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View screen / focus screen material for digital capture.


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#1 steve waschka

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Posted 18 December 2013 - 10:19 AM

A lot of my stuff is small & self funded so I cant afford the mins for great capture labs on those projects. I can project frame by frame onto a stills camera sensor with an analyser. And i get it that any stills camera does a better job of that than video capture anyways... But there are many times I want to just capture on the fly with a broadcast camera and I am looking for the holy grail in focusing screen material to project onto. I am projecting to a size a about 10" to reduce evidence of surface texture. Im open for crazy things youve tried that worked. Right now I am using thermal lamination material. I have no idea what the grain count is but I can still see it. And I have yet to fig out how to get my Xantus to tune it out. So Im still on the hunt.

 

Maybe need to point out that this is completely an "in-line" or "thru material" method. Throwing on a screen and recording reflected has never tricked me into thinking it was anything but just that. But ill try something like that if you think i missed something.


Edited by steve waschka, 18 December 2013 - 10:23 AM.

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#2 Perry Paolantonio

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Posted 18 December 2013 - 10:39 AM

Why use a screen at all?

 

When I was in college we set up a very crude aerial image system, where we projected onto a screen to get it as focused as possible. Then facing the projector was a camera that we also focused on that screen. Now remove the screen and like magic, your camera is picking up the image out of thin air because both lenses are focused on the same point in space - no screen necessary.

 

Mostly we did it because it sounded like BS when someone told us about it and we just wanted to see if it really worked. With the hardware we had back then it looked awful, but it's worth investigating, since it'll completely remove the screen texture from the equation.

 

You can find more about this in animation and special effects books.

 

-perry


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#3 steve waschka

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Posted 18 December 2013 - 10:46 AM

Perry: I studied this last night. Same thought process. "No flippin way this works" And it didn't. All i saw was the projector lens blasting light at the camera. I read that the JK printers are "aerial" so I said there has to be something to this. But they appear to me to be moving macro slide copiers. You think maybe i throw opal glass in front of the lamp and cut the power? I dont know. You guys saw an image? Maybe my light path isnt straight. Ill bet that has to be dead nuts on.


Edited by steve waschka, 18 December 2013 - 10:47 AM.

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#4 steve waschka

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Posted 18 December 2013 - 10:54 AM

7222 home rack and tray processed which I dont do anymore. Just too much work and we gotta keep the labs in business. There is fall-off as the projector did not have a diffuser in it at the time. Oh and its 4:3 cropped to 16:9 vid capture in-camera

11436312135_10795d7b2f_o.jpg


Edited by steve waschka, 18 December 2013 - 10:55 AM.

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#5 Perry Paolantonio

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Posted 18 December 2013 - 11:13 AM

This was 20 years ago and we just set it up in a room and then never did it again, so the details are fuzzy. But yes, we got an image. I remember we spent quite a bit of time getting the focus and alignment right, but our setup was basic - a 16mm projector on a table and a video camera on a tripod pointing at it. The key is that both the projector and the camera have to be focused on the exact same point in space, or it won't work.

 

At home somewhere I have a copy of "The Technique of Special Effects Cinematography" and a google search brought me to this page in google books: http://books.google....ved=0CFkQ6AEwCA

 

Don't know if it'll open to the same page, but if you can get to page 224 in that book, it walks through the setup. We had an Oxberry animation stand in school that did this. It's pretty neat, actually.

 

-perry


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#6 steve waschka

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Posted 19 December 2013 - 12:32 AM

Perry: Ive seen that book. Cool content. I appreciate you taking time to help. I got it to work tonight. I had equipment stacked on things and shimmed. Nightmare. Not a simple task to get the projector gate to size properly to present thru the projection lens to the camera. And it seems it has to be at fairly close range. And im having to double power the taking lens and use a diopter to get focused at the right distance. But I properly filled the camera frame tonight. The projector will need a good diffuser after the bulb. And I need to figure out a better lens configuration as right now i'm probably trading the focusing screen grain issue for the CA from this taking lens rig. And of course I will need to fab a bench to lock the whole rig onto to be able to repeat the process efficiently. But it works. Its not the magicalness that it seems when you read about it. But it does work.


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#7 steve waschka

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Posted 22 December 2013 - 06:55 PM

Project so far: not going real well. Ground glass type surfaces mess with the contrast level too much. Video cameras not great at handling highlights which makes for a real mess when working with negatives. The lens systems to get the aerial system to work require too much glass to do 8mm. 16mm is ok but the to get the hotspotting within check you have to use led and lots of diffusion. So far im within a stop and a half from center to corners. With simple diffusion and led it was 6 stops or more! Got a few more things to try before I abandon. This is all live rolling projector to rolling video camera. There are frame sync issues but they are not a big deal. I am using cameras with variable controls for filming screen flicker so that stuff is minimal.

 

Next will be single frame advance to single frame capture. However the if contrast and hotspotting can not be controlled in the above... I doubt I can do a good job with this either. It may be just best left to the lab.


Edited by steve waschka, 22 December 2013 - 06:57 PM.

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#8 steve waschka

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Posted 24 December 2013 - 01:13 AM

Have tried nano particle materials like digicon filters and ultracon filters. Theyd be great if they were window sized not 4x4". Wonder what that would cost...    Went back to reflected and used gesso panel. Can still see texture in the captured image and there is none to the naked naked eye. I yield. its over. And my video cameras' latitude is just sad. Id have to cut film and capture at different exposure settings just to get highlights vs shadow. I guess any house would have to do that. Until I did this testing I never worried about it. And I like the idea of being able to manipulate the latitude first hand while making the capture files. If I have to. Id rather video just have the latitude.


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#9 steve waschka

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Posted 24 December 2013 - 11:31 PM

11541642603_1fbf799bf3_b.jpg

 

The previous image was shot thru thermal lamination paper. Its darkeness prob was just the lens setting at the time on the capture camera. But It has "double the grain"... film grain plus "ground glass" grain.

 

This is reflected on gesso. The extra grain you can see as the darker flecks. Cant see the texture when looking at the board in plain light. But theres something firing the light back hotter.


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#10 steve waschka

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Posted 24 December 2013 - 11:46 PM

11541718694_006e37df7f_o.jpg

 

Aerial image. Good grain. But the light source is CRITICAL. Power, Diffusion, must be flat and bright. The projecting lens can barrel the image if the image is not coming thru as a tight cone, center area of the element. Similar to issue with adding objective teleconverters if you've ever messed with that.

 

But all three have no pop. Mostly due to issues getting exposure to work around everything else. I have a few new ideas to try.


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