sunporchmedia
Well-known member
Gopher,
Good post. Just to add, the Kino's you linked to have a pretty small green spike. They have a high 95 CRI (see my post above about the strength and limitations of CRI). Think about it: Kino bulbs are designed to NOT need minus-green (magenta) gel. Their bulb is already designed with a green spike small enough to be not noticable to the eye, to film, nor to video.
Lesser CRI bulbs will generally have a larger green spike, and require more gel correction or more correction via white balance. Old-school "practical" fluoresecent bulbs have very low CRI and are so green that even an untrained eye can pick it up.
If you white balance to a low CRI fluorescent bulb, then the camera will "see" everything lit by other light (ambient or tungsten) as being relatively magenta. In addition, lower CRI sources such as "practical" sodium and mercury vapor lamps, and some fluorescents, actually have a discontinuous spectrum---certain colors are actually missing or suppressed.
In the real world of documentary and indie filmmaking, ambient light (natural and man-made) is a big component of the illumination we deal with, so learning to effectively mix your fixtures with practical sources becomes part of your responsibility to your craft, as a DP.
Richard sells flo tubes and fixtures with a CRI just under 90, which is plenty good. In fact, Richard has a comprehensive and accurate discussion of CRI, CT and CCT, as well as the challenges of designing high-CRI bulbs, on his website here. Anyone who calls themselves a DP should already know most of this. If you don't then study Richard's article until you do know it! (not aimed at you, Gopher...you obviously do know this info.)
If you go to HD and buy a bulb, look for CRI and lumen ratings. Remember that "warm white" or "cool white" only tells you whether it is balanced toward daylight or tungsten, it does not tell you anything about how accurate the color rendering is.
Rule of thumb: if it doesn't have an advertised CRI, then it is pretty low.
Finally, Film "sees" the green spike much more than video to begin with, so it can be balanced out in video without much trouble. I would point out that CRI is somewhat related to, but is NOT the same as, the green spike phenomenon. Other factors influence CRI, which is a standard built upon how the EYE precieves color, not how a video camera or especially how a film camera, records it. So you could have a "90 CRI" tube with a small green spike, and another brand 90 CRI tube with a large green spike. The eye and video camera would probably not see the difference. Film would definitely see the difference.
But if you have low/no budget and can live with the compromises, then buy what you can afford and be sure to white balance!
Good post. Just to add, the Kino's you linked to have a pretty small green spike. They have a high 95 CRI (see my post above about the strength and limitations of CRI). Think about it: Kino bulbs are designed to NOT need minus-green (magenta) gel. Their bulb is already designed with a green spike small enough to be not noticable to the eye, to film, nor to video.
Lesser CRI bulbs will generally have a larger green spike, and require more gel correction or more correction via white balance. Old-school "practical" fluoresecent bulbs have very low CRI and are so green that even an untrained eye can pick it up.
If you white balance to a low CRI fluorescent bulb, then the camera will "see" everything lit by other light (ambient or tungsten) as being relatively magenta. In addition, lower CRI sources such as "practical" sodium and mercury vapor lamps, and some fluorescents, actually have a discontinuous spectrum---certain colors are actually missing or suppressed.
In the real world of documentary and indie filmmaking, ambient light (natural and man-made) is a big component of the illumination we deal with, so learning to effectively mix your fixtures with practical sources becomes part of your responsibility to your craft, as a DP.
Richard sells flo tubes and fixtures with a CRI just under 90, which is plenty good. In fact, Richard has a comprehensive and accurate discussion of CRI, CT and CCT, as well as the challenges of designing high-CRI bulbs, on his website here. Anyone who calls themselves a DP should already know most of this. If you don't then study Richard's article until you do know it! (not aimed at you, Gopher...you obviously do know this info.)
If you go to HD and buy a bulb, look for CRI and lumen ratings. Remember that "warm white" or "cool white" only tells you whether it is balanced toward daylight or tungsten, it does not tell you anything about how accurate the color rendering is.
Rule of thumb: if it doesn't have an advertised CRI, then it is pretty low.
Finally, Film "sees" the green spike much more than video to begin with, so it can be balanced out in video without much trouble. I would point out that CRI is somewhat related to, but is NOT the same as, the green spike phenomenon. Other factors influence CRI, which is a standard built upon how the EYE precieves color, not how a video camera or especially how a film camera, records it. So you could have a "90 CRI" tube with a small green spike, and another brand 90 CRI tube with a large green spike. The eye and video camera would probably not see the difference. Film would definitely see the difference.
But if you have low/no budget and can live with the compromises, then buy what you can afford and be sure to white balance!
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