Yea, I'm thinking of getting a cheaper one (Phottix) since I heard it works well and is tighter compared to Kenko.
However, is there a drawback in optics?
Will it be harder to focus? (I heard it won't focus to infinity if you have these and will have to manually focus sometimes)
Is there a delay in AF if this is attached?
I plan on using this on some macro (not a whole lot) and also because I hate the fact that my 80-200mm 2.8 has a minimum focusing distance of almost 2 meters
The drawback is that you will loose light (the longer the extension tube the more light you loose) so your 2.8 lens might become 4 even if it still reads 2.8 in the camera there will be less light getting to the sensor.
You will NEVER be able to focus at infinity using any brand extension tube. Optically, there is no lens in the extension tube so it shouldn't be a problem, but… I've notice that some lenses seems to work better with them than others. Maybe it has to do with the original quality of the lenses?