30mm or 50mm ?

On my 50D crop body what would be a better choice, Sigma 30mm or 50mm f/1.4 ?

For what? Both are good as paperweights.

I'm looking for a decent fast lens.

Do you use your 24-70 more often around 30 or 50? Wouldn't that be your answer?

For indoors I would go with the 30mm. I have a 50mm on my crop body and I can't back up far enough to get anything other than half body shots of my 2 year old most of the time.

If u have plenty of room to back up, the 50 is a good choice.

alexxn wrote in post #13664825
I'm looking for a decent fast lens.

Both can be bought in a fast (1.4/1.2) version - what are you going to be using the lens for?

General walkaround, indoors, outdoors, etc. need to be known before someone can suggest what would likely be right for you.

xarqi wrote in post #13664838
Do you use your 24-70 more often around 30 or 50? Wouldn't that be your answer?

Or, do you get more shots at 30mm or 50mm with the 24-70 that would have been better if you had a faster aperture available than f/2.8?

For me personally, I most commonly want very fast apertures in the range of wide (35mm lens on a 35mm sensor) to normal (50mm lens on a 35mm sensor). At longer focal lenghts I tend not to need such fast apertures as I'm usually framing tighter and the DOF is too thin with very fast apertures.

DDL wrote in post #13664843
Both can be bought in a fast (1.4/1.2) version - what are you going to be using the lens for?

General walkaround, indoors, outdoors, etc. need to be known before someone can suggest what would likely be right for you.

It's mostly for indoor low light situations.

A 30 to 35 mm f/1.4 would probably be your best bet if you want to shoot indoors without a flash. There are several good choices in this segment from a Canon 35mm f/1.4L, Sigma 30mm f/1.4, Canon 35mm f/2 (might be a little too slow).

As stated before 50mm is a bit too long to use indoors in house rooms if you want to get more than just head shots.

However, using a flash with any of these fast lens will likely give you a better picture than just counting on low ambient light - less noise and better white balance are benefits of using the flash.

Take a look at your photos to find out what focal lengths you use most. Either way, I would prefer the 30mm for indoor use on a crop…

Julius

DDL wrote in post #13664873
A 30 to 35 mm f/1.4 would probably be your best bet if you want to shoot indoors without a flash. There are several good choices in this segment from a Canon 35mm f/1.4L, Sigma 30mm f/1.4, Canon 35mm f/2 (might be a little too slow).

As stated before 50mm is a bit too long to use indoors in house rooms if you want to get more than just head shots.

However, using a flash with any of these fast lens will likely give you a better picture than just counting on low ambient light - less noise and better white balance are benefits of using the flash.

Agreed. One thing I'd like to add is that the canon 28mm f/1.8 has very accurate (and quick for a wide) AF. Plus it has a small MFD. It's not f/1.4 though.

On your crop, the 30mm (or Canon 28mm) is a "normal" lens. And, a 50mm is a short telephoto. Neither is "best", nor is either "too short" or "too long"... They serve difference purposes. You just need to decide your purpose for the lens, then base your decision on that.

Get them both and see which one you like best. Send the other one back.