21 replies to this topic

[11769]

Recent thread regarding desired tube specs made me curious what everyone has in order to have a better "feel" for observational reports and notes. Feel free to add any and all tubes.

 

Type: L3 filmless WP

EBI: 0.5e-11 phot ("0.5")

SNR: 34.3

PR: 2589uA/lm

Gain: 62675fL/fc

Resolution: 64lp/mm

Notes: Crisp, calm, a bit lacking in brightness when it gets really dark

[pwang99]

My Mod3 has the following specs:

Type: L3 filmless WP
EBI: 0.6
SNR: 36.9
PR: 2612 uA/lm
Gain: 69949 fL/fc
Resolution: 72 lp/mm

[nimitz69]

Also maybe add ‘when’ you got your tube ...

[GeezerGazer]

Mod 3C, L3 filmless WP tube:

   EBI:  1.1

   S/N:  33.8

   PR:   2680

   Gain:  61433

   Resolution:  72 lp/mm

   Halo:  .7

   Dark Spots:  zero

 

New 9/26/16

[Jeff Morgan]

Mod 3C, L3 filmless WP:

• EBI - 0.3
• S/N - 31.5
• PR - 2164
• Gain - 67850
• Resolution - 64
• Halo - 0.8

New 7/26/16

[Kurt Mihalco]

Mod 3C, L3 filmless WP tube:

   EBI:  0.6

   S/N:  34.3

   PR:   2606

   Gain:  60018

   Resolution:  72 lp/mm

   Halo:  0.8

   Dark Spots:  0

   Bright Spots: 0

 

New 4/7/17

[alanjgreen]

Photonis INTENS 4g WP tube:

   EBI:  0.04 μlx (I believe this has to be multiplied by 10 to be equivalent to the L3 scale so = 0.4)

   S/N:  31.59

   PR:   ?

   Gain:  11920 cd/m²/lx (I believe this has to be multiplied by 3.1415927 (pi) to be equivalent to the L3 scale so = 37447)

   Resolution:  69 lp/mm

   Halo:  0.80

   Dark Spots:  zero

 

New April 2018

Edited by alanjgreen, 31 August 2018 - 11:12 AM.

[AllanDystrup]

Photonis INTENS 4g WP tube; New June 2018.

PM me if you're interested in the specs (explicitly passed on to me as confidential and not for public disclosure).

Close to alanjgreen's spec though, so nothing extraordinary...

-- Allan

Edited by AllanDystrup, 01 September 2018 - 02:55 AM.

[Gavster]

Just revisiting this thread. How important do people think gain is? Eg do you think you will would notice the difference between a 65k gain tube and a 75k gain tube (with fom and ebi being the same very good quality)

[Eddgie]

The gain is the power of the signal and the stronger the signal, the more it will stand out above the noise level (as in Signal to Noise Ratio) and the EBI.

 

A gain difference of 15% would seem to be enough to be noticeable.  I know that Peter's tube has about the same amount of difference as given in your example, and while my best tube has an EBI of only .1, the difference in gain between this low EBI tube and his tube is not quite the same as in your example (about 10%) and I know that on galaxies, I can see the difference.  Galaxies are a bit brighter and have a bit more extension in his tube.

 

I have never had a chance to compare them at threshold objects where a .1 EBI would perhaps make a big difference, but on bright galaxies, I think Peter's tube does better.    I have seen some incredibly faint nebula though so EBI does matter, but I don't know which matters the most.   In a perfect world, you would get 75000 gain and .1 EBI, but it appears to be very difficult to find a tube with this kind of spec.   My second tube has an EBI of .2, and I can't see much difference, but as compared with tubes with EBI of 1 or higher, the difference is pretty glaring.  I would say that the difference between 63,000 and 70,000 is a bit more than "subtle" but only a bit. 

Edited by Eddgie, 15 March 2019 - 08:12 PM.

[chemisted]

I haven't seen a tube with gain above 70000.  Has anyone ever gotten one and, if so, what EBI did it have?

