Intro to aspheric lenses (to help you choose the best one)

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rodp
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Re: Intro to aspheric lenses (to help you choose the best on

Post by rodp » 22 Jan 2013, 21:17

sunndog wrote:
rodp wrote:
What's needed is a shorter bfl to capture more of the radiance from the led.
bang on rod....you try finding some though!

A horton will make you any size you want. but £££££££!

That's the problem with theory ain't it, it doesn't allow for the real world :lol:

I've got a couple of angle grinders, a polishing mop and an old bullseye pane of glass if anyone wants to knock a few up :roll:
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Marky610
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Re: Intro to aspheric lenses (to help you choose the best on

Post by Marky610 » 23 Jan 2013, 01:58

Humpers wrote:
Marky610 wrote:So in theory the A Horton lens should be brighter and throw further than the 66mm?

I have one, shall i knock one up and test the theory? I could do it tomorrow and test it tomorrow night ;)
Although the % capture figures suggest the ahorton could be better than the 66mm, as I said in my post with the 2nd version of the table I suspect that the longer focal length of the 66mm and hence the LED appearing as a smaller point source of light will give the 66mm the advantage at range (smaller beam into lens means smaller, more intense beamout of lens).

I've tried it with the ahorton and 50mm and there's not that much between them, probably due to the same reason, although I do need to confirm this by looking more closely at the images produced. But if you can directly compare an ahorton with a 66mm that would be great as it would confirm (or disprove) my theory.

I'm dying to try it out with a really big lens with long focal length now just to see what effect that has!

Cheers,

Humpers
Well I made it and took it out to try but it's far too bright tonight to make it a worth while test, it's going to have to wait untill the snows gone and a cloud covered sky. I could have shot rats without my nv tonight it was soo bright.

Heres a piccy anyway :mrgreen:
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Re: Intro to aspheric lenses (to help you choose the best on

Post by sunndog » 23 Jan 2013, 18:13

i bet that A horton lens will be very bright but not focus a tightly as an ant supplies 50mm
reckon it work very well on a watec spotter though
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when asking for advice, please include what n.v device and/or illumination you already have (if any) and what rifles you intend to use them on...cheers

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Re: Intro to aspheric lenses (to help you choose the best on

Post by Marky610 » 23 Jan 2013, 21:27

sunndog wrote:i bet that A horton lens will be very bright but not focus a tightly as an ant supplies 50mm
reckon it work very well on a watec spotter though
Your spot on :thumbup:

It looks good in my garage but need to get out in the dark with no bloody snow, it looks like MarkySpotter might get a modification :mrgreen:
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Re: Intro to aspheric lenses (to help you choose the best on

Post by Hartshot » 24 Jan 2013, 11:10

Out of curiosity has anybody ever tried these puppies
http://dx.com/p/35mm-16mm-8-10-degrees- ... pack-12437
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Re: Intro to aspheric lenses (to help you choose the best on

Post by Marky610 » 24 Jan 2013, 14:10

With a divergence angle of 8-10 degree's I would bover wasting my money, the lenses from any supplies are a 2 degree divergence, if someone found a 1 degree lens let me know :thumbup:
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Re: Intro to aspheric lenses (to help you choose the best on

Post by snoopy » 24 Jan 2013, 15:23

Hartshot wrote:Out of curiosity has anybody ever tried these puppies
http://dx.com/p/35mm-16mm-8-10-degrees- ... pack-12437
i think thems for the little head torch's you get for 5'vers tbh...theyre 'ok' for cree's to 20 yard or more. but... a Q5 is a load better.
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Re: Intro to aspheric lenses (to help you choose the best on

Post by Humpers » 24 Jan 2013, 17:40

Marky610 wrote:
sunndog wrote:i bet that A horton lens will be very bright but not focus a tightly as an ant supplies 50mm
reckon it work very well on a watec spotter though
Your spot on :thumbup:

It looks good in my garage but need to get out in the dark with no bloody snow, it looks like MarkySpotter might get a modification :mrgreen:
You might want to hold on Marky with modifying the MarkySpotter as I'm working on some improved figures, partly thanks to a great suggestion from Phoenix (Bruce). I'm also trying to incorporate into the results the point source effect which gives long focal length lenses the advantage over short BFL ones, and small LED dies over large ones. So I'm looking at solid angles and steradians (oooo errrr missus).

I've got some initial figures which back up my experience in the field which suggest, for example, a 50mm lens is better than an ahorton one. But I'm not sure enough about the figures yet to publish them on the thread. But I'm still interested to know how you find the ahorton performs compared to a 50mm and 66mm, just don't want you returning to the lathe on a wild goose chase!

Part of the trouble I find in the field is that the visual difference between LED/lens combinations can be so subjective. One day (night) I think one lens is better than another, and then the next night I'm not so sure. Ho hum.

Humpers

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snoopy
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Re: Intro to aspheric lenses (to help you choose the best on

Post by snoopy » 24 Jan 2013, 18:35

find a multistory carpark, bigger the better and go down stairs where theres no light...
'who is that masked man? its the kemosabby der..the bloody injun tells you every week!'

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Re: Intro to aspheric lenses (to help you choose the best on

Post by Marky610 » 24 Jan 2013, 20:06

Humpers wrote:
Marky610 wrote:
sunndog wrote:i bet that A horton lens will be very bright but not focus a tightly as an ant supplies 50mm
reckon it work very well on a watec spotter though
Your spot on :thumbup:

It looks good in my garage but need to get out in the dark with no bloody snow, it looks like MarkySpotter might get a modification :mrgreen:
You might want to hold on Marky with modifying the MarkySpotter as I'm working on some improved figures, partly thanks to a great suggestion from Phoenix (Bruce). I'm also trying to incorporate into the results the point source effect which gives long focal length lenses the advantage over short BFL ones, and small LED dies over large ones. So I'm looking at solid angles and steradians (oooo errrr missus).

I've got some initial figures which back up my experience in the field which suggest, for example, a 50mm lens is better than an ahorton one. But I'm not sure enough about the figures yet to publish them on the thread. But I'm still interested to know how you find the ahorton performs compared to a 50mm and 66mm, just don't want you returning to the lathe on a wild goose chase!

Part of the trouble I find in the field is that the visual difference between LED/lens combinations can be so subjective. One day (night) I think one lens is better than another, and then the next night I'm not so sure. Ho hum.

Humpers
Bud there's 20 minutes work in that prototype ;)

If it works well enough for my spotter, remember I use an unfocused lamp on it already, then the weight and bulk saving will be superb. One of my original idea's for a spotter was a twin 28mm asperic lamp system, I'm starting to sway back to that design as it is anyway.
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