Sunlight and How to control it.

astroanalyst

astroanalyst

Well-known member
I have a dvx100a.... How does one control the huge contrast of bright sunlight to dark shadows. It appears as if all video cameras fall short in this area. I notice that film compresses the image nicely without blowing out the whites and without loosing the blacks. The film image can be transferred to video but not captured by video. Should I be using a filter for the lens to help with the problem?
 
Re: Sunlight and How to control it.

Film can capture up to maybe 13 stops of dynamic range, video is limited to maybe 7. When film is transferred to video, usually a "low contrast" print is struck first, and it is that low-con print that gets transferred to video.

In video you have to control the light. You have to light up dark areas, you have to bounce light into the shadows, you have to put up butterflies or nets or flags to trim light off of bright areas. It's a lot easier to shoot good-looking film than it is to shoot good-looking video. Video takes a lot more work to make it look good than film does.
 
Re: Sunlight and How to control it.

[quote author=Barry_Green link=board=lighting;num=1097445489;start=0#1 date=10/10/04 at 20:35:45]Video takes a lot more work to make it look good than film does.[/quote]

So true.  And it's funny because I'd bet that so many of us are trying for the 'Film Look' - because it makes our movies (and therefore us) look better.  We should instead be trying for a GOOD video look.  That way, people don't say "was this shot on film?" - rather, they say "Wow, that looked really good, AND IT WAS SHOT ON VIDEO!" ::) ;D
 
Re: Sunlight and How to control it.

Is there any filter that can be used (like sunglasses) that can control the contrast without changing the color or resolution of the image?
 
Re: Sunlight and How to control it.

I'm presently experimenting with Grad ND/Low Contrast/Polarizer filter combinations and getting okay results but I'm just doing a documentary and I don't need much. I'd recommend trying them out though.

Caveat: it seems that I just need to keep experimenting until the choice of combination becomes intuitive and second nature. I look forward to Vol.2 of Jarred's DVX Filters Test "for exteriors" if it ever materializes.

-Moe
 
Re: Sunlight and How to control it.

[quote author=astroanalyst link=board=lighting;num=1097445489;start=0#3 date=10/11/04 at 08:32:31]Is there any filter that can be used (like sunglasses) that can control the contrast without changing the color or resolution of the image?[/quote]
Neutral Density filters are "sunglasses" for your camera.

They control exposure, but not contrast (and have no effect on color or resolution, assuming you buy a good optical quality filter and not a cheapo piece of junk of course).

There are some filters marketed that claim to help control contrast, Schneider offers the DigiCon and Tiffen offers the UltraCon lineup. There was an extensive discussion on the DigiCon here a few months ago, try searching the archives or google'ing for more info.
 
Re: Sunlight and How to control it.

I've been looking into the low contrast filters and they seem to help solve the problem. I believe these filters need a matt box?? Can you recommend a matt box for the dvx100a? I see there is one on this website advertised. Is it any good?
 
Re: Sunlight and How to control it.

Oh geez, the mattebox question. You've asked quite a mouthful... Here's a quick summary.

Matteblox: Cheap, good for the money, but sometimes it's just a *****, and it's not great with filters. And you certainly can't used a Grad ND.

Formatt: Lots of people go this route, there was a problem loading filters, but I believe someone found a way around it.

Cavision: Others go this route, has bellows and rods, very nice. Some vignetting problems I believe.

Chrosziel: The only "solid" mattebox to get if your using the anamorphic adapter. VERY expenise, but a VERY good design.
 
Re: Sunlight and How to control it.

I hate to ask the stupid question, but are you using the Neutral Density switch on the camera?
 
Re: Sunlight and How to control it.

When I use the neutral density switch it makes everything darker but doesn't reduce the contrast. The whites are still blown out and the blacks are too black. I see this happen on every video camera that is shooting in sunlight. I think if one is looking for the 'film look' then the contrast has to be controlled (with depth of field and 24p). I hope the low contrast filters do the trick.
 
Re: Sunlight and How to control it.

Neutral Density is not a Low Con filter, that's why it does nothing to the overall contrast of a picture...it's Neutral.

Call me old fashioned, but I would think you'd want to get the most amount of information in your video signal. Controlling contrast in camera just squeezes your histogram, reducing the amount of raw information in your picture. If you want to reduce contrast, I'd say that you should do it in post and afford yourself the largest latitude in your source.

