I gave up on PVS-7s a few years ago because it was almost impossible to find one with a really high quality tube. As much as I like using both eyes at the telescope, every PVS-7 I have owned simply had too much noise for my liking.
I remember being out at Mansfield dam a few years ago with my last PVS-7 and comparing the view with my Micro with F9800 tube. I could see Barnard's loop easily and brightly in my a single Mod 3 but when I used the PVS-7, while I could see the loop pretty easily, the view was extremely grainy. Now without narrow pass filters at 1x, I thought the standard PVS-7 did a really nice job, but when used in my 12" F/4.9 with a long pass filter on galaxies, the noise was just a bit to much to give really enjoyable views of galaxies.
Now two or three years ago (time flies!) there was a small lot of PVS-7s sold with filmless white phosphor tubes. At the time, I was on the fence about it so I tarried on getting one.
One night Peter and I went to Mansfield dam (after he had sorted his PVS-7 out. It was purchased in a PVS-7 A housing that had a lot of issues and he rehoused it into a PVS-7 B/D) and had some time to use the re-housed PVS-7. It was wonderful. I was really impressed with the view. It was the first time that I had ever used a PVS-7 that fully pleased me. The view was crisp and bright, and very quiet.
Time goes buy and I was PMed by a CN member yesterday that had bought one of these when they became avialable, and he was wanting to know if the price was fair. Now at the time, I did not realize it was one of the filmless tube PVS-7s. He had provided a spec for the SN of 24.1 or something and I thought it was a thin film tube so I was not so interested, but I did know someone that was looking for a PVS-7 and forwarded on to the other individual.
During the email, the other individual pointed out that the SN was actually over 30. There had been a copy of the spec sheet in seller's original PM, but as it turns out, he had apparently transposed the minimum SN date in the text of his note (with the other figures like .3 EBI and such) and when I went back to look at the spec sheet, I realized it was one of the L3 filmless tubes.
Since I had already pointed the other buyer to it, I did not fell like I should go steal the sale from him, but I told the seller if the other buyer passed, I would take it. About 18 hours later, one of the unicorn filmless WP Unicorn PVS-7s is on its way to me. How fun for me!
One of the biggest problems with a full NV binocular is that it is very hard to get more than 3x and a zoom lens is of course not really possible. I think this unit will pair really well with my 70mm to 210mm zoom. I also really look forward to using it in my 12" dob and with the zoom lens. I mostly run with full gain, so for me, the absence of a gain control is not really that important.
Some thoughts on binocular summation as it applies to the PVS-7 and full binocular...
A Mod 3 (or other binocular) has two image intensifiers and the random scintillation and noise patterns are different, so the brain kind of averages these artifacts out of the view all by itself, and with a full binocular, I do believe you get a very meaningful boost in perceived signal to noise ratio. There is nothing like using a full binocular.
The PVS-7 though uses a single tube, and both eyes see the exact same pattern, and because if this, I don't feel like one gets the same perceived signal to noise ratio benefit that is provided by a full binocular. I do believe that there is some slight improvement, but my subjective opinion is that it is not nearly the same as using a full binocular.
The brightness penalty of a standard binoviewer is not present in a PVS-7. The output brightness of a PVS-7 would not be any different from two single monoculars because the tube itself is set up to provide a minimum luminous output to each eyepiece so there is no real penalty here.
The last attribute of binocular summation is visual acuity. Just like with a standard binoviewer, the PVS-7 allows the users to use both eyes and just like with a standard binoviewer, the image will look larger than it would using one eye, and the visual acuity will be improved. This is independent of the SN issue because while there is only one image shared by both eyes, this is analogous to getting an eye exam and viewing a single visual acuity chart at a distance with one eye, then the other eye, then opening both eyes and noting an improvement in the sharpness of the letters on the vision test chart.
I am very happy to have the good fortune to get one of these unicorn PVS-7s. I have often wondered if I could find one, if it could or would displace a monocular as my primary telescope observation device. This unit does not have the SN of my best monocular, but it is very similar in specs to my first filmless tubes in my original Mod 3 binocular, and that worked quite well for years for me in my telescope as far as performance goes, so I am looking forward to seeing if the improved visual acuity and low EBI offsets the better SN of my best monoclar.
It was a real surprise to me to see one of these become available. I thought having pointed it to another CN member, it would escape me, but the Matrix must have wanted me to have it.
Weather his is not great with more dust expected in coming days, but the first chance I get, I will give some A/B comparisons in the telescope.
Hope you are all doing everything you can to stay safe. Remember, it is very dangerous out there. I appears that a lot of people out there may not be that interested in protecting you, so protect yourself.