Sigma just announced a new 180mm F2.8 macro lens that can shoot 1:1. I've only ever used 60mm and 105mm macro lenses. What are your views on whether this new lens would be any good underwater?

http://www.sigmaphoto.com/shop/apo-macro-1...sm?link=jan_m_2

Good luck getting that inside a port.

I have their 150mm 1/1 macro 2.8 lens which is very similar. I bought it for shy fish and other special effects. I had a port custom made to fit it. I think the lens I have is amazing but for underwater it is very difficult to use and the results aren't so good. Holding it steady underwater takes patience. The hsm focusing is very fast but with the low contrast environment of the underwater world it does search a lot. I also bought the dedicated 1.4 teleconverter and that just makes it harder. The working distance is so great that strobelight traveling out to the subject and back to the camera leaves a lot to be desired. Lots of movement is recorded, contrast is low, color is weak (I use dual Ikelite DS125 strobes). Not what I expected actually. Topside it is a beauty. Very sharp, fast focus, quiet, killer bokeh. A real gem. It just doesn't translate well underwater and I have tried and tried. It is amazing how much sharper images from the 105 and 60 are underwater just due to less distance (water to shoot through).

I have the 'old' Sigma 180mm macro that I use for fish portraits. Most of the photo's in this gallery are made with this lens. Working distance approx. 50 cm. Single Sea&Sea YS350 at half power for light.

I have never tried the 180mm lens, but I've had some success using the Sigma 150mm macro lens underwater. Its only good for close up macro - otherwise the strobes are just too far away. Also the auto focus tends to hunt in low light and with the port I am using there is no option to focus manually. Personally I find the 105mm to be a better macro lens under water. You could probably get some good shots with the 180mm, but it would be difficult to use and the applications would be limited.