I have a $10 CREE XM-L flashlight with a rather small “standard” aspherical lens, I believe the diameter and focal length are around 30mm. I want to get one with a larger aspherical lens, in particular with a longer focal length. I looked online but they do not list the focal length. Can anybody suggest me a cheap aspherical lens flashlight with a focal length 40mm or longer?
I'm sure there's a few of those around, I just wonder why you look for longer focal length lenses ?
What I look for in an aspherical lens flashlight is the shortest possible focal length, and rather not a longer focal length. This is because a shorter focal length lens catches more light and less light is wasted inside the flashlight, the hotspot being larger but not less bright.
Edit: longer focal length lenses do generally give a wider flood when zoomed out, some folks really appreciate that.
I am looking for a tight hotspot. Longer focal length for the same LED should help.
Thanks, the lens looks bigger than the one I have. What’s the diameter and focal length?
Why do you mean wider flood, there is some light around the projected LED shape?