Is there somewhere I can read more about telecentric lens design, that you guys would recommend?
Telecentric lenses have been around for a while, but a lot of applications use 'object space' telecentrics, which are telecentric in front of the lens. Handy for things like microscope optics or lenses used in industrial metrology to accurately measure objects, since there is no distortion or magnification changes at different object distances. Not much use for cinematography though, since the front element basically needs to be the same size as the object being filmed! Most online information relates to these kinds of industrial 'object space' telecentric lenses.
What we're talking about are 'image space' telecentric lenses, which are telecentric behind the lens. Without investing in books on digital photography technology, there's not a whole lot of online information, but here's a few pages I've come across that are informative:
You can physically check how telecentric a lens is by looking through the back of the lens at the exit pupil, which is the image of the aperture as seen through the rear optics. The deeper the aperture seems the more telecentric the lens. Lenses with a combination of shallow exit pupil and rear elements much smaller than the format size, like certain Zeiss Standard Speeds or Cooke Speed Panchros, will be far from telecentric.
Does telecentricity also mean better MTF then?
Not necessarily, better MTF is a function of the whole lens design and build quality, I'm sure you could find a crappy lens that is also telecentric.
It just means that on digital cameras you will minimise the chances of introducing uneven illumination and colour fringing.
A big advantage to telecentric lenses is that they don't breathe (change magnification as you rack focus), not something measured by MTF. But there are definite disadvantages, too. The rear element needs to be at least as large as the format size, and by limiting one design parameter other compromises might be forced on the lens design. So telecentric lenses are often larger and contain more corrective elements. Usually you'll find modern cinematography lenses described as "near-telecentric", because making them perfectly telecentric was too much of a design compromise, and being nearly telecentric is good enough.
Certain cameras, like Alexas, that have fairly large photosites are generally pretty tolerant of non-telecentric lenses. Maybe it's accepted as part of the "vintage look", but nobody seems to complain about Zeiss Standards or Cooke Speed Panchros vignetting on Alexas. Different camera sensors no doubt react differently.