 

As Eddgie has outlined, very low EBI tubes sometimes come up and coupled with a good gain figure they may be the optimum tube to shoot for in the current market.  He also points out that any comparison like this really needs to be defined in terms of the chosen target.  I only have the Micro ULT and older Collins I³ to compare but it is still interesting.  On globular clusters, the Micro clearly wins bigtime if I use my 5.5 inch refractor because the Collins has a much inferior gain and struggles with the faint stars.  That said, if I use the 10 inch RC to provide more photons the call is much closer.  The reason is the insanely low EBI of my Collins eyepiece.  Bill Collins did not supply spec sheets but this tube must be in the .1-.2 range that Eddgie mentions.  My Micro ULT tube has EBI=0.98 and on a typical spring/summer night has a background that appears very bright while the Collins is nearly black.  The fainter cluster stars that I see easily in the Micro are still present in the Collins - they are tiny, sharp pinpoints well differentiated from the background.  

 

The final comment I have about EBI is that it really is temperature dependent.  This winter when I have been out at temperatures of freezing and below the background glow of the Micro is hugely decreased and I have used it exclusively for all targets.

[Gavster]

I’ve been very impressed with my pvs-14 binocular setup. At 1x it makes a very significant difference to a mono setup imo. However I am running a photonis 4g intens wp tube on one side and a harder wp gen 3 tube on the other.
So I’ve decided to get another harder pvs-14 to be able to run a matched pair on the NV binocular setup.
I requested a tube that had very similar characteristics to the first harder tube.
I’ve just received the spec sheet for the new pvs-14 which does have virtually identical fom and ebi but this new tube has a gain of 73k vs 62k for the first one, which did rather (pleasantly) surprise me. I’m thinking I probably won’t notice much difference at the eyepiece though.

Edited by Gavster, 16 March 2019 - 09:17 PM.

[Jeff Morgan]

Great signature line Gavster!

 

After all of those years chasing down "limit observations" and other assorted ghosts, I'm with you.

[11769]

A gain of 73k is seriously impressive. Not something I see with US tubes. For L3 filmless tubes, gain seems to average around 63k. Highest I've seen was a bit over 69k and that's out of a couple dozen datapoints. Surprisingly that 69k tub had an EBI was less than 1.0, less than I expected. Some thin film tubes had a slightly higher gain where 70k was not that rare. I'm guessing the Harder tubes are thin film?

 

Would echo what others have said regarding the importance of EBI. It's the one parameter that decides if my tube is worth looking at the sky with. SNR is a secondary though still very important deciding factor. No downside to more gain if nothing else is being sacrificed but I would not prioritize extra gain at the expense of even a 0.1 delta in EBI. 

 

Looking at L3 specs, there seems to be a trend where tubes and/or process are being tweaked somehow to get better SNR at a severe expense in EBI. The maximum allowable EBI for L3 filmless tubes is 5.0! There's already been some tubes with an EBI above 4.0 that made it to vendors and then to customers. Pretty abysmal for astronomy. Just something to watch out for. 

Edited by 11769, 17 March 2019 - 10:31 PM.

[Gavster]

A gain of 73k is seriously impressive. Not something I see with US tubes. For L3 filmless tubes, gain seems to average around 63k. Highest I've seen was a bit over 69k and that's out of a couple dozen datapoints. Surprisingly that 69k tub had an EBI was less than 1.0, less than I expected. Some thin film tubes had a slightly higher gain where 70k was not that rare. I'm guessing the Harder tubes are thin film?

 

Would echo what others have said regarding the importance of EBI. It's the one parameter that decides if my tube is worth looking at the sky with. SNR is a secondary though still very important deciding factor. No downside to more gain if nothing else is being sacrificed but I would not prioritize extra gain at the expense of even a 0.1 delta in EBI. 

 

Looking at L3 specs, there seems to be a trend where tubes and/or process are being tweaked somehow to get better SNR at a severe expense in EBI. The maximum allowable EBI for L3 filmless tubes is 5.0! There's already been some tubes with an EBI above 4.0 that made it to vendors and then to customers. Pretty abysmal for astronomy. Just something to watch out for. 

