SILLY ME I THOUGHT THEY WERE DESIGNED TO MEET A SPEC.
jco
> -Original Message-
> From: [EMAIL PROTECTED]
> [mailto:[EMAIL PROTECTED]]On Behalf Of Kent Gittings
> Sent: Tuesday, November 13, 2001 9:54 AM
> To: [EMAIL PROTECTED]
> Subject: RE: 200 f2.5 question, how can f
]]On Behalf Of Knut Kampe
Sent: Friday, November 09, 2001 12:59 PM
To: [EMAIL PROTECTED]
Subject: Re: 200 f2.5 question, how can filter ring be 77mm?
At 09:18 09.11.01 -0600, you wrote:
>Lets not forget in this discussion of the maximum f/stop of a
>lens that the f/stop measurement is taken fr
Behalf Of Knut Kampe
Sent: Friday, November 09, 2001 12:59 PM
To: [EMAIL PROTECTED]
Subject: Re: 200 f2.5 question, how can filter ring be 77mm?
At 09:18 09.11.01 -0600, you wrote:
>Lets not forget in this discussion of the maximum f/stop of a
>lens that the f/stop measurement is taken fr
Correct. It can be larger but not smaller.
Kent Gittings
-Original Message-
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED]]On Behalf Of Frank Wajer
Sent: Friday, November 09, 2001 11:43 AM
To: pdml
Subject: Re: 200 f2.5 question, how can filter ring be 77mm?
> Lets not forget
At 09:18 09.11.01 -0600, you wrote:
>Lets not forget in this discussion of the maximum f/stop of a
>lens that the f/stop measurement is taken from the relationship
>of the entrance pupil and the focal length. The actual diameter
>of the front element is not part of the equation.
>William Robb
How
The f.no. calculation assumes that the lens is a simple design, eg. a
single element or more likely a symmetrical design such as view cameras
use. In practice a lot of long lenses are of the telephoto design which
means they have a teleconverter built in.
I bet the front element of this lens is
> Lets not forget in this discussion of the maximum f/stop of a
> lens that the f/stop measurement is taken from the relationship
> of the entrance pupil and the focal length. The actual diameter
> of the front element is not part of the equation.
The entrance pupil is always smaller or equal to
Lets not forget in this discussion of the maximum f/stop of a
lens that the f/stop measurement is taken from the relationship
of the entrance pupil and the focal length. The actual diameter
of the front element is not part of the equation.
William Robb
-
This message is from the Pentax-Discuss Mai
>on kmp.bdimitrov.de I saw the specs of the 200 f2.5 lens. It says that
>the filter ring is 77mm, but this means that the lens cannot be f2.5,
>as that would mean a minimum 80mm filter ring! Can anyone explain? BTW.
>Isn't it save to have some margin between the filter ring and what is
>calculated
At 13:34 09.11.01 +0100, you wrote:
>On Fri 2001-11-09 (11:30), Frank Wajer wrote:
>> on kmp.bdimitrov.de I saw the specs of the 200 f2.5 lens. It says that the
>> filter
>> ring is 77mm, but this means that the lens cannot be f2.5, as that would
>> mean
>> a minimum 80mm filter ring!
>>
>> Can
>On Fri 2001-11-09 (11:30), Frank Wajer wrote:
>> on kmp.bdimitrov.de I saw the specs of the 200 f2.5 lens. It says that the
>> filter
>> ring is 77mm, but this means that the lens cannot be f2.5, as that would
>> mean
>> a minimum 80mm filter ring!
>>
>> Can anyone explain?
It's not uncommon
-
The optimist's cup is half full,
The pessimist's is half empty,
The wise man enjoys his drink.
- Original Message -
From: Frank Wajer <[EMAIL PROTECTED]>
To: pdml <[EMAIL PROTECTED]>
Sent: Friday, November 09, 2001 5:30 AM
Subject: 200 f2.5 question, how can filte
On Fri 2001-11-09 (11:30), Frank Wajer wrote:
> on kmp.bdimitrov.de I saw the specs of the 200 f2.5 lens. It says that the
> filter
> ring is 77mm, but this means that the lens cannot be f2.5, as that would
> mean
> a minimum 80mm filter ring!
>
> Can anyone explain?
A good observation.
In fa
Frank,
I can't explain, but it is definitely a 77mm filter and cap sitting on the
one I have here.
Regards, Bob S.
[EMAIL PROTECTED] writes:
<< on kmp.bdimitrov.de I saw the specs of the 200 f2.5 lens. It says that the
filter ring is 77mm, but this means that the lens cannot be f2.5, as th
Hi,
on kmp.bdimitrov.de I saw the specs of the 200 f2.5 lens. It says that the
filter
ring is 77mm, but this means that the lens cannot be f2.5, as that would
mean
a minimum 80mm filter ring!
Can anyone explain?
BTW. Isn't it save to have some margin between the filter ring and what is
calcu
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