Just a simple test to compare the sharpness and the functionality of the IS

Another test to show the sharpness after adding a 2x TC

Equipment and settings

1dmk2N , EF300 F2.8L IS , EF300 F2.8L Non IS , kenko2x

both camera body and lens rested firmly on flat surface with another weight put on top to minimise shake
F2.8 – 1/160, iso200

F5.6 – 1/40, iso200

F8 – 1/20, iso200

raw files convert to jpg without any alteration, 100% cropped slightly off center
observations

1.sharpness seems to be best when IS is turned on

2.without IS both lenses are comparable in sharpness

3.with a 2x TC, sharpness falls a little but is still comparable

slow shutter was used deliberately to see if it makes any difference

results seems to show there will still be some shake no matter how good you stabilise your setup(i am also puzzled)

so IS is a good function to have when you are out in the field
notes

same lenses differ in quality so mine might not perform the same as yours

this test might not be 100% accurate so do not flame me if you find it untrue in any way

 
Photographs and article are copyright of Jz