By my counts, we have all four of them mentioned now. Anyone wish to sum up the four types and explain the differences between them?
[IMGR][/IMGR]
You asked for three types of
Fresnel Lenses, but you said the above.
So far we have the plano
lens (most with a
pattern to defuse the light), then there is the Con-cave
Fresnel Lens, the Oval Stlye, and the not correct for this question the
step lens. That is four.
The other variations include cheap and expenseive, cast and
ground. You also mentiond painted, that would be to control some scattering of the light.
Assuming that you are discounting the light
house lens, what else is there, except enough money to buy what we need.
Oval tends to give a flattened but broader
pattern, standerd plano is a good workhorse with a good balance of spread and brightness, con-cave is smoother and brighter and finally
step lens does not count, but has been used instead of two plano
convex.
Sums it up as best I can figure from the contents of this thread.