'William Chops" Westfield ' I'm wondering if we're going to start comparing photography stuff to > audiophile stuff. I guess we're still in the realm where differences > are measurable, but are they really viewable under normal > circumstances? Unlike audiophool stuff, most of these parameters have a solid scientific basis and are measurable. What they mean under "normal viewing conditions" is a totally different matter. First, what are "normal viewing conditions"? Does that mean a picture in a web page where it probably gets 1000 pixels accross or less? Does it mean a print you can hold in your hand? Does it mean a poster on the wall you can't get close to? Does it mean a poster on the wall you can walk right up to? Different parameters will matter in different situations. Some of the parameters don't necessarily effect what the final picture looks like, but whether it was possible to take at all, or perhaps how easy it was to take. For example, a camera with good low light capability allows a faster shutte= r speed all else being equal. That means there will be more cases where hand holding the camera with a telephoto lens will be feasible. It's not that the final picture will look better, but that you'll never get to see the ones that don't look good or weren't possible. Low light capability is useful in a number of other cases too, like action sports, in the woods, etc. A good example of this is a picture I took many years ago, http://www.embedinc.com/olin/squirrel_1024.jpg. That was with my Nikon F3-T, a 300mm lens, and Kodachrome 64 film. ISO 64 is pitifully insensitiv= e by today's standard, and was even low at the time (1985). I was using Kodachrome for other reasons than sensitivity. With film, you couldn't easily just swap out a different roll with different sensitivity as you can now with a digital camera. In any case, there I was with the squirrel, the camera, 300mm lens, and daylight. When something like this comes up, you'r= e stuck with whatever you have on you. Even if had had a tripod, I wouldn't have taken a chance on scaring the squirrel by mounting the camera on it. There were also no trees near where I was standing. The squirrel was perched in a tree at the edge of a clump of woods with a large meadow all around. All I could do was open the aperture all the way, focus really carefully, hold my breath and other tricks to keep the camera still, and take a bunch of shots and hope for the best. I took a few pictures, walked a little closer, took a few more pictures, walked closer, etc. In the end, I was amazed how close the squirrel let me get. I also got lucky that this one shot at close range didn't get wobbled. Some others did. You'll never see the ones that didn't work out. This is a case where 1 F-stop less sensitivity probably would have killed the picture. It would have been in the long list of "oh well" situations where no good picture resulted and I would have forgotten about it long ago= .. This was a case where the improbably happened. In other words, good result= s would be rare from a number of similar circumstances. Another couple F-stops of sensitivity would definitely increase the odds. Higher resolution also enables things you can't do otherwise. Let's say I want to take a picture of a problem on a circuit board to show the manufacturer. In that case I can arrange for sufficient light and/or set u= p a tripod to allow for a long exposure. In other words, sensitivity isn't a big deal in this case, but resolution is. Every 4x more pixels essentially gives me a 2x longer lens, which can be very helpful when doing macro shots of small things since it's often hard to get close and the choices of lense= s is greatly diminished. Each parameter has its purpose, although they don't all directly map to "better picture" in whatever the final viewing conditions are. ******************************************************************** Embed Inc, Littleton Massachusetts, http://www.embedinc.com/products (978) 742-9014. Gold level PIC consultants since 2000. --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .