Canon lens: does focus stay when zooming?

[Martyn]

Hi,

with the Canon zoom lenses does the focus remain constant when you zoom in/out and change aperture?

Thanks

[scwalter]

Hi,

with the Canon zoom lenses does the focus remain constant when you zoom in/out and change aperture?

Thanks

It depends on the lens and yes. The term for a lens that remains in focus when zooming is called "parfocal". A quick google search turned up this list

http://www.rogercavanagh.com/helpinfo/30_parfocal.stm

All focusing is done with the lens at its maximum aperture, it only changes when you take a picture. focus is not affected.

-Scott