Archived posting to the Leica Users Group, 2001/03/27

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Subject: Re: [Leica] Re: Equivalent Focal Lengths
From: Johnny Deadman <>
Date: Tue, 27 Mar 2001 09:57:11 -0500

on 3/27/01 8:32 AM, Dave Jenkins at wrote:

> Yeah but duh yourself, Johnny. Regardless of what you can see in a
> square format viewfinder, or on the negative for that matter, you still
> won't get any more than 40 degrees of coverage from a 75mm lens side to
> side or top to bottom.

But top to bottom that's more coverage than a 50 on 35mm.

> And if you make a print with a 3:2 aspect ratio
> from your square negative, it will show no more than a print made by a
> 35mm camera with a normal lens, although of course it can be printed
> either as a horizontal or a vertical.

Well of course but the whole point is that the aspect ratios are different.
Your assertions are perfectly valid if you insist on masking off the 6x6
frame to a 3:2 frame but not otherwise.

> If it doesn't go on the print, it
> doesn't matter how much you can see above, below, or beside the area
> that will actually be printed.

Of course again but personally I don't crop my 6x6 negatives to 3:2!

Let's assume for a moment that you frame something up with your 50mm on the
leica, and now you pull over your rolly with the 75mm and frame up the same
thing side to side. Whichever way you shake it there are some things in the
frame now on the Rolly that aren't there in the Leica frame. The angle of
view of the 75mm measured horizontally is the same as the 50 on the Leica.
Considered vertically it is substantially wider. Considered diagonally it's
still a fair bit wider.

This is why I keep hammering on the basic point that comparisons of lens
field-of-view between formats with different aspect ratios are difficult
because there is no single gold-standard to compare them. You just keep
saying that the horizontal is the gold standard. Well, it isn't.

> That's about on a par with saying my 50mm
> Summicron is wider than it is because of all the stuff I can see outside
> the frame lines

Except that my Rolly actually puts this stuff on film and I print it.
That's, er, quite a difference, isn't it?

Once again for reasons I can't fathom you seem to assume that anything shot
6x6 will be cropped down to 3:2.

- -- 
Johnny Deadman