Super 8 in a Regular 8 camera?

[Matt Pacini]

I would think it would be much easier to modify a Super 8 camera, by filing the gate, AND making it offstep by half a frame, so the sprocket hole lands in the middle of the frameline, than compeltely redesigning a regular 8 camera.

Matt Pacini

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[Scottness]

All this talk of gates and sprocket holes etc has reminded me of what a brilliant idea the 9.5 design is with the sprocket holes in between the frames. It's a shame it never caught on more (didn't that have something to do with big business and which film manufacturer was backing which format?) -- anyway if it had caught on more we'd all be shooting that with light weight cameras and big frames size - and not be hassled out by grain size etc.......I know it's still going and I saw a Beaulieu 9.5 for sale a while ago on eBay - I thought about it.......


Scot M

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[Cranium]

I don't know about sprockets that point directly at my beautiful pictures. A little slip and it could get ugly...
Actually, from what I know, that's part of why it never got too widespread.

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Mikel Z

[#Pedro]

Sprocket drives:

Shurly, film advance is possible only with pull down claws and without sprocket drives, as realized in some dual gauge projectors, almost all toy projectors and all 50 ft-S8 cameras.

Loops are always required, they are only located at differnt places, when there is no sprocket, as they are interfacing between linear and stepwise movement.

However, the claw-only systems have certain limitations, determined by the mechanical load the feeding reel and the take up friction may apply to the claw and gate.

1. limited reel size to handle this load. Even the old Kodak 200 ft cart converted the camera into a sprocket driven camera!
The very same reason for the Beaulieu design, to use a central sprocket drive.

2. when comparing both designs, there is always worse registration, more breathing, as any inconstant movement of one of the reels affects the claw. When shooting a 50 ft cardrige and a 200 ft load in the same camera, the 200 ft results with sprocket driven DS8/60 drive is always significant better, nearly no "breathing", very stable picture.

3. higher gate pressure can partly compensate this natural lack in registration, applying more force and frictionand wear to film surface, perforation and claw.

So the classic design of film advance always uses the claw system (or maltheser cross system) ONLY for registration, mostly appying a second stop-claw, holding the film during exposuring.
The feeding is made by a sprocket drive, the film between feeding reel and sprocket is moving linear, after the sprocket a 90 degree loop is feeding the gate-claw system without any force, that the claw-spring would have to handle.

After the gate, another sprocket separates the force of the take up friction from the claw and gate. So the gate pressure can be minimized to the neccessary value for pan focus registration.

In low-cost systems like 50ft-S8 carts or toy projectors, there are no sprocktes. Therefore the film path is designed in such a complicated way, with many corners, curves and springs, that act as mechanical filter for the claw. The friction of a toy projector f.e. is not strong enough, to pull the film thru the gate when the claw is out. And the loading section makes some funny curves, for not affecting the claw directly thru the reel movement, that is a constant stop-and-go process.
And in many devices, each stop and go makes the frame jump a little, even in the latest Bauer projectors without that feeding sprocket.

Therefore, for any new camera or cart design, I think sprockets are indispensable, because with only a few items produced, we have nothing to economize, but should afford the best possible quality out of the precious stock!

Pedro

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[MovieStuff]

<BLOCKQUOTE><font size="1" face="Courier, Arial">quote:</font><HR>Originally posted by #Pedro:

Loops are always required
<HR></BLOCKQUOTE>

If you are talking about isolation loops, that simply is not true. The WorkPrinters have no isolation loops and their registration is rock solid with no breathing. The DV8 uses no isolation loops and it also has rock solid registration.

In fact, one of the things I can do is pull back and reveal the sprocket holes for registration tests, as I noted in another post. The sprocket holes absolutely do not move at all during the transfer. Again, my units move slower and that may be part of the reason but to say that loops are always required is not accurate. Speed can greatly affect stability, as anyone that has shot slow motion on a super 8 camera can attest.

<BLOCKQUOTE><font size="1" face="Courier, Arial">quote:</font><HR>Originally posted by #Pedro:

1. limited reel size to handle this load. Even the old Kodak 200 ft cart converted the camera into a sprocket driven camera!
<HR></BLOCKQUOTE>

I agree that Kodak put a sprocket in the 200 foot mag but I do not agree that it was because of the larger or "heavier" load. I believe it had more to do with keeping the film from unspooling in the magazine. In fact the bigger the reel, the EASIER it is to pull film from the reel because the diameter is larger, the pulldown mechanism has more leverage and therefore there is less tension on the pulldown claw. The hardest that a super 8 claw has to work is when pulling film from a 50 foot cartridge, especially at the end of a roll. The smaller the diameter of the feed reel, the more force it takes for the claw to pull the film from that reel. Surely most have noted that registration problems occur mostly at the end of a roll than at the beginning?

