Somewhat cryptic in Canon's press release regarding the two new EF-S lenses announced yesterday is this statement about a new type of lens diaphragm:

"the EF-S 18-135mm f/3.5-5.6 IS STM features a circular aperture with an Electro Magnetic Diaphragm (EMD) which permits highly-accurate control over aperture settings."

DPReview adds in their description this little tidbit..."allowing smooth and accurate control over aperture for video shooting."

So I guess there are two questions: Is dpreview.com jumping the gun on the "smooth" thing? and if it turns out to be true, would this improve the fine aperture control on the C300?

Barry

Interesting questions Barry.

Having worked out what STM stands for ( Stepper Motor ) and read the available information I guess we will have to wait and see whether it offers smoother aperture control.

I think the image stabilisation will be excellent. But it's the advanced autofocus that this lens offer in combination with the new rebel T4i / Eos 650D that's really of interest.

But unless this lens has superb optics I don't really see it being that much of an addition for the C300 but I will certainly try it out when it hits the shelves of our local Canon dealer.