Archived posting to the Leica Users Group, 2000/11/30
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Hi Jacques, Yes - I have one book which says the APO100 is actually a 92mm at 1:2. Of course all lenses shift focal length slightly as they are focussed closer but the additional lens group of the APO100 and the IF structure of some other fixed focal length lenses as well as the more complex zooms exacerbate this shift IME: and I cannot help feeling that extension tubes are not optimal for these lenses. After all when you add tubes or a bellows behind a regular lens (where the entire optical group moves forward to focus closer) you are merely doing more of the same but with these other lenses you are at least fighting against the aberration controls designed in to the unencumbered lens. Anyhow proof of the pudding is IME the pictures and so far zooms or IF lenses with tubes are not that good so far as I have seen. The 100APO, which I must acknowledge I do not have, may of course be an exception to this though it has adopted the Elpro approach... Anyhow, if anyone knows or can find out it must be Erwin so let's see what he uncovers! In the meantime I am more than happy struggling on with my 60 Macro and my 70-180 with close-up lens when necessary! > > My understanding is that as the APO macro 100mm is focused at close > distances it acts like not like a regular 100mm on the end of a bellows but > rather like a lens of shorter focal length focused at a close distance. I > think this is what Adrian was referring to when he stated that this lens > shares some attributes with a zoom lens. _________________________________________________________ Do You Yahoo!? Get your free @yahoo.com address at http://mail.yahoo.com