# 75mm aspheric lens source



## gt40 (Aug 16, 2010)

I ordered a 75mm/ 50mm focal length lens from here:

http://search.newport.com/?q=*&x2=sku&q2=KPA055

Anyone have any experience with these? I have been pretty happy with the mg lens I have on my mag c aspheric and this one looks similar. Dividing the focal of the mg lens= .71 vs .66 for the 75mm lens. 

I am going to make a 10 amp sst90 light with it using my mag switch design and adding a LdO10c driver and more battery, kinda like a big brother to the small aspheric light I built. Any suggestions on the most compact, highest density battery solution would be appreciated.

I will post more after it arrives.


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## ahorton (Aug 16, 2010)

gt40 said:


> I will post more after it arrives.



Looking forward to seeing it.

The price seems very high to me so I hope it turns out to be very high quality.

The focal length also seems a bit long but we'll see how it goes.


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## Walterk (Aug 16, 2010)

I have some similar expensive lenses, (Edmunds, Thorlabs) and did some tests here. 
My conclusion is that the 75mm aspheric from DealExtreme is the very best value for money.

FWIW


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## gt40 (Aug 16, 2010)

Walterk said:


> I have some similar expensive lenses, (Edmunds, Thorlabs) and did some tests here.
> My conclusion is that the 75mm aspheric from DealExtreme is the very best value for money.
> 
> FWIW


 
Thanks for the info. I went ahead and ordered the deal extreme lens also so it will be interesting to see if this lens is better than that one. The focal length on the specs seems in between the thor and edmunds that you tested.

Here is the diagram of its shape:


 
KPA055: BFL= 30.5 mm, P2= -19.50 mm, Tc= 30.0 mm, Te= 3.0 mm, S2= Plano

Also, for anyone who wants to try, MG has both a 75mm and 84mm lens:

http://www.cvimellesgriot.com/Produ...denser-Lenses.aspx?lastSearch=LAG-84.0-79.0-C


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## gt40 (Aug 17, 2010)

Update: 

I got the lens. I cant wait to put it in front of an led. The clarity is flawless. 

I just don't know if it will throw.

Top shot:






Clarity is decent:





Side profile:


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## gt40 (Aug 18, 2010)

Scratch this lens off the list. I held it in front of my sst90 led on my new light I built and if you get it to show the die and square shape, there is tremendous spill. I compared it to the mg 52mm lens and there was no spill as was the case on the 32mm lens I normally have on the light.


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## Walterk (Aug 18, 2010)

gt40 said:


> Scratch this lens off the list. ......tremendous spill
> .


 
Are you talking the Newport lens here? 
Assuming the above photo's are the same Newport lens?

Edit: I had the same experience with the Edmunds 75mm lens with too short focallength.


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## gt40 (Aug 18, 2010)

Yeah, the pics are the 75mm /50 fl Newport lens. I guess I will machine a base holder for it and give it to my 12 year old as an aspheric magnifying glass. What I really would like would be something in the 4-5" range with no spill and clarity.


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## saabluster (Aug 18, 2010)

gt40 said:


> Scratch this lens off the list. I held it in front of my sst90 led on my new light I built and if you get it to show the die and square shape, there is tremendous spill. I compared it to the mg 52mm lens and there was no spill as was the case on the 32mm lens I normally have on the light.


Not surprised. It looked just like the Thorlabs version with its overly bulbous profile. A slightly longer focal length is better for our application.


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## moviles (Aug 18, 2010)

Walterk said:


> I have some similar expensive lenses, (Edmunds, Thorlabs) and did some tests here.
> My conclusion is that the 75mm aspheric from DealExtreme is the very best value for money.
> 
> FWIW



nice !!!!!!!!

you have received jet the dx 75 mm lens?

total thickness? focal lenght? perfect focus without flood effect?


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## bigtodd (Aug 18, 2010)

I have some lenses like that layin in my tool box at work! I work on BMW cars and they use those in the headlights, I saved them from broken lights, I never really had a use for them just too cool to throw in the trash!!


