Though now that I think about it there’s an easy solution to having too narrow beam.
Add more emitters. :smiling_imp:
You’ll have higher output as well and probably higher efficiency as well than with a weaker lens and fewer emitters.
Actually I see 2 uses for these lenses.
Take a powerful mule like one of the Vinh’s superlights and replace the glass lens with a negative Fresnel (or positive Fresnel + glass).
You get similar high output, nice smooth beam but narrower with sharp cutoff. Higher brightness than pure mule over a smaller area. Myself I love this kind of beam.
The other use would be a zoomie, with this style LED setup.
In flood mode it would be superb, just like any zoomie.
In throw….it would be special, in a way that’s neither good nor bad.
Astrolux FT-02 is available with 2 emitters (third on the way but this is irrelevant).
Compared to the initial SST-40, XHP50.2 offers roughly:
- twice lumens
- half intensity
- double power consumption
For some users XHP50.2 makes a significantly worse thrower but for others this kind of tradeoff works very well.
Here if we compare a regular aspheric to a super-strong fresnel we get:
- 1.5-3 times the lumens
- much lower intensity (I won’t try to guesstimate)
- same power consumption
Clearly not for everyone but it doen’t look like intristically bad tradoff.
Would put more lumens down the range than any regular reflector light with the same LED, competing with recoil setups.
And super short focal length offers new packaging possibilities.
Typically zoomies are quite bulky for whatever battery they support. They can have very short length but if they do - the diameter is significantly larger than that of a comparable reflector light. To make a narrow zoomie, the entire zooming mechanism has to be placed in front of the battery. With regular focal lengths that makes the light very long. With this kind of lens that’s not the case…
Here’s a pic that shows the concept (I think it’s slightly too compact at some places but it’s meant to show the idea rather than a design)
As narrow as a tube light and length-wise it can compete with a reflector light as well.
So…a zoomie is usually a Jack of all trades and a master of none. This kind of setup could offer different tradeoffs than regular aspherics. In some ways much worse. In some much better.