Focus Jumping?

[BrendanLeahy]

Sorry, not sure where else to post this. Both on the Canon still lenses, as well as the cinema glass I use, the focus seems to jump a little when making some micro-adjustments. Is this normal/what people refer to as "breathing"? It seems pretty drastic, as if you're shooting with a DSLR and using continuous AF.

 

[Phil Holland]

Sorry, not sure where else to post this. Both on the Canon still lenses, as well as the cinema glass I use, the focus seems to jump a little when making some micro-adjustments. Is this normal/what people refer to as "breathing"? It seems pretty drastic, as if you're shooting with a DSLR and using continuous AF.

If you are referring to image shift, where as the focus is adjusting the frame itself seems to move (or jump), this is one of the major problems with some still lenses when using them for motion. Some are worse than others.

 

[BrendanLeahy]

Yes! That's what it is. Thanks for clarifying, Phil!

 

[Mathias Erichsen]

One of my old Lomo cinema lenses does this too.. Anoying thing.

 

[Nick Gardner]

On cine lenses and old style still lenses image shift can be fixed. The cheap solution is to pack the helix in thicker grease. The expensive solution is to build up an epoxy type material in the helix and then re lap them. Probably not worth the expense on still lenses, but I think Duclos's price on the service is pretty reasonable.

Nick