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Filter for "Alexa Look"/Film Look: Tiffen Digital Diffusion FX?


M Joel W
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I suspect this reads like a primitive and poorly-researched request, but I hope it's not.

 

In my experience, the Alexa has a certain smooth look to its imagery that I don't see with the Red or F5 or C300, for instance, and that I think is meant to emulate film's halation. I've shot and done post work extensively with all these cameras, it's not something I imagined based on clips online. It's distinct and even with vintage lenses there's a different quality to the Alexa. The smoothing is of higher frequency detail, not an overall softness or decrease in contrast or saturation. There's not much loss in resolution, but it feels rounder and smoother. I've read that Arri likely puts a diffusion filter on their OLPF.

 

I've tried various diffusion filters; none have achieved this perfectly.

 

Currently the best I've used is the hdtvfx 1/2, however it flares quite strongly at times and the softening is not too pronounced. I'm not sure if it's the right amount, or slightly too little diffusion. Of course it probably depends on the focal length and I have no idea how to put a filter behind the lens. Maybe I'll get different strengths for different lenses.

 

I'm tempted to try the digital diffusion fx1 or digital diffusion fx 2 because they lack the ultracontrast filter, but I suspect those strengths might be too strong? It's very difficult to get a read on the level of diffusion here. They all look about the same. Maybe the #1 strength seems closest to the Alexa? I have no idea whatsoever from this test. The effect is too subtle:

 

 

However in use (shooting 4k raw) I notice a significant difference even with the hdtvfx 1/2. I like that filter, but sometimes the flare from the added ultra contrast is too much. It's such a strange subtle difference, but the Alexa does something different I think. I love vintage lenses and diffusion filters, in particular classic softs, but they don't impart the controlled smooth quality, more of a glow.

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The Alexa does not have a diffusion filter in the OLPF. It does flare just a little around a bright point of light like a candle flame. Mostly what you are sensing is how the Alexa gracefully rolls-off overexposure information and color saturation into the clip point, which is more due to its extended dynamic range in the highlights. If you want to use a mild filter for softening the image from a Red camera, that's fine, but there isn't specifically a filter that will emulate an Alexa look, and if there were something close, it would have to be incredibly subtle like a 1/8 Black Frost.

 

Some filters are "mistier" and are designed to cause some halation, which has some effect on lowering contrast (but contrast and black level can be adjusted, it's a digital image after all) and some are designed to soften detail with less of a misty look. Everyone has a different taste on which effect they want more of, hence why there are dozens of diffusion filters on the market. The Tiffen Black Diffusion/FX and the Schneider Radiant Softs are designed to soften with minimal halation, if that's what you want. A Schneider HD Classic Soft also softens with just a bit of a blurry glow to bright areas (the halation is less of a misty glow but is more due to that bright area being blurred and overlaid back on the sharp image). Most of the other diffusions have a more pronounced halation, and in fact, many are compound filters with an element to create a misty glow (such as the 1/8 Black Frost that is part of the Schneider Hollywood Black Magics, or the GlimmerGlass that is part of the Tiffen Black Satins.)

 

Take a look at the Black Diffusion/FX filter (the 1/2 is the lightest).

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The Alexa does not have a diffusion filter in the OLPF. It does flare just a little around a bright point of light like a candle flame. Mostly what you are sensing is how the Alexa gracefully rolls-off overexposure information and color saturation into the clip point, which is more due to its extended dynamic range in the highlights. If you want to use a mild filter for softening the image from a Red camera, that's fine, but there isn't specifically a filter that will emulate an Alexa look, and if there were something close, it would have to be incredibly subtle like a 1/8 Black Frost.

 

Some filters are "mistier" and are designed to cause some halation, which has some effect on lowering contrast (but contrast and black level can be adjusted, it's a digital image after all) and some are designed to soften detail with less of a misty look. Everyone has a different taste on which effect they want more of, hence why there are dozens of diffusion filters on the market. The Tiffen Black Diffusion/FX and the Schneider Radiant Softs are designed to soften with minimal halation, if that's what you want. A Schneider HD Classic Soft also softens with just a bit of a blurry glow to bright areas (the halation is less of a misty glow but is more due to that bright area being blurred and overlaid back on the sharp image). Most of the other diffusions have a more pronounced halation, and in fact, many are compound filters with an element to create a misty glow (such as the 1/8 Black Frost that is part of the Schneider Hollywood Black Magics, or the GlimmerGlass that is part of the Tiffen Black Satins.)

 

Take a look at the Black Diffusion/FX filter (the 1/2 is the lightest).

 

 

Thanks, David, I was hoping to get a reply from you!

 

Does the black diffusion/fx filter create speckles in the bokeh? That's one trade off I'd rather not deal with.

