[LRflex] Re: R 2x APO Extender Question

David, did this vignetting occur only with the 400 mm lens?  I was thinking 
of getting one again to use with my 180mm f/3.4 lens.

Dave
----- Original Message ----- 
From: "David Young" <telyt@xxxxxxxxx>
To: <leicareflex@xxxxxxxxxxxxx>
Sent: Saturday, March 31, 2007 7:22 PM
Subject: [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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