because if you don't pre-order you won't have yours until late summer, and soon as they are available at rental houses in the next month there will never be a 5DMK2 on another professional set, and if you plan on waiting for a MK4 then you'll be waiting 2-3 years.
since you were wondering why...
That does not really answer the question. The person is asking why people are pre-ordering a camera when there is still so little information about how well the camera will actually meet their needs or how good the improvements actually are, not to mention what design flaws might be present.. with the implication that it would be more purdent to wait a few months and see how they get vetted.
As for studios.. I am skeptical that the 5D3 will wipe out 5D2 professional use overnight like that. The camera has some marginal improvements, but I imagine quite a few places are not going to be so careless with their money that they completely convert to the 'go faster stripes' model so quickly and completely, esp when the 5D2 has proven it can be used for professional published (and televised) work that is acceptable to currend end-user standards.
well i have to say you are dead wrong on this, as someone that orders the camera package every week for my upcoming shoots, i would never order a lesser camera body then the newest model that is out and available. for example as soon as the red epic became available, there was never a red one camera on my set again. its not worth the slight discount not to have the newest technology on a professional set. as another example, since the new 70-200mm MK2 has been available, there has never been a 70-200 MK1 on my 5D sets again. sorry to inform you of this, but in my 20 years of filming professionally i see cameras come and go that fast, even back in the film world. we all shot on arri BL's, then one day the 535 came out and there was never another BL on set.
sure for your personal projects you can still shoot with it, but if you are entering or in the professional rhelm of the industry, we are moving on to the next generation of cameras and yes, its that fast!
also, if he wants to see the big Improvement, this is one of the best examples i have found, but the real reason we are all preordering is because the canon dslrs have proven themselves, so much so that by name they are actually written into treatments. "this is a 5D job"
it seems to me that the improvements are far above marginal and this price for studios in ridiculously cheap to upgrade, plus its not the studios who upgrade, its the rental houses. and you want to know what the clients really care about? that their monitors stay in HD while you are recording, for that alone nike does not allow me to shoot on 5Ds, they specify 7Ds for all their shoots and when i got to the bottom of it, the reason was client monitoring.http://www.eoshd.com/content/7328/astonishing-canon-5d-mark-iii-iso-12800-video
go ahead though, wait a few months, i will have made most of my money back on it by the time you get yours in august.
these things will be back ordered for most of the year according to some websites.