BlueEyes has the most accurate "simple" explaination of what is happening here. Great explaination on this subject matter... by a pro who reviews/test equipment:
http://www.luminous-landscape.com/tutorials/understanding-series/dslr-mag.shtml
That "so-called" jargon is actually the best way to describe it.
I agree
Coming from someone who seems to think that the EF-S lenses are
"different" with respect to these issues, I can see why you might
think that.
Actually, they are different. One: the back lens element is closer to the sensor (major difference). Two: not designed for full frames
trying to say that a Canon 70-200 mm IS lens is different
based on the camera . . . yeah, sure.
I don't see where anyone said any such thing. That's exactly the
confusion that needs to be prevented, but nobody here has said that
a lens changes based on what camera you put it on.
Not in so many words, but it's been implied in this thread by interpretations of the subject that would lead one to believe that that is what they are saying.
A 35 mm formatted lens will be a 35 mm formatted lens whether or
not it's a 35mm film plane or a 28mm digital sensor. Saying to
think of it as anything different is a little odd, to say the least.
Lenses are not "formatted". You're not making sense. Lenses are
pretty much completely characterized by a focal length, for
purposes of the present discussion.
Maybe "fromat" is a bad choice of word, but BlueEyes is correct. Let's call it "engineered" for a sensor format at a given focal length. Mounting a 35mm "engineered" lens to a MF body at the 35mm focal length, you would probably see the curvature of the image circle the lens is projecting, or at least sever vignetting. That's why MF lenses are engineered differently.
Cameras have a format. Lenses don't, except in so far as there
might be a largest format for whcih they provide low enough
vignetting.
Your statement here proves the point, just won't say "fromatted" but "engineered"
used to call it "magnification factor" because a 100mm lens on
a 10D would give you the same FOV as a 160mm lens on a 1V. A lot of people, liked that your lens was more "powerful" now.
because really, you weren't magnifying anything. ...
People confused themselves about that because they didn't
understand that the magnification is REAL in the overall system
from scene to print, but not part of the lens or camera itself.
It's in the enlargement from focal plane to a given print size that
you get 160% more magnification.
The magnification is NOT real. That's why "crop factor" is really not a bad term. Not sure what "Print size" has to do with this, subject has no bearing on post camera output. The smaller sensor is just being exposed with a smaller portion of the lens projection... this is not magnification.
... Instead, you were
taking a larger image and cropping it. My God, we have a CROP
FACTOR. Take a picture,
and assume it was shot with a 35mm film plane.
assuming your picture was an 8x10, crop it down to a 4x5. once you have your 4x5 crop,
Now you got two 8x10's, right? One looks "zoomed in" or
"magnified." Why you ask? Because you cropped it, duh.
... and then you magnified it or enlarged more.
That's enlarging it after the fact (and not a magnification on to the sensor via the lens projection) as what you would see in the viewfinder.
That's what
a 28mm digital sensor does when you attach a 35mm formatted lens
onto it.
or any lens. There's not such thing as a 35mm formatted lens.
No, not any lens. That's why you have a lens such as the EF-S 10-22. If we would have the same results with the EF lens, on 29mm, what's the point for Canon to develop the EF-S line?? Actually there ARE such things as 35mm "engineered" lenses.
A 50mm on one format may give you a 1:1 (no magnification/reduction) while the same lense on another format would not be a 1:1.
Instead of recording the entire possible image provided by
the lens, you're only recording the 4x5 crop and blowing it up to
an 8x10. See where we're going with this . . . ?
The entire possible image is a big circle that is NEVER recorded in
Actually, it would be. An EF-S lens (providing you could) mounted on a MF or Large format, would show the image "circle".
an EF-S lens, which is a 28mm formatted lens (catching up
yet?) is designed to cast it's image over a 29mm diagonal plane,
thus no croppins
If the EF-S mounted lenses happen to have a smaller image circle,
that has no bearing on anything. They are not "formatted" for 29mm.
Again, BlueEyes is correct. The EF-S, as you know, rear glass element is closer to the sensor for a shorter focal length. I think that constitutes as being "engineeered", or formatted, for the smaller sensor. If they weren't "engineered" for the 28mm then why didn't Canon design them to be mounted on the full frame also? Because, in addition to the larger mirror hitting the back of the lens you would get extreme vignetting and inherent corner aberations.
The concept of cropping relative to the
format that the lens was optimized for leads you directly to the
WRONG conclusion.
See the link I posted
if you were to stick this lens on a 35mm
film plane you would wind up with an
8x10 print with only a 4x5 image on that sheet. You would just have
a giant black frame . . .
because your mirror would jam
against the back of the lens and your shutter wouldn't open. Try
it and let us know.
Assume mirror is locked up, you would still get some black or vignetting... not so sure if it would be giant.
