What is the ISO of DV?

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pablokorona

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i've been looking around, and no one answers this simply.

what is the ISO of DV?

I don't trust the LCD/viewfinder (my NTSC monitor sits at home because its too big to take on location) and i'm going to be purchasing a light meter.

thanks in advance!
 
The answer is the sensitivity (ISO, ASA, Etc.) is variable. It changes depending on how much light there is, particularly with the DVX. This is mainly because Panasonic wanted to be able to advertise the DVX100 as an "f/11 @ 2000 Lux" camera, so they designed it to add enormous (two or three f/stops) amounts of Gain when you use the camera at or around 2000 Lux. In those environments, the camera has been found to be 1200ISO! In lower light environments the camera has been rated as slow as 320ISO. It all depends. Your mileage may vary.

If you rate it someware in the middle (I.E. - 640ISO) then you're most likely to get pretty close.

The light meter is a useful tool for measuring contrast ratios, but not much else with the DVX100.

How is that for a simple answer?
 
Also, there is no ISO of DV - that is just a data stream. Each DV camera is different.

Like thisiswells said, I wouldn't use a light meter to set you exposure. Do you use zebra pattern to show highlights peaking? They are VERY useful.
 
who cares? awesome answer. If you don't think lighting and exposure matters, then you're not even worth communicating with.

Like i said before, i was hoping to make sure everything is "correct" because the LCD display cannot be trusted. A light meter is cheaper than a NTSC monitor.

This is rather disappointing that the camera has variable gain. And no ability to have it keep an straight iso/sensitivity level. My desire is to be able to get rid of all gain, and not have it show up. Gain to me = noise.

Yet, i'm thinking - If this is true, then the manual exposure controls are a bit deceiving and would make it difficult to match exposure. There's NO way to keep it at a set sensitivity level?

I see the benefits of having variable gain. run and gun documentary style definitely benefits.

Anyhow, thank you for your knowledge.
 
pablokorona said:
who cares? awesome answer. If you don't think lighting and exposure matters, then you're not even worth communicating with.
Click to expand...

Poor John, he is not such a tech head as most of us:grin: :grin: :grin: :grin:

I would learn to trust your LCD and viewfinder. Practice with it and you will get an understanding of when things are correctly exposed. I now find going back to B&W viewfinders hard although I originally hated colour ones - well, the early LCDs weren't a patch on the best today.

Ideally you would have a broadcast monitor where ever you go, but that isn't going to happen. I have never come across anyone exposing video with a light meter, I can't see it being a good idea.
 
i still refuse to believe there's no set sensitivity level.

Shooting video is, at its base, still photography. Never seen a cinematographer use a light meter? are you kidding me? I tend to have a little bit more reverence for video as a form of photography.

But, maybe that's just the problem with pro-sumer cameras.
 
pablo - One thing you have to remember is that shooting with the DVX or any other DV camera is that you are shooting VIDEO that is digital, not still photography with FILM.
There really is no exact ISO for DV as wells stated above just as there is no ISO for any still CAMERA. It's the FILM that has a ISO rating. My Canon A-1 can use Kodachrome 25 or MAX400
So as soon as you realize that FILM and VIDEO are different and must be treated differently you'll be better off.
 
pablokorona said:
Never seen a cinematographer use a light meter? are you kidding me?
Click to expand...

No, you are just miss quoting me. Re-read what I wrote.

I am not sure if early video cameras required a separate light meter. I have a friend who collects "antique" video cameras, if I see him, I'll ask.
 
pablokorona said:
If you don't think lighting and exposure matters, then you're not even worth communicating with.
Click to expand...
First of all, hahahahha.

pablokorona said:
This is rather disappointing that the camera has variable gain. And no ability to have it keep an straight iso/sensitivity level. My desire is to be able to get rid of all gain, and not have it show up. Gain to me = noise.
Click to expand...
You and me both, brudda. But, check out the music video I posted on here last night, I shot the entire video at +9db and 1/24th it doesn't look all that noisy to me.

pablokorona said:
There's NO way to keep it at a set sensitivity level?
Click to expand...
You CAN change the iris and it's noticeably different at each f/stop. But, this camera likes to shoot at f/5.6 and will do everything possible to force you into the f/2.8 to f/8 range for the best images possible. You'll actually learn to appreciate the sophistication of this camera -- it's really hard to mess up!
 
I learned to trust the LCDs:

Set them up "by eye" with a calibrated TV and color bars.

I found that my DVX's image actually has a half or full stop more than the LCD shows, so:

When using the LCD, tell yourself, "Okay, I'll be able to see a bit more into the shadows, and have a bit more highlight detail than what I'm seeing now".

I use this method on paid shoots, with fine results.

-a
 
yeah, i've noticed this as well.. thank you very much. where i have some of my issues is HOW to look at the LCD screen, different angles produce different results, ya know? dead on doesn't give the best light level and +/- 15 degrees on the x-axis seems to be correct.
The viewfinder seems to be a truer preview...

any more pointers from anyone?
 
well, the last time i was on a shoot for the most part everything came up 1 stop under... The highlights were dim, and the shadows were dark. It makes me feel ill when i get these results.

i'll check out the music video later, but i'll be running some tests just to see whats happening with this camera at different settings with my friend's light meter... there needs some kind of control with this camera. Variables like this scare me.
 
The simple fact is, you cannot (and I repeat CANNOT) use a lightmeter to accurately meter for video with a DVX (or, presumably, any other comparable video camera). May be hard to accept, but it is the way it is.

I don't think there's any sort of variable gain going on, I think it's one of two things: either the CCD exposure curve is simply nonlinear, or perhaps it's a t-stop and f-stop calibration issue. Perhaps the lens isn't as fast as it claims on the wide-open end, and isn't as slow as it lists on the stopped-down end. If that's the case, then the exposure curve could still be linear, and there could still be a fixed gain system, but you STILL couldn't use a light meter because you don't know what the actual t-stop is.

A light meter is vaguely useful for calculating lighting ratios, but is of little practical value in lighting a video shoot. The tool you want for video is a waveform monitor, not a light meter.
 
Barry - i have heard you say this before - and it makes sense - can you give an idea of the procedure of using the waveform monitor instead of the lightmeter. How would it practically be used on set in replacing a light meter for checking ratios etc?
 
I'll send you this way as trying to explain the bene of the Waveform could be tiresome in type

(The top is for monitoring IRE and the bottom is for Color)

wavenvector2.jpg


DV Waveform Monitor & Vectorscope

Pros hate shooting "blind". How white is that white? How saturated is the background? What is the correct iris level on my camera? The only way to know for sure is objective quality monitoring and measurement. Yet we're left guessing because lugging bulky scopes that weigh five times more than a DV camera isn't practical. DV Rack's WV-150 Waveform Monitor and SC-680 Vectorscope feature industry-standard monitoring functions as well as direct DV signal input. This means you're able to monitor the actual post-compression signal as it will be recorded. Something traditional waveform and vectorscope monitors connected via composite or S-Video can't do. And the WV-150 works with DV Rack's split screen mode so you can view two clips at the same time or see live video compared to a previous clip. Because DV Rack is modular you can even open more than one scope at a time with each set to display a different mode.
  • Native DV monitoring shows post-compression signal.
  • Luma, Parade, Y-only, R-Y, B-Y modes.
  • Full screen or sweepable line mode.
  • Interactive zoom function magnifies scope display.
  • Adjust gain, trace illumination, graticule intensity, scale, and position.
Check out dvrack
 
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