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Old March 26th, 2007, 12:23 PM   #16
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I've shot two features in 35mm anamorphic with the Tiffen GlimmerGlass,"Akeelah and the Bee" and "The Astronaut Farmer". Not for everything in those movies; the first third of "Akeelah" was shot clean but with a lower-contrast filmstock and then I switched to a normal contrast film stock with the GlimmerGlass diffusion.

On "Astronaut Farmer" I used the GlimmerGlass on medium and close shots.

GlimmerGlass is a similar effect as Black ProMist. What I like about it though is that the lightest GlimmerGlass (#1) is slightly lighter than the lightest ProMist (#1/8) and that the next heavier GlimmerGlass (#2) is not as big a jump in diffusion as the next heavier ProMist, so I am freer to alternate between the #1 and #2.

Because it has glitter particles on it like the black specs of a Black ProMist, you have to make sure you are shooting fairly wide-open in video, or not too wide-angle, to avoid the filter surface itself starting to come into focus - it will look like you have a dusty lens.

I had a montage sequence in "Akeelah and the Bee" where I had to shoot the actors in HD (F900) because we had some b-roll of the real National Spelling Bee in HD. It all played in a contained montage sandwiched by 35mm. You can see some frames (attached), the first a shot from the HD footage shot clean -- the second from the 35mm anamorphic footage using a #2 GlimmerGlass. From the DVD. At this point in the story, the GlimmerGlass was part of the look, to create halation on backlight, but I had to drop the filter for the HD shots to match the HD from the real spelling bee.
Attached Thumbnails
Tiffen GlimmerGlass-aatbhd1.jpg   Tiffen GlimmerGlass-aatb351.jpg  

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Old March 26th, 2007, 08:11 PM   #17
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Quote:
Originally Posted by Marcus Marchesseault View Post
Wow, John, I would never have thought that that first image would result in that final product. Perhaps that's why I avoided using an ultracon filter in the past. I guess as long as the exposure is between the limits, there is information to work with. I think the moral of this story is that contrast filters are one part of the equation an should be finished with color correction.

That picture looks a whole lot like Hawaii! Was that shot here? That was a perfect example for me as I know exactly what locations like that look like in real life.

Ben, thanks for the tip about saturation. I might have accidentally stumbled upon that, but it's better to know about something and plan for the solution. Does in-camera saturation increase handle the problem or should it be done more selectively with color correction?
The waterfall is in a fairly hidden place in Oregon.

Ah, Hawaii... Hawaii is a beautiful place. I actually lived and worked in Honolulu for a short time (1989-1991). I also have an aunt and uncle who live on Kauai and were teachers there for many years.
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Old March 27th, 2007, 09:10 AM   #18
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Thanks for those examples, David.

This thread has been very informative for me. I've asked questions about how to increase apparent dynamic range using a filter in the same way the 35mm adapters seem to boost latitude, but I never got an explanation like we got here.

From manufacturer links and user reports, I think I understand these filters:

Low contrast - reduces contrast and has some halation around bright areas. It brings up the lows and reduces the highlights.

Ultra Contrast- reduces contrast with no halation (glow).

Soft Exposure - nobody seems to use this filter, but it reduces contrast by bringing down highlights. Halation seems to be similar to Low Contrast, but it doesn't bring up the blacks.

Glimmerglass - reduces fine details, creates glow, and slightly reduces contrast. It works like a Black ProMist, but with reflective (glitter) particles instead of black particles.

An important detail seems to be that the more a filter reduces contrast, the greater the need for color correction. This seems to be a key component to using filters that reduce contrast that is not commonly told. Perhaps this is why they aren't considered as important even though video has horrible exposure latitude and could use the help?

What sorts of situation might it be inadvisable to use a contrast-effecting filter?
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Old March 27th, 2007, 11:32 AM   #19
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It's not automatically required that any movie that uses a diffusion filter requires more color-correction. I mean, almost everything that is edited will need some post color-correction to blend shots made on different days, different cameras, different lighting conditions, etc. but diffusion filters don't increase the amount of work in color-correction unless you use them sloppily, badly, without checking what's happening in the camera.

If you are going to use a consistent level of diffusion, you can get away with a minor adjustment in your camera should you wish to counteract the lowering of contrast in-camera rather than wait until post -- you could lower the Master Black Level slightly for example, or change the Black Stretch or turn it off.

