Do all Canon DSLRs share lenses?
I'm considering either the 5d mark ii or the 7d from Canon. I'm interested mainly in portraits but other things as well. I don't know which camera to go too… It would be a huge upgrade from my current Nikon. I know the mark is full frame
Can someone explain the lens varieties to me?
No. The 7D can use all EF and EF-S mount lenses. The 5D can only use EF mount lenses. If you put an EF-S lens on a 5D it will damage the camera and lens.
EF-S = DX
EF = FX
Simple.
EF-S lenses can only be mounted on Canon cameras which have a C-MOS sensor (cropped sensor) - 7D, 60D, 50D, 550D etc.
EF lenses will work on every Canon DSLR - 1Ds, 1D, 5D, 7D, 60D etc.
The 5D Mark II is quite old now… It's due for an update this year. I'd still go with the 5D Mark II, once you go full frame you'll never go back. I find full frame cameras much better - they have much better low light capabilities too, handle high ISOs better.
There are benefits of cropped sensor cameras though…
The FOVCF (Field Of View Crop Factor) on Canon DSLRs is 1.6 (except for the 1D series - that's 1.3 because they have APS-H sensors).
This means that a 50mm lens on a 7D would effectively be an 80mm lens - this is good for long zoom lenses, more bang for your buck - so to say, not so good for wide angle lenses though.
If you're getting a 5D Mark II then I recommend the Canon EF 85mm F1.8.
If you get the 7D then I recommend the 50mm F1.8 or F1.4.
That'd be a good choice for portraits.
The 7D is really more suited towards sports photography - the 8fps burst mode it has is good for sports shooters.
I know I'm babbling on about more than you wanted to know, but I'm just trying to be a bit more helpful.
Last thing I'd say, some good set ups for each camera:
5D Mark II - Canon 15-35mm F2.8L, Canon 27-70mm F2.8L, Canon 70-200mm F2.8L IS - that would be the perfect kit for a 5D Mark II, quite expensive though.
7D - Tokina 11-16mm F2.8, Canon EF-S 17-55mm F2.8 IS, Canon 70-200mm F2.8L IS - this would be the perfect kit for a 7D, the Tokina is an excellent lens (only available for cropped sensor cameras - Nikon or Canon, make sure you get it in a Canon mount), the 17-55 is just as sharp as the 27-70 I included with the 5D Mark II, it's just wider - this is better for the cropped sensor. And the 70-200mm F2, 8 is a must for any camera. I wouldn't be able to live without mine - it's amazing for everything except for macro.
If you're not looking to spend too much money, you could get a Sigma 70-200mm F2.8 OS - just as good as the Canon and about half the price.
Right, I'll stop there. Hope that's helped!
No. The full frame can't use the ef-S line. I'd go for the 7D if I want more lens options, and for the 5D Mark II you'd have to get an external flash too because it doesn't have a built in one.
No, like the others already said. Canon's EF-S lenses are only for crop sensor cameras like the 7D, 60D, and the Rebels. You will need to buy EF lenses for the 5D Mark II. Also, the 5D Mark II is noticeably better for portraits that the 7D. The only thing the 7D is better at is moving objects like birds or sports.
I don't get why you're going for Canon, as Nikon has a very solid set of professional DSLR cameras as well.
Anyhow, Canon DSLRs come in three different sensor sizes, APS-H, APS-C, and Full Frame. Both EF and EF-S lenses can be used with APS-C cameras, while only EF lenses work with the other two.