Hi All,



An interesting comparison here - there's something i'm not saying about the image, and I won't say which is which initially, but here's a half/half image - with a 4G and 3G image side by side.






Pictures were taken within a minute of each other, and both are excellent tubes ( Actually, both are exceptional tubes ) -






Both tubes are mx11769 format - that is, both are PVS-14 tubes. One is made by L3. The other by PHOTONIS.






The 3G tube could easily pass any current OMNI MILSPEC. The 4G tube, however, is a borderline tube - that is, it only just meets 4G Milspec. It's not a supertube by any standards.






Light is NL5 ( Night Level 5 ) - Overcast Starlight. Full moon is present, but is either down below the horizon, or has just started to come up. Conditions were heavy cloud and stormy for about 200km in any direction, so it was pretty dark. Both tubes show conditions under very dark circumstances. One pic has a slight technical advantage I just realized when I put this together, but both are pretty close.  






There's a slight vignetting in the image also - and the vignetting of each tube is out by about 180 degrees.












Anyone want to take a guess at which tube is which ? ( and please tell why - ) -






Regards



David










 

Left L3, Right Photonis

Sky glow is more pronounced in the Right image. thats just my w.a.g. It could just be from the conditions changing in 2-3 minutes.

Posted Via AR15.Com Mobile

I'm also guessing the left is L3. The darker, cloudy look around the edge is what makes me think it's the L3 tube.

Let me throw an opposite guess, left is Photonis, right L3. Right seems to have more scintillation and has a steeper shadow in the curb. In reality I cannot see any meaningful difference in those images.

Edit: no matter which is which, thanks David for providing this for us. Has been interesting speculating about the tubes, but finally we get to see something real. When TheHorta was still around we had something special to see every week, but this is the one at least I've been waiting for the most. Edit: well maybe along the Kent Optronics 80 degree foveal optics. If I had to pick one, either two Intens tubes or a 80 deg optics set for a bino, it would be a hard choice.

Ill guess L3 is on the right because in the left image you can sort of make out the individual bricks in the side walk while on the right you can't.

i think i would say l3 on the right , just because the shadows are a little darker on the left which is typical of gen2 (although i am not sure what you mean by 3g and 4g - is it the  new intens tube  )

I think they both look pretty bad and grainy with nothing really in focus to make out any fine details. :-(

As always, I want to see high light, medium light, and extreme low light, from both tubes. lol.

I keep going back and forth between answers.  I don't have much experience with NV, so I'm looking forward to the answer.

It seems that the left image has a little less scintillation, which would lead me to believe that it's the Photonis tube; however, a larger part of me agrees with xjronx (L3 left, photonis right) and his reasoning.

I kind of want to say that the 4G Photonis is on the right & L3 is on the left as well. It seems the right has a little less scintillation & might be picking up more light from the increased sensitivity to different spectrums that the 4G is supposed to have? Skyglow etc? The L3 on the left because it seems to be a little easier picking up the snow in the image than on the right & it being a darker overall image, which L3 is somewhat known for.

Either way, it seems somebody finally got his mitts on a 4G tube, I'm dying to see the full review  Oh & btw, tell Photonis to stop screwing around & get us some affordable tubes!

With that being said, who is classifying these as Generation 4, and is it based mostly off the spectrum response?

I ask because of this:

The skyglow people are talking about seems to be because of the vignetting David was talking about, the other has it up, the other down, 180 degrees like he said. Might be it's just from how the images were taken, but seems like the right tube has great resolution on the edges too.

I think from the comments it's pretty clear every other is seeing the same things on both sides



I don't think anyone has said it's Generation 4, just 4G, not Gen4 or anything similar. They just made up a marketing term and any tube that conforms to the limits they set is "4G" as far as I understand, no matter what the tech. Obviously the wider spectrum is part of it, and thus no L3 tube will be 4G per Photonis' min spec for 4G.


Me too. Will be interesting to see if there is anymore any meaningful difference in very low light performance - I bet there is some, but I'm wishing the wider spectrum would turn the tables in some scenarios. Hope he has got time with this tube if it's not his own. And is it an XR5 with 4G specs or an Intens?

My guess - the Photonis is on the right, the L3 on the left.

My Photonis tube's are pretty bright and the left part of the scene seems a little bit dimmer, which L3 is known for.

