Film-Tech Forum ARCHIVE: question about intermittent

This is topic question about intermittent in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

To visit this topic, use this URL:
https://ft-forum.com/ft/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=1;t=007463

Posted by Daniel Weber (Member # 2866) on 09-22-2005, 02:23 PM:

Question,, was a high-speed intermittent ever made for the E-7?
or could one made for newer simplex picture heads fit?

extra info..
I have an old (but steady) E-7 on a SH1020 that I use to screen workprints that I shoot myself. The other day I made a 5 blade shutter from a sheet of aluminum (on my lathe) in effort to get a good transfer to ntsc video. The shutter openings are just slits from the saw blade. The video is flicker free but has ghosting. I can't adjust it out, it seems the intermittent needs more than 72 degrees of shutter rotation to complete pull down.

Thanks,
Dan

Posted by Richard Fowler (Member # 893) on 09-22-2005, 02:54 PM:

As a production item doubtful...special high speed movements where designed after the E-7 went out of production...there where telecines built using Brenkert and Simplex XL machines.

Posted by Gordon McLeod (Member # 33) on 09-22-2005, 03:15 PM:

Yes there was at one time a high speed movement for the E7 it was made by Tommy Hoade in Toronto for Telecines at the CBC and I believe he made several

Posted by Dick Prather (Member # 1136) on 09-22-2005, 03:15 PM:

GE used the E-7 in their TV systems in the late 40's. The intermittent was modified with a small version of the Power's pin cross movement. I had one at once but let it go.

The machine had different gearing for the intermediate gear and a sync motor driving a SH-1000. The shutter was driving form the sync motor shaft not from the projector. There were other modifications to the projector that I forget.

I don't know if GE or Simplex did the mods. Some Cameron books of the period show a set-up like this at TV station WGY. Finding one would be very difficult and converting a theatre version even harder.

Dick

Posted by Mark Gulbrandsen (Member # 72) on 09-22-2005, 08:57 PM:

Brenkert(RCA) had exactly the same type of movement in their "Brenkert" TV projector. I've seen several of those E-7's around and there was one for sale on E-Bay a few years ago.....

Daniel,
If you run the sound head with a sync motor and the correct gearing and line sync your TV camera it should work just fine.

Mark

Posted by Brad Miller (Member # 2) on 09-22-2005, 10:35 PM:

Just use a 24P videocamera and any shutter you desire.

Posted by Peter Brown (Member # 3272) on 09-23-2005, 02:16 AM:

Hi,

Can you give any suggestions where a 24P video camera might be purchased?

Thanks,
Pete.

Posted by Tim Reed (Member # 137) on 09-23-2005, 05:06 AM:

quote:
was a high-speed intermittent ever made for the E-7...I made a 5 blade shutter... in effort to get a good transfer to ntsc video.

It's not just a 5-bladed shutter that makes a telecine. This is a common misconception. You have to reconcile the difference between 24 frames and 30 frames per second.

The secret to telecines is that their 5-bladed shutters spin at 720 rpm (half the normal speed), AND they're geared to an intermittent which is operating in an eccentric, 3:2 pulldown fashion... also at 720 rpm. (Note, a high-speed intermittent is not a telecine intermittent.)

This eccentric pulldown is usually accomplished in the Geneva movement by a cam with two lobes, 133 deg.(?) apart (standard movement has just one lobe), so there are TWO frame advancements per rotation of the cam/shutter combination. The uneven spacing between the pulldowns create a perfect 3-field/2-field cycle. The end result is: frame one is projected three times; frame two is projected twice; frame three is projected three times; frame four is projected twice, and so on. This is how 24 becomes 30.

If you put a 5-bladed shutter in a projector with a 1440 rpm intermittent, you will have just one frame advancement per revolution of the shutter... when you actually need 2.5 at 720rpm.

The reason the shutter alone is looking pretty good right now is because it's producing 120 flashes per second, which is agreeing with your camera... but the frame pulldowns aren't synchronized with the video raster (which is what the eccentric intermittent accomplishes).

I won't complicate matters by going into the realities of color sub-carriers, 60Hz line, and 29.97 fps -- or the fact that some projectors (like XLs) created the eccentric pulldown differently -- but the basic concept is as described above.

Simple! [Razz]

Posted by Daniel Weber (Member # 2866) on 09-23-2005, 08:31 AM:

Ahh, an excuse to buy a 24p camera...

I'm not trying for perfect telecine, just ok to burn to dvd with the 24fps LTC from the 35mm mag (it's an interlock thingy)
More easy to do the audio post from the dvd.

The sound card in the computer audio work station has external word clock in (antex studio card)and the midi sync box (motu timepiece av) makes word clock from incoming LTC.

Thanks for all the good info.

Dan

Posted by Randy Bowden (Member # 587) on 09-23-2005, 11:38 AM:

Keep in mind that 24P video actaully runs at 23.97 fps. check out adamwilt.com for an in depth look at 24p video. Going from film to 24p may still require a pull down.