Archived posting to the Leica Users Group, 1996/04/17
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On 17 Apr 96 at 0:24, Eric Welch wrote about "Re: 100mm/2.8 R APO
Macro question":
> Another point on the 100 Apo Macro, that most people have never heard
> before is that it's a pseudo zoom. The focal length changes as it is
> focused to it's closest magnification (somewhere in the 90+ mm range to
> optimize performance closeup). It isn't much of a change, but that will
> mean that it's not really a 200 mm lens when focused close with the 2x
> converter. And you can't use it with extension tubes or a bellows. It's
> a great lens, and I would like to have one, but it has its limitations
> that need to be taken into consideration.
>
> I got that info from the press release announcing the lens and the lens
> design philosophy behind it. It's still in my files, somewhere.
There are more macro lenses that do this.
Actually, all lenses that I've seen so far change their focal lenght
slightly when focussing. But in the opposite direction: close focus
results in more tele, instead of less with most macro lenses.
The pseudo zoom effect you mention can at least be seen in the EOS
100mm macro, and the upcoming 180/3.5 macro. I believe the Minolta
100mm and Nikon 105mm don't have this pseudo zoom.
(BTW Roger, were you too impatient to wait for this EOS
180/3.5?....shame on you!....;-))
Bye,
_/ _/ _/_/_/_/_/ _/_/_/_/_/
_/ _/ _/ _/ _/ _/ _/
_/ _/ illem _/ _/ an _/ _/ _/ arkerink
_/_/_/
The difference
between man and boy
is in the price of their toys
<w.j.markerink@a1.nl>