53 replies to this topic

[turtle86]

Another point I'd like to make about the L3/Harris white phos unfilmed tubes we use are US ITAR protected Mil Spec tubes that are not allowed, nor can be sold to outside CONUS.  I wish we could sell these specific tubes to European customers, but we cannot.  Yes it is true these tubes are the exact tubes our US Special Operations use and are truly the best intensifier tubes in the world. 

 

These L3/Hrarris tubes we now supply TeleVue have the following Min Specs (remember these are minimum) and we always try to maintain for astronomy purposes. (Sometimes the customers rather get a tiny point higher than waiting longer for something to arrive), but we do our absolute best to support the following.

 

S/N: 33

L/P: 72

*FOM 2376* (See below)

EBI: Under 1.0, (But we always try to get to .7 or below, but at times L3 wait times for this data point can cause a wait)

HALO .8 or below

 

You also hear about "Figure of Merit" (FOM). The FOM value is calculated using the following: S/N x lp/mm (S/N = signal to noise ratio). In the TeleVue tubes, the min FOM is 2376 (which was unheard of just a few short years ago.  L3 has REALLY cracked the code on their UF tube technology.  I have handled some tubes in the 4000 FOM range that are used in some SOCOM arenas.   These tubes are NOT available so please refrain from the messages. LoL  I remember not that long ago folks were waiting a LONG time for 2376 FOM tubes, now they're routine.

 

In closing folks, can ask TeleVue for higher specs (which IMHO doesn't equate to deep sky advantages in the case of a few points higher S/N), but can increase wait times.  I have been using NV in telescopes for over 30 years now, long before this exciting technology became mainstream. Yes, you heard that right. My fist time using NV in a telescope was in 1994 with a C8 while using my first PVS-14 with a Gen 2+! 

 

I wish I would have began promoting NV in telescopes at that time!  I lived in Chicago and you can imagine the light pollution problems that even a Gen 2+ assisted with. Flash forward 5 years ago or so when Al and I started talking about it.

 

Edit:  These min specs may change at any time (at a higher level) as the routine higher spec technology keeps getting better and better out the L3/Harris doors.

 

Just want to add that the TNVC NV device that I ordered from Televue a couple of months ago comfortably exceeds most of these specs. I couldn't be happier with mine and look forward to taking it to my dark site in a couple of weeks.

[Clutch5150]

Great way to be proactive Vic! Those are solid specs. It won’t stop spec chasers, but those specs put anyone solidly in the NV game.

My only soft suggestion in order to avoid potentially disappointed astronomy customers would be to specifically call out max spot specs. I know your tubes tend to be cleaner than most, but people may appreciate slightly more information in that regard

Point well taken! We'll do that!

[Clutch5150]

Just want to add that the TNVC NV device that I ordered from Televue a couple of months ago comfortably exceeds most of these specs. I couldn't be happier with mine and look forward to taking it to my dark site in a couple of weeks.

Thanks Rob!  Indeed most of the specs do exceed at times, but what I posted are the minimums we always try to achieve. 

[Clutch5150]

Thanks again Rob for the cosmetic reminder.

 

TeleVue Astronomy Specs

Tube

S/N: 33
L/P: 72
EBI: Under 1.0
HALO .8 or below

 

Cosmetics

Z1 Clean
Z2 Clean, some very tiny peppering may be acceptable .002 or smaller
Z3 1 blem no larger than .004,  tiny peppering is acceptable.

[Mauro Da Lio]

Certainly numerical specifications are better than adjectives (I might claim to have a tube with galactic-level performance and another user might reply with supercluster-level :-) but those adjectives do not actually say anything).

 

So, back to performance quantification, there are however caveats.

 

For example, in my experience, resolution and SNR are not fully interchangeable. You can have 64 lpm and SNR 33.75 or 72 lpm SNR 30. Both have FOM 2160 but the latter is better for visual astronomy because it is hard to note the increase of resolution in mesopic conditions, but the better noise is immediately noticeable. I do not know who thought to multiply resolution and SNR to obtain the FOM index, but perhaps that is valid in photopic conditions but not in the mesopic conditions that holds for astronomy (after all those device were optimized for things other than astronomy).