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## Walterk (Aug 19, 2010)

@Saabluster; Please be specific about what Thorlabs you are talking?

In my postings here in this other thread I found this Thorlabs very good, and the Edmunds absolutely worthless:









bigtodd said:


> too cool !!


 
Glad you saw the light


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## bigtodd (Aug 19, 2010)

I measured the lenses I have, one is 75mm and 3 are 65mm, they look to be high quality. I tried one in front of my Element k2 and it threw a nice bright square spot a long way!! gt40, they aren't as "domed" as the one in the pic you posted, if you'd like one to play around with I have more than I will use!


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## ma_sha1 (Aug 19, 2010)

The 3" (~75mm) HID Projector lens for car headlights are very good,
either the OEM type or the after market ones should be fine. 
The original DEFT thread used one of those car headlight lens. 

I got a pair for $40 on ebay & used it to make the Frenken MagDEFT SST-50, well over 100K Lux @ 1meter:
https://www.candlepowerforums.com/threads/268894






It has a profile similar to the DX66mm lens, which I first tried it here in March: https://www.candlepowerforums.com/threads/264722
It's quite good too, ~100K lux with XPG. Excellent value for the money & the light is more portable than the 75mm lens. 

For playing in the 75mm range, I highly recommend the Dragon Aspherical Head, For $55 shipped, you get the lens, the head with beefy heat sink & the protective Bezel to allow head-stand:
https://www.candlepowerforums.com/threads/280670

It came out more lux than the MagDEFT but it's because the higher current pumped into the Mag Dragon SST-50. (MagDEFT used 2x DX P7 Driver in parallel, pumps 5 Amp into SST-50; MagDrgon used a *lucky* low Vf SST-50, 
which scored >7Amp direct drive with IMR 26650 & ~6 Amp after fit into the flashlight. 

It has a bigger spot than the MagDEFT due to shorter EFL, but still excellent quality, very efficient, no wasted spills. 








I haven't tried the DX 75mm, but I ordered the new DX 100mm, 
From the picture, I couldn't tell if it's even an Aepheric lens at all. 
I am hoping it is & praying that it's a good lens too, we'll see. 
Don't have a body for it, but can't let that stop me 
.
.


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## gt40 (Aug 19, 2010)

bigtodd said:


> I measured the lenses I have, one is 75mm and 3 are 65mm, they look to be high quality. I tried one in front of my Element k2 and it threw a nice bright square spot a long way!! gt40, they aren't as "domed" as the one in the pic you posted, if you'd like one to play around with I have more than I will use!


 
I would love to try one. I can pm you my address and can paypal you for shipping etc.


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## saabluster (Aug 19, 2010)

Walterk said:


> @Saabluster; Please be specific about what Thorlabs you are talking?
> 
> In my postings here in this other thread I found this Thorlabs very good, and the Edmunds absolutely worthless:



Mine is the ACL7560-A and it is totally worthless.


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## bigtodd (Aug 19, 2010)

gt40, the 65mm lenses I have look better than the 75mm, the 75mm has little rings that you can see in it but I don't think it effects the beam. PM me with your address and I'll send you a couple to try! I also have some fiber optic cable and xenon transformers and bulbs, all kinds of neat stuff inside BMW headlights!!:twothumbs


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## ma_sha1 (Aug 19, 2010)

saabluster said:


> Mine is the ACL7560-A and it is totally worthless.



Thanks, that's good to know & to avoid. At least you didn't try the AL100100-A, at $1089 per lens, that would have been one hell of a R&D expense


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## moviles (Aug 19, 2010)

the total thickness of the dx 75mm lens are only 26mm the focal lengt will be big 

what are the total thickness of the flaydragon lens? good focal lenght?


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## ma_sha1 (Aug 19, 2010)

moviles said:


> the total thickness of the dx 75mm lens are only 26mm the focal lengt will be big
> 
> what are the total thickness of the flaydragon lens? good focal lenght?



Didn't take the lens off but buy eyeballing it, probably 10mm to 1/2 inch thicker.


