It was always my understanding that a lens designer would want to use as
*few* elements in a design as possible.
In the days before lenses coating, the number of elements was crucial, since
each additional element resulted in less contrast, and less transmission of
light. Lens coating technology has greatly reduced the drawback of adding
an additional lens element to a design. However, I always thought that one
reason to use an aspherical element was to *reduce* the number of elements
in a design.
In my Leica Manual (circa 1972) it describes the design of the (two
element!) 560 mm f/5.6 Telyt as follows:
"A cemented doublet telescope objective gives excellent definition over a
semi-field of 2 or 3 degrees; therefore this simple system can be used in
lenses of 400 mm or longer focal length for a 35 mm camera. The length of
the tube from lens to film is, of course equal to the focal length.
However, the lens is very light in weight and gives excellent definition at
apertures of f/5.6 or smaller."
Granted, this is a longer focal length, but if E. Leitz thought two elements
were the right number, then I won't quarrel with them.
I think the only useful test is to go out and shoot the lens in the
situations where a focal length of 200 mm is useful. Try and minimize
camera shake as much as possible in the situation (tripod, monopod, bean
bags, self-timer etc.) If you're happy with the results, don't worry about
the "bad" test results.
Bill Stanke
----- Original Message -----
From: "Jim L'Hommedieu" <lamadoo@xxxxxxxx>
To: <olympus@xxxxxxxxxxxxxxx>
Sent: Saturday, June 22, 2002 12:26 PM
Subject: Re: [OM] Zuiko 200mm f/4
> What's your experience with the 200/4? Are you happy with your pictures?
> You haven't said and I'm curious. I used it a little but never really
> needed the reach much. When I did use it, I never came back with a
superbly
> sharp picture like I always do with the 100/2.8. Of course if you need a
> 200, the 100 isn't gonna be a substitute.
>
> I don't have the budget for the big 180s, and don't want to save up a long
> time for a focal length I rarely use. In addition, I suspect that the
> 180/2.8 would also come up lacking as it only has 5 elements (like the
> 200/4). My prejudice is that 5 elements isn't enough to make a sharp lens
> of any focal length. I could be wrong. I'm not schooled as an optical
> designer but I feel like I've gathered some expensive opinion.
>
> That's me. What's _your_ two cents?
>
> Lamadoo
>
> From: "Bryan Pilati" <bryan223@xxxxxxx>
> > I would like to know what the sudden interest in "bashing" the f/4 lens
> is.
> > For a long time the opinions were that it was a fine lens and worth
> owning,
> > and now I see lots of discussion about the f/5 lens being better, blah,
> > blah, blah.... I thought all Zuikos were good lenses. It took me a
while
> > to choose to purchase the f/4 and I based my purchase in part on the
> > opinions of this list and other OM sources.
>
>
>
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>
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