Im not sure what you mean concave convex lens? I have not had any success with them. The ones that project the best are plano convex. Double convex doesnt give as good a beam.
Thedriver mentions spherical lens very close to the LED I have some on order because a bit of research sayes that he is right. So then I will then build a 3 element projector light and see how it goes.
Sorry, my question was not clear.
I am talking about plano convex lens. At diameters larger than 100mm, the selection of aspheric plano convex lens is difficult to find. In addition, the price is also higher for large aspheric plano convex lens.
Spherical plano convex lens have more selections, are cheaper and can be produced with very high precision.
I personally never tested spherical plano convex lens before, so I am asking for how you feel using them.
Thank you for sharing experience with bicovex lens. I thought they would perform about the same.
CNCman, Here is a basic drawing of how the focus will work I done have the motors yet so not sure how they will mounted. There also needs to be a way for air to escape from between the seals. Im not even sure this will work yet.
What does the gear drive to the heatsink provide—is it for a water pump?
It will work for awhile, the airgap will reduce the cooling ability of the copper piston. It needs to contact and touch the heatsink for better performance, air is a poor thermal path.
likevvii,
The edmunds optics PCX lenses are formed from a radius. A line drawn from one point on the circumference of a circle to another is a chord. so if you then think of that circle as a sphere and cut the sphere through that line you get the PCX lens. Im not sure what the geometric term for this is. To me the plano spherical lens has a focal length close to the diameter and is a bigger portion of the sphere. So i am not really sure what the difference is. an aspheric lens is 2 lens in one lens so now I am not even sure why a zoomie is even called aspheric. Because mine are definitely not aspheric lenses.
I wondered why the w30 has a plastic double convex lens. So I got a bit of actuator housing and an old fitting and made a lens carrier for a 127mm DCX from a desktop magnifying glass. The results are not very impressive however put the light engine behind a 2 element PCX lens and the results are impressive. The focal length is also shorter with the w30 light engine that is because between the 90° mirror and the phosphor crystal there is a small lens less than 10mm diameter and less than 5mm off the phosphor. Now this lens puzzles me to me it looks like a PCX. But because of what Thedriver posted I dont think it is. So the lenses I have on order should give me the answer. So back to the DCX does this make the w30 a 2 element lens? I would say yes so that then makes the DCX lens an objective lens or primary, this makes the other lens a secondary. Which collects light and directs it toward the primary.
This is my opinion and if someone doesnt agree Im all ears as to why. The shorter the focal length of a lens the thicker it has to be the thicker the lens the bigger the loses and more distortion of the image. Therefore a longer focal length lens is thinner, the thinner it is the less the loses are. So a multiple element lens collimates the beam in steps. by using multiple lens the overall focal length can be shortened. this also distorts the led image less and the primary lens is the lens that gives you the throw and is the most important one to completely light up. So the secondary lens sets the light up for the primary to throw it down the paddock.
Big lens are expensive and heavy 
but the result is well worth it. I pondered and dreamed about them for a long until one day a few beers made me brave and I thought do yeah why not. I will only regret it untils next weeks pay, ever since I look back and think which one was it that trowed me of that cliff. 
The motor will drive the piston up and down to zoom. The light in and out. the gap will be small and filled with thermal compound. There is a lot of thermal mass in the piston, it weighs more than the K75 Light. It also has a large surface area and that is what I hope will make up for the poor heat transfer. There is a huge amount of aluminium and copper to heat up.
I wasn’t paying attention to this thread but now I look at it WOW! You got some mega throwers 
Will be watching 
Haha bigger the better, in a couple of hours I am picking up a 900mm or 36inch parabolic mirror from a 1940s carbon arc light. Oh my I am so excited I cant sleep. It was a bargain less than I paid for the 11inch mirror. Although I have to drive 3 hrs.
Hold it out in the sun and you’ll be melting aluminum cans with that thang.
Can not afford paint stripper 
It will have to go on a trailer that is a full sized carbon arc mirror. Apparently some cinema projectors are laser. I have 8x7w blue laser diodes I brought for some stupid project that wasnt smart to build. So I would like to go LEP or short arc. I also would like the light and driver to be easy to swap…the heat will be transfered to the drum using endermans method of coiling copper tube around it.
CNCman, being so excited I couldnt sleep thinking about a big mirror. Anyway I did some work on the the lights copper piston. So here is an update. The first drawing is still relevant just more detail on how I have made the piston.
The end on the piston has been filled with 45% pure silver solder and a recess for the LED machined into that. I was tempted to melt half a bar of silver bullion in there.
The brass is soft soldered with electronics solder so I can hold it in the lathe.
And this is the lead screw I have it is probably about 10 turns from end to end so I calculate I need 40rpm to give me 15sec from focused to full zoom. The motor there could be used but is only 1rpm and 24v. I have different motor and leadscrew ordered and it is a lot smaller. So I will wait for that but I was also thinking about just putting a knob through the backing plate so the leadscrew can be turned by hand. Because lets face it how often are you going to zoom in it is more for throw and is allows for that slight adjustment from focused to collimated.
For collimating light from an LED, you need an aspheric lens.
You want the whole lens to be focused at one focal plane, where the LED is.
With a regular (sperical) lens the light from a single point (like an LED) will not all leave in the same direction, some will converge and some will diverge.
A regular lens has a surface that is just a radius, part of a circle, while an aspherical lens has a complex equation that defines the surface.
The image above shows what happens with incoming light rays, to show that the normal lens has multiple focal points.
If you reverse the process, and put a single point of light emitting rays, after they go through the lens they will not all be parallel, some will go inwards and others outwards.
The aspherical lens fixes this to make them all parallel, which is called light collimation.
Thanks for clearing that up Enderman. So the lens I am using are mostly spherical. I think I had better build another test light with a different configuration to check the new information I have
Check this out!!! Just picked up this 36inch parabolic mirror from a carbon arc searchlight. Tonight I will have a play and take more photos
Awesome grin!
There is one of these on my parents property with a 2 cylinder lister diesel, 3 speed gear box, the diff has been pulled out but is there. Last time I started it it ran like a dream. So i am thinking that would look cool with the search light mounted on the front instead of the bucket.
It is crank start but easy to crank and I can mount an alternator on the motor to charge a battery pack and run the light.
Damn I am very jealous of that mirror
If your platform is this large, maybe all the disadvantages of short arc lamps will be less of an issue.
I cant believe I found it and only AU$400 and it cost less then the 11inch from the states, less than some of the lenses I have including fuel. It was well worth the 8hr drive there and back to get it.
I will go see if I can get some beam shots just holding an sbt-90 in front of it.
that’s some beautiful countryside you have there, and those rock cliffs are some interesting formations. thanks for sharing.