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## Walterk (Aug 22, 2010)

moviles said:


> the total thickness of the dx 75mm lens are only 26mm the focal lengt will be big



From comparison I estimate the back focallength to be 50mm, giving f-number 0,71 for the DX 75mm lens. 


The first Deft ( Subaru SVX '92 Hid Headlight lens - 79mm dia, bfl 54mm) is f 0.72.
In another posting (#2) the lens of the Deft with precolimator is said to be 3" inch wide 1" thick.

So, dont be angry, be anxious!!

NOte: I indeed am wrong about f number, reading ma_sha's post below, but still expect the back-focallength to be 50mm !
(I'll report once I have my lens in house. )


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## ma_sha1 (Aug 23, 2010)

Walterk said:


> The first Deft ( Subaru SVX '92 Hid Headlight lens - 79mm dia, bfl 54mm) is f 0.72.
> 
> From comparison I estimate the back focal length to be 50mm, giving f-number 0,71 for the DX 75mm lens.
> So, dont be angry, be anxious!!



Just to make some clarifications for those who may be be confused on some of the numbers. 

For the 79mm lens, The 50mm should be EFL, not BFL.
79mm/54mm is not F-number either. 

EFL is the Effective Focal length, which measures from the center of the lens somewhere to the focus point.

BFL is back focal length: The distance from back of the lens to the focal point. For the popular Surplus shed 52mm lens with EFL of 37mm, the BFL was only 12-15 mm or so, forgot the exact number but it's very close to the back of the lens. 

F-number is EFL/Diameter. The F number of the 79mm D, 50mm EFL lens =50/79 =0.63.

The EFL vs. BFL is not a big deal for lens with long Focal length, as the lens is more flat,
but for Aspherica lens, they are very different & one need to stick with EFL to shop for the correct lens profile. 

THE DX lens looks like a good profile from the picture, seeing how well the 66mm lens have worked, 
the 75mm lens should be a hit if it comes from the same manufacturer.


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## Walterk (Sep 14, 2010)

I got my 75mm DX aspheric. 

Measured:
Diameter 77,25mm
Diameter bulb 74mm
Thickness rim 5.5mm
Total thickness 30mm

Backfocal length 44.5mm to top of dome using Cree XRE-R2.

Its not imaging quality; it is a little blurry, but the light is spread out quite even and therefore perfect for aspheric flashlights. 
It is better to use then the Edmunds 75mm, but less clean image compared to Thorlabs 75mm.


And it fits the Ebay 109-led flahslight !
Again luxury got democrized: Just finished my Volkswagen-Theft, direct drive XRE-R2.

14 euro DX lens
14 euro 109-flashlight host
5 euro Cree XRE-R2 Led
4 euro 3 AA Alkalines
37 euro total. Of course it is no Deft, but it is a fun torch.

Hints: 
It helps to get the switch out to solder new wires. 
There is only shallow depth to fit heatsink, make it tight fit the tube.
Soldering a connection to bypass one battery-dock; sand down the chrome plating before soldering.
Best of all; it comes with a carry strap, as it is quite bulky !


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## Walterk (Sep 21, 2010)

Beamshots 'aspheric for the people' .


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## saabluster (Sep 21, 2010)

Yeah I found the DX 75mm to be fairly good. I ordered three of them and although there are some pretty significant defects in the lenses they perform far better than the expensive Thor Labs junk I bought.


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## Walterk (Sep 21, 2010)

I wish I could make my own lenses. Really think you should invent a new (bigger?) lensdesign while working on the led-engine.


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## bitslice (Sep 21, 2010)

I've just bought some 165mm aspheric lenses,
but not quite sure what to use them for yet

I'll also get some of those 99mm ones from DX at some point


a 60mm Kodak aspheric arrived yesterday and I've been fiddling with attaching it to some of my existing lights.

With the bulb side on I can focus the wire coil of the halogen bulb, but using the reflector with the bulb straight on, I get a mess.
Using a plain LED I can focus the die clearly, but again using the reflector I get a mess 

not sure what I'm doing wrong at the moment


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## CKOD (Sep 21, 2010)

bitslice said:


> I've just bought some 165mm aspheric lenses,
> but not quite sure what to use them for yet
> 
> I'll also get some of those 99mm ones from DX at some point
> ...


