Thanks Bert.
I like your comparison. 300mm lens packs some punch thats for sure. I was admiring you Eta mosaic the other day. May use it for a scaffold image in due time.
I might start up a new business 'scaffolding for the gentry'. Just kidding.
Anytime anyone needs an almost perfectly rectilinear image as a scaffold for a mosaic with longer length optics just ask.
We are all doing battle with the limitations of our hardware. Collaboration is one way to win.
Actually Jase the 300mm Canon F2.8L is really a 290mm focal length lens. That way they can crib a bit to call it f/2.8 with a clear aperture of 104mm. To be f/2.8 at 300mm the clear aperture would be 107mm. The real limiting factor and expense is the single crystal of Magnesium Fluoride that is the heart of this lens. This single crystal element is in an 'o' ring sealed nitrogen atmosphere. There are also two ED elements in the main front lens combination. The front element is an optical flat which can be easily replaced if damaged.
I have had this lens out in the worst conditions for many years and it still performs like new. It is fully sealed against dust and moisture!
Sorry about the rant. Imagine how long the rant would be if I had a 16" RCOS!
Bert