RE: [Leica] 50mm f1.5 Nokton question

["Lee, Jonathan" <Jonathan.Lee@hrcc.on.ca>]

The difference between the Nokton and Summilux may be less than the 0.1 f
stop. If I recall correctly, Japanese optical manufacturing codes allow for
a 5% difference between stated and actual aperture or focal length.  This
would mean that the 50 Summilux (assuming Leitz follows the same tolerances)
could have a real aperture anywhere between 1.33 to 1.47.  The Nokton could
be between 1.43 and 1.58. While I haven't actually measured the Nokton
aperture, it is possible that the 1.5 could also have been called a 1.4.

Imagine this Dilbertesque scene:

OPTICAL DESIGNER: "I've just made a great 50 f1.4 lens!"
MARKETING MANAGER: "The world is full of great 50 f1.4 lenses.  We can't
market another one."
OPTICAL DESIGNER:  "Ohhh...What about a great 50 f1.5 lens?"
MARKETING MANAGER: "That'd be super.  That would be a really unique standout
product."
OPTICAL DESIGNER:  "What a coincidence, I've just designed a great 50 f1.5
lens."

Jonathan Lee
- -----Original Message-----
From: John Collier [mailto:jbcollier@home.com]
Sent: Monday, March 06, 2000 12:18 PM
To: leica-users@mejac.palo-alto.ca.us
Subject: Re: [Leica] 50mm f1.5 Nokton question


This from a long time ago, with my memory that is about a week, but I
thought it went:

1.0~whole stop
1.1~ -1/3
1.2~ -1/2
1.3~ -2/3
1.4~ whole stop
1.5~ -1/3
1.7~ -1/2
1.8~ -2/3
2.0~ whole stop
etc

Please correct me if I am wrong and I will order the Nokton today.

John Collier

> From: Marc James Small <msmall@roanoke.infi.net>
> 
> At 06:45 AM 3/6/2000 -0700, John Collier wrote:
>> Why did they make it a 1.5 and not a 1.4? Sentimental reasons! I know it
is
>> only a 1/3 stop but it is annoying.
> 
> John
> 
> I believe it is more like 1/7 of a stop.
> 
> Marc
> 
> msmall@roanoke.infi.net  FAX:  +540/343-7315
> Cha robh bas fir gun ghras fir!
>