I have just bought a letus extreme and a canon 550d.
For the beginning I would like to buy a zoom that I can use with both: letus and T2i.
I want to do a lot of handheld stuff with the T2i - thats why I need a lens with IS (or VR as Nikon calls it).
Are these DX-format-lenses with VR ok for the use with the letus extreme?
for example:
Nikon AF-S DX NIKKOR 18-105mm/3,5-5,6G ED VR Objektiv

Or is there any other Nikon-zoom you could recommend that fits both, has constant aperture plus VR?

If this lens is a digital-only lens suitable for smaller digital sensors, it may not be ideal for the Letus.

You will be confined to a smaller area of image on the groundglass versus what is available, greater magnification of the groundglass texture by the camcorder zoom will be required to fill the frame and a lesser apparent resolution may be the outcome, not just with the Letus but other adaptors as well.

Furthurmore, the aperture range of this lens tightens with zoom-in meaning you have only about 2 stops of headroom before you risk getting artifacts, so your zoom range will not be reliably accessable.

The accepted practical limit for groundglass devices shakes down to f5.6. There are exceptions. Particular lenses, generally longer ones, sometimes perform right to f11. Others, in my experience across several adaptors, mostly wide lenses may artifact at f4.

Depending on the diameter of the exit pupil of the lens, you may experience a brightness fall-off in the corners at the wide end.

Others who have tested this lens might hopefully chime in and contest my comments.

There have been previous discussions about a Nikon constant aperture f2.8 zoom. I don't have that info to hand. It was discussed in the Letus pages here a while back.

thank you very much for your detailed reply.
i did a search in the forum - and i think there is no "one for both"-solution - at least if you need a zoom with Image STabilisation (and maybe constant aperture as well).
- if i am wrong i am very happy if someone can help me!

Any lens with an inbuilt I.S. is not going to work on the Letus and as far as I know any other adaptors because the lens requires power and signal sources which the Letus does not provide.

I bought a used tokina atx-pro, 28-70, about 2 years ago to use with my Letus Extreme. It's a nice zoom lens, is fast (2.6-2.8) and very affordable. I bought a nikon to canon adapter when I got my 7d, and the lens works fine on the 7d.
I got mine used at bh for $275, which is a good deal.
Since I got my 17-55 canon is, I rarely use the Tokina, but the extra zoom is very usefull in certain situations.
Bruce Yarock