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EBI vs SNR and thoughts on some specs

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29 replies to this topic

#26 sixela

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Posted 29 January 2024 - 02:18 PM

Yes, that makes sense. Scoptopic vision is more blurry and als integrates over a longer timespan, so it figures it's less sensitive to small scale and rapid noise. Of course filtering like that is at the cost of small detail in the regions where photopic vision already gets to participate to make vision less blurry, so it's certainly not a panacea.



#27 a__l

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Posted 30 January 2024 - 06:50 PM

I wasn’t under the impression you could order me around to do tests for you.

Of course in due course there will be observing reports; I tend to always observe objects both with glass and NVD (at least galaxies, and it’s Galaxy Season!)

“Specifics in dark sky” are rather harder to get close to Full Moon ;-).

Lengthy arguments add little to understanding. Observational examples with detailed descriptions are more accessible to most and can be repeated other observers. This is standard practice.

There is no need to translate this into the concept of "you could order".


Edited by a__l, 30 January 2024 - 07:35 PM.


#28 chemisted

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Posted 15 April 2024 - 05:02 PM

Why these two companies don't both specify radiant sensitivity at 830 or 880 nm is also anyone's guess.

The most recent L3 data sheets now have photocathode sensitivity at both wavelengths. This is great news since it enables prospective buyers to use 830 values along with all the other specs in their tube comparisons. This is the standard unfilmed tube sheet. Unfortunately, these values are not being given for the high gain model.


Edited by chemisted, 16 April 2024 - 03:33 PM.


#29 Thierry Legault

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Posted 16 April 2024 - 06:27 PM

It's a pity that NVD manufacturers don't provide the full curve. 200$ astronomical CMOS cameras manufacturers do it!



#30 chemisted

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Posted 16 April 2024 - 06:57 PM

It's a pity that NVD manufacturers don't provide the full curve. 200$ astronomical CMOS cameras manufacturers do it!

This raises an interesting question. Do they provide the actual curve for each individual camera or is it just a representative curve? When I purchased my Collins intensifier in 2002, Bill Collins had a full curve that he provided but it was not of my tube; it was just a representative curve for the ITT (currently Elbit) tubes he used. I suspect the shape of the curve stays pretty much constant but amplitudes vary widely from tube to tube.  You are right in saying the limited information provided with these devices is completely out of line with their expense.


Edited by chemisted, 16 April 2024 - 07:05 PM.



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