@ lee: missed that! When you underrun a HPS lamp the spectrum changes. One of the reasons why you don't have a single spike of sodium orange light such as a low pressure sodium lamp is the pressure buildup in the arc tube: that spreads the spectrum. At lower power that pressure is also lower, and so is the spectrum spread. All the more reason to use it together with plasma
@JohnWayneWith one HPS lamp you need to spread the light as well as you have no overlap. So based on uniformity and levels I'd do 90 cm. You can come closer easy but that will have effect on uniformity.
Here is the light 90 cm from your lamp
And to give you an idea: this is 150 cm away!
@JohnWayneWith one HPS lamp you need to spread the light as well as you have no overlap. So based on uniformity and levels I'd do 90 cm. You can come closer easy but that will have effect on uniformity.
Here is the light 90 cm from your lamp
And to give you an idea: this is 150 cm away!