Does speedbooster (ef to ef-m) work great in video mode on the M3 ?

Emana wrote:

Sittatunga wrote:

Emana wrote:

There is a Meikon case of the eos M3 with the 10-22mm version which is what I need. As nnowak said the problem is the autofocus.

And the lens of the Sony rx is not enough wide.

There is, if you mean the 11-22mm. I would strongly suggest a dome port for that lens if only to restore the angle of view to its nominal 18mm FFE focal length. At 11mm and f/3.5 or smaller I wouldn't think there's much of a problem with focus for diver shots. Without the dome port, the lens will focus on things down to around 50mm (2") across at 22mm and f/4.5 helps with depth of field but watch out for slow autofocus. Video lighting will help both with focussing and colour balance.

But screw in underwater wide-angle adapters for the RX100 case will give at least as much coverage as the 11-22mm with a dome port.

Having said all that, I've not used an M3, I have too many other M series cameras to buy another for underwater.

Yes, I was thinking about the 11-22mm. And the plan is to get a dome port with it.

Thanks for the information Sittatunga.

Wich wide angle lens do you recommend for the RX100 series ? Do you know the minimum focus distance ?

I really couldn't say, having only tried one briefly on a demo in a pool with a demo camera.  Best talk to a specialist dealer like camerasunderwater.  Inon is a brand you could look at for lenses and flash, there are others.    A dome port will require the lens to focus at a distance less a foot (300mm) away as it acts like a minus three or four dioptre lens in front of the camera lens.  (The exact value depends on the size of the dome.)  It also gives a spherical surface of best focus, so not the best for close up work.  Best take a dome or wide-angle lens off for close up.