October 12, 2013

Deep Focus: Taking a Closer Look at the Use of Split Diopters in Film

If you've ever been watching a film, say Carrie or Reservoir Dogsand you've seen a shot that had incredibly deep focus, then maybe you were looking at a shot that used a split focus (or split field) diopter. These lens attachments produce a signature look that puts objects near and far into focus, a look that made Gregg Toland a legend, and later swept over the filmmaking world in the 70s. Vashi Nedomansky of Vashi Visuals takes a look at the use of split focus diopters throughout cinema, and picks out all 15 shots from Brian De Palma's 1981 film Blow Out that use one.

Maybe you've used split focus diopters in your own work, so you're aware of the great shots they produce. But, for those who aren't familiar with them or have never considered using them in your films, many, many movies, especially in the 70s and 80s, used split diopters to get that deep focus look. Probably the most famous use of diopters is in Orson Welles' Citizen Kane, but All the President's MenThe Thing, and many of De Palma's films also utilize the effect.

Since split focus diopters are half convex glass, when attached to your camera's lens, it makes one side nearsighted, and the other farsighted. What this allows you to do is focus on multiple planes -- you could have objects in the foreground and background completely in focus. This also means that the staging of your scene must be copacetic.

The way that many cinematographers use this is to add a little mystery or uncertainty to their shot. Since our eye doesn't see things in this way naturally, it can be a jarring and disorienting experience when it does. In fact, some shots look almost like two separate images juxtaposed together, which immediately adds a layer of fantasy.

In the shot from Reservoir Dogs above, you can see that the split diopter creates a clear line down the frame, which can be masked using several techniques, like shooting the split against vertical lines or darkness.

Vashi has made a video that highlights all 15 shots from Blow Out, which might help you get a better idea of what a split diopter can do for your films. Check it out below.

What is your experience with split diopters? What are your favorite shots from films that utilize them? Let us know below in the comments.

Link: Splitting The Focus in De Palma’s ‘Blow Out’ -- Vashi Visuals

Your Comment

17 Comments

I remember seeing on in Tarantino's "Death Proof" too and thinking at the time "What the hell is that line?"

October 12, 2013 at 4:17PM, Edited September 4, 11:21AM

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Guy

I have always loved those shots but figure you can just get them by locking the camera down and doing two takes, then combining the shots in post. Just have to make sure the two subjects don't get too close to each other.

October 12, 2013 at 4:39PM, Edited September 4, 11:21AM

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Good point Luke. It's a simple task for any NLE today. I think the allure is that all the examples above where shot on film and pre-planned...before the advent of inexpensive digital editing. Love the effect no matter how you get there!

October 12, 2013 at 5:17PM, Edited September 4, 11:21AM

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Wouldn't something like the new Sony 4K Z-100 camcorder be able to give you the same depth feel with its very small sensor? (of course, it doesn't have the interchangeable lens).

October 12, 2013 at 8:51PM, Edited September 4, 11:21AM

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DLD

You can shoot at f22 on a DSLR as well... just add more light to compensate for the tiny aperture. Apparently, this splitter allows you to still shoot at f2.8 and have two different planes in focus.

Another thing - copacetic. Nice word. Had to look that one up...

October 14, 2013 at 9:22AM, Edited September 4, 11:21AM

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The difference between shooting deep DoF and a splitter, of course, is that the first everything is in focus, whereas with the latter two focal planes are and the rest is cinematically out-of-focus.

October 14, 2013 at 9:25AM, Edited September 4, 11:21AM

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I'd rather user real split field filters and stack them in a box, the problem is diopters are becoming harder and harder to find and when you do find them they are either jacked way up in price or sold for pennies on the dollar. Frankly i'm tired of asking rental houses if they have them, as every single time they don't know what they are and don't have them.

October 15, 2013 at 6:28PM, Edited September 4, 11:21AM

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Another huge (ab)user of split diopters is Star Trek: Deep Space Nine. The shuttles, runabouts, and the Defiant were all small spaces and split diopters were in almost every multi-character scene on those sets.

October 12, 2013 at 6:08PM, Edited September 4, 11:21AM

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Kevin Marshall

Ah, there's a lot of this in Deep Space 9 which I've been watching a lot of recently - wondered how they did it.

October 12, 2013 at 6:24PM, Edited September 4, 11:21AM

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Pete Harper

I absolutely love deep depth of field but I prefer clever staging or wide angle lenses to split diopters in most cases.

October 12, 2013 at 7:46PM, Edited September 4, 11:21AM

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Dan

Tongue it!

October 12, 2013 at 8:01PM, Edited September 4, 11:21AM

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Sam Biel

I don't think the Citizen Kane shot is a diopter. I remember that it was a hyperfocal shot. It doesn't appear to have the tell-tale vertical line that the others do.

October 13, 2013 at 12:15PM, Edited September 4, 11:21AM

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AnthonyD42

According to Ebert's commentary on the Kane DVD, that shot is actually two different shots married in an optical printer. You couldn't get that depth of focus and strong backlighting in the hallways and still keep Kane in focus and well-exposed in the foreground without doing Kane separately from Leland and the rest of the room.

A LOT of shots in Kane are like that - insanely clever and invisible composites. It's a REALLY effects-heavy film.

October 13, 2013 at 4:13PM, Edited September 4, 11:21AM

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I resently listened to the Bogdanovic-commentary track, where he says the same thing. Though. In this case I think it's down to viewer-recollection error. Yes, a lot of shots in Citizen Kane was double-exposures, matte-shots, glass-shots, clever wipes etc. But in that example, I think it's just a simple split diopter slanted a bit to get all of Kane in focus. The DoF is deep as it is (mid-ground to far background is still in the same focus) but there is a tell-tale line where the focal-plane is split. Also, the alternative, that is, to do a dialouge in multiple exposures is much harder than putting a piece of glass to do the same job in camera. Another possibility would be a process-shot. But that usually leaves tell-tale signs of graininess from the rephotography on the background. Not impossible, but in this case I'd go with the proverbial Razor of Occham and claim that it was probably a diopter.

October 17, 2013 at 12:47PM, Edited September 4, 11:21AM

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It's always better to do shots like this in camera, especially if you require both splits to have some aspect of performance in them.

October 13, 2013 at 4:54PM, Edited September 4, 11:21AM

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Tolland did use an optical printer. Kane has no split diopter shots. Wich is Genious If you think about it. They thought about a way to make a realy deep focus scene seamless, in a way far advanced for that period. Its simple to think about compositing now a days but back in 1941...

October 15, 2013 at 10:55AM, Edited September 4, 11:21AM

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JB

Not a fan of split diopters, they always take me out of the moment when used in a shot. De Palma is one of the biggest culprits, there's a great shot of Costner and Connery in a church in Untouchables, then it cuts to a diopter shot - ruins the moment for me!

October 16, 2013 at 12:16PM, Edited September 4, 11:21AM

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Graham Cristie