The bricks in the left side are a little bit more defined and L3 has been a leader in high resolution tubes.

Looking under the tree canopy in the right side of the image, there seems to be less shadow vs the left side. Perhaps this can be attributed to a better response to the extended skyglow wavelengths.

Just my SWAG, can't wait to get the final word.

OK, I'll go with the info now -




Some excellent thoughts there, and it's no wonder this forum is still the leading NV discussion group on the internet - There's just so much experience here even at interpreting photographs.




Yes, it is an INTENS. And it's a low-performing INTENS at that, as I have also been checking out an INTENS Supertube, and it has a slight edge on both of these in some circumstances. Also, correct on the vignetting Murtis - well spotted. And it's not actually pavement on the lower left, but the top of a roof with corrugations, which leads to the technical issue with the photo - The left image was taken with a slightly closer depth-of-field than the right image, so it's a touch blurrier in the distance, but not enough so you'd notice it. To my eye, under these sky conditions, the INTENS performed slightly better, however depending on the circumstances, sometimes Gen3 looks clearer. The tubes are matched though, with similar specs ( including higher EBI on the PHOTONIS and lower EBI on the Gen3 ), so should be almost identical.




So how were they arranged?




Left - INTENS. Right - Gen3.




But as was noticed by everyone, there's nothing in it and they could easily be two images from the same tube - For the first time, I had to take marker shots during every run, so I would know which images were which - I've never had two tubes so closely matched in everything that, in the end, the color was the only real differentiator - Both are P43 but the greens are slightly different when I process the images.




So this tube is an xx3040GK - It's the newest generation of PHOTONIS tubes, and is the one to look out for - All INTENS currently start with xx3040 and the last two digits change, so GK is the one to stick into a PVS-14. As such, it's probably the one to get for US general applications as it's optimised for a 174kOhm potentiometer and has the PVS-14 pigtail.




Now, as was noted, there was no practical difference between them and both tubes have similar specifications. I'll get into a full review as I proceed, but that does take a little time, and I need to visit a number of scenarios to view the absolutely fine difference in the tubes, but the main differences that hold constant are;




1) The PHOTONIS tubes are a little brighter all over. If you like to see that a dark area really is dark, and it's not just a lack of gain, you definitely notice this. Increasing the gain increases the brightness of dark areas slightly. This seems similar to Thin Film, except Thin Film also loses a little detail as you do this - the INTENS is a very clean tube. At this point, possibly the cleanest tubes I've seen, especially the >31 S/N models.




2) Gen3 seems to have a touch more gain. This seems related to pure amplification, and when both tubes are set to the same level ( optimised image ) they are practically identical.  This INTENS tube was a little clearer ( less scintillation ) but not outside of the lower bounds of Gen3 that I've noticed. I'd have a hard time spotting an INTENS tube in a lineup of Gen3 PVS-14's and the gain wouldn't be enough to peg the difference. The tubes are just too close.




3) There is no practical difference between Gen3 and 4G in terms of image or general use. What one can see, so can the other, and I've taken this to around 10 uLux and it still hold - in this respect, the tubes now hold their own against Gen3. ( XR5, by comparison, does eventually lose as it gets ultra-dark ). Sometimes I'll see a single spot in an image that is different, but it's usually just a spot - One example was a branch in front of deep shadow. The INTENS seems to pick up light on dark better than Gen3, while the Gen3 picks up dark over light slightly better in some circumstances. I don't know why this happens yet, but it's very slight and I can't measure the difference.




4). High light? INTENS just isn't fair. It loses almost nothing in high light scenarios and with it's super-small halo it  handles high light perfectly. However it does have MCP reflections to deal with - This is a technology difference.




5) The Specs tell all. If you follow the specifications, then the images will usually be similar. So this new generation of Photocathode really can compete natively with Gen3, which is important, because PHOTONIS came close in 2002 with the XR5, but I could never really call the XR5 the winner, but now they are very equally matched.




So at first glance, both tubes are the same...




However...



