If you could only have one lens for your camera what would it be and why???

as wide as i could get .. for both UW and Above .. so the widest i have now is 15mm fisheye (would like it on a full frame body though)

60mm micro. This is a great all around fish portrait lens. I like fish portraits. Super sharp. Focuses fast. It can even make a great macro ~1:1 lens for static subjects. Above all its simple.

17-55 f2.8
Fast and sharp
Can use topside and UW, will handle most subjects topside and UW. May not be ideal for all situations, but I only have one choice.

60mm.

16mm Nikon FE, or its cousin the 15mm Sigma: fast, sharp, and versatile.

60mm (and a "Woody") :-)

Dave

10.5mm for the stunning underwater scenes it captures... Can't use it much topside, but who cares anyway

15mm Fisheye here too.

Mathieu, have a look at this:
ImageTrends Hemi Filter

It makes for some interesting uses of the full frame fisheye topside. It seems to work like Mercator projection, restoring straightness to lines and proportion to people and other recognisable objects that rectilinear doesn't give you.

Martyn

Nice one, Martyn. It seems to correct the distortion pretty well. I've tried 2 or 3 different software before without much success. This being said, you'd have to think about the cropping that happens at the corners at the time that you're composing the shot...

Obvious, no compromises: it 'll be 10.5 mm Fisheye for me. Probably the new Tokina 10-17 mm would become my first choice if i didn't have a 10.5 mm Nikkor already. The second lens i certainly wouldn't like to miss is my 105mm VR macro lens.

cheers, Udo

prime: 60mm, zoom: sigma 17-70mm macro

I just purchased a Sigma 28-70 f2.8 lens and I think that it is going to replace the 60 mm as my favorite all around lens. Fast and focuses well in low light.

You can't do it with just one lens. You need one for wide angle, and one for fish and/or macro. Assuming you're talking about a cropped sensor camera, I'd say:

Canon 60mm 1:1 macro (for macro and fish)
Canon 10-22mm (for wide angle and big critters - sharks, mantas, etc.)

If you're talking about a full-frame camera (although if you're spending that kind of money on a body, it's unlikely you'd be even TRYING to limit yourself to one lens! ), I'd say:

Sigma 70mm 1:1 macro (for macro and fish)
Canon 17-40mm (for wide angle and big stuff)

The original premise, you only have one lens, means that any lens at either end of the spectrum essentially eliminates a significant number of shooting opportunities. It also means one has to choose a compromise lens that can be used for most subjects, though it may not be ideal for any particular subject. It has to be useable topside and UW for most situations as well, and of course fit in my housing. (Eliminates 18-200 of course). So it's a zoom; moderately wide to short tele, focuses close enough to be able to see smaller critters in the frame. In my collection the only lens that fits these criteria is the 17-55. Having said that, because I do have choices for subject specific lenses, it's probably the lens I use the least.

The new 1 to 1000mm f1.0 zoom.

Canon 10-22. I LOVE that lens.

Are you talking about the compact macro zoom lens that Canon is giving away when you buy the $25,000 lens hood???

Bart

Well, the Canon engineers tell me that the lens was easy, using their new auto-liquid vario-flex lens material.

The real challenge was engineering a lens hood that changes shape to match the zoom extremes of the lens...

I have seen some CA at f1 so I recommend stoping down the lens to 1.2 or 1.4

About the topic! If it has to be only one lens then sigma 17-70 macro...

I am just migrating to digital underwater after 20 years with Nikonos.

I have chosen for my first lens the Olympus 11-22mm f2.8-3.5 It seems like a good all-rounder for clear tropical waters.

So, I guess that would be my serious answer to the original question.

Regards
Peter

Ahh got there in the end..