Arthur, apologies for hijacking your thread. I'm glad we answered your question! Now, as respectfully as possible...
Originally posted by tux08902 It's not subjective territory. The actual magnification of the lens has not changed. Because of the smaller size of the digital sensor, some of the image projected by the lens is being cropped out. Yes, you will probably get a very similar image using a 450mm lens on a film camera to the one you would get with a 300mm lens on a dSLR. However, that's not because somehow a 300mm lens magnifies more on a dSLR and less on a film. Magnification stays the same no matter what camera you use it on. It's because the camera crops out some of the projected image. It's not semantics, it's fact.
If "you will probably get a very similar image" then it
IS subjective; some people will find it to me more similar, some less.
Please don't introduce spurious statements such as "somehow a 300mm lens magnifies..." and then dispute them; no one ever said any such thing.
My point is -- as far as most of us are concerned, the magic (or horror, if you're of the wide-angle persuasion) of the crop factor, when switching from film to digital, IS like suddenly having all of your lenses multiplied... Anyone who says otherwise without providing evidence to demonstrate that there is a VISIBLE DIFFERENCE between the two is simply muddying the waters by taking the discussion into a realm of technical fetishism, in an effort to appear more "correct".
Marc (correctly) says that
Quote: A teleconverter can increase the magnification, but often at a compromise of IQ (image quality)
Do you think there's a discernible difference between a 20x30 print from a negative shot with a 300mm lens with a 1.5 teleconverter, and a 20x30 print from a 14.6MP k20d with the same 300mm lens? After all, one has "real" magnification and the other is "just crop factor".
Maybe there is -- I don't know; but there is no evidence that anyone else in this thread so far does (based on visible evidence), either.
Oh -- just saw your edit. Good question...
Quote: By the way, one thing I don't understand is if the DA lenses are designed for dSLRs and project an image to only cover the digital sensor, then why are they still subject to the crop factor? If they vignette on film, then doesn't that mean that the actual beam of the lens is thinner meaning the entire image is being projected onto the sensors, so no cropping?
If you're just basing that on what I said, was making a supposition, so I (personally) can't say for sure that they DO vignette on film. I'd also be willing to consider the idea that a DA at 50mm (say) is
actually made to be 75mm, with a smaller circle, and
intentionally mislabled as 50, to avoid confusion.
BTW, thanks to everyone for making this boring day at work much more stimulating!