Sigma 17-70 speed

A quick question - can anyone tell me the max aperture for the Sigma 17-70 - I know it is f2.8 at 17mm and f4.5 at 70, but what is it in between say at 23mm, 30mm and 50mm? I cannot seem to find this info and it will help decide between this lens and the Tamron 17-50 which is a constant f2.8

Many thanks,

Stuart

It is no F2.8 at 50mm, if that's what you are looking for. It F3.5 or F4.
The Tamron is a great lens, but so is the sigma.
FL range is the sigmas strong point as is the almost macro.
Personally F2.8 at 50mm is nice, but at 70mm would be even nicer for portraits.

The Sigma 17-70mm changes its max aperture at these focal lengths:

f/2.8 @ 17mm
f/3.5 @ 23mm
f/4 @ 37mm
f/4.5 @ 70mm

Hope that helps with your decision, btw - the Sigma is a superb lens with fantastic build quality and feels/is very sturdy.

Brian.

Thanks guys - that is exactly the information that I was struggling to find. I have the FA 50mm f1.4 already so probably dont need anything faster at the longer end of the zoom range, but the "almost macro" and slightly longer zoom rang sounds useful!

The Tamron 17-50 F2.8 saves you having to carry/use your primes so much, and it's almost macro, too. It focuses down to 27cm (distance from subject to sensor).

I was also temped by the Sigma 17-70mm, but decided that the Tamron's f2.8 was more exciting than the Sigma's 70mm.

For a more casual general-purpose lens, I eventually (recently) got a second-hand Sigma 18-125mm as well. It's actually better than I was expecting, and 125mm is more exciting than 70mm.

Well that's enough to put anyone off buying a lens! I have the Tamron and primes - guess which one stays at home most of the time? Not because the Tamron isn't superb quality, it's big and primes make you move your feet.

I think it might turn some people on to the lens, actually. Not everyone wants to change lenses often, and the Tamron is smaller and lighter than a set of three prime lenses in total.

I appreciate that some other people will prefer a set of primes. Each to his own.