Why would I select FRESNEL lens?

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mike9999

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Why would I select FRESNEL lens as opposed to a flat lens or a prismatic?
Will it give more spread? Will it be more directional? etc.
 
A fresnel lens basically cuts out the weight and expense of a thick curved lens. By keeping the same curvature, but moving it closer to the "back" of the lens, you get the "ringed" fresnel look.
 
Yes I did some research before asking this question. All information I got is about lighthouses and how less glass material it needs to make a comparable lens.

But when you look at lensed downlights, you are presented with options on your lenses. There has to be a clear understanding before you specify such a product. Sure I can ask my rep, ... just wondering if somebody knows in the forum.
 
bcorbin said:
A fresnel lens is like what is in a lighthouse....it creates a beam.
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Oh, sorry...let me re-phrase...I only mentioned the lighthouse to give you a mental image of the effect. if you want a directional beam, choose a fresnel lens. If you want a soft, fuzzy spread, use prismatic. If you want no effect, go flat lens. Better?
 
mike9999 said:
Why would I select FRESNEL lens as opposed to a flat lens or a prismatic?
Will it give more spread? Will it be more directional? etc.
Click to expand...

It will give a different spread. Impossible to say whether it's wider, narrower, more even, less even, or whatever without looking at the photometrics.

Martin
 
The luminaire specs often give details as to how the light is distributed with each lense. Keep in mind that often lamp wattages are changed as well so ignore the levels (or convert to same watt lamp) and look at the distribution when determining the appropriate lense. Also, Lithonia has a free lighting calc program that's easy to use. Make a room and pug in some different luminaires to see the difference.

Regards,
 
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