britt777 wrote in post #11772313
So I guess my biggest question is. When looking for a lens, am I suppose to be looking for lenses for a full frame camera?
Yes.
EF-S lenses are designed specifically for a 1.6 crop sensor and may catch the mirror or vignette on a larger sensor. 'Crop' lenses from the independents are likely to be similar.
That doesn't mean that they can't be used, but may need modifying to fit and you may get vignetting or be unable to use all the zoom range. I have seen posts from people who have modified EF-S lenses to work on FF.
In the defence of the B&H people, it is hard to know exactly how every piece of kit they sell will work with other pieces of kit. They would need to know Canon, Nikon, Sigma, Tokina etc., etc., Technically, they were both right (it is a crop but is considered to need FF lenses). If they both said that they didn't know if the sigma 30mm would work, then they are just stating that it might but they can't say yes for certain. As I say, some crop lenses may work OK with minimal vignetting, it depends on the design for each lens. Without having tried it, they gave you an honest answer, they don't know.
Theoretically, it won't work properly, but it might if they designed it with an image circle a bit bigger than actually needed for a 1.6 crop sensor.