Paul said: ##Longer lenses tend to go over infinity because due to temperature variatons infinity settings may vary.##
So true Paul! In fact I have just returned from 1 week in the Hunter Valley and took with me CF: 50mm, 80mm, 120mm, 180mm and 250mm. When using the 250mm lens, I was quickly reminded that there is a fair bit of focusing "slack" at the infinity end - for exactly the reasons you stated. A year ago I learnt that the hard way - a nice image ruined by OOF because I stupidly assumed it was set a true infinity - even f11 could not provide the perception of sharpness!
If I recall correctly, I think my CF lenses have this "slack" to lesser degrees as their focal lengths shorten - eg my 50mm FLE has none.
** Yes Marc, congratulations Paul on your moderator role!!
Paul, maybe that "promotion" is what prevented me replying to your nice message sent while I was away - the "send a message" feature would not work.
Paul hard at work being a moderator here: