Canon 100-400 to tighten or not?

For those that own the canon 100 - 400. How tight or loose do you leave the ring that locks the focal length in place? Do you leave it loose so you can easily change form one distance to another or do you tighten it down every time you go to shoot? If you leave it loose does it effect image quality?

While shooting I keep mine loose. During transport I tighten it.

Tightening it doesn't affect yoour image quality.
How loose/tight you have it is entirely determined by your own preference depending on how you like to shoot.
I use mine with just enough resistence to prevent it creeping but loose enough to be able to zoom quickly.

I think it depends on your shooting style and how you use this lens. Me personally, I zoom it to 400mm and lock it there. I rarely use this lens at less than 400mm, but that's just me.

philwillmedia wrote in post #10999642
I use mine with just enough resistence to prevent it creeping but loose enough to be able to zoom quickly.

This is how I usually have mine too - just snug, but loose enough to zoom if required.

Depends what I'm doing. Sometimes in airshows, especially with paratroopers I find I like the ring a bit more snug, otherwise it will sag down from 400mm if I'm not careful. Other times for sports I like it quite loose so I can quickly go from near to far action. Just depends. As said above it doesn't affect image quality at all. I don't tighten it for transport.

tightned for transport
less tight under normal use..........just snug enough to prevent creep though

Mine is either completely tight (when transporting), or completely loose (when in use). I never use anything in between. It does not affect IQ.