how to focus for max throw?

[Starik1]

I'm sorry if this is answered somewhere, but I looked and couldn't find it.

I have a dedomed light with an aspherical lens that is adjustable. I want to adjust it for maximum throw, but I'm not sure what that looks like.

I am pointing it at the wall about 6 feet away and trying to adjust it so that the picture of the LED is as crisp as possible. But I can see a very clearly defined LED-shaped spot over a wide range. The surrounding corona goes through changes in color and size, but there isn't a clear point where this reaches a minimum. If the blue/purple of the corona is small, then the orange part is wider and vice versa.

Is there a better way to do this?

 

[Fireclaw18]

Basically just focus it until the image of the emitter die is as crisp as possible. You should see the textures on top of the die (little spots for XML2/XPG2 or current spreader lines for XML/XPG).

If you want to absolutely max throw you may need to buy a lux meter and then take measurements after making each adjustment.

 

[Starik1]

Ok, so basically what I was doing then. I see a square die with a thin rectangular protrusion extending from one side, but it looks pretty crisp over a wide adjustment range.

Thank you for your reply.

 

[inetdog]

You may find that the wall at 6' is too close though.
Depends on the focal length of the lens you use.
For a large, longer FL, lens you should double check using a more distant wall.