What is a suitable candela value for a LED to have that doesn't blind you if you stare at it, and will still allow you to view silkscreen markings on the PCB but not to dim that you can see the internal workings of the LED ?
I suppose this question is more of an experience question.
This question originally had "lumens" in the text but what I was really asking was for candela. The question has been edited with candela.
Without knowing the number, I recommend looking at some examples.
I find the raspberry pi LEDs to be Just Right, and the Arduino nano LEDs to be much too bright.
Looking at the resistors (and LED models) should give you an idea about the current you want.
After that, as Erik says, you'll need to experiment. Different colours are perceived differently, the color of your silkscreen matters to the eye, etc.
It depends on the brightness of the LED and the viewing angle. For a status indicator, I'd look for an LED with an angle of 130 degrees or so.
If you aren't sure how bright you want it to be, buy one that is brighter than you think you need. You can always use a larger resistor to make it dimmer.
Digikey P/N 732-4981-1-ND will work. No relation to Digikey or the manufacturer, just something that happened to lay in front of me so I just read the label. The brightness depends on the current setting resistor and voltage, I use [email protected].
Ambient light level matters too.
