You know, Sometimes I think we underestimate how good some of
these older, third party lenses really are. Some of my favourite
lenses are third party lenses
Same here. (Well spoken, Vic.)
As much as I like all of my (too many) samples of Pentax glass, I
also cherish some of the special
Andre wrote: Could the difference in saturation be caused by a slight
difference in exposure (because of diaphragm margin of error)?
Could be, but certain VMC coating formulations--or is it the
glass?--produced consistently more saturated colors. I can tell at a glance,
for example, which of my
. tammikuuta 2003 2:04
Aihe: RE: Vivitar 35-85 better than Pentax 24-90?
-Original Message-
From: Andre Langevin [mailto:[EMAIL PROTECTED]]
Sent: Tuesday, January 21, 2003 7:44 PM
To: [EMAIL PROTECTED]
Subject: RE: Vivitar 35-85 better than Pentax 24-90?
snipLess elements
You're absolutely right, J.C.
Each added element adds two more medium interfaces (air-to-glass,
etc.) and each have their own abberations, no matter how small, to the
whole. The more elements a lens assembly has, the more perfect each
and every lens in the whole assembly has to be, to the point
For a given focal length and speed, there is an ideal number
of elements to optimize the design.
I was unaware of that. Is there a list or chart somewhere, or a
discussion about this I could read?
Thanks for pointing that out.
Well, it's not a science, but you dont see 50mms with 10
In the 80s, the tendency, at least at Pentax with the M and then the
A lenses, has been to cut down on the number of lens elements.
But that's because of the availability of better glass and more glass types,
not because fewer elements are intrinsically better.
--Mike
J. C. O'Connell [EMAIL PROTECTED] wrote:
For a given focal length and speed, there is an ideal number
of elements to optimize the design.
I was unaware of that. Is there a list or chart somewhere, or a
discussion about this I could read?
Thanks for pointing that out.
Well, it's not a
B. BUT on
the other hand, the extra air glass surfaces REDUCE contrast
(and apparent resolution)
That was true before multicoating. Now there's a slight transmission loss
for each added element, but better correction can often result in better
contrast.
--Mike
There's no way they can get around it, except to make each new element
match the previous elements very, very well, and test them together
for final figuring.
Centering and collimation have nothing to do with the number of elements.
You can have a lens with many elements that has zero
For some reason, these two statements don't jibe. Don't match.
Like...one person is talking about one thing, and the other person
drops a non-sequitur on the pile, and hopes for the best... g
Mike Johnston wrote:
There's no way they can get around it, except to make each new element
match
And...we've not even mentioned centering or collimation problems.
Where did that come from? Not me...
That sort of thing belongs to the lens maker (grinder/polisher), so
s/he doesn't introduce such...
keith whaley
But it's always surprising to read in many tests that even expensive
lenses are
J. C. O'Connell [EMAIL PROTECTED] wrote:
There is a trade off to adding elements:
A. on one hand they reduced abberations IF precisely ground and placed
B. BUT on the other hand, the extra air glass surfaces REDUCE contrast (and
apparent resolution).
Didn't Super Multicoating (SMC)
yes for 4 to 6 element designs,
no for 12 to 15 element desings.
JCO
-Original Message-
From: Paul Franklin Stregevsky [mailto:[EMAIL PROTECTED]]
Sent: Wednesday, January 22, 2003 10:07 PM
To: 'Pentax-Discuss'
Subject: RE: Vivitar 35-85 better than Pentax 24-90?
J. C. O'Connell
On 22 Jan 2003 at 15:40, Keith Whaley wrote:
Andre Langevin wrote:
But it's always surprising to read in many tests that even expensive
lenses are not perfectly centered. Does it mean that a (good)
repairman could do better (afterwards) than the original lens maker
did at the
You know, Sometimes I think we underestimate how good some of these older,
third party lenses really are. Some of my favourite lenses are third party
lenses
Vic
and compare the Tokina AT-X 90/2.5 macro against the Vivitar
Series One 90/2.5 macro. The Tokina is no slouch in the saturation
department; it has that Nikon-like warmth that makes everyone look
as though they've been out in the sun. Fred, you own both macros;
is the coloring the same?
Isnt the viv 35-85 a varifocal ( not a true zoom)lens?
If so that combined with the narrower range could account
for it's better performance.
JCO
-Original Message-
From: Andre Langevin [mailto:[EMAIL PROTECTED]]
Sent: Tuesday, January 21, 2003 7:06 PM
To: [EMAIL PROTECTED]
Subject:
Isnt the viv 35-85 a varifocal ( not a true zoom)lens?
If so that combined with the narrower range could account
for it's better performance.
JCO
Maybe. But are all zooms varifocal lenses that have their focus
adjusted automatically by another cam inside the lens? In other
words, was a zoom
It is varifocal.
Steve Larson
Redondo Beach, California
Everyone has a photographic memory. Some just don't have film.
- Original Message -
From: J. C. O'Connell [EMAIL PROTECTED]
To: [EMAIL PROTECTED]
Sent: Tuesday, January 21, 2003 4:15 PM
Subject: RE: Vivitar 35-85 better than Pentax
-Original Message-
From: Andre Langevin [mailto:[EMAIL PROTECTED]]
Sent: Tuesday, January 21, 2003 7:44 PM
To: [EMAIL PROTECTED]
Subject: RE: Vivitar 35-85 better than Pentax 24-90?
Isnt the viv 35-85 a varifocal ( not a true zoom)lens?
If so that combined with the narrower
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