I tried a bat stencil, sawn out of thin aluminium with a fret saw, but I made it too big, the edges of the wings do not receive enough light so they appear not sharp.

So it must be made tinier, not sure if that can be done nicely with a fret saw. And I’m not sure about batman either, maybe I will end up with something entirely different

Jeff51 just posted about a batman projection contraption that uses a 100,000 lumen Imalent flashlight as a light source, and a 25cm fresnel lens with fairly long focal length. Pretty cool too, but not as silent, and maybe a bit less throwy than this one.
https://budgetlightforum.com/node/75196

Tnx.
Today I got the 14AWG wire in so I could finish the battery carrier. I chopped the front section off the flashlight head 4mm above the shelf and sawed two grooves in the remaining rim to lead the ledwires to the side. Had to ream the holes in the shelf to 4mm diameter for these quite massive wires. Smoothed everything with sand paper so there were no sharp edges to cut into the wires. The wires were fixed in position with a good bit of kapton tape, does not look extremely profi but you are not going to look inside the lamp daily.
In the picture I show the old 18AWG wires too, so that you can see that 14AWG is a whole lot thicker.

I was lucky because with a 40T at 4.12V I measured 19.85 amps now, precisely what I was hoping for

So now that the battery tube was shortened, I could check the maximum flood setting of the lamp, with the slider towards the lens with the battery tube touching it.

In the picture the flood looks a bit less wide than in reality because of the wide field of my phone camera. Trees are at 25 meters as always. (it looks like I borrowed Flahoholic’s van for the beamshot )

mooi rood is niet lelijk herinner ik me uit de jaren 70 volgens mij, zegt iets over je leeftijd

MRsDNF wrote:

Nice beam djozz. Ever have trouble finding a car park?

MascaratumB wrote:

djozz wrote:

MRsDNF wrote:

Nice beam djozz. Ever have trouble finding a car park?

Not sure what you mean, but I do not have a driving licence, never needed one over here. (I can park a 20 meter steel barge though)

I guess MRsDNF was referring to your “spotting light” to spot a place for a car! It guess it could apply to the barge too

Throwtest

For who is into throw distance as unit (distance at which the illumination is reduced to 0.25lux AKA moonlight level), that is 4.36 km.
My Extech LT45 over-reads a bit, the Tasi 8133 makes it 4.24 Mcd but that may be under-read again. Let’s agree on rather throwy

(I do not dare to use my Mobilux classA luxmeter too much lately because the cable-connection to the sensor is rather worn-out and fixing it will require a completely new calibration as well, which will cost me 300+ euros)

thefreeman wrote:

So much throw, nice work!

djozz wrote:

Speaking of which, ships often have great spotlights, my cycle trip to work is along a small part of the Amsterdam port and I’m always jealous of those marine mirror lights. They cost a fortune though..

Would These parabolic reflectors be appropriate for making somthing like this ? It doesn’t look very expensive. If I understand correctly the short focal lenght means that all light would be collected (expect in center), also it would not produce chromatic aberation as opposed to the fresnel lens.

I’m very impressed by the optical performance of these budget plastic fresnel lenses btw, the throw per surface area is very similar to the GT reflector. What helps is that the light source is small and centered (as opposed to projecting an image i.e. a slide which is a large source), the fresnel rims are only maximally optimised for light coming right from the focal point which is the case with a led.

kennybobby wrote:

djozz wrote:

Throwtest … My Extech LT45 over-reads a bit, the Tasi 8133 makes it 4.24 Mcd but that may be under-read again. Let’s agree on rather throwy

Excuse my ignorance on these calculations—i see how you calculated the luminous intensity in candela, but i struggle to understand how the Luxmeter sensor area or solid angle come into play, or if they do? Does the sensor area not matter?

If the sensor area were known, would it be possible to calculate the lumens of the beam?

I’m not sure what “solid angle” is, and the sensor area does not matter as long as it is more or less uniformly lit, as is the case because the hotspot is way larger than the aensor area.