My last comment on the subject, I swear. There is not a single lens in the world that can resolve more on film than the film will resolve.
Ciao, Graywolf http://pages.prodigy.net/graywolfphoto ----- Original Message ----- From: "Mike Johnston" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Sunday, December 15, 2002 11:05 AM Subject: Lens resolution: 35mm vs. medium-format > > All you have to do is take a look at the published MTFs for 35 mm lenses and > > compare them with those for Medium Format > > > > Again, Don and Pal are correct here. Look at any measure of resolving power > you please--visual lp/mm, MTF, whatever--the smaller the image circle, the > shorter the focal length for the same angle of view, the brighter the lens, > the higher the potential resolution. There isn't a single medium format lens > that can resolve as much on film as the best 35mm lens. > > Where medium format wins is by the measure Greywolf was referencing in his > part of the discussion--final print magnification as opposed to on-film > magnification. With normal-speed pictorial films (i.e., 100-400 ISO), the > limits of enlargement are about 8-12x (depending no so much on the > granularity of the film as upon the quality of the enlarging lens and the > technique of the printer--I'll give you a clue, if you don't know the > optimum magnification and the optimum aperture of your enlarging lens off > the top of your head, you're better off not going to 12x <g>). > > An 8x enlargement from 35mm is 12x8 inches. The same 8x enlargement from a > Hasselblad or Rollei negative is eighteen and a half inches square. You can > crop a square medium-format negative and enlarge it to 12x8 inches and > you're still only at about a 5x enlargement. What this means IN REAL-WORLD > TERMS is that a 12x8-inch enlargement from a 2 1/4 negative requires less > skill and less exacting technique from the printer, allows for some > cropping, allows for the use of a faster film, and STILL will give better > resolution in the print. Nothing to be sneezed at. > > And if what you want to end up with is an 18x12-inch print, however, that's > a 12x enlargement from a 35mm negative and, in practical terms, you are > working at the limits of 35mm--your equipment, materials, and technique had > all better be top-notch to achieve a better-than-acceptable result. But > you're only at the bottom limit of the enlargability of a 2 1/4 neg. > > In fact, subjective evaluation tests show that this is pretty much the story > with competing formats. If both formats are well under the lower > enlargability index of 8x, there isn't a whole lot to choose. By the upper > 12x limit of the smaller format, the larger format is beginning to pull away > decisively. At larger sizes, no amount of technique can "rescue" the smaller > format. > > The big headache for manufacturers (as I think the "Big Five" found out to > their dismay with APS) is that a format cannot be engineered for the > "average" enlargement--because, in the real world, what people like to do is > to have MOST of their enlargements at a certain size, but then a FEW > SELECTED images they like to be able to enlarge to a significantly greater > size. That is, the APS shooter is happy with 3R prints most of the time, but > occasonally wants an 8x10; The 35mm shooter is happy with 4x6 or 6x9 most of > the time, but SOMETIMES wants an 11x14. So format choice is not only > dependent on the comfort level it allows a fine printer at the average size > of enlargement, but it is also a matter of the LARGEST size he or she is > ever likely to print. > > Incidentally, in our subjective evaluation tests, the ideal format turned > out to be 6x7cm. In 11x14 enlargements, photographers could tell, but > visually sensitive laypeople COULD NOT TELL, the difference between 6x7 and > 4x5. Yet 6x7 DECISIVELY bettered 35mm at every size above about 6x9, > according to all viewers, and by 16x20 there was not contest at all--100% of > viewers preferred 6x7. > > Do note, however, that lens and film resolution, enlargability, print > quality, and all these interlinking qualities are NOT simply a matter of > mathematics and measurements. They are also highly dependent on the skill > and technique of the photographer/printer and the visual acuity and > "sensitivity to photo artifacts" of the viewer. Photographers can more > readily tell the differences between formats because they know the clues to > look for. Ordinary viewers don't see the differences as easily. All these > things have to be taken into account in this argument. > > --Mike > > > > > > > "At least they're not talking about my eyes any more. I was starting to get > self-conscious." (Rocky Raccoon) > > * * * > Find out about Mike Johnston's unique photography newsletter, "The 37th > Frame," at http://www.37thframe.com. >
