ledrgb
Although this question is more of an optics than electronics, it strongly involves LEDs so I think it is a good idea to post it here.
I have a simple 3W, RGB LED with a 5deg lens. Everything is connected and and works but when projecting the light on the wall I can easily see the 3 different colors. I tried using a diffuse lens with partial success as the color mix inst 100%.
Is there any way to fully mix the colors of a standard 3W RGB LED?
I assume you have one of those LEDs that include a small chip that does the blinking? In that case there is no way you can reprogram that chip.
If you want the color to be under your control use a four-legged LED with separate connections for the three colors.
Generally I think you are going about this the correct way. You have to experiment with them and pick the right one for the job. The white balance is a big factor. Many RGB leds are not balanced well. The color temp. is another one. The pros buy from several color temp. bins and mix them up (even the same part number will get binned into different color temps).
Also how well the colors mix varies from LED to LED; you just have to try them.
I can vouch for the following RGB LEG:
Ledtronics SML13RGB2KT
http://www.ledtronics.com/Products/ProductsDetails.aspx?WP=446
You will not be disappointed. Let me know if you need some, I also have a break out PCB for them.
Best Answer
I had this problem when I was making a propeller display. We bought some clear lens leds but we were getting this same problem. More precisely, the cause is that there are 3 physically different LEDs inside the package. Now there are two options which worked for me. (But take all of this advice with a grain of salt since I worked on simple 5mm low power LEDs, as the size and power goes up things change.)
Change the LEDs and get diffused lens ones. Like this here. I really don't know why someone would want a clear lens one. But I don't know much about optics. If you are really careful you can just use sandpaper to make the outer surface diffused, but I would not advise that, since I damaged some LEDs by doing that, before I got good results.
Another way is to use something to diffuse the light. I know you used lenses but those worked for me, and I don't know why they didn't work for you. Maybe a pic showing your setup would give us a clearer idea. I got good results with covering them with a little butter paper. Normal paper could be used, but of course that will dim the lights way too much.