Motion Blur on a Bolex Camera

[Tomike Atunwa]

Like the title, how would I achieve a motion blur on a bolex camera, as well as if I want the only thing in focus is someone standing in a crowd. 

Edited September 26, 2025 by Tomike Atunwa
adding tags

[Simon Wyss]

The first effect would be achieved by mistiming the claw-shutter coordination which calls for partial disassembly.

The other effect is a computer software thing of which other people understand more than me.

[Dom Jaeger]

Motion blur is something more easily achieved with still photography. In moving pictures, you are limited to the exposure times dictated by the frame rate, so to get motion blur it’s either a visual effect, or if you have a very large shutter angle then each frame in a sequence will have more motion blur than usual, but this just makes the motion appear smoother when the images are played in sequence. With a Bolex you are limited to more normal shutter angles anyway.

You could play with single frame stop-motion, using longer exposure times and an intervalometer, but when played back the motion of people moving will be sped up with large gaps in the movement.

If you deliberately mis-time the Bolex shutter, as Simon mentioned,  you will get the highlights smearing vertically, which isn’t really motion blur, unless the motion in question is the film moving in the gate. 

Edited September 27, 2025 by Dom Jaeger

[Simon Wyss]

I stand corrected, mistook film exposure during its advance for motion blur.

[Livio Colombo]

For motion blur I would think to use a very slow fps (but a Bolex goes down only to 8 or 12 fps, so you need an external motor) and rephotography with an optical printer. For example: shoot at 4fps, rephotograpy each frame 6 times for standard frame rate of 24fps.

For having only someone standing in a crowd in focus I'd try to adapt a tilt lens to your camera and tilt it on a vertical axis and throwing out of focus everything is left or right.

Or I'd try to put some clear gel on a filter, leaving only the center portion clean, where you want to stay in focus.

Edited September 27, 2025 by Livio Colombo

[Joerg Polzfusz]

Put the actor into an OSVP / StageCraft or in front of a rear projection screen and show a blurry crowd in the background.

Other than this, put the camera onto a tripod, make the actor standing still (no breathing or other movements) while the crowd is moving around him. When using long term exposure (e.g. 1s per frame), the actor will be „sharp“ while everyone else will be affected by motion blur. (Not sure whether this is possible with a Bolex or whether you would need a better camera. And beware: At 1 fps, a one minute scene needs to be shot for 24 minutes - will the actor be fit enough to stand still long enough? Not to mention that you will probably have to use an ND filter to avoid overexposure.)

 

Livio‘s tilt-shift-adapter sounds like a good idea. But I don’t know whether the effect will be „good enough“ for an actor standing in a crowd. I guess that the neighboring people would still be in focus. So maybe the filter might be a better choice… wasn’t there a discussion about a similar scene in the westside story (the original, not the remake) and how also the lighting helped?!

Edited September 29, 2025 by Joerg Polzfusz

[Joerg Polzfusz]

That’s the topic. But here, it wasn’t done in the camera, but in post.

[Phillip Mosness]

I'm thinking you're looking for that Wong Kar Wai / Chunking Express sort of look.

The Bolex's wind up motor only goes to 12 fps. (actually depends on model/year) It's maybe not a slow as one would hope for that effect, but you might still have a way of getting close.

Are the people in the crowd extras or just people on the street?

If they are extras you could shoot at 12 fps and ask everyone to walk by as fast as they can.

Then slow the footage in post to 6 or 8 fps. and you might achieve the look pretty closely. 

Edited November 13, 2025 by Phillip Mosness