Tamron 17-50mm f2.8 Focus Chart testing (Canon mount)

Shen siung · 12th April 2009

Hi All,

After reading a few similar thread about focusing issues of Tamron 17-50mm f2.8

http://www.clubsnap.com/forums/showthread.php?t=449427
http://www.clubsnap.com/forums/showthread.php?t=437001
http://www.clubsnap.com/forums/showthread.php?t=383769
http://www.clubsnap.com/forums/showthread.php?t=455002
http://www.clubsnap.com/forums/showthread.php?t=446990

some stated the back front focus problem, some showing a limited focus chart, so I thought I could input some of my effort in the focus chart.

I mounted my 450D onto a tripod, facing 45 degree downward toward the flat focusing chart, as suggested by the url
http://focustestchart.com/chart.html

Standard picture style, sharpness increased to 4 (instead of 3)
+2/3 exposure compensation
Auto ISO (hmm, this may induce some non-standard in to these picture...)
100% crop

Here is the output:

17 mm F2.8

17 mm F3.5

17 mm F5.6

Continue...

Shen siung · 12th April 2009

35 mm F2.8

35 mm F3.5

35 mm F5.6

Shen siung · 12th April 2009

50 mm F2.8

50 mm F3.5

50 mm F5.6

As you can see, out of the 9 testing situation, only when it is wide open (at 17 mm), have slightly front focus. Yet, according to the focustestchart.com, this is acceptable.

Anyway, the method I used could not be accurate. However, I will never do it again

As some said before, better go out to shoot in real. . . . . . .

Octarine · 17th April 2009

Looks pretty ok to me. As mentioned in some other threads as well: the AF system also contributes to possible focus errors. The lens might show good results in the focus test. But these are idealized conditions. In real life situations there are many factors that can affect the AF system and the focus will lock somewhere else. Also, the AF sensors are bigger than the indications in viewfinder.

12th April 2009	#1
Shen siung Member Join Date: May 2008 Posts: 1,428	Tamron 17-50mm f2.8 Focus Chart testing (Canon mount) Hi All, After reading a few similar thread about focusing issues of Tamron 17-50mm f2.8 http://www.clubsnap.com/forums/showthread.php?t=449427 http://www.clubsnap.com/forums/showthread.php?t=437001 http://www.clubsnap.com/forums/showthread.php?t=383769 http://www.clubsnap.com/forums/showthread.php?t=455002 http://www.clubsnap.com/forums/showthread.php?t=446990 some stated the back front focus problem, some showing a limited focus chart, so I thought I could input some of my effort in the focus chart. I mounted my 450D onto a tripod, facing 45 degree downward toward the flat focusing chart, as suggested by the url http://focustestchart.com/chart.html Standard picture style, sharpness increased to 4 (instead of 3) +2/3 exposure compensation Auto ISO (hmm, this may induce some non-standard in to these picture...) 100% crop Here is the output: 17 mm F2.8 17 mm F3.5 17 mm F5.6 Continue...

12th April 2009	#2
Shen siung Member Join Date: May 2008 Posts: 1,428	Re: Tamron 17-50mm f2.8 Focus Chart testing (Canon mount) 35 mm F2.8 35 mm F3.5 35 mm F5.6

12th April 2009	#3
Shen siung Member Join Date: May 2008 Posts: 1,428	Re: Tamron 17-50mm f2.8 Focus Chart testing (Canon mount) 50 mm F2.8 50 mm F3.5 50 mm F5.6 As you can see, out of the 9 testing situation, only when it is wide open (at 17 mm), have slightly front focus. Yet, according to the focustestchart.com, this is acceptable. Anyway, the method I used could not be accurate. However, I will never do it again As some said before, better go out to shoot in real. . . . . . . Last edited by Shen siung; 12th April 2009 at 11:14 AM.

17th April 2009	#4
Octarine Member Join Date: Jan 2008 Location: Pasir Ris Posts: 3,568	Re: Tamron 17-50mm f2.8 Focus Chart testing (Canon mount) Looks pretty ok to me. As mentioned in some other threads as well: the AF system also contributes to possible focus errors. The lens might show good results in the focus test. But these are idealized conditions. In real life situations there are many factors that can affect the AF system and the focus will lock somewhere else. Also, the AF sensors are bigger than the indications in viewfinder.