Three Mid Range Zooms

 Three Fast Zooms: Tokina AT-X Pro 2.8 80-200mm, Sigma EX 2.8 70-200mm and SMC Pentax FA 2.8  80-200mm ED(IF). Are they equally good? I have tested these lenses using my Pentax *ist D.  The Pentax zoom is certainly not cheap - so I decided to try the other two, more affordable alternatives.


Tokina AT-X Pro 2.8 80-200mm


I have done the tests

@  80mm, 135mm and 200mm

@   F.2.8, F.4 and F.5.6.

I have then compared the results with similar test done with

  • SMC Pentax-F 4-5.6/70-210mm
  • SMC Pentax-M 4/200mm
  • SMC Pentax-K 2.5/135mm + SMC-F 1.7 AF Adapter = 230mm
  • SMC Pentax-K 2.8/105mm + SMC-F 1.7 AF Adapter = 179mm
  • Pentax FA 2.8 80-200mm ED(IF) (1x1mm nick in front element)

I 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 : Zoom Test/contact5.html

 Notes on Focusing

The TYokina 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 choise.


Please see 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


Copyright(c) 2005 Jens Bladt Fotografi - All rights reserved.