There are a wide variety of methods that cinematographers use to control contrast, ranging from ENR, bleech bypass, flashing at various stages in development, Varicon units, and pull/push processing. Most of the results can be emulated in post, and in general, the only reason you'd want to pursue an "in camera" contrast control is if you want to "lock" your production into using that effect.

It's really hard for a studio to change low contrast footage to high contrast, so you get to effectively force your choice. For most of us, we don't need to resort to those tactics to get our way.
 
Re: Sunlight and How to control it.

Call me old fashioned, but I would think you'd want to get the most amount of information in your video signal. Controlling contrast in camera just squeezes your histogram, reducing the amount of raw information in your picture. If you want to reduce contrast, I'd say that you should do it in post and afford yourself the largest latitude in your source.
Click to expand...

I respectifully disagree. The storage medium (the video camera) cannot capture what you are giving it like film can. That is why it must be compressed. Otherwise you are really losing information by not capturing it. The gradations in the blacks will be lost and cannot be recovered in post.
 
Re: Sunlight and How to control it.

The way to control contrast and get the most signal to the camera is to control the lighting on your subject.  Bounce light into the shadows, or flag light off of bright subjects.  It's not that hard, and it's what you have to do.  Trying to record an image that has a wider contrast range than the camera can resolve will only lead to compressed shadows and blown-out highlights, so you really have no choice but to alter the lighting scheme to fit within the latitude of the camera.

And use CineGamma, it gives about a half-stop or more of extended latitude.  Just don't let the highlights overexpose or it'll get ugly.

The low-contrast filters really just introduce some controlled flare onto the picture, spreading light into the shadow areas and milking up the black portions of the picture, kind of like raising the master pedestal.
 
Re: Sunlight and How to control it.

[quote author=astroanalyst link=board=lighting;num=1097445489;start=0#11 date=10/13/04 at 08:04:14]

I respectifully disagree. The storage medium (the video camera) cannot capture what you are giving it like film can. That is why it must be compressed. Otherwise you are really losing information by not capturing it. The gradations in the blacks will be lost and cannot be recovered in post.

[/quote]

Misunderstanding. I'm refering specifically to low contrast filters.

If you light correctly and then use a low contrast filter to get some mystical "film effect", you're compressing the amount of information you're recording on tape.

You can easily toss out the extra bit depth in post if you so desire and create a low contrast "print", but applying that step in camera seems like a waste of valuable latitude to me.
 
Re: Sunlight and How to control it.

[quote author=Barry_Green link=board=lighting;num=1097445489;start=0#12 date=10/13/04 at 12:28:59]
The low-contrast filters really just introduce some controlled flare onto the picture, spreading light into the shadow areas and milking up the black portions of the picture, kind of like raising the master pedestal.[/quote]

But that gets really fun when you apply color to the shadow areas, like with a varicon!
 
Re: Sunlight and How to control it.

I must say I learned a lot from this thread which brings me to a better formulated question. I've been in the pro audio business most of my life. When I used to compress an audio signal there was always the ability to set a threshold level, that is setting the point at which the signal would be affected by the compressor.

As most of you know you can compress audio or limit audio or both. I think what I'm looking for is a 'limiting' of the video signal. A ceiling that prevents clipping of the electronics of the video camera.
I guess I'm dreaming... because filters affect the whole signal not just what is beyond a certain threshold.
In the audio business this is easy... you break the signal into three frequency bands then compress or limit the one that unstable without affecting the other frequency bands. How is this achieved in video production?
 
Re: Sunlight and How to control it.

Er...

Well...

Um...

In-camera you don't really have a function such as a compressor. There's a little bit of a limiter, which is called the knee. Set the knee at 80% and it'll attenuate the signal at anything above 80% brightness, but it's not really a limiter because it will still let the signal float up into overexposure.

As for compressing the dynamic range, CineGamma's about it. Watch it on a waveform monitor and you'll see that CineGamma compresses the dynamic range, freeing up a lot of space on the top end of the scale, giving a bit of extended exposure latitude. The various gamma curves compress or extend the exposure range within certain bands (low gives more detail in the ark areas, high=more detail in the brighter areas, etc).

But the gamma curves are going to give you maybe 1/2 stop of additional latitude...

You could also work with the master pedestal, which is almost like the knee circuit for the lower end of the exposure range, bringing up the master ped will give some more detail in the darkest areas (at the expense of making the blacks look "milky").

Other than that, there's not really a video version of a compressor in the camera itself.
 
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