Hi Ive been hearing about problems with the rear fresnel bowing.Does anyone have suggestions on the best way to mount the rear fresnel preventing the bowing.
Thanks

I think that these statements were made in regards to using Lexan. If the Lexan is not framed, it will bow and if your fresnel is somehow attached to lexan, it will bow as well. If you are going to use lexan lx10, I would definitley frame it, I have used lexan in my design and I built a frame out of 1/4" square dowels for the lexan then framed my rear fresnel to fit inside the frame for the leaxn. no problems thus far. I drill four small holes in the lexan to attach it to the wood frame. When I attached the frame, I pushed the sides in about 1/16 of an inch for the holes in the lexan to meet the pilot holes in the frame, this puts just enough tension on the lexan to keep it from bowing when it expands from the heat. (This is of course just my opinion. I don't konw how effective it really is, but my lexan has not bowed as of yet)

Thanks Fraggin

the issue with the rear fresnel bowing is of course due to heat, but the main issue is that in most of htese cases, people attached the fresnel TO the heat shield.

if you use a heat shield by itself, and set the fresnel off away from that, then your issue should be much smaller.

i would still say the ideal setup (when focusing on longevity and peace of mind) is using a tempered glass heat shield then mounting the the rear fresnel on an xl10 sheet (UV blocking AND rigidity AND another medium for the heat to dissipate into from the fresnel) although at that point with active cooling the fresnel should be fine.

thanks guys I really appreciate it.I will do just like you said araczynski by the way how much does that extra piece of lexan in front of the tempered glass drop the lumens?or is it minimal.