@azza_act: I take it you are the DoP and not just the camera guy? I think what you should think about here is a) what are you going for? (in terms of look, feel e.t.c) This is something you decide together with the director. b) what lenses, shots (angles, camera movement) a.s.o. will work in line with that goal? c) how do you light / what lighting can you use?

You think about this for the movie as a whole as well as individual scenes e.t.c. and that should give you the answers you need.. Do not get stuck in the lens setups you already own if there is no other reason than practicality involved in the decision. For the money you save on shooting with dslrs, you could easily afford to rent an Optimo f.i. (unless you are planning a protracted shoot – when it might be better to look to buy equipment, even if it´s expensive, and sell when you are done). If you are the DoP you will need to make the outlines for the look you want and how to achieve it and if you have done that properly, you will be much more free to experiment or use creativity to solve problems on set / lead your team.

There are no principal problems with using zooms.

Barry Sonnenfeld once told me that he wanted to try shooting an entire film with only primes. He went on to say that if he could only use one lens it would be a 21mm. He was refering to Super35's aperture which is just a bit larger than the GH2's. I also believe comedy is best shot wide.

I think through necessity .. if you have to. It depends on whether you want to make 'moving pictures' or advance the fine art of 'zooming pictures'.

I wouldn't do it, except if trying to emulate a section of ENG .. or mimic a B grader from the 70's

@kavadni It's a comedy so I doubt we'll be doing any "zooming". It's just for practical purposes of not haven't to change lenses in the middle of a huge crowd or a night on the streets. It's going to be fairly "guerrilla" in that sense. But I would say maybe 30% of the film will require that type of shooting. The other 70% is set in houses/ hotels and classrooms. Will have a least 2 GH2s and a GH3 (hopefully) on set, so I might throw the olly 12mm on the GH2 b- cam, then keep the 25mm on the GH3. Then just swap the cameras with the rig when I require a different lens.

Being able to design a 'perfect zoom' on a computer, is a far cry from building it at an affordable price.

I have big issue with term "affordable price". It is relative and highly subjective term.
If you get proper basis (food, home and energy prices) and compare it to zoom lense you'll discover unique stuff. This things constantly become cheaper and better.

As long as you are not zooming while filming, there are not many problems. Even a non-parfocal zoom with changing aperture can be used as a variable 'prime'. Some zooms have not so nice bokeh, but the 12-35 2.8 by Panny seems quite OK. It only has problems of keeping light constant while zooming.

I think Vitaliy is right about the "baboons sitting on forums", modern zooms can be very good. But another part of the objections against zooms comes from the video world, where many people are zooming while filming. This can look quite distracting, since human eyes don't have this feature ;-)

An occasional gentle push-in (or -out) is fine for dramatic effect, but you don't need a very long zoom for that.

Finally, it's much harder and more expensive to construct a good zoom for full frame (35mm still) than for µFT.