[LargeFormat] Intro and BEllows extension chart

[john frost]

Yup. yore a lite in the dark now. Too bad I wasted 20 (oops! 35 years
now. my, how time flies) years before some one told me!

john (:>)) don't forget: time flies like an arrow, but fruit flies like
a banana....

Brock Nanson wrote:
> 
> ----- Original Message -----
> From: "john frost" <johnfrost@sprintmail.com>
> To: <largeformat@f32.net>
> Sent: Sunday, January 19, 2003 10:42 AM
> Subject: Re: [LargeFormat] Intro and BEllows extension chart
> 
> > Too bad you spent the time doing that task. I have done that myself,
> > before someone told me how to do it with the camera lens.
> >
> > If you are using a 5.6 inch lens (measured from film plane to lensboard
> > at infinity focus), and your are set up on a target that causes your
> > film plane to lensboard measurement to be 8 inches, then you have a one
> > stop extension. A measurement of 11 inches would be a 2 stop extension,
> > yielding a 1:1 ratio, or life-size image.
> >
> > The thing to remember, is use the same units all the time.
> >
> > john (:>)) no more bellows charts for me....
> 
> I've always carried a chart around with me, but as I don't do much in the
> way of close-up work, I've never needed to consult it.  From what I
> interpret here, the factor used for a 'stop' aperature-wise (1.4) is
> directly applicable to bellows extension.  And I suppose, when you think
> about what an f-stop actually is, this makes perfect sense.  Your focal
> length is effectively changing, while the aperature remains the same.  Thus
> the ratio that is the 'f-stop' changes.
> 
> Do I have this right?  If so, I thank you for turning on the light!
> 
> Brock
> 
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