"* f2.8 on E-1 with native lens = f5.6 in 35mm terms "
As far as the deepth of field is concerned, that would seem to be correct.
BUT
I mentioned a couple of days ago that I am not a stickler for the
conventional view of DoF. I don't believe that we can take "depth of field"
as the mantra it has become. And in browsing around the various links that
have arisen over the past few days, I see that Zeiss Camera Lens News
agrees! In their summary:
"The international depth of field standard, the basis for all camera lens
manufacturers to calculate their depth of field scales and tables, dates
back from a time, when image quality was severely limited by the films
available.
Those who use depth of field scales, tables, and formulas (e. g. for
hyperfocal settings), restrict themselves - most probably without knowing
why - to the image quality potential of an average pre-World-War-II
emulsion."
They later tested various films for real-world resolution capabilities:
============================================================================
==================
"based on typical photo conditions like outside sunlight, exposures
controlled by normal camera shutters, focusing done with the normal focusing
aids of the camera, standard film developing by a normal photo finisher, and
of course, using normal Carl Zeiss photographic camera lenses. ...
Film Resolving Power [lppm]
Kodak T-Max 100 180
Fujichrome Velvia 160
Agfa Portrait XPS160 150
Kodak Portra 400s/w 150
Kodak Portra 160 VC 150
Kodak Portra 160 NC 140
Kodak Ektachrome 100 VS 130
Kodak T-Max 400 120
Fujifilm NPZ 800 110
Kodak Portra 800 90"
============================================================================
==================
So what?
Well keep in mind that the standard on which depth of field tables are
calculated is (for 35mm) 0.030mm, 30 lp/mm. Now look in the table above at
what present day film can achieve. Having second thoughts about placing too
much reliance on DoF? Yep, that's right, a good lens and good film together
will resolve detail that the conventional DoF rule deems to be within
acceptable sharpness limits. Qutoing Zeiss again "Depth of field is
insufficient is the most common complaint to meet the Carl Zeiss service
department today."
The Zeiss articles are here:
http://www.zeiss.de/C12567A8003B0478/allBySubject/86CD15AD12AAE650C125697700
53B5F0#
And here:
http://www.zeiss.de/C12567A8003B58B9/allBySubject/48D8F331DF48EE72C1256CEF00
2B0240
And a repeat recommendation to read Harold Merklinger's views:
http://www.trenholm.org/hmmerk/download.html
--
Piers
-----Original Message-----
From: olympus-owner@xxxxxxxxxx [mailto:olympus-owner@xxxxxxxxxx] On Behalf
Of jowilcox@xxxxxxxxxxxxxxxxxxx
Sent: 31 March 2005 16:05
To: olympus@xxxxxxxxxx
Subject: [OM] OM Adapter, Wrotniak article, Zuiko lens on E-1
http://www.wrotniak.net/photo/dof/index.html
So if I am getting this correctly (alert: bonehead literature person [BLP]):
* The ratio of 4/3 sensor to 35mm is 1:2
* f2.8 on E-1 with native lens = f5.6 in 35mm terms
So I think my first experiment would be to set my Zuiko with OM adapter on
E-1 to f4 and hyperfocal for f8 (or whatever) and see if the near edge is in
focus.
This seems easy enough. I must be wrong.
Joel W.
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