Hi In order to make some lens tests (200/2.8 and 100-400 with and without EF 1.4x extender) I took some photos of my test arrangement/target from distances of 3 to 7.5 meters (10 to 25 feet). It's quite close but I wanted to do it inside at my home.
When I got the results back I almost trashed the zoom (well, not really because some of my previous tests have proved it to be quite a good lens) but soon noticed the zoom photos were not properly focused. E.g. when I compared the [EMAIL PROTECTED] shot with the 100-400@[EMAIL PROTECTED] shot the background which was about 10cm (4 inches) behind the subject was much sharper in the zoom photo. The camera distance was changed so that the target was the same size in all photos. Another interesting - but false - "result" was that the zoom lens with the extender seemed to be as sharp as without when the same actual focal length (e.g. 300mm vs. 215mm+1.4x) was used. I used a flash (in manual mode) as the light source so tripod stability was not an issue (still I used 10s selftimer and mirror lock-up). Sensia 100 slide film and reasonably good 10x loupe to check the results. Question: Has anyone noticed that their EOS-3/1V focuses behind or in front of the subject with certain focal lengths (here e.g. 300mm) and/or with certain lens speeds (here f4 vs. f5.6 max apertures)? I know (think) EOS-3 has better AF at f4 when the center AF sensor is used but I'm not sure if the AF accuracy is affected (by cross-sensor vs. vertical sensor). I called Canon service and they said it is possible to adjust the AF (for different lenses) so I quess I need to send the camera and lens in. Before that I need to make another test and add a ruler in the photo so that I see if the AF accuracy is bad and if it is giving constantly the same results. Do you have any other good advice how to check the AF accuracy? regards Vesa PS. The 200/2.8 (mkI) is really good with and without 1.4x! _________________________________________________________________ MSN Photos is the easiest way to share and print your photos: http://photos.msn.com/support/worldwide.aspx * **** ******* *********************************************************** * For list instructions, including unsubscribe, see: * http://www.a1.nl/phomepag/markerink/eos_list.htm ***********************************************************
