10-01-2012, 11:22 AM
[quote name='Rover' timestamp='1349016181' post='20435']
If so, why aren't these lenses equipped with STM which was touted as a video feature? It seems as if the decision making at Canon is pretty chaotic (no video AF on 5D III while it's there on the 650D; the sheer existence of lenses like this and the 24 with no comparable longer lenses; the abovementioned lack of "video-friendly" STM motor...)
[/quote]
Well, the STM was definitively necessary for the noisy and slow micromotor lenses.
However, this lens is USM, so noise is not an issue (STM is not completely noiseless either).
Second, USM is fast, and if the correct stepping and algorithms are implement, if possibly could work the same way as STM for AF with video. Whether the USM has been adjusted for video in the 28mm IS, I don't know. I guess one has to try it on a 650D and see how it does. Anyway, the video AF implementation in the 650D seems to be still lacking in performance, so not much lost anyway if the 28mm IS doesn't do well for video AF.
If so, why aren't these lenses equipped with STM which was touted as a video feature? It seems as if the decision making at Canon is pretty chaotic (no video AF on 5D III while it's there on the 650D; the sheer existence of lenses like this and the 24 with no comparable longer lenses; the abovementioned lack of "video-friendly" STM motor...)
[/quote]
Well, the STM was definitively necessary for the noisy and slow micromotor lenses.
However, this lens is USM, so noise is not an issue (STM is not completely noiseless either).
Second, USM is fast, and if the correct stepping and algorithms are implement, if possibly could work the same way as STM for AF with video. Whether the USM has been adjusted for video in the 28mm IS, I don't know. I guess one has to try it on a 650D and see how it does. Anyway, the video AF implementation in the 650D seems to be still lacking in performance, so not much lost anyway if the 28mm IS doesn't do well for video AF.