 
A lens will project the image of the light source, or in the ideal case of a point source, project a collimated beam. An ideal reflector with a point source, will project a collimated beam. 

Make your light source non ideal, so that the reflector collimates some straight on, and the stuff not at the focal point goes forwards but off at an angle. 

So now with your mix of collimated light with spill going at a bunch of different angles, and throw a lens in front of it, Everything that isnt originating from the focal point getting sent into the lens at various angles, makes for "A mess" :thumbsup:

With a smooth reflector youre probably getting a projection of the die with a dark ring around it, and then your spill around the dark ring? Or if its a MOP reflector, the spill is all wavy and varying in brightness? 

Lenses and parabolic reflectors dont generally play nice with each other as far as making pretty beams, hence why ideally we could have a big lens with a short focal distance, to get as much light into the lens as we can. But, you also need a lens with a high NA, so that you can catch light coming in at extreme angles. I wish edmund optics listed the NA of their lens, Thor labs does, but I'd like to see that the difference was to see if that appears to actually be the key difference.


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## bitslice (Sep 21, 2010)

so I have poor reflectors then? :thumbsup:
I wasn't expecting much from one of the maglites 

I'm waiting on a small concave reflector to arrive, I'm hoping using that with a HID bulb (side on) and a large aspheric, I can get something prettier.

Much depends on the quality of each I guess, I gather the HID is a fairly poor point source too


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## Th232 (Sep 21, 2010)

No, your reflector could be the best quality in the world and it still wouldn't work for the reason CKOD gave. The light captured by the reflector goes roughly forward, but then gets refracted by the lens at some weird angle, hence the terrible pattern. With the lens you want all light to be going from the focal point to the lens, not projected straight at it.


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## CKOD (Sep 21, 2010)

bitslice said:


> so I have poor reflectors then? :thumbsup:
> I wasn't expecting much from one of the maglites
> 
> I'm waiting on a *small concave reflector to arrive, I'm hoping using that with a HID bulb (side on)* and a large aspheric, I can get something prettier.
> ...


 
However, here is where you do want a reflector though! But a spherical one, not a parabolic reflector. The spherical reflector sends any light not going forwards right back to the arc where it came from, for it to go out the front, through the focal point. 
And no, a HID is an improvement over a LED with a 2+mm die or a hot spiral of wire. It's no mercury short arc (See: Maxablaster) but its a good start. 





but the reflector should be spherical despite looking parabolic in that picture, and ditch everything after the first lens.


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## bitslice (Sep 22, 2010)

CKOD said:


> However, here is where you do want a reflector though! But a spherical one, not a parabolic reflector. The spherical reflector sends any light not going forwards right back to the arc where it came from, for it to go out the front, through the focal point.
> And no, a HID is an improvement over a LED with a 2+mm die or a hot spiral of wire. It's no mercury short arc (See: Maxablaster) but its a good start.
> 
> 
> ...




Thanks,
Yep, that's the setup I was thinking of 

the spherical reflector that came in the post today isn't half a sphere, more like a 1/3 of a sphere, so I'll have some light loss there I guess

The dual condensing lens was something I wanted to try but I don't really understand why such a system is used in projectors, surely one condensing lens is sufficient?


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## ma_sha1 (Sep 23, 2010)

Can you post a link to the 165mm lens?




bitslice said:


> I've just bought some 165mm aspheric lenses,
> but not quite sure what to use them for yet
> 
> I'll also get some of those 99mm ones from DX at some point


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## MikeAusC (Sep 23, 2010)

If you want a smaller spot, then you need to use a lens with a longer focal length. i.e. one that's not as thick as the aspherics we usually see used for torches.

Tonight I decided to try the 77mm dia 100mm focal length plano-convex lens I have as a cheap 10X Closeup lens, to go infront of your existing camera lens.

Since it's photographic quality, it's no surprise it produces a very sharp small image. 

