With respect to extension tubes: Kenko makes a set of 3 (12mm, 24mm, 36mm) for around $120 last time I checked. These are simply hollow tubes with electrical contacts, and no glass, so in my opinion there is no need to use the more expensive Canon set (which only has 2 tubes). The effect of extension is inversely proportional to focal length: 50mm of extension on a 50mm lens has a huge effect on point of focus and image magnification, but would be much more subtle on a 500mm lens. There are formulae to calculate this (I can dig them out if you'd like).hgmoore said:Asher,
No, these were all pure 300 f4, the f4 focuses a little closer then the 2.8 version.
I've been testing the 500D on the 300, but the depth of field seems about as thick as a piece of paper, even stopped down to f11. And the slightest breeze is enough to blur the subject some, even at 1/250".
I am going to set up indoors with the 300+500D, maybe sometime this weekend, and I will post results.
I think it was you who suggested extension tubes, looks like you are correct. I am going to order the smallest 1st and see how that does w/300.