 

Even if the Alexa doesn't have a diffusion filter, it seems to have a soft glow to it by comparison, and that's not just in the highlight rolloff. Recently I A/B'd C300 and Alexa footage used for the same project and it was neither the resolution nor dynamic range that gave the C300 away, but a less "smooth" feeling overall. The highlights were the next clue, though, so maybe it does have to do with the dynamic range somehow, since the tonality might also be affected by the dual gain or whatever. I feel the same way about the F55, and to a lesser extent the Dragon. I want a slight diffusion filter for a shoot on the C200. Based on the aliasing I'm seeing with this camera and the general and (for this project) undesirable "crispness" compared with the Alexa or even Dragon at least at a per-pixel level, I don't mind something that bites into the resolution a bit.

 

Does the classic soft wash out the image like an ultracon or is it a controlled flare? I should know this as I've used both, but not carefully. I love the non-hd classic soft, but haven't used the hd version. I liked the much more subtle hdtv fx (digital diffusion fx combined with ultracon) for taking the edge off until I shot a window and the flare was too extreme for my taste. Now I would only want it if that effect were intended or there were no light sources in frame.

 

Have you tried the digital fx diffusion? It seems closest to the black diffusion/fx you recommend, but I believe it doesn't have bokeh speckles. If there are no speckles with black diffusion/fx, I might just try that instead. Thanks again.

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Your best bet might be to shoot log and use an "Arri" look LUT.. Sony even made one expressly for this.. the LC709A.. (the A standing for Alexa or Arri).. LC stands for low contrast.. you have to change the color space . there a ton of them out there.. don't think any diff filter is really going to do it.. with the Venice Sony have changed the 709 color space (at last !).. no doubt learning a lot of the "Arri" look.. esp the high light color saturation thing .. that Arri do so well.. that mimics how film deals with it..

 

Sony actually put out a demo reel showing Sony 709 and the Arri LUT applied to Slog3.cine.. very comprehensive side by side.. and really I would say its impossible to see the difference except for some professional graders .. if you google it it Im sure its out there on the inter web..

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Digital Diffusion/FX is just the Black Diffusion/FX with the black dots removed (because on 2/3” HD camcorders, the dot pattern was coming into focus). They were there to restore some contrast but that can be done in the LUT or color-correction so if the specks in the bokeh bother you, then use Digital Diffusion/FX.

 

Classic Soft doesn’t have any mist particles, there is just some halation due to the dimples in the glass creating an out of focus shape of the bright area, so it is a blurry glow (almost like a double image) rather than a hazy glow. HD Classic Softs use smaller dimples so the blurring of bright areas is less obvious, again it was created originally for 2/3” HD camcorders because their greater depth of field was making the dimple pattern too obvious with regular Classic Softs.

 

Just make sure that the contrast and sharpening settings are what you want before adding a filter in the mix to soften. It may just be that the Canon applies more electronic sharpening in the chain.

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I don't think any type of glass filter will create an "Alexa" look. I think David might be on to something when he writes about "sharpening" being added, or differently applied, in the non-Alexa cameras.

 

I shot my last Alexa project with black promist filters to create significant halation effects. But, it still looked like "Alexa".

 

Differences in OLPF could create different impressions for each camera though.

 

Re: LCRec709 LUTs... eh... If you have a colorist for this project they should know how to deal with the contrast curves, even if they were using a standard Arri LogC to REC709 LUT in color correction.

 

On my last project, in color correction, I used a matrix/transform from Arri LogC that separated the contrast curve from the matrix correction. In this way I could control the contrast and "roll offs" manually and it worked quite well. Even if you use a standard Arri LogC LUT, you can change the contrast of the LogC image, before the LUT and control the contrast and roll off that way.

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Thanks, everyone. I'm aware of the F5's Arri LUT and have seen really good results with it–and would use it were I shooting Sony.

 

The Canon Log 2/Cinema Gamut I'm developing with (shooting raw) also seems designed to emulate Arri. I don't love Canon's WideDR LUT so I generated a Canon Log 2 to Alexa LUT with lutcalc and then put an Arri 709 LUT on top of that. The skin tones are even a bit more magenta than the Alexa's, and I'll never get the shadows as clean without denoising, but the look is in the ballpark of what I'm after. Surprisingly, highlight rolloff is not a significant problem. Shadow noise is a bigger one.

 

David's advice regarding sharpening is good, but I just checked my settings and the default development in Creative Cloud (and probably in Resolve) has no sharpening (or "0 setting") and I compared that against a DPX sequence rendered using Canon's development software. It's per-pixel identical with Creative Cloud and to my eye Creative Cloud matches Resolve. I haven't compared it directly with Resolve, but I suspect it's all the same. When applying sharpening in Canon raw development the image looks worse to me.

 

The reason I suspect the OLPF is stuff like this:

 

post-10185-0-44858500-1548351482_thumb.jpg

 

Bruce, the matrix/transform thing is over my head. How does that work? I agree each camera has a distinct look. It's refreshing to see that people agree. I've noticed the Alexa seems to have more micro contrast and occasionally I find what appear to be sharpening artifacts in Alexa footage (I work mostly in post and am frequently zooming in to 800% on Alexa footage) that have a wider radius, but the tonality is very "smooth" too. I can't imagine how complex the imaging chain is on that camera.

