Focus instability

[deanhamer]

I've started shooting with my new Sony PMW-EX1 and encountered a problem that I really don't understand with the focus. I'm shooting with manual focus (and it's real manual focus, with a ring that physically moves the glass). On a close- in shot with the subject about 8 feet away the focus on his face is perfect, very crisp, with nice depth of field. But when I open up to a medium shot, not changing anything else, the focus on the subject's face becomes soft and objects a few feet further back become sharper.

Am I making some sort of idotic mistake or is there something fundamentally wrong with he manual focus on this camera? I haven't changed anything except zoom. Help!

[DCSensui]

Sounds like a backfocus problem. Check out some of the threads regarding this issue.

[matthew77]

(and it's real manual focus, with a ring that physically moves the glass).

It's actually not - it's servo driven to simulate direct connection with the glass. The servo is sufficiently tight that it works just fine that way.

Backfocus is adjusted by an internal look up table linking ring position to glass position.

[Stevet]

Yes, hunt down the MANY back focus threads.
You will learn how to adjust back focus called FB "Flange Back" in the service menu.

[thxdave]

My EX1 lost the ability to focus out to infinity a couple days ago. The FB adjust initially didn't work properly (wouldn't even finish the adjustment routine) but I kept running it over and over and I think it got me back into proper operation....I hope. I'm testing it now but still can't figure out why it went SO far out of adjustment.

[deanhamer]

OK I've read a bunch of posts on how to adjust back focus - but some of them say that using the maintenance menu is not advised by Sony and could void the warranty. True? Also, is it "normal" for a camera to have so many focus issues? I bought one of the very first FX1s and it never had these sot of issues.

[basspig]

No it won't void your warranty--I did it and after that I sent it to Sony for firmware update--they paid freight--both ways--and I got it back the same week that I sent it out.

Per chance, were you shooting with the ND filter on? That is a known issue with the old firmware. New version fixes it.