Yes, yes, you are perfectly right!
It is not the circle, that gives the limitation but the frame-window in the
camera body!
Now it's my turn, to say: sorry Paul
Greetings from (red faced now)
Jochen (Hans-Joachim)
----- Original Message -----
From: "Paul Farrar" <farrar@xxxxxxxxxxxx>
To: <olympus@xxxxxxxxxxxxxxx>
Sent: Friday, May 04, 2001 4:31 PM
Subject: Re: [OM] 18mm is no substitute for a 24mm shift
> >
> > Sorry, Paul,
> >
> > but you must be wrong. Within a circle that covers a rectangle of
24x36mm
> > you can draw a rectangle 27mm broad with a greater height than 24mm!
> > A mathematician better than you and me may tell us the useable height.
> >
> > Greetings
> > Jochen (Hans-Joachim)
>
> That's precisely my point. You CAN draw a 27mm rectangle higher than 24mm
> within the 43mm image circle of the 18mm lens. What you CAN'T do is take
> a picture with it on the 18mm because your 27mm wide * 18mm high subframe
> is imprisoned within the 36*24mm frame of the 18mm lens. If the 18mm was
> a shift you could do it.
>
> Here is a diagram that shows the difference:
>
> http://www.datasync.com/~farrar/shift.htm
>
> The image circles of the two lenses have been scaled to the same size.
> The 24mm is 33% larger in real life. Note the large unusable areas of the
> 18mm image circle. They have image in them, but you can't put film there.
>
> BTW, in a minimum full frame image circle a 27mm wide rectangle can be
> 34mm high.
>
> 2*SQRT((24/2)**2 + (36/2)**2 - (27/2)**2)
>
> Paul Farrar
>
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