Olympus-OM
[Top] [All Lists]

Re: [OM] Olympus OM lens size vs Leica M (e.g. 21mm f/2.0)

Subject: Re: [OM] Olympus OM lens size vs Leica M (e.g. 21mm f/2.0)
From: "Carlos J. Santisteban" <zuiko21@xxxxxxxxx>
Date: Tue, 8 Jun 2010 12:43:03 +0200
Hi Dawid and all,

From: Dawid Loubser <dawidl@xxxxxxxxxxx>
>Now, this may apply to certain optics in the standard-to-medium-wide
>category (usually slow aperture ones)

I'd say rangefinder lenses do have some advantage up to moderate-wide --
_some_ RF 50mm are relatively large.

The sadly discontinued CV 50/2.5 has a surprising 7-element construction for
such a slow lens, it allows a very compact barrel... but it's heavy! On the
other hand, simpler designs like the Russians Industar-22, 50 & 61
(Tessar-like, but not exactly) have much longer barrels -- mostly empty
inside, but long. On SLR mount these designs make _pancakes_, this time the
shorter register of RFs is a disadvantage.

>but one of the most telling
>examples is at the 21mm focal length. Naysayers continue to post that
>rangefinder optics "do not have to be retrofocus"

Unless we're dealing with simple, theoretical thin lenses, the retrofocus
issue is not qualitative, but _quantitative_. With so much optical trickery
in any "modern" lens, it's really hard to tell sometimes, but the 'pupil
magnification' (the diameter ratio between the exit and entrance pupils)
could be an indicator of "how much" retrofocus is a certain lens.

>(and no, they don't
>- look at the Mamiya 7 lenses, for example)

Much larger format means much larger lenses. Anyway, compare a Mamiya-7 wide
with any equivalent MF SLR wide...

>but the Leica 21mm f/2.8
>(a thoroughly modern design) is indeed a retrofocus lens,

It's reasonable, like many of the CV wides, especially the 28/1.9 -- but the
tiny 28/3.5 has near-unity pupil magnification, and the 35/2.5 is definitely
a "tele".

>and at f/
>2.8, it's a full stop slower than the Zuiko 21mm f/2.0, yet it's
>larger and heavier in all respects. I wonder why this is?

It's an unfair comparison :-) The 21/2 is, IMHO, Olympus' Masterwork --
there's NO match for it from any other maker. In fact, many SLR 21's at
around f/3.5-4 ara much, much larger! It's also amazing that they were able
pack the 'regular' Zuiko 21/3.5 into the small '50/1.8 form-factor', so
early in the OM-system life.

>but the genius of the Maitani team really is apparent when looking at
>the remarkable 21/2.0.

It _IS_ remarkable, nobody doubts it ;-)

>== Leica 21/2.8 ASPH ==
>Length:   59mm
>Filters:  55mm
>Weight:   317g
>
>== Zuiko 21/2.0 ==
>Length:   44mm
>Filters:  55mm
>Weight:   250g

Sure, but what about other makers?

==Zeiss Distagon 21/2.8 (Contax/Yashica)==
Length:   90.5mm
Filters:   82mm
Weight:   530g

And a pupil magnification of 3.04 (strong retrofocus). Roughly the
dimensions of a Tamron 500mm (!) but only the front gets that wide...

On the other hand, the equivalent lens from the same maker for a non-SLR
system is indeed much smaller:

==Zeiss Biogon 21/2.8 (Contax G)==
Length:   35mm
Filters:   55mm
Weigth:   200g

Pupil magnification:   1.067 (almost no retrofocus)

>Coupled with the fact that an OM-1 body is smaller (volume-wise) than
>an M body (it's only higher at its highest point because of the prism)

But you're overlooking the _depth_ of the body because of the mirror box!
That's what makes a SLR body-only hardly pocketable, unlike a RF body.

Then, when you consider the whole optical system (that is, including the
flange-to-film distance) RF lenses (esp. wides) are indeed shorter -- this
does make a difference when using adapters for micro-four-thirds cameras.
>From your previous example,  the Leica 21/2.8 is about 87mm (59+28) from the
front of the lens to the film/sensor plane, whereas our beloved Zuiko 21/2
is a bit longer at 90mm (44+46). With some other lenses, the comparison gets
amazing -- say, Summicron 35/2 IV pre-ASPH vs. the (awful to me) Zuiko
35/2...

Back to the 21mm focal length, I did a graphical comparison:
<http://www.flickr.com/photos/zuiko21/3661112828/in/set-72157620559243432/>

And that's without hoods... the Skopar's hood is diminutive, while the
Zuiko's is huge! If you look at the next photo in the set, you may notice
(it's hard to see in that pic) that the Skopar's front element is way
smaller. This seems quite logical, since the front vertex is much closer to
the principal plane, thus the "light cone" subtends a much smaller area --
allowing a much, much smaller hood, in turn. IME, this also has effect on
flare resistance, more than what 30 years of coating advances could suggest.

>I would say that, apart from noise and possibly higher shock caused by
>the Mirror, for low-light, wide-angle shooting, an OM body beats the
>pants off any rangefinder,

...the viewfinder black-out during the crucial moment (the exposure!) --
although nobody prevents you from using a 'fiddly, external finder' on top
of a SLR :-)

>especially because of, for the 21mm focal
>length, the superiority of a accurate 0.91x reflex finder vs. a

Focusing a super-wide on the matte field is difficult indeed (at least to
me), especially with the f/3.5 version. A properly designed microprism or
split image may help, but they are comparatively "slow" and/or unsuited for
the slow version. OTOH, the CV 21 on the Bessa-T (long RF base) is
unnecessarily accurate -- you don't actually need to "match" the images,
getting them "close" will suffice!

>fiddly, external finder (which admittedly will be brighter, but
>doesn't help with focusing).

And then there's the remarkable Bessa R4M / R4A with their built-in
21-to-50mm finder+rangefinder... BTW, looking thru this finder is a
_completely different_ experience from the OM finder with a 21mm lens on it
-- despite the slightly wider field (you can see a bit _outside_ the frame
;-) perspective doesn't look so exaggerated...


>"Contemplating black coffee"
><http://tinyurl.com/335lyon> <http://tinyurl.com/335lyon>

A nice, relaxing picture... with a sad story behind. Really well captured.

>The OM-1 is amazing for this sort of work, after
>guessing exposure, I set shutter speed, aperture, and guess focus, by
"feel"
>while the camera was hidden on my lap, and then in an instant took the
>image.

You could operate a RF the same way. It's not the camera who takes the
picture...

>I have had the pleasure of only shooting about 100 frames of Pan F in
>my life, but I think I absolutely adore its qualities

Much like the same here... although doesn't seem that hard to get, I can buy
it even locally!

>Speaking of adoring things, I also adore the 135/3.5 lens, it blows my mind
that
>such a budget lens could be built so well, so small, so smooth. What a
jewel!

It is indeed. The only "flaw" I can see on it is its comparatively poor
flare resistance -- and this is one of the _few_ Zuikos never made with
multi-coating, not even the latest ones marked 'Zuiko Auto-T 135mm 1:3,5'
:-(

Cheers,
-- 
Carlos J. Santisteban Salinas
IES Turaniana (Roquetas de Mar, Almeria)
<http://cjss.sytes.net/>
-- 
_________________________________________________________________
Options: http://lists.thomasclausen.net/mailman/listinfo/olympus
Archives: http://lists.thomasclausen.net/mailman/private/olympus/
Themed Olympus Photo Exhibition: http://www.tope.nl/

<Prev in Thread] Current Thread [Next in Thread>
Sponsored by Tako
Impressum | Datenschutz