Will Steer
As a colourist I must say: both a very important, perhaps equally so.
If you're making a film and want it to look polished or cinematic, you need good glass and good grading.
There's a huge difference between a film shot on Hawk anamorphic glass and Lomo anamoprhic glass, and those are the same kind of lens, broadly. Spherical lenses have a similar variety. Not to mention the relationship between film gate/sensor size, aspect ratio and focal length.
If you shoot in log, there will naturally be a huge difference between the image you shot and the final image, but that's like pointing out that the negative and positive look wildly different: one is an unprocessed image and one is a ready for the viewing public.
Someone earlier in the thread said that lighting and production design are much more important than grading or lenses, I thoroughly agree with that,
I've seen colourists use technical LUTs to bring log footage into Rec709, but never for creative purposes.
Personally I avoid them unless it's superfast turnaround work and just use contrast or lift/gamm/gain to bring a shot to a pleasing level of contrast that doesn't clip in the wrong places on my scopes.
I'm a Resolve colourist. :)
Baselight editions is the only plugin that works within FCP and Avid with features close enough to a full grading application.
To all those people going 'how do I do this in X/Y/Z editing program': you can't, at least with nowhere near the nuance the above tip demonstrates.
Unless you want to pay for, install and learn the Baselight Editions, which is almost as complex and just as GPU-hungry as Resolve.
This is why colourists exist.
13:1 is roughly equivalent to RC36 which people using the Red One have shot with for years. You'll have no problem with compression, Red's wavelet codec is excellent.
You have been fed some serious misinformation, and I've seen this happen before.
Digital compared to film blows out highlights in an extremely unpleasant way so you should never overexpose digital unless you want your film to look very harsh and blown-out.
Moreover, once an area is completely overexposed it cannot be reversed in post, especially when shooting for Rec709.
The answer is simply should shoot it right, and not rely on post to save your film.
Even if you were shooting log this would be true.
I'm a colourist by the way, and I've seen the work of good and bad DoP's and camera ops. The best material is always the stuff where they try to get it right in camera.