""WANTED t20 ir 940nm pill""

[blueeyes]

It does reduce it by about a quarter might even be slightly more, and as for throw should be fine for air gun range do what I done just bought a pill and dropped it into the T20.

[pauls]

Just put a ir 940nm pill in my t20 (got same from marky) used on my airrifle with the SB no scope rig,using it for ratting at a mates who rears pheasants all the sheds are empty now as the pheasants have gone to be shot.Sheds are about 20yd long can easily make out rats at 20yd with light on lowest setting.

[some bloke]

I've long maintained that high power LEDs are sometimes OTT for subsonic applications if you have the right rig.

Bruce - Do you and your very special kit have the means to compare light emissions from a high power 850nm OB on low and medium power settings to a 940 one on high?

I got the feeling a low power setting 850nm might do a similar job to a 940 on high whilst trying the 'stinger test' in my IR or no IR video here:

https://www.youtube.com/watch?v=t6nPsp8 ... -OWKFJadkw

[phoenix]

Dave,
I don't think measuring the intensity produced by an 850 at various power settings and comparing it to a 940 at various power settings would tell us very much.
I
My instrument is calibrated to give accurate numbers at both those wavelengths and I fancy both LEDs would be producing about the same amount of optical power (microwatts per square centimetre).
The difference is in the sensitivity of the camera.
Here's an old graph showing the spectral response of a Watec 902H (the E700 and EJ230 will be very simialr)

Notice that at 850nm the camera has about 35% of it's peak sensitivity, but at 940nm it only has about 12% of it's peak sensitivty.
From those numbers I'd say your not far wrong in suggesting that an 850 on low power would produce a similar image to a 940 on high power

Cheers

Bruce