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[OM] C-U Lens follies

Subject: [OM] C-U Lens follies
From: Mike Gordon via olympus <olympus@xxxxxxxxxxxxxxxxx>
Date: Sun, 1 May 2016 16:11:10 -0400
Cc: usher99@xxxxxxx
Interesting!  Not a folly of any sort.  You certainly confirm the therory that  
a +1.5 diopter should focus at 1/1.5m  or 26.4"---close enough.  The FL of lens 
behind the diopter will not affect the working distance but only mag--all will 
focus at 26." if set at infinity.   I have never read that that was from the 
front of the CU lens but makes sense.  The diopters were designed for max FL of 
200mm and I have never read anywhere if sensor  size or Effective FL based on 
FOV makes any difference.  Have to think about that.

JS has stated that on a 300mm lens (FF) he would not risk a diopter over 
+1.0---never have seen a high quality one of that strength easily available.  I 
am thus not overly surprised that the +1..5 Nikon out performed the  +2.0 
Canyon at 400mm--might be worth a quick check at shorter FL.  The lens already 
gets to an impressive 0.25mag natively and thus must be over 0.8 with the 
diopter at 400mm.  I also still wonder how the IQ with all the extension would 
behave but would not get anywhere close to that mag at that FL but could try at 
shorter FL--might be better IQ for largish B'flys.

Another question is how much does the diopter throw off the optimization for 
the IS? (not that anything can be done but would be applicable to a MF lenses)

Paying close attention,  Mike

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