Focus & Exposure

[indigo]

I'm currently in Beijing, China.... moving slowly towards Lahsa in Tibet, catching the train to Xian tonight.

Anyway I've always been curious regarding the focusing and exposure on the HVX. Beijing has really brough it into sharp focus (no pun intended!). Anyone that has been to Beijing will testify that the polution is truely HORIFFIC! One of the results is that by the time the suns light has passed through the smog it becomes very flat washing out colours.

Right, I was filming in Tian'amen square yesterday (yes, they did allow me to even with an HVX!) and the on screen display kept indicatimg say "ND 1/64" or some such YET using that setting totally underexposed the scene. Leaving it time to adjust the iris did nothing.... am I missing something here?

Although the above is annoying the focus issue I'm having is making me mad as I'm losing good shots. A few days ago at the Great Wall Of China I zoomed (fairly slowly from the floor up to the Wall disappearing into the far distance. On checking the shot on my Mac laptop the camera loses focus and hunts for half a second before locking again then loses it then finds it again. I had this problem in India when trying to film birds of prey gliding around himalayan peaks i.e. they would come into and out of focus to the point where the shots where unusable :(

Hands up I'm not an expert cameraman but I'm trying to learn... I'd appreciate any advice in resolving these two inajor ssues for me!
Regards

Indy... in Beijing China!

I'd like to post some footage of the problem but all I'll say is China and Internet :(

The BBC news site is banned!!!!

[n8ture]

Did you have zebras turned on?
Did you have the brightness turned up on your LCD?

Don't use autofocus.

[THoff]

I would rely on zebras or the marker to determine exposure, especially if much of the scene consists of sky. You are better off blowing out the hazy sky (which has little or no detail anyway) than underexposing buildings and people.

Regarding the focus problem, you can't use autofocus when shooting against low-contrast backgrounds like the sky. The camera needs edges to determine focus, and a bird or plane that's bouncing around the scene just isn't going to cut it. When the camera loses focus (or thinks it does, because there are no edges), it will cycle through the complete focus range trying to re-establish focus. Your best bet will be to close down the iris to select a smaller and more forgiving aperture (more DOF), and use manual focus.