Archived posting to the Leica Users Group, 2000/11/29
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Erwin Puts wrote: > > Dear Adrian, > > I will try to answer your post: > > >Oh dear Erwin - I seem to have erred! Well perhaps you can give us the low > >down on why Leica chose to use the Elpro approach for 1:1.1 to 1:2 for the > >100 APO. > Actually: performance with ELPRO lenses drops significantly, even stopped > down. They are however easy to use as not everyone has bellows or tubes. The > problem with any close-up or macro work is that you magnify the smaller > detail structures to a level where you now see the details you could not > detect normally (that is the idea of close-up work), but the MTF values drop > rapidly at these magnifications. So your eye will note details not seen > before in normal situations, and your eye has no reference of what to > expect. And you magnify the details with lowered MTF values. It is > therefore difficult to have a clear idea of what image quality to look for. > So you need to experiment to know what to expect. ><Snip> Erwin!! Not a huge surprise to me that the use of magnifier lenses on the front of a camera lens to be optically inferior to tubes. But in THIS case Leica's method to get 1:1 out of it's legendary 100 macro 2.8 is with a multi element lens group dedicated to that lens!! Would a tube have made for better 1:1 results from this lens? In MY case I'll screw (or bayonet) on a magnifier in front of a lens to do some medium format copy work or a tighter head shot. I have even done this in large format so as to not have to rack out my bellows so much. I try to make it so when a lens has such a magnifier attached I"ll should be shooting as close to infinity as possible… not racking out the lens to focus in if at all possible. A #1 magnifier at infinity will give you one meter. A #2 will give you half a meter. And i believe so on. I believe the results obtainable are optimised for the better if you use the right number for the job so that the lens can be racked in at as close to infinity as possible. With results deteriorating if one racks out the lens to focus to any extent at all. I think we get much less curvature of field this way and much better all round results. I've done much copy work this way never having any tubes. Sounds like it's time to invest in a tube er two! For my Hasselblads to start with. Curious what everyone thinks about all this... Tubularly yours! mark rabiner :) http://spokenword.to/rabiner/ http://people.oven.com/jbm/temp-displays/Mark_Rabiner/Marks_Zone_System.pdf How about Bellows? , he bellowed!