus point to test rather than evaluative? Or should I just check the camera's picking the center point when testing? TIA!

Last edited by Kiwigeezer; 11-13-2018 at 03:09 PM. Reason: Add pic

**tduell** · 11-13-2018, 03:30 PM

Use spot focus, with a tripod and remote shutter, SR off.
Take a few shots, manually defocus between each shot, and compare results before making an adjustment.

Cheers,
Terry

khardur · 11-13-2018, 03:51 PM

Definitely use center focus point/ spot focus with that one point.

One thing I do - - to expand on Terry's instructions: I just write +1 +2 +3 +4 on cards (or -1 -2 -3 -4 -5 -6 etc),
I'll adjust the camera to +1, put the +1 card in the scene off to the side... and do a series of shots with that adjustment.

Then I'll change to +2, put the +2 card in the scene somewhere, then do a series of shots with that adjustment...

Rinse and repeat... then you can sit and pixel peep across a range of adjustments to compare what has the best results. That's just my take on things.

slartibartfast01 · 11-13-2018, 04:04 PM

Have a look at this thread as well. The Tamron has a focus shift at f/5.6.

https://www.dpreview.com/forums/post/41307182

Kiwigeezer · 11-13-2018, 07:23 PM

Great suggestions, esp the numbered cards. Also good to have a heads up on the focus shift issue, I'll check for it. Lens was as new and a bargain, so I'm happy to spend some time and a little cash on it as some of the results have been great so far.

11-13-2018, 03:07 PM	#1
Kiwigeezer Senior Member Join Date: Sep 2014 Location: Nelson Photos: Gallery \| Albums Posts: 266	Sorting out a front-focussing Tamron 17-50: Newly purchased Tammy 17-50 appears to be front focussing on my K5 IIs. Have made up a focus-checking rig (as per 'Andy's Handy Focussing Checker'). REALLY dumb question -presume I'd set focus select to spot/middle focus point to test rather than evaluative? Or should I just check the camera's picking the center point when testing? TIA! Last edited by Kiwigeezer; 11-13-2018 at 03:09 PM. Reason: Add pic

11-13-2018, 07:23 PM	#5
Kiwigeezer Senior Member Join Date: Sep 2014 Location: Nelson Photos: Gallery \| Albums Posts: 266 Original Poster	Many thanks for the speedy replies. Great suggestions, esp the numbered cards. Also good to have a heads up on the focus shift issue, I'll check for it. Lens was as new and a bargain, so I'm happy to spend some time and a little cash on it as some of the results have been great so far.

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11-13-2018, 03:30 PM	#2
tduell Loyal Site Supporter Join Date: May 2015 Location: Melbourne Posts: 1,517	Use spot focus, with a tripod and remote shutter, SR off. Take a few shots, manually defocus between each shot, and compare results before making an adjustment. Cheers, Terry

11-13-2018, 03:51 PM	#3
khardur Veteran Member Join Date: Feb 2007 Location: NW Massachusetts Photos: Gallery Posts: 1,560	Definitely use center focus point/ spot focus with that one point. One thing I do - - to expand on Terry's instructions: I just write +1 +2 +3 +4 on cards (or -1 -2 -3 -4 -5 -6 etc), I'll adjust the camera to +1, put the +1 card in the scene off to the side... and do a series of shots with that adjustment. Then I'll change to +2, put the +2 card in the scene somewhere, then do a series of shots with that adjustment... Rinse and repeat... then you can sit and pixel peep across a range of adjustments to compare what has the best results. That's just my take on things.

11-13-2018, 04:04 PM	#4
slartibartfast01 Pentaxian Join Date: May 2015 Photos: Gallery Posts: 1,931	Have a look at this thread as well. The Tamron has a focus shift at f/5.6. https://www.dpreview.com/forums/post/41307182