Canon 100mm vs. Sigma 150 mm under water, help??

Hi there,

has anyone tried both of these underwater ?

• Canon EF 100mm f/2.8 Macro USM
  
• Sigma 150mm f/2.8 APO Macro DG
  

I think they are both very similar in terms of optical quality (very good so I gather), but the 150mm will obviously give me more working distance.

The sorts of things that would be interesting are:

How quick is the autofocus underwater?

How difficult is it to focus when peering through the tiny viewfinder of a housed 1.6x crop camera ?

With what sort of creatures does the increased working distance really pay off ? (I am heading to Lembeh next year)

Does it get very jittery working with the 150mm due do to the narrow field of view ?

... and anything else you can think of that's worht mentioning when using either of these two underwater.

I guess that hundreds here have used the Canon 100mm underwater, but very very have tried the rather recent Sigma 150mm. And possibly even fewer folks have had the chance to try both

I'll be using it on a housed 300D and my light comes from a 550EX in a strobe-tube set to E-TTL. I have already used the EF-S 60mm macro under water and loved it (e.g. Solar-powered nudibranch). I found it difficult on really small stuff though, because when you need to get really close the strobe gets in the way and you can't get any light into the tight space between the port and the subject.

Thanks

Fred Wobus

The Sigma 150mm macro lens is not an easy lens to aim underwater (with a cropped sensor camera) and I would suggest the 100mm lens as a better buy. Generally I find a 60mm macro lens much more use in Lembeh, than longer macro lenses.

I'd wait for a few more opinions too.

Alex

I recommend getting the 100mm and an 1.4x teleconverter. That'll give you the flexibility of having a 100mm and a 140mm lens. For underwater use, where there's little opportunity to shoot a 150mm lens anywhere close to wide open, there's not a huge advantage to having the extra stop of the Sigma 150mm. At F/8 or smaller, where you'll use it almost all the time, I don't think you'll see much difference in the image quality. The Canon 100mm is great at autofocus and does very well even with an 1.4x.

Even if cost is not a consideration, I'd take the extra 1.4x magnification of the 100mm 1.4x combination over the 150mm and it's extra stop.

I recommend getting the 100mm and an 1.4x teleconverter. ....

Thanks herbko, that is a very good point. I never thought of a tele converter, possibly because of its name I only associated it with telephoto lenses.

I already own the Sigma 1.4x and a quick google-around found a thread in another forum that revealed that they do match up.

What a great idea. I have tested the Sigma 1.4x on the Canon EF 70-200 F4L and found that it doesn't noticably degrade image quality (not with a 6MP crop body anyway). So I'll look for a port extension that will fit both, the 100mm with and without the converter.

Cheers

Fred