ultra contrast filter or adjust contrast in post

S

shaun_au

Active member
Don't know if this is the right forum for my question.

If they do the samething: increase the contrast of your image, then what's the advantage of spending $150 on an untracon filter over simply adjusting the contrast in any NLE?
 
Increasing the contrast would mean lowering the latitude. These filters attempt to do the opposite, decreasing contrast. If they actually do what they say they're doing, decreasing contrast, that should mean that you could see more detail deeper in the shadows and retain more detail in the highlights. That's something you could never do in post.

I've heard 'em described as basically a controlled flare, using the idea that flare washes out contrast, and therefore will lift the black levels. I don't know how much validity there may be to any of this.

I've got one of those around here somewhere, I should dig it up and try it with the DVX...
 
Barry_Green said:
Increasing the contrast would mean lowering the latitude. These filters attempt to do the opposite, decreasing contrast. If they actually do what they say they're doing, decreasing contrast, that should mean that you could see more detail deeper in the shadows and retain more detail in the highlights. That's something you could never do in post.

I've heard 'em described as basically a controlled flare, using the idea that flare washes out contrast, and therefore will lift the black levels. I don't know how much validity there may be to any of this.

I've got one of those around here somewhere, I should dig it up and try it with the DVX...
Click to expand...

Barry, I think I know what you said here. So increasing contrast in post means losing details in dark and bright areas(that makes sense). So the filters controll flare, give you more contrast without loosing details, right?
 
Barry,

I have the Schneider DigiCon 1 and 2 at home. Would be happy to provide some stills frames using them in various situations if it would be helpful. I'll be back home Saturday.

Let me know if this would be helpful to anyone.

Thanks,
Brian
 
Barry_Green said:
I've heard 'em described as basically a controlled flare, using the idea that flare washes out contrast, and therefore will lift the black levels. I don't know how much validity there may be to any of this.
Click to expand...

Yeah, it is controlled (or clumbsy) flaring/flashing. It's similar to how a Varicon works, but the varicon has a tiny lamp built unto the base so it's effectively "flashing" the entire frame and raising the black levels.
 
This sounds very cool, although dynamic range in highlights concerns me much more than in shadows. I suppose this would allow you to under-expose a bit more, though. I'm looking forward to seeing some samples as well.
 
Never heard of a Varicon.. sounds really interesting, J_Barnes.

Darned vacations! Too bad I didn't bring my matte box and filters with me!

Will try to post some stuff later this weekend (4/2 - 4/3)

brian wells
 
It's made by Arriflex and it's available in many rental catalogues. Essentially, it's a clear glass filter with a small light source attached to the bottom. When turned on, it flashes the filter with light and effectively fogs the film. What makes the Varicon so cool is that the effect is "dimmable" using a rotary dimmer, and it is also capable of taking small clippings of gels so that the fog is toned.

For example, with a varicon, you can fog your shots with a coral filter so that all your shadows have a slight coral warmth.
 
shaun_au said:
So the filters controll flare, give you more contrast without loosing details, right?
Click to expand...
No, they give you LESS contrast. More dynamic range = less contrast, less dynamic range = more contrast.

I can't speak as to whether they do this without losing detail though. Frankly I don't quite get how they can claim to do what they do, yet IINM, Tiffen won a technical Oscar for developing it, so maybe they do.
 
These basically seem to do the same thing as turning your master ped up....

Hmmm....seems pretty darned cool anyway.
 
I dunno...you would think that it does the same thing as raising the master ped...but in seeing some of the comparisons, it's almost as if doing a flash/fog in camera somehow discerns detail in shadow areas that you don't get with a level adjustment in post.

I'm tired and I've had three glasses of shiraz, but if you think about it in terms of digital electronics, this makes some sense.

If you've got a bunch of numeric ranges that are all squashed down in the lower bit ranges, then you're really short on degrees of difference from one shade of dark to another. For example, if you've got a 1:2 ratio of tones...the degrees of difference depend on how the tones are recorded. A "1" value versus a "2" value retains a 1:2 ratio, but a "4" value versus an "8" value retains the same ratio using a much more detailed scale.

If you can raise all the dark levels up a bit so they're not forced into the low end, you might just be able to record a wider spread between tones.

I'm thinking something similar to digital recording of live sound. If you've got a quiet sound, and you record it without modifying the signal (say for example, leaving the signal so it peaks at half below unity)...then you wind up with a sound that is recorded using half the available bandwith for information.

However, if you take that signal and amplifiy it so that the peak volume reaches the top end of the recording capabilities, then you're spreading that signal across the entire potential bit depth and thereby arriving at a more accurate and detailed sampling of the original analogue waveform using the most information possible.