6) There's one other factor. Remember I said there were practical issues to consider about the band? Well, the spectral band that increases isn't quite what I expected, as in, it fell short of my expectations. However, there were other factors about this that I hadn't taken into consideration last year, and this tube is a Gen3 killer. As in, I think I can safely say that the Gen3 era is now over. That's a pretty big thing to state, but once the extra factors are taken into consideration, then the difference between Gen3 and INTENS is as tactically different as the difference between Gen3 and Gen1. There's more to this, but there is technology leakage from INTENS down to the XR5's at present.  Here's an initial image I'll share pre-review. ( since it isn't an INTENS, but is an XR5 ).








From this, it's absolutely clear what 4G is about - and the easiest way to describe it is that Gen3 is simply blind to a tactical spectrum that it really does need to see, however there's no chance it will see it because Gen3 uses Gallium Arsenide, which is transparent in this new band, in fact they even make lenses out of it for this reason. That means it's not really suitable as a photocathode for the 950-1050nm band.




Surprisingly though, not only can the XR5 tubes see part of this band, but so can AN/PVS-5C with extended-red photocathode.




Now it's taken me months to fully research the story about this, and I've had to review dozens of documents, especially historical published Litton documents, and I'm just waiting on some minor aspects that haven't been previously published to be cleared for publication, and then I'll share it with everyone.




Regards


David.


 

I wish I had gone with my gut on the phosphor color.

Posted Via AR15.Com Mobile

 
Hi Rich,


Typical 4G tubes are also > FOM 2000. This particular tube I was testing was > FOM 1800, but it's a close match for my Gen3, so it makes an excellent comparison tube.




Keep in mind that the only official US standards are Second Generation and Third Generation and Super Second Generation as a non-US standard.  4G is more of a tactical specification than a generation IMO, but PHOTONIS don't exclude others from using it, although I am not aware of any US made tubes that can meet the specification at this point in time. L3 would be the closest to meeting it though. Then maybe China, who seem to be noticing the differences.


Being a tactical specification, it's a pretty good idea. In this way, it does actually trump pure technological specifications. It's kind of like measuring engine output as power-to-weight ratio over a minimum power level, instead of just counting the number of cylinders. It makes a lot of sense and I think that the term 4G might actually eclipse Generation 4, though I can see it being abused by some resellers who will take advantage of the ambiguity.


Still, tactical specifications don't mean much to most civilians who are just using NV to shoot at night anyway, but they are absolutely critical to the military, and will become even more critical to law enforcement and security personnel - perhaps more so than to the military.


Regards

David.

I always appreciate these threads and understand the tactical advantages of being able to see outside the spectrum that typical Gen 3 covers, but from a civilian standpoint, I really only care if it gathers additional light from outside the Gen3 spectrum that helps me see better at night, and those are the photo comparisons I would rather see.

IF the 4G tube struggles in the darkest environments and needs IR illumination to help the tube over say... L3 Filmless, wouldn't that also pose a tactical disadvantage unless that illumination was also completely outside the Gen3 spectrum?

 
Well, yes, if a tube struggled in the darkest environments, that would still be an issue, however the 4G tubes don't seem to have an issue in those situations, even with normal spectrum and well into NL6. ( Night Level 6 ).


And yes, it is possible to effectively illuminate a target with light that Gen3 cannot see at all. Actually, it's kind of spooky to see it in action. A bit like ultra-violet pens when you see them for the first time. Or light that's hidden by polarization. I think it was L3 who first identified that the US was missing the tactical advantage in the 950-1050nm intensified band. Certainly their published documents from around the turn of the century would indicate so.


But from a purely civilian aspect, I think that it would just come down to cost. Though being able to illuminate animals at long range with a light they can't see, even if looking straight at the source?  That has value for civilian application.


Regards

David.

David, are there any photos comparing an Intens to an L3 Filmless at 70 or below ulux (Night Level 6)?  This condition would be something along the lines of inside an unlit warehouse with only slight starlight peeking in through the entry doorway - or an unlit basement, or something along those lines, right?

 
Not unless L3 want to get directly involved in the comparison.






In any case, it's not like the outcome isn't predictable, and others have performed the tests and collected the data. Filmless isn't a massive performance increase over thin film and filmed tubes per se, it's just another way to dress the tube. Performance characteristics of the tube are known from other details such as the S/N, resolution and EBI. These tend to become the limiting factors for most tubes since there are practical limits to how much gain you can get out of a tube without destroying the image.






