Page 11 - RD_0314

Back to the story
In the United States, with their 60 HzTV system, neither 24 FPS or 25 FPS is
workable with a standard two or three blade shutter (do the maths). The ‘work
around ‘ for this is the Five Blade Shutter. Running the projector at 24 FPS, with
a five blade shutter, the flicker rate is 120 per second (24 x 5), as 120 is a
multiple of 60, no flicker on the TV transfer is evident.

From the foregoing, it can be seen that the use of a five blade shutter on a
projector used for film to video transfer in Australia is not workable.

What about silent speed transfers?
With the Australian 50 hz TV system, a projector with a three blade shutter
running at 16 2/3 FPS (sixteen and two thirds fps) equals a flicker rate of 50,
which is the same as the TV scan rate and will be quite workable. 18 FPS sound
home movies present a special challenge!

All of the above has been written with analogue TV systems in mind, as most in-
home video transfers are done using standard home use video cameras. However,
much of it also applies to consumer digital systems.

The camera
There are many variables involved in copying film to video, especially with the
video camera. Many cameras have adjustable shutter speeds, generally 50 FPS and
upwards - the camera must be set to 50 FPS. Also on some of the older cameras,
the “steady shot” setting has the effect of increasing the shutter rate and will
cause flicker regardless - turn it off! And of course, set the camera to “manual” if
it is possible, to avoid “focus hunting” and the camera trying to compensate for
brightness changes in the film.

With the ‘magic’ of advanced digital equipment, it is no possible to transfer at
pretty much any film speed without flicker. But we wont go down that path this
time.

Projector Two blade shutter Three blade shutter
speed slicker rate flicker rate
16 32 X 48 X
16.666 33.333 X 50� �
18 36 X 54 X
24 48 X 72 X
25 50� �� 75 X
Mike Trickett

Reel Deals - 11 - June 2014