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Old October 9th, 2003, 07:30 PM   #1
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Super 8 Dubbing: Would 6fps Give Good Results?

Hi All
I have a few old Super 8 films that I want to transfer to DV. I've read all the old threads about different methods, and they've been helpful.

I have a PDX-10 to "film the film", as it were, and I'll project it on a small screen and just go for it. My question is about the projection speed: I have a Chinon 4000GL projector that can run at 6fps and 2fps, besides 18fps.

I was wondering if there was any possible benefit to using the 6fps setting, and then adjusting the speed in post. Might I get a better image than at standard 18fps?

I'd just test it both ways and find out, but I'm really paranoid about how many passes these films can make through the projector before they wear and tear too much. Also, it would be nice if I could get through this dubbing without blowing the bulb prematurely...

Thanks in advance for any thoughts!
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Old October 9th, 2003, 07:56 PM   #2
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In order to get a "flicker free" image captured on your camcorder, you have to match the Screen flicker to the video scan rate.

Video scans at 30 frames per second. But thats two interlaced fields = 60i

In order to avoid the flickering effect, you must come close to matching that.

Your super 8 projector has a three-bladed shutter in it. Every frame is "Projected" three times, when it is in front of the lens.

If you show the film at 18fps. A total of 54 images per second. Results in 'flicker' because 54 will not go into either 30 or 60 egually.

HOWEVER if you show the film at twenty frames per second, you will have 60 images per second, which will look smooth on video.

The problem is, you must have a projector with a variable speed motor in order to tune the speed. You can actually see the flicker dissapear on your monitor.

I suppose you could shoot at 2fps. This would make six images per second, which would spread out evenly over sixty interlaced fields. (One image for every ten fields, or five frames of interlaced video). But it would take a while, and be a bit of a headache. It would work if you didn't have a variable speed projector. Then you would speed it back up in post. Same for 6fps. This equals 18 images per second, which is one image for every six frames of video.

You just have to hope that the shutter blade and scan lines match up at the beginning. (SHoot with your slowest shutter speed on the camera)

Might be easier to send it to a transfer house, where they use either a rank cintel, or a computer "workprinter" to transfer each scanned frame to a single frame of video.

Good luck.
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Old October 10th, 2003, 12:17 AM   #3
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If your camera has "clearscan" then it'll sync with the projector. I've done it and the results are quite good.

You can also double-check it with a waveform monitor. If you adjust until the waveform settles down, then you know you've minimized the flickering.

Dean Sensui
Base Two Productions
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Old October 10th, 2003, 07:57 PM   #4
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Thanks for the replies. Pretty much what I was thinking. I have no idea what "clearscan" is, so I don't think I have it. :^)

Is it a variable shutter control of some sort?
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Old October 10th, 2003, 09:53 PM   #5
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Hi Chris...

Clearscan is a shutter speed adjustment available on most pro-level cameras and might be available on the camera you have.

For example, the Canon XL1s has it but the earlier model, the Canon XL1, doesn't.

Clearscan will allow slight shutter speed adjustments, usually in fractional frame/second increments or thereabouts. It gets rid of flicker when shooting computer screens and other, similar situations.

Dean Sensui
Base Two Productions
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Old October 11th, 2003, 07:58 AM   #6
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Thanks Dean
Nope, that's not a feature of my camera. I'm going to shoot and see what happens...I've seen acceptible (to me, at least) results from basic set-ups like mine, so I'm hoping to be pleasantly surprised by my results.

The PDX-10 has a shutter speed adjustment, but only in the larger, "normal" increments--4, 8, 15, 30, 60, 90, 100, 125, 180, 250, 350, 500, 725, 1000--->10,000. But nothing (unless I've missed something) in fractional increments.

Thanks again!
Chris
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Old October 11th, 2003, 08:27 AM   #7
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Another thought. A buddy of mine has a DVX-100, and it has a Synchro-Scan mode on it, to eliminate scanlines when shooting TVs and monitors. I wonder if that would be a help--for instance, run the projector at the regular 18fps, and adjust the shutter to...what, 36 or 72? Or just mess with it until clear.

Worth looking into. I invested in a new bulb for the projector, so that's covered. Hope the film splices hold up (they're 30 years old, and were done by a 15 year old--me!)

:^)
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Old October 11th, 2003, 01:26 PM   #8
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Synchro scan might do it. It might just be a different term for the same function.

Just run the projector at a normal speed and make adjustments until it clears up.

Depending on the shutter speed of the projector, the setting on the camera could be anywhere from the high 60's to the mid 70's. Experimenting will prove which is best.

Dean Sensui
Base Two Productions
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Old October 13th, 2003, 08:45 AM   #9
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A revelation:

This morning, I dug out the projector (Chinon 4000GL) to clean it up and check it out...and got QUITE a pleasant surprise!

Lo! and Behold! The blessed Chinon 4000GL come equipped with a Variable Speed Control knob!! I can't quite believe it. It's my girlfriend's projector, so I wasn't as thoroughly versed in its virtues as I would have been, had it been my own. (Though I did look at the manual a while back, and have no idea why I didn't remember seeing this feature mentioned....)

Anyway, things are looking up! Thanks for everyone's help.
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