Disappointing Aspheric lens

wechnivag · Feb 28, 2008

I have just received [FONT=Arial, Helvetica, sans-serif]a 41mm aspheric L3953 from SS.
http://www.surplusshed.com/pages/item/l3953.html
The results are quite disappointing. With 41mm diameter and about 23mm BFL, i reckon the lens is getting a 90 degree cone of light from the LED. I can get the sharp focus square image of the die (can see the 2 wire leads on the die), however there is a large ring of spillbeam around the square image even in sharp focus. Is also noticed that the curvature of this lense is quite different compared to the ~50mm lens used with great success on the MAGs.

Will try to take some pics of beamshots later to illustrate the problem.

Any idea where i went wrong? :thinking:The reason i got the 41mm lens is because the 50mm ones are all out, and this one seemed to have decent diameter to back focal length ratio, close to unity. 40 mm is also the bezel diameter of my current light.

So back to the catalog for another lens. Has anyone tried this lens? The diameter to BFL ratio should allow up to 130 degress of light captured from the LED. Unfortunately, it is not a true PCX, however one side is only mildly curved. What is the effect of using a DCX lens of similar diameter and focal length compared to a PCX?
http://www.surplusshed.com/pages/item/l3461.html

Yet another option, very thick, large diameter and good focal length. Most importantly, still in stock!
http://www.surplusshed.com/pages/item/pl1032.html

Thanks in advance for any comments!

Gavin
[/FONT]

Gunner12 · Feb 28, 2008

What LED are you using?

The lens is focusing anything that is sending light towards it. For example, with a Cree XR-E, the metal ring will reflect some of the light and it shows up when you use a lens at full focus.

:welcome:

LukeA · Feb 28, 2008

Is the reflector still in the light? It doesn't need to be in there.

As for pl1032, (the only lens type I could claim to have used) It looks like it would work great if the mag bezel was 2mm larger in diameter. Stock, the mag bezel's ID is 53mm. One could conceivably modify the bezel (cut the threads out) and epoxy the bezel to the head, thereby securing the lens. IIRC, a few mm also will need to be cut off the top of the mag head for a lens this size, but this lens could be made to fit and would have excellent results, due to the relatively long FL and large diameter.

mash.m · Feb 29, 2008

LukeA said:
Is the reflector still in the light? It doesn't need to be in there.

As for pl1032, (the only lens type I could claim to have used) It looks like it would work great if the mag bezel was 2mm larger in diameter. Stock, the mag bezel's ID is 53mm. One could conceivably modify the bezel (cut the threads out) and epoxy the bezel to the head, thereby securing the lens. IIRC, a few mm also will need to be cut off the top of the mag head for a lens this size, but this lens could be made to fit and would have excellent results, due to the relatively long FL and large diameter.

i also use the pl1032 for my next mag project, but i had to rub down the lens so it now will fit perfect into the org mag bezel! i have done this with a grinding machine.
i can make a foto later this day!

markus

wechnivag · Feb 29, 2008

Gunner12 said:
What LED are you using?

The lens is focusing anything that is sending light towards it. For example, with a Cree XR-E, the metal ring will reflect some of the light and it shows up when you use a lens at full focus.

:welcome:

Thanks for the welcome, :party:

I am testing the lens handheld in front a lux 3 light, just bare emitter with no reflecter. Just testing the concept to satisfy myself that it actually works. The plan is to replace the lux 3 LED with a Cree.:twothumbs

Anyway, here are the pics as promised.
The 41mm PCX lens with the wierd spill beam (no reflector). The spillbeam is offset because i'm holding the lens by hand in front of the Lux 3 while taking the pic.
http://www.flickr.com/photos/24250360@N04/2299763166/in/set-72157604008440367/
http://www.flickr.com/photos/24250360@N04/2298966945/in/set-72157604008440367/

Using this lens DCX 50mm x 30mm FL SS L4366, i get the 'normal' square image with no spill beam.
http://www.flickr.com/photos/24250360@N04/2299763156/in/set-72157604008440367/
http://www.flickr.com/photos/24250360@N04/2299763186/in/set-72157604008440367/

The 2 lens side by side.
http://www.flickr.com/photos/24250360@N04/2298966897/in/set-72157604008440367/

Did i get a 'bad' or wierd lens? Guess not all PCX aspherics behave the same.

