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Hi, all!
I am considering an accessory for the WorkPrinter that would mount in the back as a replacement for the rear housing. Below is a diagram for a color correction module that would allow the user to tweak their color in real time as the film is transfered to computer via the WorkPrinter.
http://www.afterimagephoto.tv/color.jpg
The principle is simple: Three small color bulbs (red, blue and green) combine together to create "white" light that the video camera white balances to. Then, using simple dimmers, the level of each bulb can be lowered thereby changing the balance of the light.
For the greatest degree of control, the dimmers would be all at full for white balancing the video camera and you would subtract colors to get the color changes you want. However, should that prove confusing to some, the dimmers could be set at the 50% mark for white balancing the camera which means that one could increase or decrease each bulb for the desired color change. This would allow for "adding red" by increasing the red slider from the mid position as opposed to "reducing red" by decreasing the red slider from the full position.
At any rate, this unit would be most effective when used with a camera that has manual white balance. However, it seems that even those with auto white balance can be manipulated to a certain degree by changing the light. I am curious as my home miniDV camera has only auto white balance; how many of you have a miniDV cam with manual white balance?
Roger
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Roger Evans
MovieStuff
http://www.afterimagephoto.tv/moviestuff.html
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Mine does, and I have a cheap one: a Sharp wd255-u (I think that's it). Hovever, I'm in a bit of a panic at the moment because I seem to have misplaced the manual for it... yikes...
BTW Roger: I'm still petitioning for the return of the Cinemate, perhaps with some of the modifications you made to the WP2. Wouldn't this device make that unit a lot more appealing to people?
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[This message has been edited by dogstarman (edited November 27, 2001).]
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Roger:
How would a person compensate for the natural trait of bulbs to slowly get dimmer during its life cycle, especially if each bulb do so at a different rate?
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<BLOCKQUOTE><font size="1" face="Courier, Arial">quote:</font><HR>Originally posted by crimsonson:
How would a person compensate for the natural trait of bulbs to slowly get dimmer during its life cycle, especially if each bulb do so at a different rate?
<HR></BLOCKQUOTE>
Well, these bulbs last about 1,500 hours each! That's a whole lotta' transfers!
Bulbs don't change significantly over their life span. It is generally right at the end before they go out. Also, the controls on this are not set up in printer's points or anything that exact. These are "subjective" controls, much like the variable speed on a movie projector. You may never know exactly the speed the projector is playing but you DO know if it looks like what you want on the screen when you hit the speed desired. Once you turn off the projector and come back to it days later, that speed will have changed a little bit and you compensate by turning the knob until you get what you want again.
Likewise, the controls on this unit are just basic dimmers that you adjust until you like what you see on the screen. They will be stable enough to hold their color trait during the transfer sessions, but days later you may find that you have to re-tweak their position slightly to get the same effect.
In that sense, any changes in the bulbs due to their natural wear characteristics, becomes academic. The user will simply adjust until he/she likes what they see on screen.
Roger
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Roger Evans
MovieStuff
http://www.afterimagephoto.tv/moviestuff.html
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Very interesting! Your mind is always working. I gadgeteer a little bit, but no wheres at the level of Jedi, Obiwan 'Rog' Kenobi (I am a mere learner).
Wonder if you can get the different light colors to actually mix? Like, if red light is turned up, will it only illuminate the left side of film frame? Maybe the deeper the light mix chamber the more it can mix?
About the Cinemate.....I believe Roger announced awhile ago, that it was discontinued due to unavailability of 5 bladed shutters for GAF projectors? Was this some kind of accessory to retrofit the stock Gaf's? The shutters on my couple of Super8 projectors are 3 bladed and they're made out of aluminum sheet metal. I once contemplated on making my own custom 5 blade shutter (I can do general metal work) but, I suspect that would be very tricky, in trying to design the shutter opening & angle so that it exactly exposes the projected frame while it's held stationary in the gate (projector running at 24fps / during transfer).
