Best lens for filming with a DSLR

[jtiggatrost]

I am buying a 24-105 f4L lens. Is it good for filming?

 

[Gavjenks]

Yes, the lens is parfocal. Which is the main stumbling block for many DSLR lenses.
It also has a fixed maximum aperture, which is good.

This is no cine lens, though, of course.
* It is not optimized for precision focus pulling in terms of its focus controls
* It doesn't have the build and precision machining required for consistency in the same way
* it doesn't have T-stop calibration
* It breathes a bit with focusing

Note that if you are using autofocus instead of manually pulling focus, it probably won't SEEM parfocal when you zoom in, because the AF isn't as precise at wider angles (wide DOF = hard for the sensors to nail it dead center). Zooming from long to short will show parfocal behavior though using autofocus.
Also note that it has a quiet motor, but not a silent one, if you try to use AF for focus. It will likely pollute your audio, unless you record that separately. Canon's STM lenses avoid this issue for those wanting to use AF for video with on-board audio recording. Sadly, there are no STM lenses (yet) that are parfocal or that zoom with fixed maximum aperture, though. So that's not a good tradeoff.
Also note that it's going to have pretty crappy AF when using the sensor alone, if you're relying on that. The new 70D would be a better choice, despite being crop frame, if you really want to use a Canon DSLR for serious cinematography using AF. Due to its new live view AF technology.

Pulling manually resolves most of those issues, of course.


But for DSLR lens prices, and with appropriate aftermarket addons it's going to be pretty good, considering

 

[jtiggatrost]

Thank you very much