EF 24-70mm f/2.8 L USM - No IS

[Alan]

I think the 85L would be too difficult to design - the IS elements would need to be similar in size to those in a supertele lens, and the 85L is already enough of a cannonball. But, the EF-S 17-55mm f/2.8 IS has IS, and it's FF-equivalent focal range is 27-88mm, pretty close to 24-70mm...

What makes the difference in the 17-55, in terms of the size, for IS design? I mean, they fit IS into it, and it's not a cannonball.


Besides, the 27-70 is also a cannonball. People already complain about its weight. That doesn't stop them from buying it, nor does it stop them from buying the truly BIG cannonballs: the long teles.


Or, should the long teles be called Cannons?

[Jon Ruyle]

If Canon made a 24 f/1.4 with a 4-stop IS, they'd be putting Manfrotto and Gitzo out of business! []

[Alan]

If Canon made a 24 f/1.4 with a 4-stop IS, they'd be putting Manfrotto and Gitzo out of business! [img]/emoticons/emotion-5.gif[/img]

Funny.....


Two questions: why don't they, then?


Second question: Doesn't Ken Rockwell say as much? []

[wickerprints]

There are no lenses faster than f/2 that have an IS unit. The sole exception is the EF 200/2L IS. All other lenses with IS are f/2.8 or slower. This in itself makes the 200/2L a rather remarkable lens.


There are two fundamental challenges with respect to IS; the first is space constraints, and the second is optical constraints. Furthermore, these are somewhat interrelated.


The space constraint means that there needs to be enough physical room inside the lens to accommodate the IS assembly, with additional room allowed for the IS group to actually move within the lens.


The optical constraints, however, are even more difficult to overcome. As the aperture gets larger, the IS group would also have to be correspondingly larger--or else the lens would not achieve the desired f-number. An f/1.2 lens has a much larger exit pupil than an f/2.8 lens, and even an f/2 lens. Then, the larger the IS group, the heavier it is and the slower it would be to respond to movement. So the technology doesn

[Raid]

If I may get back to the point.


I think the post from Wickerprints is spot on, the reason why this lens does not have IS could be optical constraints. This lens is (for me) somewhat unusual because it is wide (24mm) when the barrel is fully extended, and narrow when retracted (makes the lens hood easy). It may not be possible to deliver an IS with the current lens configuration, which means a totally new design, which could mean years of testing.


From reading Canon Rumors (OK this is no authoritative source) there are at least 5 test 24-70 lenses in the field, with and without IS, so something may be comming.


Now let us give Canon some credit their knowledge of optics. Canon is not one of those companies who just want to sell the same product unchanged for the next 20 years. Canon is one of the great innovators in optics and engineering today, if IS is both possible and provides an advantage, then it will come.