Is the air in the Canon tubes better than the air in the Kenko tubes? For most applications, the Kenko tubes are just fine (the only reason I went with Canon tubes is that my main use is to reduce the MFD of a supertele, and I wanted to be sure of the mount strength - not an issue of concern for macro lenses).For starters math is not my strong point. Just curious as to how much the MFD is reduced on a 600mm lens when using extension tubes. I currently have two setups.
1. 300/2.8 w/ 2x TC, MFD ~ 10ft.
2. 600/4(non-IS), MFD ~ 20ft.
Will an extension tube(s) get my 600 MFD to ~10 ft?
My slight understanding of the math says no.
Thanks for any enlightenment you may provide.
An EF 25 tube will get your 600/4 to an MFD of ~15 feet.