Re: [Leica] image quality and format

["David L. Duff" <duffdl@uswest.net>]

Erwin and group,
    From watching the marvelous posts from everyone on this topic, I've
decided that I'm not going to save my pennies to upgrade my M4-P to an
M6.
    I'm going to save 'em for Leica's version of the Mamiya 7. Of course
the Leica 7 would also have TTL flash, mechanical speeds (like a Pentax
LX only more of 'em), auto shutter (like the LX), a vacuum back (like the
Contax), be smaller, lighter, more durable (than the Mamiya or
Hasselblad), and of course, have the Leica glass. Only, I envision the
Leica 7's glass to made to the same standards as the 35mm M-line. Of
course the cost, well, I wouldn't be considering hocking the M4-P to pay
a mid-wife bill, when I could hock the Leica 7 and pay off my house
instead.
    But then our discussion would be about the 120 Leica 7 vs. 4x5 and
8x10. I guess the quest never stops.
    Thanks for the excellent posts all. I look forward to seeing more.
    Best of light, David L. Duff.

Erwin Puts wrote:

> There is some confusion about the topic identified in the header.
> When talking about image quality we have three variables: the optical
> quality of the lens, the negative format and the enlargement factor.
> You can not discuss these topics meaningfully when mixing them
> together. My original statement was simply this: The Leica lens has
> better optical quality than the Hasselblad lens. When the Leica lens
> records 40 lp/mm and the Hasselblad also 40 lp/mm, but with reduced
> contrast, the Leica lens is optically the better one. Because 40 lp
> per millimeter is an absolute number. A square millimeter on a
> Hasselblad negative is identical to a square millimeter on a Leica
> negative. So when both lenses record an object at identical
> reproduction ratio, the Leica has per square millimeter  better
> quality. So if we would enlarge that square millimeter with the same
> enlargement factor, the Leica lens would win, assuming the same film
> of course. So optically there is really no dispute or contest.
> Now the format. A 35mm negative has an area of 864 square
> millimeters. To make the 6x6 format comparable, we need the same 2:3
> ratio for the Hasselblad negative and that is 38x56mm or 2101 square
> millimeters. So the Hasselblad has an advantage of 2.5 times for
> area. That implies that the same object that fills the frame in the
> Leica case, will fill the frame in the Hasselblad case with an
> advantage of  2.5 times. So now we have the situation that one square
> millimeter of image area in the Leica case has 2.5 square millimeters
> in the Hasselblad case. Assume that we need the limit of 40 lp/mm for
> the object details when taking the picture with the Leica. We need
> only 16 lp/mm for the Hasselblad picture to cover the same detail at
> the equivalent resolution. So OF COURSE the Hasselblad negative has a
> big advantage.
> Now the third part of the equation: the enlargement. If we use the
> same enlargement factor of 10 for the Leica negative and the
> Hasselblad one, the Hasselblad advantage is lost. OF COURSE the
> resulting print will be much bigger in the Hasselblad case. But we
> were talking about the optical quality. Now if we assume the same
> print area, than OF COURSE the Hasselblad negative needs to be
> enlarged only 0.4 times the enlargement factor of the Leica negative.
> Now the limiting factor here is the quality of the film. If we can
> use a film that has a granularity size and resolving power that is
> below the enlargement ratio of the Leica negative, I dare to say that
> there will be no difference in print quality. That would be the case
> with Technical Pan.  If the granularity threshold is in the just
> visible limit than of course the Hasselblad print would show less
> graininess and will reproduce the subtle shades of grey and the
> smallest details with greater clarity. No doubt here.
> So what is bottom line the situation:
> Optical quality: advantage Leica
> Negative area: advantage Hasselblad
> Quality of the emulsion: depends
> Print size and print quality: depends
> So when discussing these topics let us be aware of the variables and
> their interdependence.
>
> Erwin