Depth of field/aperture for action shots?

[rayortiz313]

Hey guys,


I'm tnew to DSLR moviemaking and just got a T3i and the obligatory nifty-fifty F1.8 50mm lens.


I'll be shooting action scenes and may want to use the 50 for closeups and maybe even some medium shots of stuff like two people wrestling for a gun, someone leaping towards the camera with a knife, etc.

I'm doing no-budget one-man crew thing and noone to follow focus or any of that other stuff-its a learning piece, not a professional production or anything.


Clearly I dont need razor-thin DOF where the subjects eyes in focus and their nose isn't.


I know the short answer is to go do some tests, but what is a good aperture for this in order to get some background seperation/bokeh and still have some breathing room with the focus (I have a varable ND to give me the fexibility to choose one)?


Again I'll be testing it out but maybe by asking the question I'll get some thoughts on depth of field/lenses and shooting action in general.

 

[Michael Carter]

There's no hard and fast answer, and it's so easy to to just block out a scene and try a couple different variations. It's not even really a "testing" scenario, anyone shooting such a scene would likely dial this in on set.

A follow focus with hard stops can make this sort of thing much easier in a rehearsed scene. The Fotga DP II (or whatever, it's on Amazon) is a killer value. You'd need at least a cheap set of rails, Amazon as well. But it's money well spent until you can afford a $1k+ unit - and your bang for the buck would be minimal compared to the fotga anyway.

This sort of scene might really call for a wider lens though - nothing crazy, a 28 or 24 or 20 gets you in the normal-to-a-little-wide range on that sensor. But that's generally another thing you'd dial in while blocking, unless you really have a specific, mild-telephoto look in mind. But if you're stuck with the 50, make it work. Keep in mind, you can stick about anything on that camera with a $20 adapter. Keep an eye on eBay and KEH for an old film DSLR lens - Canon pre-EOS, Nikkor, aftermarket. I'd 100 times rather spend $50-$100 on an old prime that's decently sharp at 2.8 than some kit zoom that limits you to 5.6 or something. And in your case of just wanting to learn stuff, the lens doesn't even have to be that great… a 28mm Nikon Series E is a so-so lens wide open but not terrible and can be found cheap - look on eBay for old Nikon film cameras that come with a lens, often that's cheaper that just buying a lens alone - sometimes $20 for a body and glass (and then you'll have a cool old film camera for room decor).

 

[DLD]

Also depends on how many closeups you want. In the "old style" Bruce Lee type flick, it looks like a 20-25 mm wide shot and a "live" filming of the entire fight scene. Often with the overhead lighting too. But, if you want a lot of closeups, then you're the master of that domain. Spielberg spent what, a month shooting the Normandy landing scene in "SPR"? And they'd probably spent more editing it. One thing though, you better make your shot list beforehand.

 

[Michael Carter]

Yes, choreographing this stuff is really key; keeping a sense of the geography of the scene, who's where and when, how they move through the space… storyboarding and rehearsal is really key.

Potentially going through the whole scene in single wider takes, or breaking it up into sections and going wide - then doing closeups and details to amplify moments and provide coverage for edits.

Watch the fight scenes that strike you as good ones and see what you can learn. Try watching a scene you can rewind a pause, and diagramming out the action and camera angles.

But as for DOF - it's going to vary with lens, and the variables of distance from lens to subject to background. which (in an action scene) are likely to be in constant flux. Getting a cohesive whole to the edit is usually the main goal. And for intercutting, I see so many instances - even on hollywood films - where cuts are obvious due to body motions and action not "following through". Someone is raising her had to touch her hair in a wide and it's not carried through in the medium, or even just a sense of momentum carrying through a cut.

 

[DLD]

... Potentially going through the whole scene in single wider takes, or breaking it up into sections and going wide - then doing closeups and details to amplify moments and provide coverage for edits...

And, in this scenario, you also better bring along a lot of chalk or gaffer tape in various colors because you don't want your actor to swing his fist standing in front of a window - as an example - and finish it some three-four feet to the window's side.

PS. I recall an account of an aging theater actor who basically had no clue what "hitting your mark" meant, when he was chosen for a very important (early 70's) TV series role. He tended to wander off whenever he felt like it (a Method guy, naturally), so the director really had to solve the problem, especially during closeups. IIRC, she "solved it" by yelling at him a lot. Loudly.

The actor nonetheless went on to ace what became the role of his life and became hugely popular for it.