Sigma 85mm/1.4 Art on Canon t7i?

Hi all, I am new to this forum and fairly new to photography. I currently have a Canon t7i and while I would love to get an upgraded body, right now I only have the budget for a lens OR a body. From what I've read, the lens is going to be the first choice to upgrade? 

I have a local camera shop not far from me that has a Sigma 85mm/1.4 Art lens I can rent, but is this compatible with my Canon t7i? Quick internet search says theres some error that pops up but from what I can see I can just ignore that and use it anyway. Is this true?

I'd rather rent from the local business than from a website. I was looking at the Canon 85mm 1.2L but the shop doesn't have that for me to try out. Any advice welcome, sorry if I sound like an idiot! I'm doing my best to learn!

Both the Sigma 85mm/1.4 Art and Canon 85mm/1.2 are excellent lenses.  They are designed for full frame cameras, but they should also work on cropped-sensor cameras like your Canon t7i.  The Canon t7i specs indicate it has an APS-C sensor, which means it is cropped, not full-frame.  The crop factor for Canon APS-C cameras is typically 1.6.  So you need to multiply the 85mm by 1.6 for your camera and that means that the lenses you mentioned will effectively be 136mm lenses for your camera.  If you really want to shoot at an 85mm focal length on your camera, then a 50mm lens built for full frame cameras may be more appropriate. The Sigma 50mm/1.4 Art lens is also an excellent lens--that will yield an effective focal length of 80mm on your camera's sensor. Both the Sigma Art and Canon L lenses are excellent.  You will find the Sigmas are indeed heavier, if that is an important consideration for you. Good luck!

tcananphoto wrote: The crop factor for Canon APS-C cameras is typically 1.6.  So you need to multiply the 85mm by 1.6 for your camera and that means that the lenses you mentioned will effectively be 136mm lenses for your camera.  If you really want to shoot at an 85mm focal length on your camera, then a 50mm lens built for full frame cameras may be more appropriate.

No, no, no. Please.. just stop.

Nothing can change the focal length of a lens. You can not modify the physical attributes of the glass by sticking it onto a different camera.

What changes is one thing: the view angle, which is smaller on a smaller sensor. This is a geometry issue only. An 85mm lens remains an 85mm lens no matter where it used. Whether you can get a desired image rendering out of it is a separate issue.

The manufacturers did everyone a huge disservice by trying to compare smaller sensors to a 35mm frame, and then misrepresenting how that image will be rendered. First off, how many people worked with film? Long enough to know what a 35mm frame looks like? And then moved to digital? I'll wager not nearly enough to matter. Most of us have no point of reference. That makes the comparison meaningless.

And if you read carefully, most manufacturers state "comparable view angle". Not all, I've seen, but most. This is unfortunately misinterpreted often. Nonetheless, the "crop factor" applies to the viewing area through the lens. Nothing more, nothing else.

And unless you're comparing how a given lens behaves on one camera vs. another with a differently sized sensor, it doesn't matter. What matters is whether the lens produces what you want. And if you want to do close-up portraiture, get an 85mm lens, or longer.

The OP started out asking about compatibility. I'm only familiar with Nikon, but Canon appears to enjoy a comparable level. And if the OP has a local spot that rents equipment, I would encourage the OP to take the camera into the establishment and try it out there. And talk to them about how lenses work on Canons. They'll likely be happy to explain it all to you.

Yikes, I didn't meant to cause such a strong reaction.  I agree there is no changing the focal length of a lens; I was just pointing out that the there is a difference on how a single lens may fill the sensor of a full frame camera vs. a cropped sensor camera.  I used the term "effective" suggesting the results are different.  If the same photo is taken from the same position with an 85mm lens on a full frame camera and a cropped-sensor camera, the result will be different.  I never asserted the physical attributes of the lens changes; rather, the results of the shoot from the same lens has an "effective" difference depending on the type of sensor in the camera. If the OP was used to shooting with 85mm on a film SLR, they need to understand that to achieve the same result in an APS-C Canon using the same 85mm lens, they will need to stand farther back from the subject. So if they don't want to get used to standing farther away to achieve the same result, then maybe a 50mm lens might be more appropriate.