WS out of focus, may be macro setting

[John Carrithers]

Greetings,

One of the gigs I have is to shoot broll of plays for a theatre in Houston. the camera holds up well in the theatre lighting and colors look gorgeous. However, when I set focus and zoom out wide I've noticed that everything goes a little soft. I decided to play with the camera today to figure it out before my next shoot. I set up in my living room (monitoring the camera on a large TV) and would zoom in on an object in the kitchen, set focus and then zoom out. Sure enough the shot looked very soft once in the WS. Eventually I found my way to turning the macro ring slightly away from it's default position and the wideshot came into focus. I zoomed in and set focus on another object in the kitchen, zoomed out and the wide appeared to be much sharper and in focus. I fine tuned the macro setting by watching a bright light source in a wide shot. When the light source appeared to bloom I would turn the ring in the other direction.

This in mainly something I wanted post incase some else is having the same issue with wide shots going out of focus. If your WS are misteriously out of focus, play the the macro. However, if anyone has any insight on why this is happening I would greatly appreciate it. Is there a way to calibrate your lense's macro setting so your shot is not utlizing the macro focus ring in it's off/locked position?

Thanks,
JC

[Brian Drysdale]

Sounds like your backfocus needs to be set.

Basically you set the macro ring to the default position, set the exposure so that the iris aperture is wide open. Zoom into a Sieman Star chart set up around 6 feet away, focus with the front focus ring, then zoom out to the wide end of the zoom.

Loosen the small screw on the backfocus adjustment (that's the ring where the macro is located - dont touch the macro). Adjust the backfocus ring until the bundle at the centre of the Siemans star is at it's tightest.

Zoom in again, check the focus with the front focus ring, repeat the backfocus adjustment. You should repeat this procedure until you can see no improvement, then tighten the screw on the backfocus ring. You should check that in tightening the screw you haven't accidentally knocked off the backfocus.

You'll find the instructions in the camera manual. You should check the backfocus regularly - with HD I check it everyday, or if there's a temperature change.

[Michael Lafleur]

Hi John,

It sounds like you need to properly set the back focus on your camera. Here is a thread that you might find useful. Download and print out the focus charts and follow the instructions and see if that doesn't resolve your focusing issues.

http://www.dvinfo.net/conf/showthrea...k+focus+charts

Michael Lafleur

[John Carrithers]

Thanks for the help. I really appreaciate it. I thought it might be the backfocus based on some other information on this forum, but to tell you the truth I had know idea what it was or how to fix it. thanks again.

[John Carrithers]

Brilliant. It worked like a charm, thanks so much.
JC