So, perhaps that's what you wind up with electronically when you flash/fog/digicon an image in camera...dark tones that are sampled at a wider range.

sound plausable?

Now obviously this isn't the direct function that would cause a digicon filter to work, but there's obviously some curve at work in the exposure scale of a CCD. The direct response from photons at the low end of the scale can't be purely linear, there's some function of quantum momentum that causes an individual pixel to begin responding to light as signal rather then noise. Perhaps in an electronic sense, raising the quantity of photons indicative of black/dark tones results in a quicker response at the pixel/capacitor end. Maybe there's some function between the two that cause a camera to resolve detail in shadows while using a digicon filter. Perhaps it's a combination of increasing the photonic volume of a dark tone, paired with the longer scale of a raised value that results in a minute increase of accutance.

I donno.

I took a stab.
 
I havent had any experience with the varicon, but i've used tiffen ultracontrast filters quite a bit on my dvx. Like barry said, these filters actually lessen the overall contrast of the image, which in many cases, especially bright exteriors, is extremely helpful. I never thought of it like a controlled flare, but now thinking about it, thats probably exactly right. When my crew was shooting my feature docu down in cali, we had tons of low (I mean LOW) light situations where you could hardly see anything. Thank god we had removed the lens hoods on the cameras!! when my operators aimed the camera towards a streetlight, the flare brought all my shadow detail out and we ended up with a decently usable image. but back to the point:

I use ultracons alot outside, they effectively raise your exposure latitude, unearthing shadow detail and crushing highlights. very very helpful, and they create some beautiful images. and others are correct on the forum here, the ultracon filters will get you extra information that you *will not* be able to recover in post. The one gamble here, however, is that these filters ride a very fine line with the detail quality of the camera - if you use an ultracon make sure you are getting pretty dang close to the image you want - and use a field monitor - because we've noticed footage shot with ultracons do not like alot of correction - and the picture will chunk up quickly.

I used ultracons to achieve day-for-night shots in broad daylight complemented by monochromatic blue WB and color settings.. these filters can be very helpful, you just have to know what you want out of them.

HTH
 
Very cool. What master ped setitngs do you shoot with?

I guess it makes sense that there would be more posterization in post. Dynamic range is limited by NTSC as much as by the CCDs. Also, what strength do you shoot with? I think I may have to buy one of these things if they really work as you explain.
 
So the main use of ultracons is when shooting outside or in situations where you cant control contrast with reflectors, butterflies, flags or lighting.

IS the following reasoning accurate?

Now if the ultracon raises the levels of the shadows this means that you can then underexpose abit more. This underexposure would allow you to decrease the highlights in your scenes whilst preventing you from crushing the blacks. Furthermore if you have your gamma setting on high this further raises your shadows allowing you to further underexpose and hence reduce the brightness of the highlights again.

The master pedestal raises or lowers the brightness of your shadows and your highligts together. Therefore using the ultracon or high gamma is different because it only affects one end (high gamma) or both in opposite directions(ultracon).
 
To the extent of my knowledge, this sounds about right. with the ultracons you will gain shadow detail in areas that you wouldn't be able to control with reflectors or anything more "proximity" oriented. I was able to pull out details in shadow areas further away from the lens where we wouldnt be able to light anyway. And you are correct to a certain extent in that the ultracons will bring your black brightness level up, so technically you could under expose and crush the highlights even more than they will be by the ultracon in the first place. I can't remember what my master ped was at on those shoots, but usually at least a couple in the negative direction. I shot with a +3 - some people noted on my demo reel they thought the images were soft - the untracons definately have something to do with it.. its not as gritty as standard DVX look, so again it comes down to what you want out of the image.

sean
 
How do you feel it compares to a black promist? I know that they do different things, but the black promist, does increase latitude in the blacks.
 
I honestly couldnt say... i've used both, but not in a comparison manner.. next time i think about it I'll grab all the filters from the university and run some comparison shots for you guys.
 
sporter: I just got a DVX100a and I'm taking it to Ethiopia to shoot a documentary - a lot of exterior scenes with kids, run n gun stuff. I'd like to take an ultracon and can't afford more than 1 - do you recommend a # for this kind of daytime hi contrast stuff? Is a 3 too drastic? Will I get anything out of a 1 or 2?
 
I would just bring a 1. They were designed for 35mm film, so for the 1/3" chips, they have a stronger apparent effect.

As they compare to a Black Pro Mist , the BPM hs more of a "halo" type effect, while the ultracon is more like an even wash, bring up the balck level, allowing you to reach more into the whites w/o clipping.

I wouldn't use the Ultracon on a 1-time doccu with out a lot of testing and a field monitor. I would stick with a polo to help keep the sky in range, and mabye a 1/4BPM to make it look nice, if that's what you want.
 
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