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PVS-14 quality, is this normal?
6/3/2012 10:13:02 AM
I recently acquired a PVS-14. I have never looked through a NVD before, so I am not sure if what I am seeing is normal or not. I have looked through all the definitions, FAQs, etc and have not seen this described anywhere, so I thought I'd ask.
The lens on my PVS-14 appears to be cloudy. Within the first 10 seconds of me looking through the device, I thought there was probably a fingerprint smudge on the ocular lens. Both lenses are clean on the outside. After playing with it for a couple of hours over a few days, this is what I have found.
I have a few small black spots in the picture. I understand that this is normal, and it doesn't bother me anyway. Upon looking through the tube with a bright IR light, similar to noticing honeycomb, I notice thousands of tiny random spots all over the screen. Maybe these are what would normally turn into black spots that are always seen, not sure? Now imagine that each of those thousands of spots is a mound of dirt on a wall, and you squirt a few streams of water at each mound of dirt. Diluted, muddy water will run down the wall, originating from the mound of dirt, right? This is what I am seeing. It is very noticeable (with bright light around) as spots and straight line runs, all going in the same direction. Not too big of a deal, as I don't really anticipate using such bright light all the time.
However, in a normal viewing, low-light situation, all those "dirt runs" put together appear to cloud the picture overall. With low light, or even just the built-in IR, I cannot see the individual thousands of spots and runs, but it all adds up to a "smudgy" image.
I'm a pretty picky person, especially when it comes to spending money. I can focus the PVS-14 and get a crisp image. I can see excellent in low light. I can make out individual small objects, etc. I just didn't expect the "smudgy" image. It's one of those things that if I don't think about, I probably won't notice. Once the newness wears off and I just use it, it will probably be well and forgotten.
Thoughts on what I am seeing? Is it normal?
Thanks for your help.
The lens on my PVS-14 appears to be cloudy. Within the first 10 seconds of me looking through the device, I thought there was probably a fingerprint smudge on the ocular lens. Both lenses are clean on the outside. After playing with it for a couple of hours over a few days, this is what I have found.
I have a few small black spots in the picture. I understand that this is normal, and it doesn't bother me anyway. Upon looking through the tube with a bright IR light, similar to noticing honeycomb, I notice thousands of tiny random spots all over the screen. Maybe these are what would normally turn into black spots that are always seen, not sure? Now imagine that each of those thousands of spots is a mound of dirt on a wall, and you squirt a few streams of water at each mound of dirt. Diluted, muddy water will run down the wall, originating from the mound of dirt, right? This is what I am seeing. It is very noticeable (with bright light around) as spots and straight line runs, all going in the same direction. Not too big of a deal, as I don't really anticipate using such bright light all the time.
However, in a normal viewing, low-light situation, all those "dirt runs" put together appear to cloud the picture overall. With low light, or even just the built-in IR, I cannot see the individual thousands of spots and runs, but it all adds up to a "smudgy" image.
I'm a pretty picky person, especially when it comes to spending money. I can focus the PVS-14 and get a crisp image. I can see excellent in low light. I can make out individual small objects, etc. I just didn't expect the "smudgy" image. It's one of those things that if I don't think about, I probably won't notice. Once the newness wears off and I just use it, it will probably be well and forgotten.
Thoughts on what I am seeing? Is it normal?
Thanks for your help.
6/3/2012 11:02:41 AM
I'm a rookie in this forum, but it doesn't sound normal
6/3/2012 11:34:01 AM
Possible Dirty Cathode?
It's a condition where there's thousands of tiny or near microscopic spots on the photocathode, sort of like a fine dust. They degreade the resolution depending on how bad the condition is.
It's a condition where there's thousands of tiny or near microscopic spots on the photocathode, sort of like a fine dust. They degreade the resolution depending on how bad the condition is.
6/3/2012 12:51:58 PM
Does not sound normal based on the NVGs I've seen. Did you buy new? Whose setup?
6/3/2012 3:21:28 PM
Originally Posted By TDunn:
Does not sound normal based on the NVGs I've seen. Did you buy new? Whose setup?
Does not sound normal based on the NVGs I've seen. Did you buy new? Whose setup?
this
6/3/2012 4:13:29 PM
I THINK thats considered "output brightness variation". I have a tube that has larger area that looks like a smudge or brush strokes that are more noticeable depending on lighting. ETA it generally is manufacturing defect in the fiber optics and won't degrade tube life or anything, just spoil the view a little. I would also look up the great video on youtube how to disassemble a pvs14 and check the inside of the lenses and the tubes glass surfaces as well.
Brent
Brent
6/4/2012 9:59:45 AM
Thanks for the replies. It doesn't sound like this is normal, although I don't know if it is a defect, or if something inside just needs to be cleaned. I won't be disassembling the unit any time soon, as it is still under warranty.
