Dana Fuller wrote: >"Rule of thumb" any lens other than a pin hole camera or > lenses at F45 or F96 which could be considered pin hole (see the movie > "Citizen Kane") is at it's sharpest two stops closed from wide open. I > therefore find my electronic camera at F16 or more in full sun.
Stopping down too much also causes refraction which leads to the image sharpness falling off towards the edges of the frame. Most of my lenses are sharpest in their mid aperture range. This is really noticeable with 4x5 transparencies and a loupe. The same goes for smaller formats. I would have to say that two stops down from wide open would average better results, but none of this really matters because we don't know which particular lenses we are talking about here, and one thing I have learned about lenses in general is that there is no accurate 'rule of thumb' formula for sharp images. You need to shoot at different apertures and look at your film with a good loupe to really see what your lens is capable of; anything less is a guess (I still won't bet on an educated guess). How many people wait until they are out actually using their lens to 'test' it? The first thing I do with a new lens, or one that I am considering, is to shoot at least a couple of test rolls with it and look at the film. Why? Because it's my money, and I don't like fuzzy images. I don't consider a lens a 'keeper' until I have thoroughly examined the results from it on film and I know what it is capable of. If I don't like it, I sell it, return it, or trade it in. There are a lot of fuzzy lenses out there that make this 'nit-pick' very important if you require sharp images for whatever reason. And just because the lens says Nikon, or Canon, or Zeiss, or Stinger or Rodenstock on it, doesn't mean that every lens that those companies ever made will be sharp at the apertures that you will use them at, but I have found for the most part, that the better the optical reputation of the lens company, the more consistency there is from one lens of the same type to another. Needless to say that when out using 35mm gear on moving subjects and we can't use the aperture of choice because of our exposure, that we are compromising. Dave Cohen Photographer Action Photographic Webmaster [EMAIL PROTECTED] http://www.anet-stl.com/acphotog/home/ -> SPORRS: 'Serious Photographers Of Railroad Related Subjects' -> Web Site: http://www.anet-stl.com/acphotog/sporrs/ -> Message © 1998 SPORRS® - All Rights Reserved
