100 2,8L macro 1:1 or not ?

[Eolo]

Excuse my ignorance, I am to buy a 100 mm 2,8 L macro, in 10D that works as a 160 mm (x1.6).
My question is.... as the Macro it does work 1:1? it is the same as a SLR or it also changes the proportion of 1:1 for the digital format (CMOS)

Thank you.

Mario.

[hmhm]

The 100/2.8 macro is indeed 1:1. This means that for a subject at the closest focusing distance, an image will be projected on the film/sensor plane that is the same size as the subject.

If the camera is a 35mm film camera (or full-frame digital like a 1Ds), then a single frame will capture 24mm x 36mm of this image, and so the frame can be filled by a subject of that size. If the camera is a 10D, then the sensor will capture 15.1mm x 22.7mm of the image the lens produces, and so the frame can be filled by a subject of that size.
-harry

[ifurlong]

this is not an L lens, but its a great lens

[ifurlong]

also, the magnification is invariant of the croping factor. The reason is that by definition 1:1 i.e., life size, the lens will reproduce, e.g., a ladybug, on the sensor as it appears in real life, so it is irrelavant what the size of the "device" that captures the image, a diagram of the lens and its image will help see this. Consider a 8in by 10in large format camera, if you were to take a macro with our 10d, then with the 8 by 10, you would hardly think the 8 by 10 was a macro, since you would get the ladybug and a bunch of stuff around it, but with the 10d, you get the ladybug and just a little bit, hence giving the effect of 'being in there'