Harder tubes are thin-filmed. Certainly I requested a low ebi tube and both harder tubes have an ebi well below 1. I am able to see the Eridanus Loop with my existing Harder so threshold nebula visibility appears reasonable.

Just seen this post from cnoct where he suggests that it’s worth trying to aim for a gain over 70k - see post number 18

https://www.cloudyni...osphor-nv-tube/

 

Edited by Gavster, 18 March 2019 - 12:57 AM.

[Vondragonnoggin]

My mx10130 pvs 7 tube:

 

PCR (white): 2315
EBI: 1.07
Halo: 1.18
Resolution: 72 lp/mm
Signal to noise ratio: 27.8.
System Gain: 5570
Tube Gain: 68,008
Format = 18mm
Phosphor: P-43
Image Quality: Clean

 

purchased Nov, 2015

Edited by Vondragonnoggin, 18 March 2019 - 03:31 AM.

[bdg]

Mod 3C, L3 filmless WP tube:
   EBI:  0.3
   S/N:  34.5
   PR:   2692
   Gain:  65496
   Resolution:  72 lp/mm
   Halo:  0.7
   Dark Spots:  One spot @ Zone 3 
   Bright Spots: 0

 

Purchased New on 6/2019

[shams42]

My Mod3 WP:

 

PR: 2626

EBI: 0.8

Gain: 66059

S/N: 35.0

Resolution: 72

Halo: 0.7

Spots: none

[Eddgie]

These were purchased as a matched pair for a Mod 3 Binocular

 

I have noticed that as a general rule, there seems to be a rather linear relationship between the photocatode sensitivity and EBI. I see tubes with specs better than this but the EBI is almost always higher.  Also, my own summer observing conditions can best be described as "hot" (90f at 11:00 PM is common), so a low EBI was important to me because the summer Milky Way is my favorite target. While I do think that EBI is a very important metric, I also think that sacrificing a lot of photocathode sensitivity to get it is kind of a mixed bag in terms of tradeoff.   More on that in a moment. 

 

 

11769UW-EA-C000-1-20UM

 

PR:    2163

EBI:   .1

Gain: 63954

SN:    32.2

Halo: .8

Resolution is 64 lppm

 

11769UW-EA-C000-1-20UM

PR: 2019

EBI .2

Gain: 62685

SN: 31

Resolution is 64 lppm 

Neither of these are what I would call super tubes, but when it comes to detecting faint nebula, I believe that they do well.  The sky is practically black in the absence any stars and nebula, and I can see far more nebula than I ever realized existed.  In particular, seeing that M29 sits in a nebula was a big surprise to me, and quite easy on a hot September night under dark skies.   I have since duplicated this observation under red zone ski in August a 92 degrees Fahrenheit.

 

I have two other tubes but these do not have spec sheets, so I am going to give my gut feel based on having owned a surprisingly large number of tubes (mosty 10130 D/UV)

 

10130 D/UV (as a class, and all but one have been Omni VII)

PR: 

SN:  23 to 25. I know there is much debate about the specs that the Omni Table shows, but I have compared these tubes to a true Omni VII level performance tube, and it is dead easy to see that the noise level on the 10130 D/UV Omni VII is simply not as good as a tube that really does have 28 SN.  

EBI:  Varies.  Again, comparing to known tubes, I have owned tubes with EBI from 1.99 to .1, and I would estimate these to range between 1 and 1.5 or so.  Again, one had EBI of 1.99, and this is at the edge of what one would want for EBI, and only on a cooler night.  On hot nights, even though this tube had amazing gain and SN (or a PVS-7) it did not work well for nebula under these conditions.  This was my big lesson on EBI.

Gain:  Except for the noise and EBI, I can see almost everything in my PVS-7 that can be seen in  and Mod 3s, so I am guessing the gain is quite good. 

64 lppm

 

F9800VG (P43) spec tube (typical of that used in Military aviation goggles and equivalent to the 10160C/AVS Omni VI and Omni VII tubes)

Photocathode: Estimate is above the 2200 mininum spec.  

