Sunday, July 18, 2010


About a month ago I wrote a blog here about a new LED lamp made by Fobsun in China. And here is the essential information I had at the time: “I took interest in Fobsun because they sent me a news item about a downlight they make that has a standard lamp socket as used in America and white light output near 6500K color temperature. This lamp is also about as bright as a 40 watt incandescent lamp. To me its color temperature close to that of an LCD computer display and moderate brightness makes it an ideal candidate as an illumination source for environmental lighting where computer digital photography is done and prints are being made, in a light source matching the computer screen. It is a Fobsun Horizon Down Lights Adopting SMD LEDs, FLB-E27-90W-H, E27 base SMD bulb, 38*160mm, 90LEDs,7W,100-260VAC, white color, 6000-6500k,630lm.”

A business friend helped and joined with me to order 5 of these lamps for test and trial that were shipped directly to me by air. When they arrived I was quite positively impressed with the fine quality and features of the 90 LED lamp design. It is about six inches long and about one and five/eights inches wide, so the light panel of LED’s is four inches long. The E-27 is a standard US-type lamp screw in with a collar to grip to install. And the lamp also turns on axis around 180 degrees so once installed in a socket it can be adjusted in light pattern direction.

For me making fittings to use these lamps only required a few dollars in standard lamp parts at a local hardware store, and some odds and ends of studio clamps I had kept from the days I owned a photo studio. The actual work of making sockets and attachments to hold two of the Fobsun E27 LED lamps was easy to do and I had them installed in my digital darkroom in short order. One was attached to he end of a “C” stand arm and the other to an above desk, steel bookcase where one of my computers is installed. This second one is located over and extension of that desk that is used for for one of my printers, and the lamp provides illumination for the printer output. After turning on the Fobsun LED’s I was surprised how bright they are, measured about ⅔’s of a stop brighter than my computer screen. In addition the area illuminated is quite even in brightness with little fall-off at the edges of the illuminated area. But the color of the light is cooler than the 5000K lamps I had been using, so it was perceptually very evident. Then after using the Fobsun LED’s for a few days my perception adapted.

To adjust the light level on the desktop of the first unit installed on the “C’ stand I just raised the lamp height a little. With the other lamp over the printer I could not move it higher so put a half-silk nylon ripstop filter under it and got the illumination level to match the computer LCD screen brightness. finally I put a 14x10x7 inch black box around this lamp to shield the side light and provide a holder for the silk. I measured the color balance of the Fobsun LED lamps compared to the computer LCD set at 6500K. The difference was small, just 2% cyan and 2% blue would make a balance; or I could lower the color temperature of the computer LCD a couple of hundred degrees. There were no gels as thin as I needed available, and after trying the computer LCD at a lower color temperature, I decided the difference was perceptually not worth adjusting. My evaluation of prints compared to the image appearance on-screen confirmed this. The difference between projected illumination of an LCD screen and the reflected light from a print obscure the small difference in the color balance. In other words close enough is in reality ideal.

After years of never having an affordable and comfortable light balance between my darkroom and my computer displays, the Fobsun LED’s have provided a very comfortable environment for viewing prints and seeing how well they match their on-screen image. It is such a pleasure to have this light match, and now that I am getting comfortable working with it, I also feel comfortable recommending anyone interested to give it a try. Just take a look at for their section on Horizon Downlights. It would be better of course if Fobsun had an American distributor, but maybe that will happen some day.

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