[LRflex] Re: R 2x APO Extender Question

Frank Filippone wrote:

>I don't get this......   Why would a tele converter vignette 
>?  Especially when used on  a long lens with really perpendicular rays?

I don't know.  But it does.

>Are you sure this is not an issue of maybe a close up tube?

Nope.  Don't own one. Besides, the problem was consistent over 
hundreds of shots.

See: http://www.telyt.50megs.com/nab_Blue%20Heron.htm

>   Wrong Hood?

Don't think so...it's built into the lens.  I've never used any other.

>Is there a logical explanation?

Probably.    My suspicion (I have no proof) is that the lens 
diameter, within the 2x is smaller than the lens diameter in the APO 
converter.  But, when I had the APO, I tested it (I had it only for a 
short time) but neglected to measure lens diameters.  In other words, 
I think the problem is mechanical, not optical.  Result is the same!

>I have never seen this effect with all the teleconverters I have had 
>over a number of years.....  (

Neither have I, except for this combination.  As I said, the APO 
converter does not do this.

>I do not nor have I ever owned the Leica converter in question....)

Perhaps you should rectify that...  and try it for yourself. ;-)

Cheers!
---

David Young,
Logan Lake, CANADA

Wildlife Photographs: http://www.telyt.com/
Personal Web-pages: http://www3.telus.net/~telyt




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