I"m not sure if this is common knowledge but i'll post it anyways incase there are some of you who are unaware of this.

The lens collar on my canon 500/F4 has been kinda stiff for a little over a year. I never knew why, and I remember reading other posts about people being unhappy with their non-fluid collars.

I recently bought a lenscoat for the 500, and in the instructions, it says to take the lens collar foot off since it makes it way easier. I did this, then after put it back on. A few minutes later the collar jammed and would only move an inch both ways. I was scared that it was broken and i'd have to send it in.

I took the lens collar foot off again, and found that one of the little screws in there that holds the super tiny bearing casings on was very very loose (the screw was so high which stopped the collar movement). So basically I tightened it up, and checked all the other bearing screws and they were all loose too. After tightening them all up and putting the foot back on, the lens collar felt like new. The original fluid collar feel was restored!

So, if your collar is a bit stiff, simply just tighten up the little screws. Hope this helps!

Is there any benefit to a bit of lubrication applied to the roller bearings inside the lens collar? Any harm?

Regards,
TonyQ

The bearings appear to be marginally sized for the service, there have been articles posted elsewhere in replacing them with improved bearings. A good idea is to apply loctite to the screw to prevent it loosening, you want the grade that allows you to undo the screw.

Lubrication probably wouldn't help, you can only apply it to "open" bearings, that is without a seal/coverplate. Only problem is that the lubrication then is not contained and is prone to picking up grit and dust. The article I referred to above was how to replace bearings on a 400mm f2.8 collar, that showed the bearings as being open. I seem to recall when I installed my lens foot on my 500mm f4 that the bearings were closed/sealed type.

All you have to do is get an 800mm. They have a huge collar that doesn't hang up. Never mind the $13,000+