Lionel
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Hi Roger,
I have a Hi8, Tr3200 from Sony. (IMHO, one of the best Hi8 cameras, except for the VX1, which has 3 CCDs). It has a full manual white balance.
While many consumer video cameras lack manual features such as a full manual WB, most Sony and Panasonic camcorders I have seen have presets for tungsten (3200K) and daylight (5400K). Which is enough for what you're thinking of, really. If you manage to roughly 'calibrate' your colour corrector to one or the other (whatever the lamps you use come closer to), then you can just use a WB preset instead of doing a manual one.
One possible problem ... I don't know what lamps you'd be using, but with normal bulbs, you might want to consider that putting less current through them doesn't only make them darker, it also makes it shift towards red or orange.
Just had another thought ... How about putting something like a Varicon in front of the film... then you could change not only the colour of the entire picture, but also for mainly dark parts of the picture (like a 'black balance'). Don't know if that would work, just an idea.
Daniel
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<BLOCKQUOTE><font size="1" face="Courier, Arial">quote:</font><HR>Originally posted by Vurfer:
most Sony and Panasonic camcorders I have seen have presets for tungsten (3200K) and daylight (5400K). Which is enough for what you're thinking of, really. If you manage to roughly 'calibrate' your colour corrector to one or the other (whatever the lamps you use come closer to), then you can just use a WB preset instead of doing a manual one.
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Right idea, wrong move. The last thing you would want to do is go to a preset of 3,200K. That would defeat the whole purpose of the unit and would limit its range.
The whole idea behind this device is to capatilize on video's ability to white balance to virtually anything. These bulbs are not 3,200 degrees which is one reason that they are so cool on the film. The idea is to white balance the camera so that it sees the combined output as white and then variations off that are created by adjusting the dimmers. Manual white balance is a must for the system to work best. A 3,200K preset will result in a white balance that is too warm as these bulbs are not 3,200K.
<BLOCKQUOTE><font size="1" face="Courier, Arial">quote:</font><HR>Originally posted by Vurfer:
One possible problem ... I don't know what lamps you'd be using, but with normal bulbs, you might want to consider that putting less current through them doesn't only make them darker, it also makes it shift towards red or orange.
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This is totally true. However, as I pointed out, these are "subjective" controls, not controls set up in printer's points anything that critical.
Basically it's very simple: You level out the controls, white balance, then adjust the controls until you see the desired results on the monitor.
The fact that the bulbs will go warmer as voltage is reduced is academic as you will keep adjusting until the overall mix, including such warm anomolies, gives you the desired result.
<BLOCKQUOTE><font size="1" face="Courier, Arial">quote:</font><HR>Originally posted by Vurfer:
Just had another thought ... How about putting something like a Varicon in front of the film... then you could change not only the colour of the entire picture, but also for mainly dark parts of the picture (like a 'black balance'). Don't know if that would work, just an idea.
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Well, the whole idea is to keep it simple and cheap. I can think of nothing cheaper than some colored bulbs and three dimmers. It would work every time and last for years with zero maintenance. The video cameras can achieve their own black balance with no outside help and, once white balanced to the light source, will reflect changes created in the placement of the dimmers. Should be very reliable, but thanks for the ideas!
Roger
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Roger Evans
MovieStuff
http://www.afterimagephoto.tv/moviestuff.html
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Once again, Roger, you've come up with an idea that is brilliant in its simplicity!
I WANT ONE!!!
Now, the big question, HOW MUCH!
And can I add it to my WP3 later without sending it in to you?
Or does it require Rogification?
Cool!
Matt Pacini
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<BLOCKQUOTE><font size="1" face="Courier, Arial">quote:</font><HR>Originally posted by StopMoWorks:
Wonder if you can get the different light colors to actually mix? Like, if red light is turned up, will it only illuminate the left side of film frame?
