I've been looking for a sigma 24-70mm as I'm looking to do some low light photography with a fairly Ok zoom.
Just a question, will the f/2.8 help me to get sharper images or should I actually be looking for an image stabilising lens ? I've had a look at some IS images and it seems to reduce blur quite significantly. Will a 2.8 lens do the same as it let's more light in ?
In short I'm trying to figure out if IS is better for getting sharper shots then a wider aperture lens? Obviously the quality of the glass matters a great deal but if I'm looking to do low light photography and some street photography would it bit better to invest in an IS with some zoom range or go for a wider aperture like the sigma 24-70 f2.8 ?
I'm working with a 350d and find myself constantly shooting with ISO1600 and I'm guessing this is why my indoor pictures are more blury with noise then if it was possible to shoot in a lower ISO? Please correct me if I'm wrong and any advice is appreciated as I'm a beginner.
If you want moving objects to be sharp then the only way to do this is with fast shutter speeds, no amount of IS will help with this, however if you are happy with blurred people, or even 'ghosts' then the IS will help.
f/2.8 is as fast as you can go with a zoom lens, however primes go a lot faster, so if you can live with the fixed focal length and the shallow depth of field they are a good alternative.
The Sigma 24 - 70mm is a reasonable lens but it is quite cheap, if you want to buy an f/2.8 lens with IS you'll have to pay about 3x as much (Canon 17 - 55mm f/2.8 IS) of course it's cheaper second hand.
If you are wanting to take indoor shots, especially at this time of year, you'd be better buying yourself a flash or even a couple, slave units can be bought very cheaply.