Surely a lens maker does not differ between crop and full frame. As I mentioned earlier regarding the Tamron 28-75mm lens. The specs are identical and the description only mentions DI. I am confused about this.
The Tamron 28-75 is a fullframe lens. As such it can be used on Aps-C, too, without any problems apart from the changed field of view because the image circle of the lens, is far bigger than the aps-c sensor.
Third party manufacturer do in fact differntiate between Aps-c and full frame lenses. They usally use differnt letter codings in the lens names to identify for which sensor size a lens was made. APs-C lenses have a smaller image circle which results in black corners when mounted on fullframe.This is why it does not make sense to use Aps-c lenses on full frame. (In case of Canon aps-c lenses (called EF-S) it isnt even possible to physically mount an aps-c lens on a fullframe body, because of the mount. Canon full frame lenses can be mounted on aps-c cameras however.)
Unlike Canon themselves, third party lensesmaker do not use the EF-S mount for APS-C lenses. This is why their Aps-C lenses can be physically mounted on full frame cameras, without damaging the mirror. If done so, Aps-C lenses do deliver black corners, however, because their image circle is not sufficient for full frame.
[quote name='geriatric' timestamp='1281163284' post='1563']
Surely a lens maker does not differ between crop and full frame. As I mentioned earlier regarding the Tamron 28-75mm lens. The specs are identical and the description only mentions DI. I am confused about this.
[/quote]
APS-C lenses just have to have a less wide image circle, making them potentially lighter, and cheaper to make.
Full frame lenses can be used on both ASP-C and full frame lenses.
Canon calls their APS-C lenses EF-S, full frame lenses are called EF (electro-focus). The S stands for Short, the distance between sensor and lens can be a bit shorter for their APS-C lenses.
Lens brands and their APS-C naming conventions:
Brand : full frame / APS-C
Canon : EF / EF-S
Tamron : Di / Di II
Sigma : DG / DC
Tokina : - / DX
Nikon : - / DX
Sony : - / DT
Pentax : A big mess.
[quote name='Brightcolours' timestamp='1281185211' post='1566']
APS-C lenses just have to have a less wide image circle, making them potentially lighter, and cheaper to make.
Full frame lenses can be used on both ASP-C and full frame lenses.
Canon calls their APS-C lenses EF-S, full frame lenses are called EF (electro-focus). The S stands for Short, the distance between sensor and lens can be a bit shorter for their APS-C lenses.
Lens brands and their APS-C naming conventions:
Brand : full frame / APS-C
Canon : EF / EF-S
Tamron : Di / Di II
Sigma : DG / DC
Tokina : - / DX
Nikon : - / DX
Sony : - / DT
Pentax : A big mess.
[/quote]
Pentax a big mess? DA is for digital, FA for 135 film (which of course would cover a 36x24mm sensor), and they do have a couple of D FA lenses. I don't see the mess.
Some DA lenses do cover the 36x24mm area as well, but the lenses are still intended for APS-C sized sensors.
