With 1:2.3 reproduction, this should be an attractive option for new dslr converts who miss their compact camera's versatile zoom lens.

I thought that as well. Especially the reproduction ratio should make it quiet versatile (that is even close to what the Canon 50mm Macro does). It doesn’t seem to be advertised as an EX lens, so it might be quiet affordable. f2.8 at the wide end isn’t bad at all.

Julian

At F/4.5 at the tele end, the autofocus will not be that good. It'll be a challenge to use as a macro lens. At the wide end a dome will be required. I can't see recommending this for underwater use.

I don’t think this lens could replace any speciality lens (macro/ww/fisheye). But I do believe this lens is an interesting beginner choice over some existing kit lenses like the 300D/350D kit lens. Behind a dome glass, it should be a versatile choice if you jump into DSLR underwater photography. The close-up distance is pretty good too for usage behind a dome glass. If money is no factor, of course, one can buy all good glass at once :-)
I still like the range of my 18-50 f2.8 EX for underwater too.

Julian

Hi Julian,

What is your experience with the Sigma 18-50mm f2.8 in terms of autofocus speed and accurary. Are you shooting without dioptre behind a dome. Finally is anyone using this in an Ikelite housing. It's not listed on Ike's port table but based on the dimensions I think it should fit.

Bart

Hi Bart,

besides being a non USM/HSM lens, AF is quiet fast and accurate. f2.8 helps the AF system too. I know there have been some threads in the net about the lens having AF trouble/offset topside in conjunction with speedlight AF assist beams. But I've never experienced such things.

I use it without dioptre behind the Sealux dome and close focus is a few inches from the dome glass. But I might try +1/+2 in the future.

Julian

Neither of the limitations you mention are any different than the lenses found on compact digital cameras like the Canon S70, Olympus C7070, etc. Lots of people use them w/ their limited telephoto max-aperture, and behind flat ports. I know of pro shooters who use 24mm and 28mm full frame lenses behind flat ports, tolerating the loss of image quality for a different perspective.

I agree w/ Julian. I don't expect I'll buy this, but it is more attractive to me than either a 17-40L from Canon or 17-55dx from Nikon due to close focusing ability.

People tolerate lower performance because of lower cost. There're also wet lenses for improving wide angle performance. I can't see putting out the expense and trouble of a DSLR only to stop short here and settle for this.