My approach to lighting has taken a different direction, and here’s why.
Our eyes are amazing optical devices. Amazing lens, iris and sensor. So, thinking about the, as such. Optical lenses are sharpest at apertures one or two stops from wide open. They get a bit soft at max aperture and suffer diffusion at small apertures. So, maxing out lumens may not be a helpful as you think. Reducing your pupils to pinholes worsens your sharpness and perception of depth.
Many of these light sources produce tons of glare. If you are able to see the light source itself—the underside of those incandescent lamp shades, and the led lights with the leds nearly at the surface with no shade—your eyes will experience lens flare. Off axis light hits your eye. It doesn't enter your iris, but scatters across the lens causing the flare causing diffusion and reducing contrast. It’s also uncomfortable and is fatiguing to your eyes.
You may want to consider putting shades, barndoors or snoots on your lamps. Thinking of those high powered led lights with the cylindrical lamp heads, with harsh light, in your face. I added a snoot to mine. A short black tube of rubber or poster board added to the output end of the lamp heads will narrow the beam, and prevent the light from hitting your eyes. The difference is quite dramatic. With the incandescent lamps be sure that you cannot see the underside of the shade, only the black topside. The result will be less eye fatigue, better contrast and sharpness. (Note. Keep the cooling fins clear)
How many sources?
In nature, there are two kinds of light. A point source (main light or key light) which is the sun. Bright, unidirectional, a small point. Only one source as we only have one sun. The light is hard and the shadows black (think of the dark side of the moon). Shadows on earth generally aren’t completely black due to reflected light. More reflection gives lighter shadows. This is called fill light.
On an overcast day there are very few shadows, or shadows are nearly filled. The clouds diffuse the light making the sky a giant soft box. (Soft lights are used in photography, especially portraits due to their ability to make wrinkles vanish). Multiple lamps tend to act light a cloudy day and obliterate scratches.
What then, is most helpful to us at the lathe?
My solution is to use two lights. The first, the main light is a studio fresnel with barn doors. A fresnel is a single point light behind a fresnel lens to widen or narrow the beam of light. The barn doors control the light not need/wanted, the light that would hit my eyes. I can position and aim the light from most anywhere around the lathe. This is my sunlight.
The second light is a Laguna lathe mounted lamp. Two led tubes. Being a larger source (approx 3 x 12 inches) the light is soft. Let’s call that the fill light (it fills in shadows). Even that light gave glare! It has a diffuser. The edges of which are very bright! So I added simple barn doors. One inch wide poster board around three sides, extending an inch downward. Fixed!
Both lights are adjustable in brightness.
I prefer to work with ONLY these two. Truly. No overhead lights.
I position my main light, the studio light wherever makes the most sense, puts light where I need. I narrow or widen the beam for best results, and adjust the barn doors to bloke unwanted/unneeded light. Then adjust my fill light for comfort and best view of the piece. More fill = more overall light. Less fill= enhanced perception of surface quality, ability to easily see torn fibers and scratches.
I’ve been using my “system” for several years. I enjoy elimination of glare and eye fatigue, the enhanced sharpness and contrast, and that I’m much better able to judge the form, since beyond my piece is very dark.
It’s quality, not just quantity.
