At 05:37 PM 7/24/2003 -0400, T Rittenhouse wrote:
No, Mark, f-stop is focal-length divided by aperture-diameter. So, by
definition focal-length divided by f-stop is aperture-diameter (that is, a
100mm lens at f4.0 has a 25mm aperture).
Actually, that formula in the original form had the value f =
Maybe I need to see a shrink, but if you saw me mentioning the focal length, I suggest
you re-read
my message and keep your imagination in check.
I was talking about *dimensions*:
d has dimensions of *length* (m, yards, leagues)
c has dimensions of *length* (mm, inches, miles, a.e)
m is dimensio
Acceptable DOF is calculated based on the circle of confusion which varies
by format.
At 08:20 AM 7/24/03 -0400, you wrote:
Isn't DOF computed via f stop, regardless of format? I do know that a 165mm
lens projects an image the same size on the film regardless of format. In
other words, if a 165mm
://pages.prodigy.net/graywolfphoto
- Original Message -
From: "mishka" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Thursday, July 24, 2003 7:08 PM
Subject: Re: Shallow DOF with 6X7 lenses (was: 6x7 lenses - Brotherhood
comments solicited)
> T Rittenhouse wrote:
>
sage -
From: "Mark Cassino" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Thursday, July 24, 2003 12:27 PM
Subject: Re: Shallow DOF with 6X7 lenses (was: 6x7 lenses - Brotherhood
comments solicited)
> At 09:32 AM 7/24/2003 -0400, T Rittenhouse wrote:
>
>
At 09:32 AM 7/24/2003 -0400, T Rittenhouse wrote:
Your verbal explaination is great, Mark. But there is a bit of a problem
with your math. Simply put f-stop is a light transmission factor, not and
not the same thing as aperture size. I know I played with that same formula
for a long time, and it d
The COC factor used to produce lens DOF scales varies between manufacturers
within the same format.
For instance Carl Zeiss Contax SLR lenses have a far more generous DOF scale
Pentax 35mm lenses. However there is no difference in the apparent DOF in
prints made at the same aperture and FL using P
-stop) to a (aperture diameter) and it works fine.
Ciao,
Graywolf
http://pages.prodigy.net/graywolfphoto
- Original Message -
From: "Mark Cassino" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>
Sent: Thursday, July 24, 2003 8:38 AM
Subject: Re:
;Bill Owens" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Thursday, July 24, 2003 8:20 AM
Subject: Re: Shallow DOF with 6X7 lenses (was: 6x7 lenses - Brotherhood
comments solicited)
> Isn't DOF computed via f stop, regardless of format? I do know that a
165mm
> lens p
Thanks to all who responded. The (circle of) confusion is now very clear!
Steve Larson
Redondo Beach, California
- Original Message -
From: "Steve Larson" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Thursday, July 24, 2003 4:28 AM
Subject: Shallow DOF with 6X7 lenses (was: 6x7 len
On 24 Jul 2003 at 13:41, Chris Stoddart wrote:
> Having said that, does anyone know if the d-o-f is the same for all lenses
> of a given focal length? In other words, does every 165mm lens from every
> maunfacturer have the same d-o-f? Or can they 'tune' it a bit with better
> optical design? Yes
At 04:28 AM 7/24/2003 -0700, Steve Larson wrote:
Why do 6X7 lenses have a shallow depth of field even stopped down
all the way? Chris mentioned it with the 165/2.8. Are they all like that?
I could understand it if it was at close focus with tubes WO, but for a
landscape shooting at infinity? Pleas
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