 

Similarly, for astronomical use under dark sky there is a missing spec: the sensitivity across the whole spectrum. The IR is plagued by airglow, and so, two devices with say the same "numbers" may perform differently under a dark sky when forced to use an IR-cut filter to remove the airglow. They may also perform differently in single spectral lines (e.g., H-alpha) and the one which is better with IR-cut might not be the better in one line. Again, those device were optimized for things other than astronomy and it is not surprising that numerical specs do not say the whole story.

 

I definitely believe that US made intensifiers are the best ones. Unfortunately, in the EU we cannot buy them. So we must be happy with what we can buy (which is still quite good). This is fortunately possible.

Edited by Mauro Da Lio, 25 April 2024 - 12:37 PM.

[PEterW]

What wavelength of ir cut wavelength do you suggest, I use a 685nm long pass filter to enable me to see anything from the city. Wonder whether I’ve ever had the view affected by them.

Peter

[DeepSkyFocus]

Vic and Carina at TNVC have been very kind, helpful and responsive to the matter.

I've been sent me 2 tube specs that I can choose from.


Hoping the experienced NV folks here can guide me to which is best for astronomy(mostly visual) or should I wait for the next batch.

Tube 1
FOM - 2613
EBI - 0.9
SNR - 36.3
Resolution - 72
Halo - 0.6
Photocathode Sensitivity - 2237

Tube 2
FOM - 2469
EBI - 0.7
SNR - 34.3
Resolution - 72
Halo - 0.7
Photocathode Sensitivity - 2280

Edited by DeepSkyFocus, 25 April 2024 - 09:11 PM.

[chemisted]

The Halo and SNR on #1 are really quite excellent; I would go for that one. The EBI values are close to each other and, unless you live in a very hot climate, should probably not drive a decision to the other tube. I usually ask for photocathode sensitivity and you might request that from them to help with the decision.

Edited by chemisted, 25 April 2024 - 06:24 PM.

[Mazerski]

I agree with the chemist in choosing #1. 

[DeepSkyFocus]

I've update the specs with the Photocathode Sensitivity numbers.

I live in Central Florida where it can get quite warm.

Edited by DeepSkyFocus, 25 April 2024 - 09:14 PM.

[chemisted]

The PS numbers are just OK. I usually recommend 2400 but those are close.

Your climate may be the curve ball. Do your summer nights stay in the 80s? If so, and you would like to pick one of these tubes, you could go for #2. Halo and SNR are good on it, the PS and EBI are marginally better and I am assuming there are no objectionable spots or blemishes on either tube.

EBI changes by a factor of two for every 9 degree F change in ambient temperature. I live in NC and have 3 intensifiers. My best one has EBI=0.98. I do live in the mountains, though, and my nighttime viewing is never warmer than the 70s.

Good luck with your deliberation.

Edited by chemisted, 26 April 2024 - 03:40 AM.

[sixela]

Depends on the objects you want to see best too: if using broadband filters EBI is less important (at least unless it’s higher than 1.0) than when using really narrow band filters at a dark site.

For galaxies and anything that includes stellar objects I’d pick the first tube over the second.

There’s even merit in saying that nebulae are already so much better with NVD that for “general use” I’d pick the first tube as well. Galaxies are a much harder but to crack, and SNR is really important there.

If you’re mainly interested in the really faint wisps of emission nebulae at a dark site using a 3 nm filter the EBI becomes a more significant worry.

Edited by sixela, 26 April 2024 - 05:26 AM.

[DeepSkyFocus]

The PS numbers are just OK. I usually recommend 2400 but those are close.

Your climate may be the curve ball. Do your summer nights stay in the 80s? If so, and you would like to pick one of these tubes, you could go for #2. Halo and SNR are good on it, the PS and EBI are marginally better and I am assuming there are no objectionable spots or blemishes on either tube.

EBI changes by a factor of two for every 9 degree F change in ambient temperature. I live in NC and have 3 intensifiers. My best one has EBI=0.98. I do live in the mountains, though, and my nighttime viewing is never warmer than the 70s.

