Yes that's true. In my laboratory reproduction ratios and camera lengths were all important. Most calculations were based upon distances between diffraction spots of millimetres and small fractions thereof and camera lengths of metres. The calculations were simple trigonometry and we ended up doing it all on an HP 1000 system with a drum scanner attached. I got it with a grant from a US group.
But so what? Let us consider magnification as well. Say we have a small object to be photographed. We want to see detail and we decide a magnification of 10 times will do the trick. We have all the cameras we need from 10 x 8 down to 35 mm - throw in a Minox for good measure. The final image, at 10X, will fit on 35 mm and on all the others, upwards, as well. What do we choose? A 10 x 8 Kardan, or a fine 35 mm SLR with a good Macro lens? Without thought the majority of folk jump for larger formats. When asked why, they invariably fall back on magnification saying bigger images on the film are better, less grain and so on and on. All missing the point. The magnification is done with, decided, no longer relevant. I tried hard to explain that if the image would fit on 35 mm it was a mistake to use anything bigger? Then the balls came back to me, over and over, 'magnification', 'bigger images better resolution', 'less grain' and so on - all irrelevant. But they had no better answers. None seem able to grasp the basic concept. If the final image, magnified or not, fits on 35 mm then you use 35 mm because to use anything bigger would be pointless. "Better tonality" was my favourite. But let us say we have no 'camera' at all. Just an optical bench and a selection of film backs. We select a 10mm Zeiss objective from the cupboard, set up the lighting and end up with a nice sharp magnified image, showing the detail we want, on our ground glass. The image is 5 cm high. Do we try to put it on 35 mm? No we take out a 6 x 7 roll film holder and stick that in the slot, stop down our lens, turn off the main lights and take our picture. We didn't use 35 mm because the image wouldn't have fit, anything bigger than 6 x 7 would have been pointless. Its so simple a concept that no one seemed able to grasp it. I was simply extolling one particular virtue of 35 mm. That's it *excels* at macro work for *small things*. There are other reasons that 35 mm is better, in some ways, than larger formats for this, but I'm sure if I brought them up there would be more nonsense - and I mean that in the dictionary definition sense of the word - for which I don't have patience. I'm going to let this poor dog die. Don Dr E D F Williams http://personal.inet.fi/cool/don.williams Author's Web Site and Photo Gallery Updated: March 30, 2002 ----- Original Message ----- From: "Mike Johnston" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Sunday, December 15, 2002 6:34 PM Subject: Re: An experiment in tonality > > But you too are missing the point. It is that the film is the same, whether > > it be 35mm or a piece the size of you bedroom wall. The emulsions may differ > > a bit of course. So when the image is of a size that fits 35 mm there is no > > point in using a bigger piece for Heavens sake! > > Don, > Without meaning any offense, your argument may seem somewhat specious to > non-scientific photographers. What you are assuming is that the end result > that is wanted is a 1:1 magnification _on film_. So you're comparing > "fitting" a small image on a piece of 35mm film or "floating" an on-film > image of the exact same size in the middle of a 4x5 sheet. > > Of course this just isn't how pictorial photographers think. We never have > any reason to deal with exact on-film magnification ratios--the only reason > we speak of it at all is to compare the potential magnification of different > lenses...and then, only because that's how the manufacturers choose to label > the lenses in the first place. > > Even among macro photographers, I doubt 1 in 100 could tell you the exact > magnification ratio they used for any particular pictorial shot. So the > source of your difficulty in communicating may be that you're presuming an > end goal that would simply never occur to most photographers. > > --Mike > > > > > > > > [ NOTE: I don't have time to read every PDML digest and may not see every > message posted. If you have a message or response you'd like me to see, > please copy my personal e-mail address. Thanks! ] > > > >
