BICONVEX lenses...why dont we use them

Flashlight Modding and DIY Parts
1

i hear and see a lot of aspheric lens flashlights but never have i really seen much in the way of biconvex lenses. As i understand a aspheric lens will collimate light, but not perfectly, the light will always diverge and hence loose its intensity as it gets further away from its source.
So this brings me to biconvex lenses. as i understand they will perfectly collminate light to infinity, so this way you will end up with a column of light that wont loose its intensity as it gets further away from its source. Wouldn’t this be what we would be striving to achieve in a super throwing flashlight?? So why dont we use biconvex lens systems instead of aspheric lenses?
correct me if i am wrong but i must be missing something here….i have included some pics to better understand what im trying to say, a picture says a thousand words!!

2

You can get great flashlights with these kinds of lenses. the original inova x1, for example.

3

Uh, I use DCX lenses in small pocket throwers. If the design is right and you can live with a little barrel distortion in the image of the die they can be great.

4

I’m interested in this. Can you show any beamshots?

5

Since we are talking about optics, I just want to give you guys a heads up, Surplusshed.com has all their optical lenses at $2 each, no matter what size, focal length or coatings, the deal ends today IIRC

Here is the lens finder search page

http://www.surplusshed.com/lens.cfm

6

Wait, what’s the difference between Bi convex and double convex? I want to order some from this sale to play with

7

So, if I want to make a thrower out of a little light, what type do I buy?

I want to take advantage of the deal Alex posted.

8

Aspheric or plano convex or bi convex, with a short focal length. For reference the maglight C and D aspherics used a 38mm focal lenght for optimum focus. ahorton aspherics for a modded lumapower light I have has a 20 something mm FL (24mm IIRC) so short FL is what you are looking for, what light do you want to install an aspheric?

9

Some kind of tube light… Convoy S6? S2? The screw-in pills should allow easy fine-tuning. The stock lenses are 20.5mm x 1.4mm. The S6 reflector is ~20mm tall, the S2’s is ~10.5mm

10

Let us know what you get PD68. I might have to follow you in the ailes with a shopping cart…

Stock numbers
L10928 BCX
L14255 DCX
L4464 PCX

All coated lenses

11

Well I found a few DCX like kkw mentioned, but it sounds like I need BCX?

12

So, what your saying is that if i were to make a super thrower id be best off using a doublet lens settup? This way i wouldnt suffer from chromatic arberation. Seems like a cleaner way of projecting light forward. Do the usually come as a matching pair when brought or do i have to match them myself?
Also, if this a better way then why has no one tried this yet…