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Posted: 2/21/2024 9:46:48 AM EDT
I think I have somewhat of an idea what different NV specs mean in real use, but just wanted to get some clarification from the hive to see if I have misunderstood what various specs mean. If I am off in my understanding please enlighten me.

Halo: This is the size of the circular bloom around bright pinpoints of light. The smaller the number, the smaller the halo. This appears to me to be some kind of direct measurement because the NV units I have seen with half the halo had half the blooming circle size for a given light source and 2/3 the halo spec looked to be about 2/3 the circle size... does this hold true at much different figures on the extreme? If you compare a 2.0 to 0.5 halo is the circle 1/4 the size? Would a 0.9 halo be 3x bigger than a 0.3? Would a 0.1 be 9x smaller than 0.9?

Resolution lp/mm: This is the smallest line pairs per mm separation you can detect on a chart. Higher is better. While the human eye can't see better than about 64 lp/mm unaided by magnification for 20/20 vision, I know resolution goes down in brighter or dimmer than ideal lighting conditions for NV. Would this translate to higher resolution specs staying above 64 lp/mm for longer in brighter or dimmer than ideal conditions, all else being equal? If true, this would mean higher resolution tubes would ONLY have advantages over 64lp tubes in goggles at slightly brighter or dimmer than ideal conditions but some level of "better" would exist for ALL non perfect lighting conditions, all else being equal.

EBI: My understanding of this has always been something akin to black levels of a TV or computer monitor. In my mind it notes the lowest level of screen brightness before your "black" merges in with the background illumination glow. High EBI would be like an LED screen with shitty black levels that are always some form of glowing gray. Super low EBI would be like an OLED, where the black levels are so low you can barely see that a black screen is on comparing the black screen to a black bezel. This would improve contrast in very dark scenes. Would this mean less in a supergain tube where the background is always bumped up with everything else or would lowcEBI be even more important to not have the background become a washed out glow of gray on a supergain tube?

S/N: This signal to noise spec determines how bright of an image you get at a certain scene and gain level. It determines how much you can bump up the gain before snow starts setting in and ruining your ability to see a dark scene. Higher SNR with adjustable gain means you can crank up gain and see in the dark without "snow" and see in lower light levels. For fixed gain units it determines what scene illumination brightness causes snow to start and eventually to overcome your ability to see. Higher SNR delays the resolution drop as light levels decrease and ultimately determines what illumination floor your NV device has before supplemental illumination is required. Is that accurate?

I am not sure what other specs mean such as photocathode sensitivity or how it relates to real world use.
VP
Link Posted: 2/21/2024 3:24:53 PM EDT
[Last Edit: Hodgi_] [#1]
IIRC TNVC has a glossary on their site somewhere with all sorts of definitions of nv related words.

it's worth reading imo

ETA: It's under their general FAQ's HERE
Link Posted: 2/21/2024 6:39:35 PM EDT
[#2]
Originally Posted By DevL:
I think I have somewhat of an idea what different NV specs mean in real use, but just wanted to get some clarification from the hive to see if I have misunderstood what various specs mean. If I am off in my understanding please enlighten me.

Halo: This is the size of the circular bloom around bright pinpoints of light. The smaller the number, the smaller the halo. This appears to me to be some kind of direct measurement because the NV units I have seen with half the halo had half the blooming circle size for a given light source and 2/3 the halo spec looked to be about 2/3 the circle size... does this hold true at much different figures on the extreme? If you compare a 2.0 to 0.5 halo is the circle 1/4 the size? Would a 0.9 halo be 3x bigger than a 0.3? Would a 0.1 be 9x smaller than 0.9?

Resolution lp/mm: This is the smallest line pairs per mm separation you can detect on a chart. Higher is better. While the human eye can't see better than about 64 lp/mm unaided by magnification for 20/20 vision, I know resolution goes down in brighter or dimmer than ideal lighting conditions for NV. Would this translate to higher resolution specs staying above 64 lp/mm for longer in brighter or dimmer than ideal conditions, all else being equal? If true, this would mean higher resolution tubes would ONLY have advantages over 64lp tubes in goggles at slightly brighter or dimmer than ideal conditions but some level of "better" would exist for ALL non perfect lighting conditions, all else being equal.

EBI: My understanding of this has always been something akin to black levels of a TV or computer monitor. In my mind it notes the lowest level of screen brightness before your "black" merges in with the background illumination glow. High EBI would be like an LED screen with shitty black levels that are always some form of glowing gray. Super low EBI would be like an OLED, where the black levels are so low you can barely see that a black screen is on comparing the black screen to a black bezel. This would improve contrast in very dark scenes. Would this mean less in a supergain tube where the background is always bumped up with everything else or would lowcEBI be even more important to not have the background become a washed out glow of gray on a supergain tube?

S/N: This signal to noise spec determines how bright of an image you get at a certain scene and gain level. It determines how much you can bump up the gain before snow starts setting in and ruining your ability to see a dark scene. Higher SNR with adjustable gain means you can crank up gain and see in the dark without "snow" and see in lower light levels. For fixed gain units it determines what scene illumination brightness causes snow to start and eventually to overcome your ability to see. Higher SNR delays the resolution drop as light levels decrease and ultimately determines what illumination floor your NV device has before supplemental illumination is required. Is that accurate?

I am not sure what other specs mean such as photocathode sensitivity or how it relates to real world use.
View Quote


In terms of Halo, I’ve found that L3 Filmless is superior than thin filmed.

Here’s a comparison of two devices with the same .7 halo, but with wildly different results

Attachment Attached File


Attachment Attached File


It will make a big difference when using your laser, or in urban environments with a lot of street lights
Link Posted: 2/25/2024 4:36:26 PM EDT
[#3]
I am no expert but this is how I see it and a simple way to explain them.
HALO, bloom around a light source, smaller # the better.
EBI is similar to contrast, lower # better contrast
Snr is similar to resolution in regards to how little its pixelated, the sparkles you see in a image, higher # better
Resolution is just that but of the tube, so add a good SNR picture, tiny pixels, the better FOM.
Photocathode sensitivity is its ability to gather the photons, higher the better
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