All to turn of/on and do dimming/brightening. The board had a capacitive disc for switching, unmarked IC, A09T transistor, a few capacitors and resistors. All looked fine and there was 5v on the circuit board from the USB supply, as expected. I pealed off the back which was held on with double sided adhesive tape to expose the tiny circuit board with its string of 21 LED’s. The IMMEDIATE SURFACE has to be completely evenly illuminated.My Savfy A4 LED lightbox (model A4-DWT) stopped turning on after about 2yrs. There won't be intervening space to allow that further diffusion like an LED head intended for enlargement, or a flat panel intended for general portrait lighting from a distance, etc. Remember, this is for sake of color sheet film being copied when laying right atop a diffuser. And at the present time I cannot fully recommend any affordable LED option.

I've been through all this rightside-up, upside down, sideways, backwards, you name it. But always start with a precise control like a LF chrome of a MacBeth Color Checker Chart shot under ideal exposure and color temp conditions.

I should add that truly calibrating any such system requires a good color eye and goes beyond shortcut instrumentation. Lots of authentic options but you don't get something for nothing. You could also obtain something from the MacBeth Prooflite series (now owned by XRite, I believe). Three brands have already come up - Kaiser, Just Normlicht, and Graphiclite. Since the colorhead option is generally unrealistic, there are indeed high quality light boxes made for this kind of purpose. An ideal light source would be a modern upside-down 8x10 colorhead, except that it would be hot and probably blind you too. CRI 95 is far from ideal, especially when you need to factor in about a 15% BS Coefficient in how cheap gear is advertised. And reading them with a color temp meter will give them the final blow. All it takes it one look at these things actually turned on to detect that flaw. Not only will the color temp be way off from the advertised rating, but the illuminated surface will be quite uneven in a dimply-looking sense. No Pere, that cheap toy you post would be inappropriate for copying applications for reasons I already mentioned. The thinner the box, the more some kind of compromise comes into play. Quite a bit goes into this kind of project, including special interior paint. I went to the trouble of making my own duping copystand lightbox using very high quality German tubes and an optical glass top. Merely light balancing your camera might not correct for certain imbalances. Some of these LED lighting devices are more than a thousand degrees K off from the rated specs. If it were me I'd want to at the very least have the right of return if my color temp meter detected something significantly out of whack which can not be easily corrected with filters. I mention this because duplicating work is a more demanding application than just slide viewing. Kaiser is certainly a reputable brand, but squeezing this all into such a slim package introduces some real issues which their older tried-and-true, deeper tube technology is known to have ironed out. If the LED's are allegedly 5000K, it means the light box is not, because you still have a color bias in the diffuser, backing, and quite possibly a quality control issue. Why do you specifically want LED? Right off the bat I detect a potential discrepancy in the ad. Whether it is LED or not, are there any commercial color-balanced lightboxes that you can recommend for digitizing film?

I can't think of anything LED that color accurate. I went to the trouble of making my own duping copystand lightbox using very high quality CRI 98 German color-matching tubes and an optical glass top.

Usb light table