New Tamron Lens on an APS-C Sensor

[xmacvicar]

Please help me with this one, I am unsure and its not clear...

I have a Rebel XTi body which features the 1.6x crop factor. However, I just got a Tamron 17-50 f/2.8 XR Di II lens which is specifically MADE for these smaller sensors....as a result, does this mean that when i shoot at the wide end (17 mm) that im actually GETTING 17 mm or is it still kind of 27mm due to the crop factor?!

Can anyone shed some light on this for me?

[coreypolis]

no, its the 17 x 1.6.

[xmacvicar]

damn... hahaha...so what is so 'specific' about them to the 1.6x sized sensors?

[dansellbuddy]

means it won't work on a full frame camera. it produces a smaller image circle using less glass and hypothetically making it a cheaper lens. manufacturers also like to throw in that they use some sort of special multicoating on the lens.

the most imporant thing about a "specifically for aps-c sized sensors" lens, is it doesn't work on full frame.

[Tee Why]

For convention, all lenses made for dslr follow the focal length for 35mm film camera.
I think the focal length doesn't change anyway, only the size of the image circle and the sensor size to capture the light.

[Wilt]

The APS-C sensor is smaller, so that it captures a smaller section of the image circle of the lens, compared to a FF sensor. In fact, FF is 1.6x larger in each dimension (for example, 24 / 15 = 1.6) So you capture an image on APS-C which fills the frame the same as capturing an image with 1.6x longer lens on FF camera. So 17mm on APS-C grabs an image similar to 27mm on FF camera. Understand?

[StewartR]

means it won't work on a full frame camera. it produces a smaller image circle using less glass and hypothetically making it a cheaper lens. manufacturers also like to throw in that they use some sort of special multicoating on the lens.

the most imporant thing about a "specifically for aps-c sized sensors" lens, is it doesn't work on full frame.Right.For convention, all lenses made for dslr follow the focal length for 35mm film camera.
I think the focal length doesn't change anyway, only the size of the image circle and the sensor size to capture the light.Right.The APS-C sensor is smaller, so that it captures a smaller section of the image circle of the lens, compared to a FF sensor. In fact, FF is 1.6x larger in each dimension (for example, 24 / 15 = 1.6) So you capture an image on APS-C which fills the frame the same as capturing an image with 1.6x longer lens on FF camera. So 17mm on APS-C grabs an image similar to 27mm on FF camera. Understand?Right.

Remember that it's still a 17mm lens, so if you're doing Depth Of Field calculations then that's the value you have to use.

[Mike R]

I remember reading that the design of the lens will cause the rear elements to hit the inside of cameras with a full size sensor. I have the lens you are taking about. It does a great job :)