Another lens that i am very interested in is this.
http://www.surplusshed.com/pages/item/l3461.html
Has anyone tried it before? It has a diameter to FL ratio of 2, very high compared to the 50/38 used on the M@Gs... Should be able to capture a lot of the light from the CREE.

wechnivag · Feb 29, 2008

mash.m said:
i will also use the pl1032 for my next mag project, but i have to rub down the lens so it now will fit perfect into the org mag bezel! i have done this with a grinding machine.
i can make a foto later this day!

markus

Markus, i'm eagerly awaiting your beamshots and pics of your light. :thumbsup:

I am also planning to get a PL1032 for my M@G 3D.

mash.m · Feb 29, 2008

it will take some days untill this light will be ready, cause at this moment i have only the aspherical lens, the ostar and the shark driver. the mag is on the road to me. it will be a cutdown 1D size mag with 4 x 14650 lion. this will be a very compact and bright light.
i will use the orginial narrow beam franel reflector so no light will be loosed. i know that the focused beam will not so beautiful, but i think this is the best way to make a small bright light!

i make a picture of my pl1032 that fits perfectly in the original mag head. this process takes about 20 minutes

markus

LukeA · Feb 29, 2008

mash.m said:
i also use the pl1032 for my next mag project, but i had to rub down the lens so it now will fit perfect into the org mag bezel! i have done this with a grinding machine.
i can make a foto later this day!

markus

I figured that that could be done, but that it would be easier to mill aluminum than glass, but, hey, if you've got the tools...

LukeA · Feb 29, 2008

wechnivag said:
Thanks for the welcome,

I am testing the lens handheld in front a lux 3 light, just bare emitter with no reflecter. Just testing the concept to satisfy myself that it actually works. The plan is to replace the lux 3 LED with a Cree.:twothumbs

Anyway, here are the pics as promised.
The 41mm PCX lens with the wierd spill beam (no reflector). The spillbeam is offset because i'm holding the lens by hand in front of the Lux 3 while taking the pic.
http://www.flickr.com/photos/24250360@N04/2299763166/in/set-72157604008440367/
http://www.flickr.com/photos/24250360@N04/2298966945/in/set-72157604008440367/

Using this lens DCX 50mm x 30mm FL SS L4366, i get the 'normal' square image with no spill beam.
http://www.flickr.com/photos/24250360@N04/2299763156/in/set-72157604008440367/
http://www.flickr.com/photos/24250360@N04/2299763186/in/set-72157604008440367/

The 2 lens side by side.
http://www.flickr.com/photos/24250360@N04/2298966897/in/set-72157604008440367/

Did i get a 'bad' or wierd lens? Guess not all PCX aspherics behave the same.

Another lens that i am very interested in is this.
http://www.surplusshed.com/pages/item/l3461.html
Has anyone tried it before? It has a diameter to FL ratio of 2, very high compared to the 50/38 used on the M@Gs... Should be able to capture a lot of the light from the CREE.

So the biconvex lens works? Sweet. I might get one. I kind of cracked the edge of my pl1028 (50mm dia * 35mm FL PCX). It still works great, but if I ever want to build another one, I'll get one of these.

The other lens looks to me like it's just slightly closer to the emitter than it should be. But I have to believe you when you say that it always has that halo. I guess it is just a funky lens.

Gunner12 · Feb 29, 2008

That's odd, probably a bad lens than(or maybe the lens is focusing the stuff around the LED).

I've tried this with a normal lens and the lens focused so I could see the star, the soldering and other stuff around the LED. That was through a glass window so some of the light is reflected back into the light to illuminate the star and other components.

wechnivag · Feb 29, 2008

Gunner12 said:
That's odd, probably a bad lens than(or maybe the lens is focusing the stuff around the LED).

