Hey, this is my first post on here, the rules seemed a bit strict so I hope I'm posting in the right place. Anyways, I've been wanting to build my own Icelight (http://fjwestcott.com/product/the-ice-light). It seems pretty straight forward, I'll be using an 18 inch led light tube, probably around 7 watts.
The biggest problem I'm running into is Dimming. I don't know wether to use PWM or CCR. PWM seems perfect, except for flickering, which may cause problems with photography, here's a link to someone that had issues with PWM in video (http://provideocoalition.com/aadams/story/pulse_width_modulation_is_not_your_friend/). I don't plan on doing a lot of video, but I don't want to run into issues if I do, I guess I can always put it on full power if I need to.
CCR, on the other hand, doesn't flicker, but does have color shift issues, after a ton of time on google I still don't know exactly how much color shifting it does, and if it'll be a problem in photography. I think I've heard somewhere that it can get hot too.
Is there a clear reason to choose one or the other, or do i just have to choose which pros and cons I'd rather deal with?
Another important question, how much can an Arduino take? What can I do if the light needs more power than the Arduino can work with. eventually I want to use an Arduino mini or nano, would that be wise with a project like this? I'm still learning about circuitry and how all that voltage and wattage and...stuff works....
My last question would be how do I know how many lumens is acceptable, that's probably more of a question for a photography forum, so i don't expect too many people to know here, but If you do, I'd appreciate it.
I know some of these questions might be silly. my first one is most important. I tried googling it... a lot. but I can't really find any clear answers.
CCR ( constant current regulation ) is not a method of dimming LEDs it is a method for powering high power LEDs, that is currents above about 50mA.
Do you mean a variable constant current regulator? That is another matter. What makes you think there is significant colour shift? It only tends to affect the warmness of white.
PWM is only a problem with low frequency PWM, if it is faster than the video frame rate by a few times it won't be a problem.
No. What are you wanting to take a photograph of? Is it moving fast?
Also PWM usually has at least 200hz, which is cycles per second, so any shutter speed faster than 1/200s runs the risk of catching the flicker.
That is way too slow for PWM on the arduino and you can set it to be faster if you want. http://playground.arduino.cc/Code/PwmFrequency
6KHz is no problem, get a mechanical shutter to go at that speed.
I need a way to know exactly what that shift is though,
Very simple just look in the data sheet of the LEDs you are using.
I'm not sure what the TRIAC Dimming is
You can not dim an LED with a triac, you can only dim incandescent AC mains lamps with triacs.
You are a typical beginner worrying about things you have no need to worry about.
But as you don't need me to tell you then there is little point in me trying to help you.
Multiplexing is exactly the same as PWM as regard to what the LED does. That is how little you know.
Good luck and one day you might learn that when you ask for advice then you should be smart enough to accept it.
However, you don't seem to have as much of an interest in photography, I could be wrong
You are. I was a professional photographer for three years.
I was simply trying to get some friendly advice here.
And that is what you got until you started throwing it back at me.
Obviously coming to the most credited forums i know of for this topic was a mistake.
The reason it is "most credited" is down the the quality of advice. Your mistake was coming with attitude. If you want attitude you have to be able to back it up.
Quite a shame really, that we can't put our heads together and make it work.
I feel the same way but if you will send comments like:-
I'm looking for a solution to a problem I already know of, not someone to tell me it's not important.
Then what can you expect. I showed you a way round any problem but you chose to ignore it. Fine but don't then moan when I get shirty with you.
so, to me, no flicker is my choice above seemingly imperceptible flicker
So why did you even mention PWM as a possibility?
Anyway there is no "seemingly" about this.