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Topic: "Pulsing" high contrast area on digicam recording of Super 8 projection
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Greg Matthews
Junior
Posts: 11
From: Burlington, NC, USA
Registered: Jan 2015
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posted February 08, 2015 11:45 AM
Here's a link to a recording I just made. This setup is obviously not for recording. I'm trying to get everything set correctly (camera position, lighting, zoom, focus, etc) before I lock it all down so excuse the fact that the Film Transfer System has the top cut off in this video! I had my iPhone propped up between two D cell batteries lol.
I just recorded it so it's obviously still light outside. You can see the reflection of window blinds on the right, but the room is actually low light.
In the recording here the pulsing is pretty much gone (don't know what changed), but the contrast is still extreme. When viewing the film images coming out of the projector with my eyes there are no contrast changes, but in the recording you see extreme contrast in colors with any whites in the center of the film completely whiting out the recording in that spot. Why are whites on the outside edges not in high contrast?
The very slight flicker in the video is me adjusting the projector speed as it plays. One of the comments said to set the speed to 25fps, but my projector only has +/- adjustments, nothing exact.
My rough video with high contrast
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Brad Miller
Administrator
Posts: 525
From: Dallas, TX, USA
Registered: Jun 2003
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posted February 08, 2015 06:01 PM
Once you have clipped the highlights, the data is gone. It's always best to slightly underexpose in any form of digital photography (which is precisely what this is). You can always brighten it up a bit in post, but you cannot put back the data that was captured as pure white pixels.
On the flicker, if you are using a 3 bladed shutter and have film shot at 18FPS (typical for silent and some sound), then you actually have to project at 20FPS if you are using a conventional 60i video camera. If you have 24FPS footage, you either have to convert the projector to a 5 bladed shutter, or you can use either a 2 or 3 bladed shutter with a 24P video camera.
I can't find any useful specs on that model camcorder, so I must assume it is a 60i model. The resolution definitely hints at that. Since most Super 8 projectors are going to be 3 bladed shutters, this means your only choice IS to run the projector at 20FPS.
What you need to do is crank up the shutter speed on your camera as high as it will go. Then with film running (because the load is different on the projector), carefully adjust the speed until the strobing is minimized in the camera. Then lower your shutter speed on the camera back to a normal setting. That will eliminate any flicker.
Then you need to also remember to do the same thing with your focus. Zoom in as far as the camera will permit, then carefully focus manually, then zoom back out so the image fits your viewfinder.
On the hot spot, you really need a diopter of some sort. I've seen some people take a coffee straw and mount it vertically in front of the lens of the projector and then dead center of the beam of light put something round and "fatter" on the straw to block more of the light. If you put it very close to the lens, it won't affect the image, but the idea here is to DARKEN the middle of the projected image so the video camera can cope with it. Right now the center of your image is brighter than the corners. You don't really notice it with your eyes, but your video camera absolutely does.
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