Good luck with your deliberation.

It does easily stay well in the 80's with high humidity during summer nights.

 

I may just wait it out until I get something closer to Tube # 2 specs with higher Photocathode Sensitivity and SNR.

 

I'm in no rush and can wait for a well rounded tube.

 

This community is incredible 

[chemisted]

It does easily stay well in the 80's with high humidity during summer nights.

 

I may just wait it out until I get something closer to Tube # 2 specs with higher Photocathode Sensitivity and SNR.

 

I'm in no rush and can wait for a well rounded tube.

 

This community is incredible 

Those increases would be fine but an EBI that is lower than 0.7 would be highly desirable too since you have the time to wait. With a temp of 80F that 0.7 becomes 1.4 and at 89F it doubles again to 2.8.

Edited by chemisted, 26 April 2024 - 09:48 AM.

[Joko]

Those increases would be fine but an EBI that is lower than 0.7 would be highly desirable too since you have the time to wait. With a temp of 80F that 0.7 becomes 1.4 and at 89F it doubles again to 2.8.

I completely agree with you.

As an NV vendor, we don't supply tubes with an EBI higher than 0.5 for astronomy.

Edited by Joko, 26 April 2024 - 10:04 AM.

[Clutch5150]

Vic and Carina at TNVC have been very kind, helpful and responsive to the matter.

I've been sent me 2 tube specs that I can choose from.


Hoping the experienced NV folks here can guide me to which is best for astronomy(mostly visual) or should I wait for the next batch.

Tube 1
FOM - 2613
EBI - 0.9
SNR - 36.3
Resolution - 72
Halo - 0.6
Photocathode Sensitivity - 2237

Tube 2
FOM - 2469
EBI - 0.7
SNR - 34.3
Resolution - 72
Halo - 0.7
Photocathode Sensitivity - 2280

Tube #2 based on your location would be my choice. 

 

Had several messages on the tubes we use.  Yes these are factory US L3/Harris Mil-Spec Unfilmed Gen 3 white phosphor, the very best tubes currently in production IMHO. Yes, L3 is the only company producing unfilmed tubes.  US Special Operations are the main customers of these tubes, and a whole bunch of astronomers.   It's funny at times at our training classes around the country when we talk about looking up and the vast amount of amateur astronomers out there who use these tubes with telescopes.  The looks we get (like really?) is pretty comical. Some just never think outside the shooting world. 

[Mauro Da Lio]

What wavelength of ir cut wavelength do you suggest, I use a 685nm long pass filter to enable me to see anything from the city. Wonder whether I’ve ever had the view affected by them.

Peter

Under light pollution (SQM<19-20) the sky is brighter in the visual band due to artificial light. Hence IR-pass is a good choice.

However, under a dark sky (SQM>20-21) the sky is brighter in the IR due to airglow (the airglow is always the same ~20: it is the V band that becomes darker at 20-21+) . In this case it is better to get rid of wavelengths above 700-710 nm (e.g. Astronomik L1). https://www.cloudyni.../#entry13035142

Edited by Mauro Da Lio, 26 April 2024 - 10:44 AM.

[WheezyGod]

I also recommend waiting for a tube with a lower EBI. My tube’s EBI is 0.7, but nights rarely get above 70 degrees where I am in Mass so to chemisted’s point it doesn’t have as much of an impact as it will for you in Florida.

If you can get something with an EBI of 0.4 or below with a SNR of 34 or better then that’s a great device for your location.

On the positive side, you have access to some awesome objects for NV that most of us don’t have depending on where you are in Florida. I can only see the cat’s paw nebula for example for maybe a month at certain times at night when it’s positioned between two tree lines from my backyard. If it was higher in the sky I would see it much better. Centaurus A is another that I can’t see at all that you’d be able to. NGC6188 is another.

[vicuna]

just my opinion as an observer and a recent purchaser of a PVS-14 (not from TNVC). only posting because this thread will die down eventually but it'll come up in a search in the future.

