Flavio, is the Tokina an IF design? Then towards the closest focus it progressively shortens the focal length in order to minimize the lens group displacement. Still, at infinity the focal length should be nominal. Try an infinity comparison with your FA 100/2.8 (which btw, performs in a similar manner, going to around 70 mm at 1:1). One word about the FA 28-70/4: this cheap, little, plasticky lens with poor build feeling is constantly underrated on the list. Yet it's a surprisingly tough performer, with excellent flare control, delivering great 10x enlargements.
Servus, Alin Flavio wrote: FM> Hi all, FM> a question aimed at the Tokina 28-105/3.5-4.5 but related to any lens. I FM> ran some tests this weekend involving the lenses I own covering 100mm FM> F.L. and found out this lens seems to be much shorter than 105mm at the FM> long end. I have a TIPA test covering all the 28-105 available a couple FM> of years ago and the actual F.L. measured for the Tokina was 102mm or FM> so. In my tests it seemed much closer to the short end of my 70-210 and FM> not even close to the framing offered by the FA 100 macro which I think FM> should be quite accurate. The tests were not performed with focus to FM> infinity but to a consistent distance of about 1.2 mt/4 feet. FM> I still have to see the slides but the different seemed apparent even FM> through the viewfinder. What is your experience in the matter? I've been FM> looking around for 28-105s because I felt 70/80 mm to be too short for FM> my needs, if this is the actual F.L. of my zoom I think I'll dump it and FM> get a Pentax 28-70/4 as I'm getting annoyed with the poor performance of FM> this lens WRT flare control and contrast. - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
