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Film camera Steadiness testing


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#1 Paul Scaglione

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Posted 27 March 2017 - 02:09 PM

Image steadiness test for 35mm film motion picture cameras:
1) Load a known good 400' magazine with fresh non-dated color-negative film stock.
2) After mounting on the camera body and assuring correct loop position, roll the shutter open exposing a frame of film through the open lens port.
Reaching through the open lens port with a black "Sharpie" marker, trace the edge of the film gate on the film emulsion with a large "X" corner-to-corner filling the gate outline.
3) Line up a steadiness chart in the camera viewfinder fully filling the frame level and square with the framing lines within the viewfinder being critical with your focus and shoot a 100' pass at 24fps exposing as normal making sure to use an insert slate briefly at the head of the roll with camera serial #, date and "Steady Test" for reference.
***CLOSE OR COVER THE EYEPIECE!!!!!! during the pass and do not view while shooting as this can slightly jiggle the camera and nullify the test.
4) In a completely dark bag or room, remove the exposed footage and using film rewinds, back-spool onto an empty core to then be reintroduced into the feed side of the same magazine. Can down any leftover footage in the feed-side of the same magazine and store. Load the magazine as normal with the exposed footage and inch over until the "X" marked box reveals itself from the mag throat.
5) Re-thread the mag on to your camera being careful to not only get the mag loop into the correct relationship within your camera body but also to place the "X" box on the emulsion side of your loop precisely in the gate just as originally loaded.
6) The line-up of the steadiness chart to the camera must now be altered to reveal any steadiness issues for the second pass. To do this just "Dutch" the camera over slightly to the right or left by a few degrees trying to keep the center of the chart relatively centered to the ground glass cross hairs and lock down.
7) Again, close or cover the eyepiece and make your second pass. At this point, you can if you choose make the test reveal any steadiness issues at different filming speeds by marking the chart with a small piece of tape with frame rates; 24fps. (shoot 25'), 30fps. (shoot 25'), 36fps. (shoot 25') etc. up to the top speed of the camera. In the case of a non sync-sound camera such as an ARRI 35-III or 435 you would use a larger initial load, say at least 200' as you would burn through a lot more stock getting up to speed at higher frame rates and therefore would want to budget more stock for the camera to get up to speed and "settle in" at each frame rate for an accurate test. At any speed, at the moment of camera start-up a small amount of unsteadiness is not uncommon as the camera "settles in".

** This same test also works on all 16mm cameras however there is no need to mark an initial frame as each frame is relative to each perforation along the film edge.

In closing, this method of double-exposure steady test will reveal the camera's image steadiness capabilities and rule out any observed image movement introduced by a factor after the camera such as an unsteady film transfer machine or a worn projector film plane. Just observe the line pairs from the two chart exposures relative to one another for your answer.

Written by Paul Scaglione Monday, 3/27/2017 for Nikita Moyer at Virginia Commonwealth University


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#2 Paul Scaglione

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Posted 27 March 2017 - 02:11 PM

For a digital copy of a steadiness chart you can email me directly: paul@visualproducts.com and I will shoot you back a quick shot of a chart I did in our shop for Nikita at VCU that you can then print and use for your own steady tests. It is too large a file to attach here so need to go play outside....
It is a simple cell phone shot but will do the trick.
I won't be able to spend time there answering any questions so please post anything here and I will answer as time allows-

Just let me know you posted a question so I know to log on & check when I can.

Best,

-Paul


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#3 Tyler Purcell

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Posted 27 March 2017 - 03:33 PM

Good tip Paul! Thanks for sharing! :)
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#4 Dom Jaeger

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Posted 27 March 2017 - 07:48 PM

Thanks Paul, nice to have you on the forum!

 

The only things I would add:

 

Make sure the camera is well supported (ie not on a flimsy tripod) and on a solid floor to avoid introducing any vibration that might be mistaken for camera unsteadiness. Avoid using a long focal length lens which will also accentuate any camera vibration. For the second pass I used to tilt the chart rather than tilt the camera, but whatever's easier. :)

 

With quick change 16mm cameras like Aatons or modern Arris where the mag forms part of the gate assembly, we used to steady test each mag.

 

If you have a projector, the simplest way to view a steady test is to just project the processed negative. Don't worry about overall steadiness, just watch for any movement between the two chart exposures.


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#5 Paul Scaglione

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Posted 28 March 2017 - 02:09 PM

Hi Dom,

 Thanks for chiming in.... Yes!- Some of the things you pointed out are things I take for granted having handled cameras for so many years but not things that people first navigating these sorts of things would already take in to account so glad you mentioned.

 I find myself now talking quite regularly to young people that had "grown up" on digital acquisition and are now just gearing up to start shooting some analogue so there are many bits of knowledge to be passed on to these new pioneers.

Anything we can collectively pass on to make their experiences and results more satisfying helps to keep a long respected medium still relevant. Great tips on the 16mm mags as well..... For the Arri SR cameras, I was perplexed many years ago with finicky steadiness and how mag spacer plate gap and pressure pad tension seemed to be part of the steadiness equation so maybe 15 years ago or more just started replacing every registration pin south of 1.256mm with a fresh pin and started re-furbing & re-setting the gate rails and pretty much took the mag out of the steadiness equation. Sometimes sound level at the film plane suffered ever so slightly but could always be tweaked by fine-tuning the pitch & stroke.

Best,

- Paul


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