 

I'll try the digital diffusion fx 1/2 or 1 filter next. Slightly flared shadows are fine. David, I appreciate the detailed info because I might be combining this with a Classic Soft 1 or 1/2. Should probably just rent an Alexa at this point lol.

Edited by M Joel W
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  • 2 weeks later...

ARRI does not put a diffusion filter into its OLPF, but the design of an OLPF has a huge impact on the look of an image. We spend a LOT of money on ours. There's a balance between eliminating detail and preserving it, and every manufacturer makes different choices.

 

There is some sharpening applied to ProRes material. As ProRes is compressed and often ends up being broadcast, it needs a little something or it appears soft. I believe the level can be adjusted in the Mini and the Amira (not sure about the SXT), although I wouldn't as our engineers tend to be pretty smart about such things.

 

Any sharpening applied to ARRIRAW is metadata only and can be removed. A default amount is typically applied during format conversions.

 

I remember learning about this with the Sony F900 years ago. We all though HD would be sharp enough without any additional sharpening, but that only worked for film outputs. For broadcast, eliminating all sharpening yielded a very soft image. Setting detail at -40 SAU (Sony Arbitrary Units) added just enough sharpening to create a great-looking HD and SD image for TV.

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ARRI does not put a diffusion filter into its OLPF, but the design of an OLPF has a huge impact on the look of an image. We spend a LOT of money on ours. There's a balance between eliminating detail and preserving it, and every manufacturer makes different choices.

 

There is some sharpening applied to ProRes material. As ProRes is compressed and often ends up being broadcast, it needs a little something or it appears soft. I believe the level can be adjusted in the Mini and the Amira (not sure about the SXT), although I wouldn't as our engineers tend to be pretty smart about such things.

 

Any sharpening applied to ARRIRAW is metadata only and can be removed. A default amount is typically applied during format conversions.

 

I remember learning about this with the Sony F900 years ago. We all though HD would be sharp enough without any additional sharpening, but that only worked for film outputs. For broadcast, eliminating all sharpening yielded a very soft image. Setting detail at -40 SAU (Sony Arbitrary Units) added just enough sharpening to create a great-looking HD and SD image for TV.

 

 

Thanks for the clarification and transparency. I'd read elsewhere that Arri might use a diffusion filter in the Alexa and I'll make a note not to repeat it.

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  • 1 year later...

I own a Tiffen Digital Diffusion FX/1, and this filter DOES introduce speckles in the bokeh. Pretty horrible in fact (shaped like horseshoes). When it doesn't show up though, it truly adds to the Alexa emulation. Very transparent, but makes blurry backgrounds creamier. It seems to add a tiny bit of thickness to high contrast details, while softening light textures like skin. Unfortunately, the extremely strong artifacts in the bokeh balls is a no-go for me, so I stopped using it.

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A few years back I tried a cut piece of Formatt Hitech 1/8 contrast filter behind the OPLF in a SI2K camera. There was a subtle "apparent" slight extension of the histogram but as for the look, not much seemed to change. I also tried IRND to place the lens iris in the sweet spot and an Ultracon 3. Whatever the ARRI secret sauce is, the optical filter panel in the camera throat is probably not it.

 

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  • 3 weeks later...
On 1/24/2019 at 5:28 AM, David Mullen ASC said:

The Alexa does not have a diffusion filter in the OLPF. It does flare just a little around a bright point of light like a candle flame. Mostly what you are sensing is how the Alexa gracefully rolls-off overexposure information and color saturation into the clip point, which is more due to its extended dynamic range in the highlights. If you want to use a mild filter for softening the image from a Red camera, that's fine, but there isn't specifically a filter that will emulate an Alexa look, and if there were something close, it would have to be incredibly subtle like a 1/8 Black Frost.

 

Some filters are "mistier" and are designed to cause some halation, which has some effect on lowering contrast (but contrast and black level can be adjusted, it's a digital image after all) and some are designed to soften detail with less of a misty look. Everyone has a different taste on which effect they want more of, hence why there are dozens of diffusion filters on the market. The Tiffen Black Diffusion/FX and the Schneider Radiant Softs are designed to soften with minimal halation, if that's what you want. A Schneider HD Classic Soft also softens with just a bit of a blurry glow to bright areas (the halation is less of a misty glow but is more due to that bright area being blurred and overlaid back on the sharp image). Most of the other diffusions have a more pronounced halation, and in fact, many are compound filters with an element to create a misty glow (such as the 1/8 Black Frost that is part of the Schneider Hollywood Black Magics, or the GlimmerGlass that is part of the Tiffen Black Satins.)

 

Take a look at the Black Diffusion/FX filter (the 1/2 is the lightest).

If this topic is still open I’d love to hear more from different peoples experiences and preferences, I like Tiffen Digital Diffusion (1/2) but I would like to try 1 or heavier and I’ve gone with a 1 Tiffen Black Gimmer glass but I was wondering has anyone used the Kippertie carbon OPLF on a RED DSMC2 camera?I have the RED skin tone OPLF which is very nice.

I suppose can you really remove as much fine detail from skin without blooming out all the highlights or sources ?  

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