 

TNVC seems like a perfect partner for TeleVue. they need a high volume vendor with great customer service that knows what they are doing and will be around for years to come.

 

TNVC was one of the vendors I talked to and they were super helpful. I wound up buying a bunch of accessories from them. their storage pouch is awesome.

 

I wound up buying my PVS-14 from a small shop who happened to be a 30 minute drive from me and I was able to handpick the specs (nobody on here would refuse these...super solid), and he had it in stock.

 

they aren't active here but active on gun forums...they are super helpful, make great videos that aren't just pure infomercials. 

 

did you know if you buy from them, they will clean your tube for you every year?

 

I am going to chalk this up to a mistake. sounds like both Televue and TNVC saw these specs and it slipped through. hopefully they weren't just trying to pass it off to someone who might not know better...and hopefully they can get to the bottom of how that happened...or add one more check on their checklist? 

 

but all's well that ends well. sounds like TNVC will take care of OP.

[turtle86]

I also recommend waiting for a tube with a lower EBI. My tube’s EBI is 0.7, but nights rarely get above 70 degrees where I am in Mass so to chemisted’s point it doesn’t have as much of an impact as it will for you in Florida.

If you can get something with an EBI of 0.4 or below with a SNR of 34 or better then that’s a great device for your location.

On the positive side, you have access to some awesome objects for NV that most of us don’t have depending on where you are in Florida. I can only see the cat’s paw nebula for example for maybe a month at certain times at night when it’s positioned between two tree lines from my backyard. If it was higher in the sky I would see it much better. Centaurus A is another that I can’t see at all that you’d be able to. NGC6188 is another.

 

I'm in central Florida myself so I was very happy that the tube I got from them has an EBI of 0.3 and an SNR of 34.7.

[WheezyGod]

I'm in central Florida myself so I was very happy that the tube I got from them has an EBI of 0.3 and an SNR of 34.7.

Yup that’s a great example of an ideal tube for that area!

[WheezyGod]

just my opinion as an observer and a recent purchaser of a PVS-14 (not from TNVC). only posting because this thread will die down eventually but it'll come up in a search in the future.

TNVC seems like a perfect partner for TeleVue. they need a high volume vendor with great customer service that knows what they are doing and will be around for years to come.

TNVC was one of the vendors I talked to and they were super helpful. I wound up buying a bunch of accessories from them. their storage pouch is awesome.

I wound up buying my PVS-14 from a small shop who happened to be a 30 minute drive from me and I was able to handpick the specs (nobody on here would refuse these...super solid), and he had it in stock.

they aren't active here but active on gun forums...they are super helpful, make great videos that aren't just pure infomercials.

did you know if you buy from them, they will clean your tube for you every year?

I am going to chalk this up to a mistake. sounds like both Televue and TNVC saw these specs and it slipped through. hopefully they weren't just trying to pass it off to someone who might not know better...and hopefully they can get to the bottom of how that happened...or add one more check on their checklist?

but all's well that ends well. sounds like TNVC will take care of OP.

I wish I had a vendor close by that I could just drive to and talk to in person. I could drop off and pick up my device for the free cleanings they offer as well and any maintenance.

[vicuna]

I wish I had a vendor close by that I could just drive to and talk to in person. I could drop off and pick up my device for the free cleanings they offer as well and any maintenance.

yeah I got super lucky there...that was a top reason I went with them...especially being a newbie to night vision.

 

I had one of the plastic lock rings snap that stop the focus at infinity...and just drove it over there - he popped another one on and purged it while i went for a walk and had a coffee. no charge for anything. he said those rings cost 50 cents or something. I would have probably not mailed it for that...or been nervous for a week while it was gone.

[sixela]

Why? The device works fine without the infinity stop ring.

Edited by sixela, 28 April 2024 - 10:27 AM.

[vicuna]

Why? The device works fine without the infinity stop ring.

i use my PVS-14s for other stuff too where I have focus closer...so I like having it and it was easy enough to drive and get it sorted out.

 

you're right though I wouldn't have gone to a lot of trouble

 

sry didn't mean to derail.