Talk To You Lumberjack.
----- Original Message -----
From: "Paul Jones" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Monday, July 16, 2001 10:05 PM
Subject: Re: Greeting from newcomer & aperture question
> Hey Doug,
>
> What does TTYL mean?
>
> Cya
> ----- Original Message -----
> From: "Doug Franklin" <[EMAIL PROTECTED]>
> To: <[EMAIL PROTECTED]>
> Sent: Tuesday, July 17, 2001 2:51 PM
> Subject: Re: Greeting from newcomer & aperture question
>
>
> > On Mon, 16 Jul 2001 22:25:20 -0400, Jeff Eikenberry wrote:
> >
> > > Hello to all! I'm Jeff Eikenberry from Muskegon, MI. I've been into
> > > photography for 2-1/2 yrs and at the "seriously obsessed" level for
> about a
> > > year. I just discovered this site last week, and found it to be very
> > > informative (and a complete riot:)
> >
> > Boy, I hope you've got a job that pays well! :-)
> >
> > > I was under the impression that full-stop apertures
> > > were in the following increments: 1.4 2.0 2.8 3.5 5.6 8.0 11 16
> 22
> > > 32 45 64+
> >
> > Each full stop lets in twice as much light as the stop "below" it and
> > half as much as the stop "above" it. The thing to remember is that the
> > amount of light is proportional to the area of the lens opening, while
> > the f-stop is proportional to the diameter (or radius) of that opening.
> > So, doubling the light means doubling the area, but only multiplies the
> > f-stop by 1.414 (square root of 2). On the other side, halving the
> > light means halving the area, but reduces the f-stop to 0.707 of the
> > higher value (1 over the square root of 2). So, one possible full stop
> > progression would run like
> >
> > 1.0 1.4 2.8 4.0 5.6 8 11 16 22 32 45
> >
> > So, I'm basically saying that you're right. :-)
> >
> > > 1- Are these "odd ball" apertures considered to be full stops, ie f13
to
> f16
> > > being one stop?
> >
> > They're not full stops, but they're perfectly valid aperture values.
> > Just because the viewfinder shows 13 then 16 does _not_ mean that
> > they're a stop apart. What it means is that's the smallest difference
> > the _viewfinder_ can show at that point in the exposure scale.
> > Actually, f/13 and f/16 are more like a half stop apart. If I had the
> > gumption I'd figure it out ... something like log2(16) - log2(13) or
> > some such.
> >
> > > 2- When in "Auto Aperture" mode on the lense, can I actually shoot at
> f13,
> > > 19 ect.
> >
> > Yes, you can. The viewfinder is telling you (as closely as it can) what
> > aperture the computer in the camera selected. It is not restricted to
> > full stops. It might even not be using the exact value shown in the
> > viewfinder; e.g., it could have chosen f/15.6 and only be able to show
> > f/16. It would be a bit of a pain in the old wazoo if the computer was
> > restricted that way. In fact, the computer can pursue apetures that you
> > can't select from the aperture ring on the lens, because it can control
> > the lens aperture with finer "grain" than the aperture ring.
> >
> > Hope this helps. :-)
> >
> > TTYL,
> > DougF
> >
> >
> > -
> > This message is from the Pentax-Discuss Mail List. To unsubscribe,
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> > visit the Pentax Users' Gallery at http://pug.komkon.org .
> >
> >
> -
> This message is from the Pentax-Discuss Mail List. To unsubscribe,
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