Archived posting to the Leica Users Group, 2008/12/13

[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]

Subject: [Leica] Half stop, third stop, stop the madness
From: tedgrant at shaw.ca (Ted Grant)
Date: Sat Dec 13 22:11:57 2008

Do you really want to know what this is all about?  Quite frankly Bu. Sh.T!

Forget all this if you are serious about taking pictures for the fun of it!
Professional or amateur! Like really who cares as long as any picture you
shoot works! Isn't that the bottom line?

 

Just have a look at the neat pictures Howard took in San Francisco at the
LUG gathering dinner.

 

Like guys, I try to read all this number stuff and you really don't want to
know what I think of it.. BUT TOUGH!

 

Howard, in his ability as a fine photographer, without all this tech number
stuff, shot some very fine photographs by available whatever light was
available during the San Fran dinner and made some fine exposures. And I'd
bet a hundred dollars to a dime that not one second while making his fine
exposures did he ever think of one aperture or another!

 

But he did take neat photographs! The bottom line?

He shot fine pictures and they turned out and who the hell cares what
aperture it was on what lens!     Jeeeeeeeeeeeeeshhhhhhhhhhhhhh!

 

Take pictures for the fun of it and forget all this crappy techie stuff!
Like really who cares? Yeah I know someone is going to come back and say
they get huggie poo hot flashes over the techie stuff and if it isn't of any
interest to me.. Delete or Don't reply! Cool! 

But damn I'm a photojournalist, not a number twit! So I take pictures while
some of you yap on about stuff that has absolutely no relevance to our
producing interesting photographs. 

 

You folks should be far more concerned about "Observation and seeing" than
the numbers!

 

If I'm wrong, I apologies and will carry on!

 

After all it is supposed to be fun! Isn't it?

ted

 

-----Original Message-----
From: lug-bounces+tedgrant=shaw.ca@leica-users.org
[mailto:lug-bounces+tedgrant=shaw.ca@leica-users.org] On Behalf Of Howard
Ritter
Sent: Saturday, December 13, 2008 8:19 PM
To: Leica Users Group
Subject: [Leica] Half stop, third stop, stop the madness

 

 

No, it actually is MORE than 1/2 stop, not less, and way more than 1/3  

stop. Remember, f/4 is already a full stop down from  f/2.8, so the  

jump from f/2.8 to f3.5, already well over halfway numerically, is way  

more geometrically.

 

Squaring the reciprocal of the f-ratio gives a number that is  

proportional to the aperture's area.

A full stop is an areal ratio of 2, corresponding to a ratio between f- 

ratios equal to the square root of 2. A half-stop is an areal ratio of  

sqrt (2), about 1.4, corresponding to a ratio between f-ratios equal  

to sqrt(sqrt( 2)), about 1.189.

 

2.8 x 1.189 = about 3.3.

3.3 x 1.189 = about 3.9.

So 1/2 stop down from f/2.8 is about f/3.3, with another equal- 

proportion areal step down to f4.

 

One-third of a stop is an areal ratio of the cube root of 2 (for three  

equal-proportion areal steps from one full stop to the next),  

corresponding to a ratio between f-ratios equal to the cube root of  

sqrt(2), or about 1.12.

 

2.8 x 1.12 = about 3.1.

3.1 x 1.12 = about 3.47.

3.47 x 1.12 = about 3.9.

So 1/3 of a stop down from 2.8 is about f/3.1, with two more equal- 

proportion areal steps down to f4.

 

So from f/2.8 to f3.5 is actually 2/3 stop. Unless you were talking  

about going from f/4 to f/3.5, which is 1/3 stop. (If you turn it  

around and take 4/1.12, you get 3.57. The numbers are rounded because  

they're irrational except for the alternate full stops f/1, 2, 4, 8,  

16..., as well as approximated in order to give numbers ending in an  

even digit or a 5.)

 

--howard

 

 

On Dec 13, 2008, at 12:50 PM, Marc James Small wrote:

> At 12:05 PM 12/13/2008, Lawrence Zeitlin wrote:

> 

> >

> >I simply quoted Emil Keller's book. He was there. None of use were.

> >He specifically mentions the lens as an f3.5 Summaron although he

> >does err in stating that the diaphragm modification added a full stop

> >instead of half a stop.

> 

> 

> Larry

> 

> With respect, it is a third of a stop, not a half-stop.  The  

> European apertures are 1/3 of a stop different from the  

> International scale which has been the norm since the 1950's.

> 

> Marc

 

_______________________________________________

Leica Users Group.

See http://leica-users.org/mailman/listinfo/lug for more information

No virus found in this incoming message.

Checked by AVG - http://www.avg.com 

Version: 8.0.176 / Virus Database: 270.9.17/1847 - Release Date: 12/13/2008
4:56 PM


In reply to: Message from hlritter at bex.net (Howard Ritter) ([Leica] Half stop, third stop, stop the madness)