I did a movie in HD where I shot some flashbacks with a #1/2 ProMist and lowered the Black level down 5 points to compensate for those shots. I could have waited until post of course.

The truth is that whenever you use a format that has more exposure latitude -- color negative film being the greatest example -- the more information you are dragging into the post environment and the more flexibility you have to make corrections. That's normally considered a GOOD thing, but it does mean that you have to correct the material to achieve the final look. The opposite end of the spectrum is a poor latitude format -- color slide film for example -- where you have to pretty much nail the look when you shoot it. But on the other hand, then you don't have to spend much time in post adjusting it, assuming you shot it correctly.

So it's not a "problem" that wider-latitude images need more time in post to correct. That's not a flaw or mistake.

But using diffusion or low-contrast filters does require that you make adjustments while shooting if the filter is reacting too strongly to some element in the frame. For example, a heavier UltraCon can complete fog-out the image momentarily if you pan the camera past a glare on water. This is why you carry a few different strengths of filters.

The reason why these filters are not used as much as you'd think is simply that no filter can improve the exposure latitude all that much. Beyond allowing maybe a stop more shadow information (if that) all that these contrast-lowering filters are doing is lifting the blacks, and once you reset the blacks to "0" in post, you find that there was not much more information in the image. They aren't magic. Contrast-lowering filters only help a little and are part of an overall approach that involves using other filters (Polas, ND grads maybe), gamma and knee controls, lighting & grip work, etc. to control contrast. But you're always better off working with a camera or system that provides more exposure information from the start because there are no free lunches in digital manipulation.
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Old March 27th, 2007, 04:20 PM   #20
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"Contrast-lowering filters only help a little and are part of an overall approach that involves using other filters (Polas, ND grads maybe), gamma and knee controls, lighting & grip work, etc. to control contrast. But you're always better off working with a camera or system that provides more exposure information from the start because there are no free lunches in digital manipulation."

I can't agree more with that statement.

One thing I find interesting is that the highlights in the sample Ben posted were reduced to the point that the sky turned blue and the tree branches across the sky stopped smearing out. The only thing that can explain that is reduction of exposure in that area. It is also obvious that the rest of the scene did not reduce exposure. In fact, like you said, the blacks are brought up a bit even though there is little information increase.

I'll take an extra f-stop of latitude any way I can get it. I can't afford film or a high-end HD camera, but I have lighting and grip equipment and can add a contrast filter for the times it may be helpful. I already have and know how to use polarizers, ND filters, knee, black compensation, reflectors, scrims, and lights. I didn't know how to use contrast filters so now I have one last tool in the never-ending fight to control contrast.

Correct me if i'm wrong, but it seems like controlling contrast is the biggest battle in image manipulation. Any new tool I know how to use in the pursuit of better exposure is very much welcome. Thanks for all the information everyone!
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Old March 28th, 2007, 11:06 AM   #21
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You may be interested in these tests of the Schneider "Digicon" filter:

http://www.alfonsoparra.com/pages/press/e18.html
http://www.cinematography.net/digicon-test.htm
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Old March 29th, 2007, 02:55 AM   #22
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Thanks, David, I had read about the digicon a while back but forgot about it. I only remember things once I understand them fully. Contrast filters were a mystery to me until this week.
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Old March 29th, 2007, 10:50 AM   #23
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DigiCon is something of a cross between a Tiffen SoftCon and an UltraCon. Like SoftCons, they have an ND component (don't know if it's specks or overall) to knock down exposure in the highlights, and a low-con aspect. But the low-con element is more like an UltraCon, no halation (glowing).

I've never figured out if these filters can just darken highlights maybe with specks of black, because an overall ND would mean that you could do the same thing with a normal UltraCon and just underexpose it slightly.
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Old March 30th, 2007, 06:30 AM   #24
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I'm still bemused about how a filter can knock down highlights and elevate shadows simultaneously, but at least I now know the results and how to deal with it in color correction. I would assume that a grey softcon filter would just soften and darken the whole image, but that doesn't seem to be the case. Also, Tiffen specifically instructs not to change exposure when adding the softcon. If the digicon works in a similar way, it shouldn't be just a type of ND. Those images from the link you posted of the digicon really show the highlights in the sky at the above left of the picture to be brought down significantly. The shadows also are brought up a bit and, interestingly, color is slightly enhanced in the shadows. These may be test images, but they are pretty impressive assuming the results aren't just marketing spin.
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