[SML] Masking Projector Black

e-mail frank.wood95 frank.wood95 at ntlworld.com
Tue Feb 10 23:57:17 UTC 2015


I have used the shutter mechanism from Aldis lamps, with good results.
These are Venetian blind shutters from naval signalling lamps. They
are electrically operated, and extremely fast.

I first used one to project individual lightning flashes onto the cyc
from a 2KW Strand Patt 252 projector, using photographic slides. If
these are made on the appropriate film, they are very much 'all or
nothing'. Kodalith was the name of the film, and, when appropriately
processed, have a "brick wall" transfer characteristic.

I think that they are fast enough to do a strobe effect, with a little
bit of electronics behind them. For a single flash, I just discharged
a suitable capacitor into the operating circuit. Yes, there was a tiny
bit of design skill to re-charge the capacitor.

I am often alarmed by the general reluctance of lighting designers and
technicians to design and build gear to solve specific problems.
Everyone seems to be looking for a piece of commercial kit. Jerry
Durand and I seem to be the only list members who are prepared to do
this sort of thing. Perhaps it is because I, at least, earned my
living an an electronics engineer, working as an LD on an amateur
basis, in a theatre which was strapped for cash.

Obviously, I made use of my employer's facilities. But, in a
maintenance department, if nobody has broken any gear, you have time
on your hands. If you are a real engineer, you will have a private
project going. Our maintenance team designed and built three computers
of increasing complexity (this was before Windows reared its ugly
head). Our manager encouraged this, as he could see which way the wind
was blowing. Ben Palmer, I salute you!

On 10 February 2015 at 19:55, Dorian Kelly via Stagecraft
<stagecraft at theatrical.net> wrote:
> I made one using a cd mech and an iris. Looked like hell, gave some nice results .
>
>
> Sent from my iPhone from illuminati. Please excuse brevity and autocorrect errors if any.
>
> On 10 Feb 2015, at 19:19, Richard John Archer via Stagecraft <stagecraft at theatrical.net> wrote:
>
>>>
>>> That may have been my first attempt at product development... I should have sold them!
>>>
>>> -Ford
>>
>> They are likely still here and yes
>
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-- 
Frank Wood




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