RE: [Leica] DOF surprises

["B. D. Colen" <bdcolen@earthlink.net>]

Bob - Don't be sacred off the 75 Summilux. Focusing wide open takes
practice, but practice makes reasonably close to perfect. This is a terrific
low-light lens that produces wonderful images.

- -----Original Message-----
From: owner-leica-users@mejac.palo-alto.ca.us
[mailto:owner-leica-users@mejac.palo-alto.ca.us]On Behalf Of BOB KRAMER
Sent: Friday, February 04, 2000 6:42 PM
To: 'leica-users@mejac.palo-alto.ca.us'
Subject: RE: [Leica] DOF surprises


Okay, now we are getting into some cool stuff here!  I stand corrected on
the Noctilux focus.  There is room to move with this baby!  I guess, per Jim
Brick's analysis, the 75mm Summilux gets the award for no depth of field.
But for most everything else it looks like we have about 2" to 3" of DOF to
play with wide open at a six foot distance.  Yeah, I think I could work with
that.  So.  Some conclusions:

1.  75 Summilux can not be focused under certain conditions.  I will pass on
this lens.  Besides, no 75mm framelines in my M3.

2.  You can have as little as 1-1/4" of DOF with the f2.8 135.  I will pass
on this lens, but only because it is so damn ugly with those funky bug eyes.
I think I would rather strap a visoflex to my camera!

3.  The 90mm Summicron.  Could be my next lens.  2-1/4" of DOF will at least
get me an eyeball in focus.  The M3 VF magnification should help here, also.
Of course, I might wimp out and get the 2.8 Elmarit-M instead.  Us Sunday
shooters do have to know our limitations.  ;-)

Jim, Guido, thanks for the information!  It really is helpful.

Bob Kramer
Atlanta, GA

> -----Original Message-----
>
> From: "Guido Ridoli" <guirid@numerica.it>
> Subject: [Leica] DOF surprises
>
> 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
>