have done the tests
80mm, 135mm and 200mm
F.2.8, F.4 and F.5.6.
have then compared the results with similar test done
Pentax-K 2.5/135mm + SMC-F 1.7 AF Adapter =
Pentax-K 2.8/105mm + SMC-F 1.7 AF Adapter =
FA 2.8 80-200mm ED(IF) (1x1mm nick in front element)
know that comparing the Tokina test results with those done with
the AF adapter is not quite right because the adapter
does in fact require longer shutter speeds. The loss of light in the adapter is similar
to 1½ f-stop. Using the adapter with a lens
at F. 2.8 is equal to
apr. F.4.5 - shutter speed wise.
The test images shown are
the whole frame, resized to 26% of the original size.
No other editing has been performed to the images.
For this reason I have done
The Practice Test - i.e. the Tokina aginst SMC Pentax-K
2.5/135mm + SMC-F 1.7 X AF adapter. In this test I have
shot the same scene, maintaining the same shutter speed,
letting AE choose the F-stop setting. Look at :
lens was difficult to focus in AF mode. A very slight
turn of the focus ring makes a huge difference. This Tokina lens seems to work
very accurately and smoothly, but on my Pentax *ist
D I often had my doubts about the subject being actually
in focus. Perhaps this camera-lens combo is not the optimal
test done with a Sigma EX 2.8/70-200mm APO (IF) and SMC Pentax-FA 2.8/80-200mm
ED(IF) (Pentax'en har en lille skade på frontelementet)
udført af Jostein Øksne