SN: Minimum is 28. With the above info about the PVS-7 10130 D/UV above, in direct comparison (which I can do any night of the week because I own both) it is easy to see that the 10130 D/UV has considerably higher noise than the F9800VG type tube, which itself is very close to my L3 tubes.  When filtered, the 10130 D/UV Omni VII is almost as limited by the noise as by the EBI.  I was able to see Barnard's loop with every 10160 D/UV I have owned and of the four 10130 D/UVs I have owned (always in search of the perfect tube), all fell well short of the F9800VG spec tube (and the ULT spec tube) when it came to noise and especially when filtered.

EBI:  In direct comparison, this tube has slightly higher EBI than the PVS-7 10130 D/UV I own, but much less than the PVS-7 with 1.99 EBI. I would estimate in the 1.5 range based on these comparisons

64 lppm 

 

The F9800VG is outstanding on stars. It seems to show tighter stars with much more dynamic range than the L3 filmless tubes.  The L3 tubes tend to flatten out the dynamic range in stars.  They look more different for the size than for the limiting magnitude, with brighter stars having a bit more bloated appearance than in the F9800VG spec tube. In the then filmed P43 F9800VG spec tube, stars the pinpoints seem smaller for brighter stars, and when I view with it, stars jut have this brilliance that I find a bit lacking (by comparison) in the L3 filmess P45 tubes.  In fact, what I used mostly for telescope work on non-nebula targets is the F9800VG spec tube.   This tube conforms to the MIL-PRF-A3279602 standard, and this is the standard that is used to select tubes for military aviation goggles.  In other words, this represents some of the best thin film tubes made.  The military wanted people flying multi-million dollar airplanes to have the best. 

Where the F9800VG tube type really excels is in high light resolution.  Once again, the L3 filmless tubes kind of look flatter in response in high light.  If you made me pick a tube for general NV use, this would probably be the tube I would use (My first Micro had the NV Depot ULT grade tube which had better specs and lower EBI, and I wish I had not sold it.)

 

I know that this was supposed to be just about the specs, and I hope people don't hate that I have included a lot more in my post than just the numbers, but the point is that the numbers don't tell the whole story.  Tubes do behave differently and while everyone wants thin film white phosphor tubes,  I would say that having used both, I have gravitated back to the F9800VG spec tube for most of my non-binocular observing. It is an amazing tube.  I look at the sky, and stars have amazing dynamic range and sharpness. 

 

I think low EBI is important, but I would not throw SN, Gain, and Photocathode sensitivity under the bus to get  to .1 EBI. In comparison to  Peter's tube, I can see that for most targets  including even fairly dim nebula and on cooler nights, his higher spec tube, even thought it has a higher EBI, is a better tube.  On a hot summer night though, I can eek out nebula that still surprises me.  The rest of the year though, I wish I had Peter's tube.

[Solar storm]

Here are the specs for PVS-7 Green Phosphor one.  I also have a white phosphor one but I cant find my specs for that at the moment.

 

Photocathode response: 2274
Equivalent background input: 0.49
Resolution: 73 lp/mm
Signal to noise ratio: 28.2
Figure of Merit: 2058.6
Halo: 0.8
System gain: 4570  (I did get a gain knob installed in this unit and I love it with gain control) 

[bdg]

Updated:

Mod 3C, L3 filmless WP tube:
   EBI:  0.3
   S/N:  34.5
   PR:   2392
   Gain:  65496
   Resolution:  72 lp/mm
   Halo:  0.7
   Dark Spots:  One spot @ Zone 3
   Bright Spots: 0

 

Purchased New on 7/2019

[Joko]

Here in Europe our choice is between Photonis (GEN2) and HarderDigital (GEN3 thinfilm)

 

I have a HarderDigital, thinfilm WP:

EBI - 0.7
S/N - 34.2
PR - 2260
Gain - 69950
Resolution - 72

FOM - 2462

 

I'm a vendor and my customers have better tubes ! 

Edited by Joko, 18 November 2019 - 02:43 PM.