6/4/2012 11:35:58 AM
Originally Posted By Eight:
I recently acquired a PVS-14. I have never looked through a NVD before, so I am not sure if what I am seeing is normal or not. I have looked through all the definitions, FAQs, etc and have not seen this described anywhere, so I thought I'd ask.
The lens on my PVS-14 appears to be cloudy. Within the first 10 seconds of me looking through the device, I thought there was probably a fingerprint smudge on the ocular lens. Both lenses are clean on the outside. After playing with it for a couple of hours over a few days, this is what I have found.
I have a few small black spots in the picture. I understand that this is normal, and it doesn't bother me anyway. Upon looking through the tube with a bright IR light, similar to noticing honeycomb, I notice thousands of tiny random spots all over the screen. Maybe these are what would normally turn into black spots that are always seen, not sure? Now imagine that each of those thousands of spots is a mound of dirt on a wall, and you squirt a few streams of water at each mound of dirt. Diluted, muddy water will run down the wall, originating from the mound of dirt, right? This is what I am seeing. It is very noticeable (with bright light around) as spots and straight line runs, all going in the same direction. Not too big of a deal, as I don't really anticipate using such bright light all the time.
However, in a normal viewing, low-light situation, all those "dirt runs" put together appear to cloud the picture overall. With low light, or even just the built-in IR, I cannot see the individual thousands of spots and runs, but it all adds up to a "smudgy" image.
I'm a pretty picky person, especially when it comes to spending money. I can focus the PVS-14 and get a crisp image. I can see excellent in low light. I can make out individual small objects, etc. I just didn't expect the "smudgy" image. It's one of those things that if I don't think about, I probably won't notice. Once the newness wears off and I just use it, it will probably be well and forgotten.
Thoughts on what I am seeing? Is it normal?
Thanks for your help.
I recently acquired a PVS-14. I have never looked through a NVD before, so I am not sure if what I am seeing is normal or not. I have looked through all the definitions, FAQs, etc and have not seen this described anywhere, so I thought I'd ask.
The lens on my PVS-14 appears to be cloudy. Within the first 10 seconds of me looking through the device, I thought there was probably a fingerprint smudge on the ocular lens. Both lenses are clean on the outside. After playing with it for a couple of hours over a few days, this is what I have found.
I have a few small black spots in the picture. I understand that this is normal, and it doesn't bother me anyway. Upon looking through the tube with a bright IR light, similar to noticing honeycomb, I notice thousands of tiny random spots all over the screen. Maybe these are what would normally turn into black spots that are always seen, not sure? Now imagine that each of those thousands of spots is a mound of dirt on a wall, and you squirt a few streams of water at each mound of dirt. Diluted, muddy water will run down the wall, originating from the mound of dirt, right? This is what I am seeing. It is very noticeable (with bright light around) as spots and straight line runs, all going in the same direction. Not too big of a deal, as I don't really anticipate using such bright light all the time.
However, in a normal viewing, low-light situation, all those "dirt runs" put together appear to cloud the picture overall. With low light, or even just the built-in IR, I cannot see the individual thousands of spots and runs, but it all adds up to a "smudgy" image.
I'm a pretty picky person, especially when it comes to spending money. I can focus the PVS-14 and get a crisp image. I can see excellent in low light. I can make out individual small objects, etc. I just didn't expect the "smudgy" image. It's one of those things that if I don't think about, I probably won't notice. Once the newness wears off and I just use it, it will probably be well and forgotten.
Thoughts on what I am seeing? Is it normal?
Thanks for your help.
Hard to diagnose from just a description. When you use a intense IR light you get depletion of the photocathode. This is why you get the dark lines that appear to run down the screen. Bright lights will shorten your tube life over time and you should avoid as much as possible. Brent hit on a good point as well. Haziness you percieve could just be a high EBI level and also moisture inside the scope. Most likely it is just the normal defects tubes have.
I have tubes that do exactly what you are describing. Beautiful thing about NV tubes is no two are alike. They all have individual characteristics. If it really concerns you send it in to have it checked out. You said it is under warranty so get it checked.
6/4/2012 10:15:29 PM
Originally Posted By Dino1130:
Hard to diagnose from just a description. When you use a intense IR light you get depletion of the photocathode. This is why you get the dark lines that appear to run down the screen. Bright lights will shorten your tube life over time and you should avoid as much as possible. Brent hit on a good point as well. Haziness you percieve could just be a high EBI level and also moisture inside the scope. Most likely it is just the normal defects tubes have.
