Diffusion filters have seemingly become the most popular tool for filmmakers and cinematographers seeking a filmic look when shooting digitally. But how much diffusion is too much?
Since the rise of digital cinema, filmmakers have been looking for ways to find a best of both worlds scenario: The convenience of digital acquisition, with the character of motion picture film.
It’s a worthy goal, and one that I certainly share.
It’s why I’ve written at length about making your digital footage to look like it was shot on film. And why I’ve spent so much time creating film emulation LUTs and film grain scans to replicate the look and texture of motion picture film.
But if I’ve leavened anything about emulating the film look digitally, it’s that it requires a variety of techniques that only work when combined methodically.
There is no one technique that works in isolation, yet many filmmakers tend to hyper focus on just one specific tool, which leads over-stylization of their footage.
Until recently, shallow depth of field has been the most obvious example of this.
A decade ago when DSLRs first opened the door for cinematic digital capture on a budget, the filmmaking community went wild.
No longer did they need to use 35mm adapters to achieve a 35mm motion picture look. They could now just shoot on a prosumer Canon 5D MK II and achieve razor thin focus thanks to the larger sensor and interchangeable lenses.
Even your average home movie could have shallower DOF than many features shot in Hollywood on 35mm film.
In no time though, the shallow DOF trend became painfully over-saturated. Everyone started shooting wide open on full frame sensors, and racing to capture the thinnest possible focal plane. The resulting images almost always looked sub-par, and certainly never looked anything like motion picture film.
Before long, too much shallow depth of field became a case in point for not over stylizing your image with any one tool.
Thankfully, this trend died down and hasn’t resurfaced in the past few years.
In each of the above cases, a technique was used in hopes of creating a more filmic or “cinematic” final look, only to backfire and have the exact opposite effect.
Over the past couple years, another frustrating trend has emerged that falls right in line with the rest:
The overuse of diffusion filters.
Among other things, diffusion filters are often employed to soften overly sharp 4K+ digital cinema footage, and make it more pleasing to the eye.
The idea is that motion picture film (even 35mm) is a touch softer and more inviting than digital. So if we want to make our shots look less digital, why not just soften them up with diffusion?
It’s a fair hypothesis, but one that works far better in theory than practice… Because again, there is no one factor that makes an image look filmic.
It’s a combination of frame size, camera movement, motion cadence, dynamic range, color balance, texture, and countless other interrelated variables.
It’s impossible to single out any one variable and make a case that it is the X factor behind the cinematic look. There is no such thing.
And if there were, it definitely wouldn’t be diffusion. Especially when you consider that the vast majority of movies shot on film are incredibly sharp and don’t have a diffused look whatsoever.
Try putting some 65mm IMAX film next to run of the mill DSLR footage and see which one looks more crisp. The film will win in a landslide.
But even if we assume that all film is inherently softer than digital (which is simply not true), there is still no reason to go overboard with diffusion – Because what makes film appear softer is not diffusion, it’s the format itself.
Another argument for diffusion is that it improves highlight rolloff and halation, which makes the image more filmic. This isn’t necessarily accurate either though.
While in many cases diffusion will improve the subjective appearance of highlights, it does not emulate the look of actual film. At best it gets in the same ballpark.
None of this is to say diffusion filters aren’t without their place.
A subtle 1/8 or 1/4 pro mist can be used tastefully to add a dreamy quality to your shots or help smooth out skin tones. And more aggressive diffusion might work well for highly stylized projects like music videos or experimental shorts.
The question isn’t whether diffusion can create beautiful visual results (of course it can), but whether those results are emblematic of film – which they are typically not, unless paired with other techniques.
Personally, when I want a more analog / 35mm look from my digital footage, I almost always opt to use vintage glass on the camera instead of diffusion filters.
A nice vintage lens (or even a modern lens with vintage-like qualities), can go a long way in adding character to your shots, while tempering down the harshness of digital.
It can soften your edges without adding unnecessary haze, and looks far better (to my eye at least) than clean modern glass that is over-softened with filtration.
The same could be said about using a nice soft light source, a touch of haze, or the right in-camera LUT.
All that said though, diffusion filters still hold their place in my gear kit, and I’m sure always will.
They are as important a tool as any other, and capable of beautiful results in the right hands. They just aren’t a magic bullet for making digital footage look like film – but then again, nothing is.
Do you like to use diffusion filters? Leave a comment below.