Therefore, I would suggest that if there is a size limitation, it is the opposite of what you maintain; that claw-only designs work better on larger reels, not smaller reels. The DV8 handles 1200 feet and and has perfect registration from the beginning to the end. However, I did find that we must transfer all incoming footage to reels with larger center hubs because working off the smaller 50 foot reels did affect registration due to the resistance against the claw that would normally be negated by an isolation loop. So isolation loops are necessary, sometimes, but no always depending on the speed or size of of the reel being handled.

<BLOCKQUOTE><font size="1" face="Courier, Arial">quote:</font><HR>Originally posted by #Pedro:

3. higher gate pressure can partly compensate this natural lack in registration, applying more force and frictionand wear to film surface, perforation and claw.
<HR></BLOCKQUOTE>

If a super 8 pressure plate is designed correctly, the plate never touches the picture area. If you look at the pressure plate/gate assembly on super 8 projectors, you will find that there are raised surfaces that handle the film by the edges only. I have yet to see one that had two metal plates that press down on the picture area of the super 8 film. No matter how polished, that would lead to scratches as soon as the tiniest bit of dust got trapped between them. I experimented with increased spring tension when developing the WorkPrinters and found it wasn't necessary but the increased tension never caused a problem with scratching the film since the gates handle the film by the edges only. I will agree that increasing the tension puts more wear on the claw and sprocket holes, though.

Roger

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Roger Evans
MovieStuff
http://www.afterimagephoto.tv/moviestuff.html

[Matt Pacini]

<BLOCKQUOTE><font size="1" face="Courier, Arial">quote:</font><HR>Originally posted by MovieStuff:
...I experimented with increased spring tension when developing the WorkPrinters and found it wasn't necessary but the increased tension never caused a problem with scratching the film since the gates handle the film by the edges only...

Roger

<HR></BLOCKQUOTE>


Roger, how is this possible, with the gate being enlarged?
I thought it was enlarged out past the sides.
Or is it just enlarged vertically, but not horizontally?

Matt Pacini

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[MovieStuff]

Hi, Matt!

The pressure plate still has some "meat" on it at the edges and a lot more "meat" above and below. So there is still some "friendly friction" that helps keep the film in place during the dwell time of the claw but the picture area is not touched ever on the WorkPrinters or the DV8.

Now, I need to correct myself about something I did write above. I had said, "I have yet to see one (standard projector) that had two metal plates that press down on the picture area of the super 8 film."

I apologize but this is patently incorrect. I've spent so many years in my life building optical printers, which have pressure plates that DON'T touch the picture area that I simply forgot that most unaltered projectors do actually have pressure plates that ride the picture area. Optical printers have cool light sources and don't have to combat film buckling. Standard projectors continually battle film warpage issues due to the higher heat at the gate so it is absolutely necessary for there to be compression of the film on all edges. Hence, there is a very tiny area that surrounds the frame that will actually touch the picture area during pulldown. Scratches can still be a problem for the reasons I listed but projector pressure plates do not strictly handle the film by the edges only like optical printers (and WorkPrinters or the DV8!) do.

Roger

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Roger Evans
MovieStuff
http://www.afterimagephoto.tv/moviestuff.html

[charonjr]

A fellow that I bought a K25 100' Bolex roll from has a Bolex DS8. He wasn't aware that it used DS8, thought it used D8 and ruined two rolls of D8 film in the camera.

Not sure, but the Bolex has a second retainer claw that steadies the film in the gate, giving a pin registration characteristic. It's possible these trailing and leading claws miss their respective sprocket holes and chew the film.

Actually, scratch that, more likely the sprocket gears tore up the the film.

The only other question to consider, is that if S8 can be run through a R8 camera like an altered Bolex H-8, using S8 sprockets, but a R8 claw, can projectors work with the frame line repositioned next to the S8 sprocket hole?

If so, there should be no problem with obtaining an Ultra S8 image.

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