I have tubes that do exactly what you are describing. Beautiful thing about NV tubes is no two are alike. They all have individual characteristics. If it really concerns you send it in to have it checked out. You said it is under warranty so get it checked.
Hard to diagnose from just a description. When you use a intense IR light you get depletion of the photocathode. This is why you get the dark lines that appear to run down the screen. Bright lights will shorten your tube life over time and you should avoid as much as possible. Brent hit on a good point as well. Haziness you percieve could just be a high EBI level and also moisture inside the scope. Most likely it is just the normal defects tubes have.
I have tubes that do exactly what you are describing. Beautiful thing about NV tubes is no two are alike. They all have individual characteristics. If it really concerns you send it in to have it checked out. You said it is under warranty so get it checked.
Hi Dino, can you explain what you mean by the part in red above? Are you saying that in any instance when you use an intense light this happens, or are you saying that over time, the more intense light that the tube is exposed to, that dark lines start to form permanently? Thank you for the warning about the bright lights. I have read about that, and am just doing short experiments at this time. No intentions of continually doing this.
Also, can you explain EBI? I have read about it, but reading standard definitions makes it hard to visualize what effect EBI has on the real-life picture.
6/5/2012 12:02:28 AM
Originally Posted By Eight:
Hi Dino, can you explain what you mean by the part in red above? Are you saying that in any instance when you use an intense light this happens, or are you saying that over time, the more intense light that the tube is exposed to, that dark lines start to form permanently? Thank you for the warning about the bright lights. I have read about that, and am just doing short experiments at this time. No intentions of continually doing this.
Also, can you explain EBI? I have read about it, but reading standard definitions makes it hard to visualize what effect EBI has on the real-life picture.
Originally Posted By Dino1130:
Hard to diagnose from just a description. When you use a intense IR light you get depletion of the photocathode. This is why you get the dark lines that appear to run down the screen. Bright lights will shorten your tube life over time and you should avoid as much as possible. Brent hit on a good point as well. Haziness you percieve could just be a high EBI level and also moisture inside the scope. Most likely it is just the normal defects tubes have.
I have tubes that do exactly what you are describing. Beautiful thing about NV tubes is no two are alike. They all have individual characteristics. If it really concerns you send it in to have it checked out. You said it is under warranty so get it checked.
Hard to diagnose from just a description. When you use a intense IR light you get depletion of the photocathode. This is why you get the dark lines that appear to run down the screen. Bright lights will shorten your tube life over time and you should avoid as much as possible. Brent hit on a good point as well. Haziness you percieve could just be a high EBI level and also moisture inside the scope. Most likely it is just the normal defects tubes have.
I have tubes that do exactly what you are describing. Beautiful thing about NV tubes is no two are alike. They all have individual characteristics. If it really concerns you send it in to have it checked out. You said it is under warranty so get it checked.
Hi Dino, can you explain what you mean by the part in red above? Are you saying that in any instance when you use an intense light this happens, or are you saying that over time, the more intense light that the tube is exposed to, that dark lines start to form permanently? Thank you for the warning about the bright lights. I have read about that, and am just doing short experiments at this time. No intentions of continually doing this.
Also, can you explain EBI? I have read about it, but reading standard definitions makes it hard to visualize what effect EBI has on the real-life picture.
Rather then type a long explanation of EBI I will give you the link to a good video that explains it. The former member who authored the video REALLY hates high EBI. Myself, I am fine with moderate levels of EBI as long as they are below milspec. If you are into astronomy and such super low EBI values are important. For most of us 3 and below is just fine. I like to see it below 2 but make exceptions if other attributes of the tube are attractive.
EBI video
When you point your scope at a bright light many tubes will exhibit temporary dark lines through the image.Some tubes are worse than others. I believe the power supply has some effect on this. This is because those areas of the photocathode were overexposed and became temporarily depleted. I am giving you the layman's explanation. If you point at a bright light for an extended time you can permanently deplete an area of the photocathode. We call this a burn in the tube. I don't really deal in the deep science of night vision tubes. It gets really complicated and CJ7Hawk is much better at explaining the science involved than I.
It involves photons and electrons and a whole bunch of stuff that makes my head hurt. I know what to do and what not to do and am satisfied with that. If my memory serves me, white lines through the screen are a depletion in the phosphor screen. Maybe CJ7Hawk can chime in and explain the science more. I have heard it many times over but consider myself more of a mechanic than an engineer. I leave all that physics and science stuff to the really smart guys.
ETA: If you really and truly want to learn how a photocathode works CJ7 did a small article awhile back. I am sure he won't mind if you read it. I will warn you it is science heavy !
Photocathodes and how they work
6/5/2012 7:39:10 AM
Are you able to take a picture?
What you describe might also be damage caused by flare/laser.
Regards
David.
David.
