Caveman wrote:
> Read again. My grip were the "professionals" riding high horses and > stating that Fuji lies and the film is actually 40 ISO etc. Of course, > none of them was basing his statements on a decent measured test against > the film's data sheets and the ISO definition. Pretty much like your > claims of getting 1/3 precision on 100% shots. The professionals are not concerned about what is labeled on the box or via a densitometer. They are concerned about what THEY think is correct exposure on film from the calibrated zero point THEY use on other films. This is about consistency. It doesn't matter what ISO number is printed on the Velvia box, or what the ISO on the camera is set at, as long as it provide what the photographer wants. John Shaw in one (several?) of his excellent and widely acclaimed books, state that he wished that camera manufacturers didn't put ISO values on camera bodies but the letter A, B, C, D etc and that film manufacturers should state on the film box that the photographer should set the camera to whatever letter that give the photographer the expousre HE is happy with when using THAT film. Hence, whether a photographer expose Velvia at 40 or 50 ISO depend on what HE thinks give HIM the correct exposure. What Henry Kissinger thinks or anyone else is really not of any importance. No professional photographer I know of set out to test whther Velvia is really a 50ISO film. They don't care. They expose it at whatever value that turn them on. With consistency. Very often this is 40ISO and 1/3 stop makes a difference on Velvia. It makes a difference because 1/3s is possible to nail consistently. The pros have long figured out that he want to realise the exposure he set out to achieve when he press the shutter release. For this he wants 1/3s accuracy with Velvia. Therefore it matter whether his cameras meter is set at 40 or 50 ISO. If the error margin was equally large and random, as some have suggested, this issue would never have arisen because the problem would have been irrelevant. If a photographer is going to able to master exposure, which everyone wants, he must be able to nail it consistently and not rely on wild bracketing in hope of accidentally hitting it. If the photographer fails to nail exposure it is his fault. Not the camera, the lab, the processing the lenses whatever, providing his infrastructure work properly. I realise it must be comfortable to think for those who don't get the exposure they want within 1/3s, and I take the freedom to include those who says it is impossible (why else should they say it is impossible?), to believe that this is indeed impossible due to some external factor out of their control, like film and processing. Comfortable tought, yes, but simply not true, and it is certain not a worldview that will make the person learn mastering exposure. And as for basing statements on data; you don't. You may heed Fujis ISO rating (well you really don't as you claim it may be off with more than 1/3s) but you conveniently ignore all other data available, like Fujis ISO consistency rating, laboratory consistency and accuracy, camera meter calibration accuracy, aperture accuracy, shutter accuracy and simple fact that the proof is in the pudding for thousands, if not millions, of photographers who are able to assign tonalities on Velvia within 1/3s accuracy on modern equipment. There are books written about it, and countless of articles but you conveniently ignore that too! You have no personal data either: the fact that you may not be able to nail exposure consistently within 1/3s doesn't prove anything about the rest of us. Or our equipment, film or laboratories. Pål