A 35 S/N filmless would probably beat the 28 S/N tube pictured above in passive tests, but maybe not so with a 32 S/N INTENS, which can outperform the Gen3 pictured. It's kind of relative, though, and the first thing you notice is a loss of resolution, rather than any real change in the course detail of the image - At these kinds of light levels, gain is really important as well.






To that extent, the INTENS doesn't quite match the maximum gains of Filmless ( around 90,000x ) however, the milspecs on filmless also don't usually go that high, and many come out around 50,000 - pretty much the same as the lower-gain INTENS, and most come out with pretty much around 57000~58000 which says something about their power supplies,  so to that extent, the value of filmless, tactically speaking, and assuming milspec, wouldn't necessarily exceed that of INTENS anyway - though perhaps the newer PSUs are better.






The chinese government research into filmless L3 tubes and PHOTONIS INTENS tubes in their low-light-level night vision laboratory ranks baseline INTENS above thin-filmed and below filmless for S/N. (30/28/33 respectively ) however filmless have a lot of ion noise activity which damages the tactical usefulness of the higher S/N - For thin film ( Excelis ) it was 1.7, and L3 was 1.4, however INTENS comes in at 1.05 - so the INTENS offsets the lower S/N with a much calmer image, and when looking at NL6 ( below 70 uLux ) scenes, that actually has a surprising benefit. They also have some interesting new phosphors and I'm not sure what role they play, but they are very calm to look at, even below 70 uLux.






And that's all before you take into account the spectral differences, which the Chinese research also noted - After that, it's a different situation. If the variation in spectral sensitivity was considered, INTENS and Filmless could well be on equal footing.






In any event, in an unlit warehouse, with only starlight, the active OOB aspect of the INTENS would become a significant factor and provide an overwhelming tactical advantage. Once you go into NL6 the typical INTENS might be about the same passive as the typical filmless, but if used in active mode the INTENS would absolutely dominate. The difference, then, is massive.






This doesn't come only from me - it is something L3 determined back when they first developed filmless and were getting tubes with S/N as high as 45. Yet they were willing to give up more than 80% of their tube performance to cover active use in this 950-990nm band and saw it as a reasonable trade off. And this was at a time when they didn't really have any natural predators in that spectral band either.






Now there's a tube that can see extremely well far outside the spectrum of Gen3 and otherwise performs about as well as high-end Gen3. There's a big story behind that and there's significant tactical implications involved too.






Regards,



David.






Note: If you knocked 80% of the performance off of a tube, you'd still have a good tube - It would be somewhere around Gen2+ performance.



















 

do the intens tubes have increased luminance sensitivity , i have had proper milspec xd4 type tubes up to about 800 ua/lm on the sheet , and xr5 that must be more as they perform way ahead of those xd4. it seems to make a good difference the higher you get , i know they widened the bandwidth  for the intens , just wondered how much that helped the luminance sensitivity of them.

I believe it's up around 1000uA/lm by the 2856K standard, so well above XR5, but that doesn't take into account the increased response above 950nm, which I think is way higher than XR5.

 

Regards

David

That sounds rather bad, 80% for some increase in sensitivity. Can you explain what that 80% means? Surely not 80% cut away of any numeric performance value we have in spec sheets..?

Quoted because my iPhone won't show pics.

 
Yes, that's correct. Around 80% of raw performance is lost. Specifically, the Photocathode Response, so it's coming straight off the signal -  I'd estimate that they can probably achieve similar performance somewhere between Gen2+ and Supergen.


InGaAs has some amazing spectral range, but the more you increase the range into the SWIR, the lower the overall PR. If they go above 1000nm, it's probably more than 80%, but if they keep it below 1000nm and achieve useful gain in a narrow tactical band there, then it's probably still around 75% to 80% based on their published data. They make the claim that they still have useful photoresponse with that much of a reduction, and for what it's worth, I agree with them. That figure ( percentage ) wasn't stated exactly, but could be inferred from the numbers they published.


However, I believe they are no longer researching that technology, and I don't believe it has anywhere near enough gain to come anywhere close to the 4G specification. I would imagine they are pulling it out and dusting it off at the moment.


Regards

David.

 
But there wasn't an actual question in your post? ( or did I miss it? )


Anyway, if you can't see images, the original link is;


http://aunv.blackice.com.au/userfiles/david-4G-vs-G3.jpg


Regards

David