As I was finding it difficult to gauge the bean colour wirh the default USB light, I supplemented the same with a table lamp with an LED bulb.
During the course of the roast the yellow stage just passed by and I failed to notice it at all. During my second stage, turned off the lamp for the initial few minutes ans then realized that the bean colour under the USB light was worlds apart from that under the extra light.
I figured it was due to the colour temperature of the bulb I was using. It is a 3000k warm light. I think a cool temperature bulb should be better.
I agree that the color of light produced by the USB that was provided with my V2 doesn’t show yellowing well. I supplement it with a flashlight that has an old incandescent bulb which works well but isn’t too convenient. I believe that the USB is too blue, not enough red, which strangely means the color temperature is too high. If anyone finds a replacement USB light with color temperature of say 2700 I’d love to give it a try.
do some research on CRI - Color Rendition Index. Most cheap LED lights have very poor CRI. If you want to see colors accurately you need a light with 90 or better CRI. For example:
(color science was a key part of my business for many years)
Thank you for your insight. My issue was very basic actually: between warm and cool led light, which showed the changes in bean colour better. Got a daylight bulb as suggested and its colour temperature matches that of the supplied USB light. So, managing to track the colour changes better. Thanks everyone.
Just tried the lohas LED light recommended by @wm1. It is EXCELLENT. The size is smaller than it looked on Amazon, just a little bigger than the light supplied by Aillio, and it fits into the tool pouch easily. The clip works great on the side of the cooling tray. Best of all, the colors are superb. There are several choices that work very well. Thanks Will for sharing your expertise! - Brad