Few quick questions

October 30, 2007

1. To focus in video, you zoom in on an object, focus, then zoom back out. Is this the same with shooting on film with a zoom lens?

2. If I wanted to see someone's breath in the cold, can I shoot 48 fps and then speed it up in post to make the breath look more noticeable?

3. If I wanted to shoot a skyline of a city at night, how do I expose for the city/get a light meter reading?

Adrian Sierkowski · October 30, 2007

#1) AFAIK Yes

2) Not sure. But if you back-light it it'll come out fine (same for smoke/rain)

3) I'd use a spot meter and aim it at the buildings, to get a rough idea, keeping in mind that the exposure you get would set a dark blue building to neutral gray same as it would a bright white building. . . so you'd compensate for that. else you could, in theory, do an incident reading under whatever you determine you "key" to be, i.e. a street light, and set that as exposure.

my 3 cents.

David Mullen ASC · October 30, 2007

1. To focus in video, you zoom in on an object, focus, then zoom back out. Is this the same with shooting on film with a zoom lens?
2. If I wanted to see someone's breath in the cold, can I shoot 48 fps and then speed it up in post to make the breath look more noticeable?

3. If I wanted to shoot a skyline of a city at night, how do I expose for the city/get a light meter reading?

1. Yes, assuming the back focus is set correctly (more of an issue with video cameras.) You can, of course, measure the focus with a tape measure or other devise rather than zooming in and out.

2. No, that wouldn't help. The only way to see the breath is to backlight it. Slow-motion would elongate how long it was on film, but speeding the footage back to normal would just cancel that.

3. Generally you can't overexpose a city skyline at 24 fps, unless it is a tight shot of the lights of Las Vegas, so most people just shoot at the widest-open f-stop they feel comfortable shooting at, and balance the foreground lights to match that. Now for specific lit-up areas, like a shot of a billboard, etc. you can use a spot meter.

Often for a shot of the skyline, the problem is getting enough exposure on 500T film, so besides using a fast lens shot wide-open, they might undercrank the camera to gain more exposure, within limits of what looks realistic (12 fps, which is one more stop of exposure, might be as much as you can get away with without the cars moving too fast to be realistic. Again it depends on how tight you are on details.)