Low Light Filming: Auto Focus Problems

vegasnewbie wrote on 7/12/2004, 2:04 PM
I have a Sony DCR-PC330E camera, and I have experienced a few problems with the auto focus function, particularly when filming in low light situations, such as sunsets, or indoors at night. The problem is that in these situations, the auto focus seems to struggle to keep the picture in focus, and some of the output is a bit out of focus (fuzzy). I am aware that, with auto focus, the camera will focus on the nearest object, but I have experienced fuzzy pictures even when shooting a sunset of a distant horizon with no nearer objects to "distract" the auto focus. I guess the simple answer is to turn the auto focus off and get used to focusing manually all the time.

I wondered whether there are other people who have stopped using auto focus because of these types of problems. I have tried using the "sharpen" function of Vegas 5 to improve any fuzzy video, but this was not too successful. Are there any other techniques that can be used to improve out of focus video? Thanks for your help.

Regards, Fred

Comments

Grazie wrote on 7/12/2004, 2:29 PM
Manual Focus . .

no hocus pocus will stop us from gettin outta focus . .

cos everything else is just bogus
and surplus to making us famous by copius spurious nonsense . .

Trust us!

Manual Focus gives us all what must've

Been near us and Far . . from us

. .. . ..

G
BrianStanding wrote on 7/12/2004, 2:32 PM
As a general rule, I try to use autofocus as little as possible, and then only when absolutely necessary and under good lighting. I only turn on autofocus when I am in a "run and gun" news gathering situation with rapidly moving subjects outdoors or in a very brightly lit room. My understanding is that autofocus uses contrast levels to determine whether an image is or is not in focus. Low light = low contrast = poor autofocus response.

Does your camera have a button to temporarily engage autofocus, and then return to manual focus? If so, you may want to use this instead. I find on my PD-150 that pressing this while my subject is centered in the frame is the fastest, surest way to lock focus and avoid the "focus drift" problems you describe.

As for fixing the results, in Vegas, I'll be interested to see what others say. I've only had mediocre success.
Grazie wrote on 7/12/2004, 2:38 PM
I only use manual focus in low light. Auto gets me all over the place . . .. correcting in Vegas? A bit of a non starter. If you've got something that you must really really have - we've all been there - and only for a brief time .. use a touch of sharpen then add a very small amount of Gaussian Blur to take off the "exact" edges . . But if you want stuff to be in focus there is no real substitue for accurate focus and good lighting .. . . ..

Best regards,

Grazie
farss wrote on 7/12/2004, 3:20 PM
From what I know the autofocus works by looking for edges, with low light or soft subjects it has a hard time. Things get worse with slow shutter and progressive scan, I heard of one test done with the DVX100 at 1/4 sec shutter in progressive it took over a minute to find focus.
Best trick in low light is to zoom into what you want in focus in auto, once the camera has found focus then switch to manual and zoom out. Problem with manual focus on consummer cameras is those useless color EVFs are too soft to judge focus. At least on the DVX100A they've added focus assist.