I've tried this with a normal lens and the lens focused so I could see the star, the soldering and other stuff around the LED. That was through a glass window so some of the light is reflected back into the light to illuminate the star and other components.

Now that you mentioned, the wierd spill beam is not present when i compare the 2 lenses using a 5mm white keychain light. The LED in my old light is sitting rather deep inside the barrel, maybe some light is getting reflected around. Strange thing is, the reflected light should affect the DCX lens the same way?
So maybe the lens is not bad after all!! hooray!! :clap:

BTW, i just came across this thread about the SS 30mmx15mm lens for smaller diameter lights. This i will give them a try too! They are also not pure PCX, but one side of the convex is much milder than the other.
https://www.candlepowerforums.com/threads/166958

Can't wait to see the results. Markus, keep us updated!

mash.m · Mar 2, 2008

here now a picture of the cuttet lens from ss:

fits perfect into the mag head now.

at this moment there is an apsherical lens at kaidomain that fits also perfectly into a mag head. this lens have a very short back focal lengh!

http://www.kaidomain.com/WEBUI/ProductDetail.aspx?TranID=4167

markus

yellow · Mar 2, 2008

why remove the reflector?
in a setup like the one pictured above, it doest not interfere with the lens and should grab light.

even if this light gets directed into some strange direction, it will leave the head at least.
Without the refli it will just be lost at the sidewall.

or am I thinking the wrong direction?

Monkeyboab · Mar 2, 2008

What lens is the cuttet lens from dx? Can believe kaidomain have finally brought out than lens, twice the price than it was going to be though. typical when I've just ordered a couple of pl1032's from SS

Rob

LukeA · Mar 2, 2008

yellow said:
why remove the reflector?
in a setup like the one pictured above, it doest not interfere with the lens and should grab light.

even if this light gets directed into some strange direction, it will leave the head at least.
Without the refli it will just be lost at the sidewall.

or am I thinking the wrong direction?

The reflected light looks absolutely terrible and isn't useful.

mash.m · Mar 3, 2008

Monkeyboab said:
What lens is the cuttet lens from dx? Can believe kaidomain have finally brought out than lens, twice the price than it was going to be though. typical when I've just ordered a couple of pl1032's from SS

Rob

sorry my mistake. it was ss not dx!!! rigth

l1032

markus

HarryN · Mar 3, 2008

LukeA said:
The reflected light looks absolutely terrible and isn't useful.

I have done this kind of work before - using a reflector + lens combo. It is MUCH more challenging to obtain a decent beam, but it is possible. One of the more interesting aspects is trying to define what a "nice" beam actually is - even if you are the only judge.

I think I dropped a few grand into playing with reflectors / custom reflectors + lens / custom lens combos before I found a setup I liked well enough to show others. Not the best use of money, but I guess that is why it is called a hobby. :shrug:

I will tell you this, if you decide to use a combo setup, then the light quality / color uniformity / intensity coming from the LED package must be VERY uniform over the emitted area - or the beam gets ugly very fast. 2 years ago, only Lumileds LEDs could meet this need - not sure now.

mash.m · Mar 4, 2008

HarryN said:
One of the more interesting aspects is trying to define what a "nice" beam actually is - even if you are the only judge.
.

absolutely right! my next light will be a ostared mag with the franel reflector and a aspherical lens. the light from the reflector looks absolute nice.

markus

Bunk3r · Mar 4, 2008

----edited, after reading kai's thread in the marketplace explaining the availability of the new lens etc. this post can be deleted-----

wechnivag · Mar 5, 2008

mash.m said:
here now a picture of the cuttet lens from ss:

fits perfect into the mag head now.

at this moment there is an apsherical lens at kaidomain that fits also perfectly into a mag head. this lens have a very short back focal lengh!

http://www.kaidomain.com/WEBUI/ProductDetail.aspx?TranID=4167

markus

Wat, i can't believe no one requested for a beamshot yet!! :poke:

Markus, taken any pics of your laser beam yet? :twothumbs

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