Since it's further from the LED than short-focal length lenses, it gathers less light - I didn't take measurements, but it didn't seem that much dimmer than the DX.12834 50mm aspheric.

The image size at 10 metres was the same size as from the 140mm dia biconvex lens I took out of a CRT Projector Lens assembly, that I was planning to use for a Bush Search and Rescue Squad searchlight.

Surprisingly the 77mm dia 100mm focal length lens is only $14 from Hong Kong - dealextreme sku.29028


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## moviles (Sep 23, 2010)

Walterk said:


> I got my 75mm DX aspheric.
> 
> Measured:
> Diameter 77,25mm
> ...



Total thickness are 30mm really? or 26mm?????? (dx say 26mm)

I wish 30


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## saabluster (Sep 23, 2010)

moviles said:


> Total thickness are 30mm really? or 26mm?????? (dx say 26mm)
> 
> I wish 30


They are right about 29.5mm.


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## Walterk (Sep 23, 2010)

Measured again:
Diameter 77,25mm
Diameter bulb 74mm
Thickness rim 5.0mm
Total thickness 29,75mm


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## bitslice (Sep 23, 2010)

ma_sha1 said:


> Can you post a link to the 165mm lens?


sorry, I found them on ebay,
I paid an arm and a leg for them too, I was hoping that nobody else would be interested 

I expect these large lenses are just Victorian oddities though

HID kit has arrived, so I hope to set some mirrors up this weekend - I need a big handful of blutack or something


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## moviles (Sep 24, 2010)

saabluster said:


> They are right about 29.5mm.





Walterk said:


> Measured again:
> Diameter 77,25mm
> Diameter bulb 74mm
> Thickness rim 5.0mm
> Total thickness 29,75mm




nice,ty

.....but with 44mm focal lenght maybe we will lose many lumens


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## gt40 (Oct 4, 2010)

I got some video of the dx 75mm lens in my new sst90 build:

http://vimeo.com/15550793

The light is custom build with raptor dc converter, magnetic ring switch, sst90 gn bin and 2 26650 battery space batteries...


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## moviles (Oct 5, 2010)

you recomend this 75mm dx lens? no flood efects?

44mm focal lenght maybe are too much, I dont like lose too many light my favorite 50mm lens have only 19mm focal lenght

the number 9 are my favorite 49.7mm x 22.44mm and 19mm focal lenght ( small focal lenght)






I want 75mm lens with good focal lenght...... but the dx lens have good price...


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## gt40 (Oct 5, 2010)

There is no spill on the dx- really nice tight beam and black as night except for the blinding square. I have to re make my head that holds the aspheric as I have some steps in it that form a bit of a cone shape in the space between the led and the lens and it makes a couple of ring reflections. I painted it black but still a bit. If you just hold the lens in front of the sst, there is no spill at all.


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## moviles (Oct 8, 2010)

Which is the best place to buy the 109 leds host for this 75mm lens?

I found it on ebay at 15$ and on dx at 20$, are exactly the same one?


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## Walterk (Oct 8, 2010)

Confident they are 100% same. Maybe difference in single-mode, two-mode.


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## gt40 (Oct 8, 2010)

moviles said:


> you recomend this 75mm dx lens? no flood efects?
> 
> 44mm focal lenght maybe are too much, I dont like lose too many light my favorite 50mm lens have only 19mm focal lenght
> 
> ...


 

Here is are some beamshots of the 75mm dx lens:




http://www.mccomsey.net/75mm/beamshot1.jpg

farther away:


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## Walterk (Oct 16, 2010)

FYI stumbled upon another resource: topledlight.com

78 x 28mm (for 9USD incl shipping ) and a 100mm lens among others.
They have a shop, and under the same name sell on Ebay.


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## ak_ping70 (Aug 21, 2017)

Hello dear friendsWe are a research students in seoul national university and in our project we need to create about 45cm to 45cm squared concentrated beam with minimum or no highlight around it from a distance of 50 cm to 1 meter or a bit higher. which aspheric lens and LED we have to use? I really appreciate any help. (sorry our major is not about lightening system at all but in our project we need to light up such a shape my major is sport science).﻿


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