DV Camera Question

escozooz

escozooz

Well-known member
This is a quote from an article on the shooting of 28 Days Later.

"
Dod Mantle shot as wide open as possible with ND filters to minimize DV's seemingly infinite depth of field, and he underexposed by one to two stops to get more information on tape. (The XL1 has an exposure value of about 320 ASA without altering the shutter speed.)
Click to expand...

I would understand this if it was a film camera but how do these terms relate to the XL1 or the DVX100?

When you ND filter the camera and then adjust the exposure, is that the same as adjusting the aperature? How do you change the aperature on a DV camera?

Also I've never heard about the ASA for a DV camera.

Also how does changing the shutter speed effect the picture? Is there any relation to the aperature?

Just trying to figure things out, thanks.
 
When you put on ND filters you're cutting down light so you have to compensate but opening the aperature. (f-stop) By shooting wide open you get less depth of field so your background can go softer.
Any DV camera with manual controls allows you to change the aperature.
On the DVX turn off Auto Iris and turn the Iris Dial (left side of camera in front of LCD)
On the DVX you also have 2 ND's built in. 1/8 and 1/64 setting on left side as well.

Yes, video cameras have an ASA. Do a search here for past discussions. There are ways of calculating this.

Shutter speed- High shutter speed creates non-blurred images that tend to strobe. Think Saving Private Ryan. Slow shutter speeds tend to create more motion blur in moving objects so creates a dream look.
Shutter speed affects the exposure.
Length of time (shutter speed) and how much light coming through the lens (aperature) will determine final exposure. Think of filling a sink with water. You can have a small stream of water (small aperature) and it will take a long time (slow shutter speed) to fill the sink.
If the water is gushing (wide aperature) then it will take a very short time (fast shutter) to fill the sink.
Faster shutter speed requires more light (wider aperature) Slower requires less light (smaller aperature)
 
<Yes, video cameras have an ASA.>

Actually they do not and technically only still film has an ASA. Motion picture film has an EI (exposure index). It one of the reasons why video manufacturers use such phrases as f11 at 2000 lux. Technically they can not use any form of measurement with video cameras that we are used to in film. ANd anyone that uses a term such as 320 ASA is only giving you a measurement for sensitivity at a specific f-stop. At another f-stop with a video camera EI changes.

You can measure sensitivity for a camera but it is not the same across the scale of exposure. This has to do with both the CCD chips and the plastic lenses they use on the front of the lenses that help least when you need them most. I'll save the technicalness and simply say that you DV cameras EI is not the same at one f-stop with a certain level of light as it might be with more light and a different s-stop. So what I'm saying is you may be able to measure an EI of 300 indoors but that same camera adjusted for outdoor light may now be 600 EI. Its one of the reasons why light meters really don't work well with video cameras over the full range of exposure. DV cameras have nearly limitless depth of field. For a filmmaker part of the illusion is with a very shallow depth of field. So many filmmakers try to make the camera always at the end of the scale making lenses as wide open and using as little light as possible along with long lenses to help try to achieve short DoF.
 
Yes, technically video cameras don't have ASA but it can still be a useful starting point and is in fact covered in a number of video books.
Yes, EI may be the latest way to express motion picture film exposure but for years it was listed as a ASA and meters and many DPs still refer to it as such.
 
Can be as misleading as it is leading. As for "newest", motion picture film has always been rated with EI. Meters were mostly designed for still photog and hence asa.
 
thanks for the replies.

So...I was just on a 16mm shoot where the DP was constantly checking the lighting with a hand held meter (looking through it) and then putting ND on certain things and adjusting the Fstop on the Arri S Cam.

What is the equivilent for digital; say the dvx100 for example. The goal is to get a properly exposed image that will lend itself to post grading.

What is the best way to achieve the exposure that a good film DP could get with a light meter and a film camera but with a DVX100 or XL2? A really good production monitor?

Variables In Digital --(no in camera effects)
- lighting
- exposure
- iris
- white balance
- 24p

Among other things I'm trying to figure out the digital equivilants of film terms. Like aperature, f-stop, etc. What does exposure mean for film as opposed to a DV camera? Is there a film equiv of iris?

EDIT---

I just read the "exposing for outdoors" and the suggestions seemed to be expose by eye with teh zebras. There isn't a more precise way?
 
A good production monitor certainly helps. Using a program like DVrack can also help you get precise results.

There has been a lot of discussion here about zebras lately. Certainly they are an excellent tool. The DVX also alows you to see the IRE (using the zebra button) of a certain area of the frame.
 
I started out shooting film and am comfortable with a light meter, but trying to use one with a video camera drives me crazy, because what what Walt is talking about, the variation over the exposure range. Having a good, calibrated monitor is the way that I like to work now. I still like to get a shot from each lighting set-up of a white reference, a black reference and a gray card. This really helps in post.

While shooting, I try to maintain one aperture setting (fstop or iris setting, call it what you want) for each scene and adjust my lighting to stay at that fstop. This helps with consistancy from shot to shot. I am not a fan of changes in shutter speed or in gain. The only thing I will adjust on the camera (for exposure control) is the aperature and ND filter settings. The rest I try to do with lights. (of course I do mostly fictional narrative, it would be different for run and gun doc style stuff)
 
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