Hello Everyone,
Recently, I have been trying to take some still captures of images projected onto a wall from a video projector. The endeavor is to document, as a consumer, various aspects of a given projector.
Some of the things I am trying to capture (using photography) include, but are not limited to, the following:
Black Level
White Level
Scene (Instataneous) Contrast
Vertical (V) Resolution
Horizontal (H) Resolution
V+H Resolution
Moire
Color Uniformity
Color Balance
Color Temperature
Light Spill
Heat (causing optical distortion) ... and so on.
My problem lies in the environment in which the projector and projected image occur in. The room has a considerable amount of light control, and thus the ambient light is nearly non-existent and well below the minimum light levels of the projector and projection.
My concern is for the accurate representation for what my eyes are seeing. I fully recognize that what my eyes see may be more or less than what someone else can see. But, its what I'm seeing that I am trying to document, albeit accurately.
Now, my next comments are not meant to place a particular technology in bad light, but more to simply recognize what I've experience through my documentation attempts. With that said, I have found that the two digital cameras I have (Kodak DC260 and DC215) they have a poor ability for low-light detection and capture. Furthermore, these two digital cameras seem incapable of capture an accurate exposure when using the camera's internal metering system.
What captures I have been able to produce are accomplished through a series of long-duration exposures ranging from 1.5 to 5 seconds. If I make a 4-5 second exposure to capture an absolute black level for the projector (i.e. the projector's ability to produce a 0-IRE full-field test pattern), I can immediately see something in much less time than the camera can capture via short-exposure. This tells me that my eyes are more sensitive to low-light levels than the digital cameras I own.
Also, if I take the same 4-5 second exposure of a movie seen projected, the exposure is all wrong, and typically requiring an exposure 1/3 as long. This somewhat tells me the dynamic range of my digital cameras has a strong limitation.
So, imagine a completely unlit, sealed projection room with black (or extremely dark-colored) walls and a projector projecting a full-field 0-IRE test pattern, but having its on faults comparable to a 10-15 IRE (or higher) result, and then trying to capture this photographically.
With conventional film, one can chose a film speed more sensitive to low-light levels (e.g. 800 ISO or faster) and make multiple exposures to zero in the dynamic range boundaies to best capture the best representation, while functionalizing against said determined exposure length for a projected image.
The final intent is to produce an image in digital form (whether direct or through film-to-digital conversion) which, when viewed on a calibrated monitor, best represents what my eyes are seeing and without manipulation (dodging or burning, etc.) prior to the end result.
Note: IRE is a measure of light, which ranges from zero (0) for no light (black), to 100 for full-light (white). NTSC, or SDTV, assumes a black is 7.5-IRE in the United States, but in Japan its 0-IRE for black. HDTV uses 0-IRE for black. I am trying to capture conditions in which the 'representation') projected image for 0-IRE is not being accurately projected, and in doing so trying to capture for the determination of what IRE the projected image best represents.
Recently, I have been trying to take some still captures of images projected onto a wall from a video projector. The endeavor is to document, as a consumer, various aspects of a given projector.
Some of the things I am trying to capture (using photography) include, but are not limited to, the following:
Black Level
White Level
Scene (Instataneous) Contrast
Vertical (V) Resolution
Horizontal (H) Resolution
V+H Resolution
Moire
Color Uniformity
Color Balance
Color Temperature
Light Spill
Heat (causing optical distortion) ... and so on.
My problem lies in the environment in which the projector and projected image occur in. The room has a considerable amount of light control, and thus the ambient light is nearly non-existent and well below the minimum light levels of the projector and projection.
My concern is for the accurate representation for what my eyes are seeing. I fully recognize that what my eyes see may be more or less than what someone else can see. But, its what I'm seeing that I am trying to document, albeit accurately.
Now, my next comments are not meant to place a particular technology in bad light, but more to simply recognize what I've experience through my documentation attempts. With that said, I have found that the two digital cameras I have (Kodak DC260 and DC215) they have a poor ability for low-light detection and capture. Furthermore, these two digital cameras seem incapable of capture an accurate exposure when using the camera's internal metering system.
What captures I have been able to produce are accomplished through a series of long-duration exposures ranging from 1.5 to 5 seconds. If I make a 4-5 second exposure to capture an absolute black level for the projector (i.e. the projector's ability to produce a 0-IRE full-field test pattern), I can immediately see something in much less time than the camera can capture via short-exposure. This tells me that my eyes are more sensitive to low-light levels than the digital cameras I own.
Also, if I take the same 4-5 second exposure of a movie seen projected, the exposure is all wrong, and typically requiring an exposure 1/3 as long. This somewhat tells me the dynamic range of my digital cameras has a strong limitation.
So, imagine a completely unlit, sealed projection room with black (or extremely dark-colored) walls and a projector projecting a full-field 0-IRE test pattern, but having its on faults comparable to a 10-15 IRE (or higher) result, and then trying to capture this photographically.
With conventional film, one can chose a film speed more sensitive to low-light levels (e.g. 800 ISO or faster) and make multiple exposures to zero in the dynamic range boundaies to best capture the best representation, while functionalizing against said determined exposure length for a projected image.
The final intent is to produce an image in digital form (whether direct or through film-to-digital conversion) which, when viewed on a calibrated monitor, best represents what my eyes are seeing and without manipulation (dodging or burning, etc.) prior to the end result.
Note: IRE is a measure of light, which ranges from zero (0) for no light (black), to 100 for full-light (white). NTSC, or SDTV, assumes a black is 7.5-IRE in the United States, but in Japan its 0-IRE for black. HDTV uses 0-IRE for black. I am trying to capture conditions in which the 'representation') projected image for 0-IRE is not being accurately projected, and in doing so trying to capture for the determination of what IRE the projected image best represents.
