[Leica] DOF surprises

["Guido Ridoli" <guirid@numerica.it>]

Bob:

my results http://members.home.net/gillettm/DOF.html are:

Focus a 75 Summilux at f/1.4, at 2 meters and the DOF is 1.971m to
2.029m  (.058m)
Focus a 50 Noctilux at f/1.0, at 2 meters and the DOF is 1.954m to
2.047m    (.093m)
Focus a 90 Summicron at f/2,0 at 2 meters and the DOF is 1.972m to
2.028m (.056m)
Focus a 135 Elmarit at f/2,8 at 2 meters and the DOF is 1.982m to
2.017m     (.034m)

Please be careful with the Elmarit 135/2,8 and summicron 90/2
The Nocti is the easyer lens to focus wide open :-))

        Guido Ridoli
  LEICA M SUPERFAN
      (PAT. PENDING)
     guirid@numerica.it


- -----Messaggio originale-----
Da: Jim Brick <jimbrick@photoaccess.com>
A: leica-users@mejac.palo-alto.ca.us
<leica-users@mejac.palo-alto.ca.us>
Data: venerd́ 4 febbraio 2000 2.50
Oggetto: [Leica] Noctilux vs 75 Summilux DOF


:Bob,
:
:You should never buy a 75/1.4 Summilux because it has LESS depth of
field,
:wide open, focused at the same distance as the Noctilux (also wide
open). I
:do not have any problem getting an extremely sharp plane of focus
with the
:75 at f/1.4 . Just because the Noctilux is f/1.0 doesn't mean that
DOF is
:non existent. And, as I said, there's more of it than with the 75 at
f/1.4
:
:Focus a Noctilux at f/1.0, at 2 meters and the DOF is 1.96m to 2.04m
(.08m)
:Focus a 75 Summilux at f/1.4, at 2 meters and the DOF is 1.98m to
2.02m (.04m)
:
:And it gets worse.
:
:Against the close focus stop, 1.0m for the Noctilux and .75m for the
75
:Summilux, the DOF calculates to:
:
:Noctilux .99 to 1.01 meter (.02m)
:75 Summilux  .75m to .75m (.00m)
:
:So if you would have trouble with the Noctilux, you would have more
trouble
:with the 75 Summilux.
:
:Of course the image size with the 75 is larger which is why the DOF
is
:less. But the whole exercise here is to show that the 75 Summilux
exhibits
:less DOF than the Noctilux.
:
:Jim
:
:
:
:At 11:27 AM 2/3/00 -0500, BOB KRAMER wrote:
:> [BOB KRAMER]  Ha!  That's a good one, John!  And serves to
:>illustrate one of the problems I have with the Noctilux (the going
without
:>food to afford it being another <g> ).  Not to mention that I have
yet to
:>see a sharp image... er... excuse me... yet to see a sharp *photo*
:-) taken
:>with this lens.  The plane of focus appears to be non existent!
Using this
:>lens wide open, the question isn't "Do I want the eyelashes to be in
:>focus?", it is "*Which* eyelash do I want to be in focus?".  Combine
this
:>problem with the high lens cost, the inevitable even if minor
optical
:>compromises that result with this fast a lens, and the lens size and
weight,
:>and I just don't feel a burning desire to own it.
:>
:> I guess the Summilux appeals to me because I have been shooting
with
:>a 1.4 50mm since I bought a Canon F1 back in 1972, and have become
very
:>comfortable with this speed of lens.  Enough DOF to work with and
enough
:>speed to get the shot the lion's share of the time.  Besides, I
still need
:>21/24mm, 35mm, and 90mm lenses since the 50mm focal length is all I
have
:>right now for my Leica.  Not to mention that good user M4 and/or M5
I am
:>lusting for.
:>
:> Bob Kramer
:
: