Supporting a matte box
 

Some matte boxes say that no rails are required. Is it a good idea to trust this assertion, or are rails still recommended?

Rails are always recommended if possible. I have one of those matteboxes that are lens mounted and it is light enough that it does work. I modified it so that rails also support it. I just don't feel comfortable putting all of the stress on the lens.

marcel - can you give some details as to the parts you used to make the modification. I've looked in to doing it but the parts I have found are very expensive

IMHO Short term lens mounted matte boxes (like the Image 2000) are fine if you have a lens that does not rotate at the end while you operate (Nikkor/ Cooke). But if you do then its a situation the demands a rails mounted system. To that end I have learned that saving money on cheap units with rail mounts actually just makes your life harder in the end. It is very frustrating to attempt to slide a follow focus on the rails only to find that they are not well machined. I like Zacuto as the quality is very high, as are the prices - but you get what you pay for.

Peter, the rails I got from IndiFocus had a basic mount that came with the rails. I just built a litle L bracket that I was able to attach to that mount and then mount the other end of the bracket to back of the mattbox with a thumbscrew for easy removal. You could probably buy that rail mount from Tim at IndiFocus at a decent price. The L-bracket and thumbscrew is probably under $2 in hardware.

thanks Marcel - I actually already have the rods - but I spoke with Tim at indifocus and he can send me the attachment I need for $10

they have some nice looking product - and great prices!

Yes, I have not been disappointed with their products and Tim is very accomodating. Glad you got what you needed.