Anyone out there used the Canon 180mm macro lens or the Sigma 180mm macro lens?

There is no good way to shoot super macro with Canon cameras while using the 100mm. Stacking the Canon 2X tele- requires the use of an extension tube between the telecoverter and the 100mm lens. This makes auto-focusing REALLY, REALLY slow + unreliable, and at those lens lengths, focus rings won't engage reliably (because they squeeze into ovals very easily).

I'm thinking of trying a 180mm macro w/diopters, instead.

Nope. The Canon 180mm is supposed to be slightly better than the Sigma, which is about the extent of what I know of it.

What about putting a diopter on something like a 70-200 IS? Aside from the massive size that is.

I have the 70-200/4L lens, which is very light. But you'd need a pretty massive diopter to get past 1:1, which is what I would like. Someone know how to do the math?

The Canon looks promising because it accepts the 1.4 and 2X converters, which I already have. But it is around $500 more than the Sigma lists for. The ports I have will work with it, I'm pretty sure. But I might have to get yet another extension to use it with a teleconverter.

I'm looking forward to shooting super-macro again. The last time I strugged to get sharp images with my stacked 100/extension tube/converter (and failed!). I'm going to print out a resolution chart and do some tests as soon as I get a chance (to see what apertures maximize sharpness) -- probably in late May or early July.

Canon really needs to revamp their macro lens lineup. They need a better 50mm macro (needs internal focus with USM) and some sort of zoom macro like Nikon has.

I've used the Nikon 200mm with diopters, the 105 + 2x and the 105 + 1.4x. Between them I preferred the 105 + 1.4x because the crop factor makes the longer focal lengths hard to handle. For full frame I think I would prefer a 180 or 200 to the 105 + 2x, but the 105 + 2x does work really well. I always thought that the Sigma 180 was and heard the Tamron was as well. When using the 200mm I used a +3 plus a wetmount.

Here is an interesting comparison of all the macro lenses:
http://orchideen-kartierung.de/Macro100E.html

What strength diopter were you thinking of putting on the 70-200L?

Are the extension tubes you're using cheap ones? I know the Kenko extension tubes have more flex than the Canon ones.

I tried the 400/5.6L with a diopter a couple of days ago, and it looked like the magnification factor was pretty good. May be a bit challenging to find a port for, though!

Eric: One thought (although it is a bit goofy) is to use the reversing ring setup from Novoflex. Works great on land with the 28-105 lens and can go to super macro quite easily. Don't know about ports though.

BVA