8mm Forum: Bolex Sp8- Special speed questions

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Topic: Bolex Sp8- Special speed questions

Darren Glen
Junior
Posts: 4
From: Australia
Registered: Apr 2012

posted April 17, 2012 09:40 AM

hi, i am new to this forum, although i have spent many nights reading up in it. Awsome stuff.

I have my fathers Bolex SP8-Special projector from the 70s and a giant box of his super8 movies.

from reading up it sounds like the Bolex SP8-Special is the same as the Eumig 820? or definately one of the 800 series.

i guess im like many others, trying to get a variable speed out of the thing, so i can capture at high def to my Canon EOS.

I tried wiring two different brands of 240v dimmers (one was a fan dimmer 350W and the other a light dimmer 400W) in series with just the projector motor but the projector motor cant seem to get started properly with even the dimmers cranked to full open. it kinda makes some unhealthy noises like its seized up and i only give it a few seconds to work and then turn it off.

So ive resorted to the ole "fiddle with the speed slider" to mechanically vary the speed a bit but its really no accurate. i get black bars that scroll lazily across the picture. And its frustrating as hell.

Heres the question really...just when i think i have the frame in sync with the camera...a scene "splice" rolls through the projector. But about 2 seconds before every scene change, i get rolling bars on my camera, as if the frame rate has varied just before the original camera stopped recording. Is it possible that on the old lo-tech battery camera that was capturing the film back in the day that the "squeeze button" that was starting and stopping the film was somehow varying the frame rate a bit due to crappy contacts or whatever? i thought the frame rate on playback had to be static as the frames are locked to the teeth positions on the film or is this not the case?

i keep feeling like im chasing my tail trying to get this film to sync, it seems every scene has been recorded at a different frame rate and i get the black bars rolling at different amounts across the screen for every scene! the scenes can be on the same strip of film (not necessarily a physical splice) but possibly filmed on different days with different % of battery power in the original filming camera.

wierd stuff goin on ...

many thanks for your replies. i hope this one is solvable..

cheers,

darren.

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frank arnstein
Jedi Master Film Handler

Posts: 534
From: Gold Coast. Australia
Registered: Jan 2005

posted April 19, 2012 03:05 AM

Hi Darren

The way to solve this is to use a projector thats more suitable for what you are trying to do.

For silent films get a dual 8mm variable speed projector with external reostatic control. The Bolex is not really capable of maintaining the incremental speed changes that are required for quality telecine work.

For sound movies, a 900 series Eumig would be much better suited than the Bolex. Its upgraded transmission gives better speed control and less chance of slip at the disc than the 800 series Bolex.

dogtor frankarnstein

[Smile]

--------------------
At Projector Heaven the Focus is always on Detail.

____
[o:/o]<|=- dogtor@projectorheaven.com.au
//``\\
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Lee Mannering
Film God

Posts: 3216
From: The Projection Box
Registered: Nov 2006

posted April 19, 2012 06:46 AM

Darren. If you take the back off the proj, on the right top inside you will see a 50/60hz switch. Rotate it and this will then enable you to slow the projector under 18fps.
Happy days!

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Darren Glen
Junior
Posts: 4
From: Australia
Registered: Apr 2012

posted April 24, 2012 08:30 AM

hi Frank / Lee,

thanks for responding.

there are some trimpots inside also that seem like they are on a main PCB. i wander if they are speed trimpots or if they are a trim for sound bias (something completely unrelated to speed)...u know the ones i am referring to ? i can take a pic if you like. i wander if anyone has ever tweaked them...

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Martin Jones
Phenomenal Film Handler

Posts: 1269
From: Thetford , Norfolk,England
Registered: May 2008

posted April 24, 2012 08:52 AM

No, do not alter them; they are to do with sound bias as you suggest.Speed changing is purely MECHANICAL on this range of projectors.

--------------------
Retired TV Service Engineer
Ongoing interest in Telecine....

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Darren Glen
Junior
Posts: 4
From: Australia
Registered: Apr 2012

posted May 11, 2012 07:15 AM

thank you for your responses.

i have ordered the Quasar AC motor speed controller that others have used here. It works with induction motors which the Bolex has. so hopefully i can do some speed control with it. I already have the wires to the AC motor split off and running to the outside of the projector so i will only be running the actual ac motor thru the speed controller. I will post the results.

thanks again,
Darren.

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Darren Glen
Junior
Posts: 4
From: Australia
Registered: Apr 2012

posted May 31, 2012 08:38 AM

hi all,

i recieved the Quasar board. it works great.

my Bolex had problems getting to 24fps using the board because it only operates to 98% of the "bypassed" voltage. So i was still getting a slow scroll when shooting to my SLR at 24fps.

I am running at 240v here in AUS and the solution is to run your Bolex / Emiug at 230v. its a simple case of moving the jumper across on the board on the back inside, its clearly labelled.

now i can take the machine up past 24fps and then using the pot bring it down in the tiniest of %. works great!!! ie just keep asjusting the pot until black scrolling stops and the fps is "syncing" with my Dig SLR.

Happy Days! thanks for the tips here!

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