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Gosh no. The light mixes in the mixing chamber and is then diffused again on the way out. It then bounces off a 45 degree diffusion panel where the projector's mirror used to be. So it is triple diffused. The light will be pure and nicely homogenized long before it gets to the film plane. Besides, the 45 degree diffusion panel is well behind the film plane and, therefore, way out of focus. So we have diffusion at four different levels!
<BLOCKQUOTE><font size="1" face="Courier, Arial">quote:</font><HR>Originally posted by StopMoWorks:
About the Cinemate.....I believe Roger announced awhile ago, that it was discontinued due to unavailability of 5 bladed shutters for GAF projectors? Was this some kind of accessory to retrofit the stock Gaf's?
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No, they were custom made here locally but the guy was involved in a life altering car accident and was charging too much per shutter, anyway.
<BLOCKQUOTE><font size="1" face="Courier, Arial">quote:</font><HR>Originally posted by StopMoWorks:
I once contemplated on making my own custom 5 blade shutter (I can do general metal work) but, I suspect that would be very tricky, in trying to design the shutter opening & angle so that it exactly exposes the projected frame while it's held stationary in the gate (projector running at 24fps / during transfer).
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Well, that was the other thing about the CineMate. The pulldown on the GAFs isn't particularly fast, compared to other projectors, and setting the phase so that the pulldown was covered by the more-narrow telecine shutter was trick-eee. Took forever and was a general pain in the keester. I do not miss making the CineMate at all.
However, I will probably re-introduce the CineMate as a 20fps unit mounted with the cooler bulb and condenser lens set up. This will allow me to use the original three bladed shutter so phase adjustment won't be a problem. All I have to do is put a slightly larger pulley on it and add a variable speed control. Hopefully, for those that shoot 18fps all the time, this will be a useful device for high quality transfers, since 18fps footage doesn't work as well on the WP as 18 can't be mathmatically divided against 30 evenly though typical frame doubling.
Roger
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Roger Evans
MovieStuff
http://www.afterimagephoto.tv/moviestuff.html
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<BLOCKQUOTE><font size="1" face="Courier, Arial">quote:</font><HR>Originally posted by StopMoWorks:
In the past, when I experimented with some home-brew, front projected Super8 to video transfer tests, I used ambient light on the screen to somewhat control contrast....
However, maybe I am possibly missing some information with regards to this "manual" white balance control/feature on some camcorders? (i don't have it) Does the white balance have any affect on contrast?
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Well, some people feel that using ambient light helps to control contrast when copying from a projected image. I supposed it does to a degree but not in the same way that flashing film does in normal photography. When you pre-flash film, you pre-sensitize it so that shadow areas become more responsive by taking advantage of negative's natural ability to handle over-exposure. The end result is more detail in the shadows and lower contrast.
Video, however, doesn't really respond the same way. To what degree that using amibient light lowers contrast is purely a subjective issue. In others words, you might not gain any more shadow detail but if it looks nicer to the eye, then that's all that matters to some people.
From a purely technical point of view, I think you are better off not contaminating the image with ambient light and using contrast controls found in Premier or Photoshop to do the dirty work instead. Again, once you've contaminated the shadow areas, there is nothing you can do to reverse the process. In fact, if you decide that you don't like the look of your "flashed" transfer, you are likely to end up with something even MORE contrasty if you try to correct that footage electronically after the fact.
The white balance really should not affect contrast in most situations. All you're doing is telling the camera what constitutes "white light". This is typically done by holding a piece of white paper in front of the camera and depressing the white balance button. It recalibrates the camera's internal color so that what ever light is hitting the paper it sees as white, even if it really isn't! Because video cameras have this unique ability, it is common for video DPs to carry around a small pad of different colored paper to white balance against. If the scene is a bit warm and they don't want to add filtration, they can use a warm piece of paper to white balance against and that will correct the color balance without losing stops.
Roger
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Roger Evans
MovieStuff
http://www.afterimagephoto.tv/moviestuff.html
