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Re: (meteorobs) Re: All-sky and Intensifier Systems
>
> Hello Felix:
> Thank you very much for your email. Where did you get your 1st
> generation 3 stage intensifier and how much do they cost? What is the
> diameter of the cathode? Also, could astrometry be done with out
> objectionable distortion? We are thinking of using surplus 2nd generation
> intensifiers which I understand have less gain than the 1st generation
> devices. They have other advantages however. I'm thinking of using a
> Russian fisheye lens and am checking on the availability of these. Final
> cost is a big factor.
> Thank you again for your email.
>
> Best regards: Ed Majden
Hi Ed,
The intensifier I have in use comes from DEP (Delft Electronic
Products) in Roden, the Netherlands (http://wwwdot depdot nl). It has a cathode
diameter of 25mm, the luminosity gain is around 40,000x. New they cost
unfortunately around $5000. You have to look around to find used
ones or surplus to save a lot of money.
These type of intensifiers have a lot of distorsion on the edge of the
field of view, however that is not a real problem doing
astrometry. Nevertheless the sharpness is less on the edge as well, and
that will reduce your accuracy for sure.
I did not yet measure an image taken with the decribed intensifier and
fisheye lens, so I cannot tell about my exeperience.
At the moment I'm investigating some tapes taken with this intensifier,
but with another lens (50mm focallength). Probably I can tell you more
about the influence of the distorsion produced by the intensifier in a
while.
For your information:
The limiting magnitude on La Palma during the test run with the fisheye
was +6.5 to +6.9.
I used the intensifier during Leonid maximum (1999) on La Palma with a
28mm/F2.8: field of view around 50deg, limiting magnitude around +7
Nowadays I use it the Netherlands, in the city center of a 300,000
inhabitants town, with 50mm/F8 (F8 because of light pollution), field of
view 30deg, limiting magnitude around +5.5-6.0.
You are right. GenII intensifiers don't have distorsion, however do have
a much lower gain.
Cheers,
Felix Bettonvil
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