will the 20mm suffice in lieu of the 24-70

for starting off? im shooting on a 5d and currently only have a 50mm 1.8. i'm looking for a wider lens, and am planning to get a 70-200 (either f/4 or 2.8, havent decided yet) in the long run. i am starting to do portraits, high school senior pictures, and aspire to be an engagement and wedding photographer. does anyone think the 20mm is a good buy? does anyone happen to have any samples on a FF camera? thanks in advance!

I've never even heard of it. If you want to be a professional you'll need to invest in equipment. Wedding FAQ.

you must mean the sigma 20mm f/1.8.

Personally, I would rather take a 16-35/17-40 to go with your 24-70 instead of the 20mm. The 20mm is wide, but not quite 'ultra' wide. It's not that popular of a lens.

picturecrazy wrote in post #7706877
you must mean the sigma 20mm f/1.8.

Personally, I would rather take a 16-35/17-40 to go with your 24-70 instead of the 20mm. The 20mm is wide, but not quite 'ultra' wide. It's not that popular of a lens.

even on a 5d??

ngrohosky wrote in post #7707408
even on a 5d??

even on a 5D. 20mm isn't a giant step wider than 24mm.

I can't imagine that being a good choice, and those Sigma lenses 20, 24 and 28mm are noted for focus issues too. If you want wider the other options suggested are ideal for the 5D for weddings - 16-35 being better for the extra stop of light.

i mean the canon 20mm.

I have the Canon 20mm f/2.8. I've seen a lot of people who downgrade this lens, but there have been a few who like it as I do. I don't do a lot of wide-angle but have used it for interior shots as well as landscapes and it is a keeper, and a lot cheaper than the zooms everyone is recommending.
If you can afford it, the 17-40 is probably your all-around best buy, but if money is a problem, check out the underrated 20mm f/2.8.
Now, if money is NO problem and weight isn't an issue, the 16-35 II is your best bet.
My 2 cents,
Al Rohrer

For group protrait on FF body, 20mm is too wide. Even 24mm is a little too wide. You will need to avoid framing people toward the edge to avoid perspetive distortion. It is almost like using a longer lens. Otherwise, if body parts are distorted, it is not pleasing looking. Persoanlly, I will try to stay above 28mm for group protrait.

Another thing is aperture, you will not be using F1.8 or even F2.8 group shots. You will probably need to be at F5.6 or F8 and above. So having a fast 20mm won't help on group protrait.

After all, I think you will be better off with 24-70L for group protrait.