Hi,
I've been using Nikon primes on the 5d and 7d. with Bartech follow focus. the widest I've shot is 20mm and I can get my shoulder in sometimes when not carefull. I find the nikons to be of good quality and with a bit more focus travel than any lens made for canon eos mount. I have a 20 2.8, 24 2.0, 28 2.0, 35 2.0, 50 2.0, and 85 1.4. Truthfully the 85 is a demanding lens not just for me on the pilot (which flexes quite a bit and this can be discerned at this focal length) but also for my focus puller. If you want a good set of practice lenses i would recommend you buy used Nikon glass. Make sure to get Ais lenses as they are the ones with the most modern coatings. I most highly recommend the Nikon 50 2.0 ai. This lens was replaced by the 50 1.8, which is not as good. The 50 f2 is probably the only photo lens that does not breathe when focused and it's frickin pin sharp wide open. For the $80 dollars you might spend on this lens you will be shocked. I avoid canon lenses as they have several issues. first is their speed usually 2.8 for the zooms. the primes are usually 1.4 or 1.2 in the case of the 50 and 85 though they be good the breathing and focus shift i've experienced with these optics is considerable, breathing while focusing and shifting while stopping down, incidently stopping down is always noticeable due to the nature of the aperture being electronic. Second is the focus travel very short. third is they focus past infinity, this is not so good when calibrating follow focus, ( a diligent AC will help here but even so one can not be absolutely certain where infinity actually is, because canon lenses are designed to expand and contract with ambient conditions. If it's cold infinity maybe further than when it's hot). and four price for the cost of an L series lens around 1400 on average you can buy 4 or 5 nikon primes each a stop faster than the zooms. Hope I've been of some service.
