Fast f2.8 Lenses for UW Use

So the advantages for fast lenses topsode are clear (ok, becoming less important with low noise bodies like the D70, but still) My question is do these same advantages translate to UW use? I would think more so given the light-filtering effects of water.

e.g. will the Nikon 17-55 f2.8 DX perform better (sharper, faster focusing, better saturation, etc) than the slower 18-70 f3.5-4.5 DX?

I guess the other thing to worry about is loss of depth of fiels when shooting at f2.8.

So what has the experience of this forum been?

Thanks,

Brad

Faster the better.

All my lenses are fast primes, so I can't really talk about the performance of the slower zooms.

Years ago I did take my Noct underwater to see what the difference would be. WOW! The brighter viewfinder was amazing, and lots easier to judge focus. So if you're using slow stuff now, switching to something faster might give you the same impression.

Just thinking that AF performance would have to degrade with slower lenses. And I've never been a fan of zooms with a varying f-stop depending on focal length. Makes for an extra mental gymnastic when shooting manual strobes.

For me, the big advantage has been while composing, etc, when the lens is wide open; not when depressing the shutter, when the lens stops down. And of course you benefit from the better lens quality, too.

All the best, James

My take on this.

Fast lenses are useful for wide angle particularly for natural light shots. See http://www.users.on.net/~abowie/VW2004h/VWindex.html for some recent wreck shots. Most of the natural light shots were at f2.8 and around 1/15th.

Much less important for macro as you'll always be using strobe lighting and usually using smaller apertures for improving DOF. Mind you the good macro lenses will in general come in at f2.8 anyway. My 60mm is an excellent land portrait lens at this aperture.

Zoom lenses are always an optical compromise that will work best at one focal length and not as well at others. How this ties in with the optics of your port and housing plus any dioptres required to get the virtual image right is a lottery. Some will say that they give you a lot more creative leeway underwater but I find that composing is as easy as moving closer (or much less fequently further away). I don't use them.

Which housing will you be using it with. Not every housing manufacturers support the 17-55mm yet, eg Sea and Sea and Nexus.

Since both are zoom lens, I guess prime vs zoom debate is moot anyway. I have the 18-70 and my buddy has a 17-55 and I think that the 17-55mm is definitely a much better lens, optically. The 18-70 does not focus very close anyhow so it is not a very useful camera for macro so the extra 15mm or so is not all that important.

The 17-55 is def. a better lens for UW. Primarily because of the closer focusing distance. The faster (2.8) speed of the 17-55 is superior' not because you will normally shoot it that wide open' but because it usually indicates an optically superior lens. One that will keep it's optical qualities at wider F stops. Of course I've noticed a number of Zeiss and Lecia lenses don't go to 2.8 yet are considered superior lenses.

In further explanation a 2.8 lens might be sharp at an F stop of 4.0 where a 3.5 or 4.0 lens might not be as sharp at 5.6. Thus though you might not shoot the fast lens at 2.8 you can probably shoot it a stop or two faster than you can a slower lens and probably still have a sharper lens.

If you are financially challenged you might note that your 3.5 or 4.0 lens might be quite sharp at apertures of around 6.3 to 8.0. If this doesn't let you have enough light remember you are shooting digital. Boost your ISO to 200 or 400 and you might be able to shoot at the smaller aperture.

The 17-55 is a fine lens but perhaps a little narrow for wide angle UW. Consider the 12-24 and shoot it at 5.6 or higher.

It may be difficult to exploit the large aperture with a dome port due to curvature of field. One needs to do actual comparative tests to see if anything significant is gained.

Tom

2.8 lens are the best optically and are worth it topsde and under. The same qualities that you use them topside matter underwater. They cost more and are worth it. The macro lens are lower dollar anyway. heck the newer nikon 200 1 to 1 is still a F4 dog. It still cost $1300. 2.8 -60 and 105 are almost free compared to the 200. You often pay for what you get. Mark

I've just started using f1.4 lenses underwater (the Canon 24/1.4L and 35/1.4L), and I am really, really enjoying the quality, especially compared to the crappy Canon 16-35L/17-40L lenses, which are nearly unusable around the corners on a full-frame camera, and only sharp at f7.1 or 8 and above.

But the 24 and 30? Love 'em.

Not as happy with the Canon 20/2.8 lens, so I picked up a Sigma 20/1.8 to try out here in French Polynesia. Results will be online when I return.

The "good" zooms tend to be pro lenses that happen to be f2.8 and expensive. It would be great to find smaller, lighter lenses that perform well at middle apertures. No real benefit from a 2.8 lens if you aren't going to shoot anywhere near 2.8...

oops

No real benefit from a 2.8 lens if you aren't going to shoot anywhere near 2.8...

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Viewfinder brightness and autofocus performance?