Subjective Comments please.

As the Sigma's 18-35mm F1.8 DC HSM is still not available to buy for Pentax (early september)
I just wanted to ask which of these lens would you buy? I know they are different focal lengths and one is a prime vs a Zoom. Obviously comments will be subjective, but I am interested in opinions and reasons why, for and against.

Pentax 31mm f/1.8 FA Limited
Sigma 18-35mm F1.8 DC HSM

If I could afford either (which I can't) I'd go for the 31mm Ltd.

For me, a lens this fast is something I use rarely, but when I want it there's nothing else that will do. Therefore my fast lens has to be small enough to live in my camera bag without taking up too much space. The sigma is just too large to take on this role for me, and the range is too short for an everyday standard zoom.

The 31mm Ltd on the other hand would live where my FA 50 1.4 currently does, nestled in the bottom of one of my bag pockets, ready for action at a moments notice but otherwise out of the way.

I know the 31mm LTD has such a great reputation that if I had the chance thats what I would be seizing. The size makes it a special thing - both for carrying when you don't want a camera bag, plus the handling when on the camera.

Of course, f1.8 for any zoom is also special, and no doubt this Sigma is a quality item. But surely for most applications at the wider end of this range (18mm+) f2.8 would be wide enough? I'm not sure there would be that many images that would demand f1.8, or even benefit from it,at this wider end?

Traditionally such wide apertures were for the light gathering aspect, not extreme DOF, and now we can get the light gathering through higher ISO anyway.

If it were a straight choice probably the Sigma.

I just feel that based on the 2 Sigma lenses that I own that the quality is superb and the flexibility of the 18-35 zoom range would be nice to have.

I'd get the Sigma. 1.8 @ 18mm through to 35mm would be great.

Thanks for your views guys. Looks like it's 50 / 50 as to what people would choose. I have ordered the Sigma as I think the focal lengths will cover a few bases and I love that fixed f/1.8. The FA 31 still seems to wear a crown in reviews though. I wonder if the FA Ltd's will get the HD coating treatment, and are the blades in the FA 31 rounded?

Let us know how you get on with it as I quite fancy one!

I will do Andrew, I think they are due for UK distribution early October.

I'd definitely go for the Sigma, more versatile, and they've really upped their game in the last couple of years. I love my 15mm Ltd, but I have to say that the Sigma 8-16mm out-performs it at 15mm, except in distortion, which I've now got the hang of anyway.