There will be a gap.I guess a thicker lens to replace the stock lens will do the trick. I just use what I have on hand. I have stacked a 1.47mm thick lens in between the noctigan mcpcb and the shelf to test out. Sanded the stock mcpcb to about the same thickness.
Thanks
I have built several S41 using a T-Pad quad and Carclo and no additional spacer was needed, Why I asked as that should be essentially the same.
And just a heads up… Lenses in the S41 size are hard to find. Think it was only flashlight lenses dot com or something was the only close fit and expensive, otherwise its astrolux.