Well I’m no professional photographer and not even a gifted amateur.

According to Canon Rumors there were at least 5 test versions of the 24-70 and at least 1 with IS. Again according to Canon Rumors the reason for not going with the IS version was the increased size and weight of the lens.

Now I have no idea why Canon didn’t make this lens with IS, but I also don’t know why Canon would sell a 5.3Kg (11.8lbs) prime with IS, as I could never hold it.

Any large company like Canon would monitor the market but they monitor the sections of the market they target with their products. Understanding who and why people buy your products is a key. The only thing we do know for sure about Canon is that IQ is one of their major drivers.

We all know that Canon has a selected group of pro photographers it provides with test lenses and bodies. If IS was a make or break factor for these users would they have released a non-IS version? We now need to ask, what part of the market is Canon aiming for with this lens?

To be serious, If Canon were to read all of the forums for what users want is an EF 10-600mm IS f2. It must have perfect IQ with no CA, no distortion, < 1kg (2.2lbs) and be no bigger than 100mm x 200mm (4x8”).

The only place we are going to get the real answer is from Canon directly.