A week or so ago I posted here on EAA regarding my interest in a PVS-7 night vision goggle that I had found at a good price online. While the responses on that thread were not many, I did receive some helpful PMs from a couple of members cautioning me to perhaps keep looking. Among those from whom I received helpful advice was Eddgie, and we have been corresponding ever since then. Thanks to Ed, I have obtained a used PVS-7 that was found on Ebay. I wanted to tell about my trials and tribulations, as well as the final results. Forgive me if this turns into a wall of text that is too long to read!
I was first exposed to night vision astronomy a few years ago when a friend showed me the Horse Head from his light polluted home with a 20” dob and a Collins I3 piece. He then showed me the HH through his TV NP101. I was floored, and vowed that one day I would have one.
A week or so ago I read the excellent article on CN that was written by Eddgie, The Ardent and Vondragonnoggin, and I decided that maybe now was the time to start looking to get into this. My home site, which used to be a green/blue zone 25 years ago, is becoming more and more light polluted as the city of Tallahassee moves ever closer, and I am not really in a position to buy more property further out in the country, so NV seemed the perfect solution. I had tried a Mallincam a few years back, but looking at images on the computer and having to make all of those connections didn’t float my boat so, again, I was back to looking at NV.
Last Saturday, after extensive searching, I found a seller on Ebay who had what sounded like the perfect PVS-7 for astronomy. The seller listed the tube as being rated at least Omni vii, with resolution of 64-72lp/mm, and s/n ratio of 28. The seller turned out to be an amateur astronomer, who assured me that I would love this tube for astronomy. The photos taken through the device that he sent looked good too. Though the price was a little more than I had planned on, the 14 day money back guarantee was enough for me to click on Buy it Now.
After a delay in shipping due to a sick child, I received the PVS-7 this past Saturday. Upon opening it, I took it into a dark interior bathroom to check it out. I was pretty surprised to see the shower curtain and towel rack even though the cap was on, until I realized that there is a pin hole in the cap for bright light testing of the device. Off came the cap and the whole bathroom lit up! Pretty amazing stuff.
So, I had about six more hours to wait until nightfall to really give this thing a spin. Finally, around 7:30 and after wolfing down dinner, I grabbed the PVS-7 and headed outdoors, aimed it at the sky and adjusted the objective to infinity focus. Dang it, no matter how much I turned the diopters, I could not reach focus for my eye. So, back indoors I went to PM Eddgie, whose patience must have been waning by this point (we had already turned to page two of our PM exchanges), and the seller asking for advice on how to focus this thing. Eddgie informed me that the two large knurled knobs at the base of the eyepieces, the ones that I thought were knobs to lock down the eyepieces after adjusting for IPD, were actually the diopters. Being a long time user of binoviewers, I was twisting the upper part of the eyepieces, but all that was doing was spinning the eyecups around and around. Well, didn’t I just feel like a complete idiot? I emailed the seller to inform him of that.
Back outside I went to try again. Turned the diopters and voila, perfect focus! And that’s when I saw the big black spot just above the exact center of the fov. “This can’t be right” I was thinking, but there it was. After several more PMs with Eddgie we determined that it was either a faulty tube that wasn’t disclosed or it was dust somewhere on the tube or the collimator lens. Not wanting to accuse the seller unjustly or ask for a refund just yet, I opted for cleaning.
The next day I took the thing apart in a dimly lit room with my camel hair brush, a can of compressed air and some Kim Wipes. I brushed, wiped, etc., took it into my dark room again to try it out. The big black spot appeared to be gone, but now there were several others. Now in full panic mode, I thought that I had ruined something, but decided to try to clean it a bit more. This time I had a very hard time replacing the housing for the tube, so I took a well needed break and walked away from it. A few hours later I pulled the tube again and brushed both ends. As for the collimator lens, I took a page from Roland Christen’s book and licked the end of my pinky finger and rubbed the lens, following with a Kim Wipe, and put it back together. This time in the dark room I didn’t see anything but one very small speck near the extreme 4:00 position. As Eddgie advised, and against my personal nature, I decided not to get too **** about that.
OK, now fast forward to 8:00 last night when I finally got out for a decent first light. With some trepidation I turned the unit on and turned to Orion. I was treated to a brilliant display with no black spots, but more stars than I could have ever expected to see with a moon that was just past first quarter. I could plainly see nebulosity around Alnitak, and the haze that is M42. Turning toward the area of Perseus and Cassiopeia the Heart and Soul Nebulae were quite easy. This could be addicting! All told I spent about 20-30 minutes just sweeping around the sky in awe at the thousands of stars that were visible. As I told Eddgie, there’s a bit of cognitive dissonance when you are looking through the night vision device, and you see all of these stars that I normally wouldn’t see if the moon weren’t up, yet the image is bright and green. I can’t wait to get a look when there is no moon up, just to compare the brightness. I also can’t wait to drop this device into my 11” dob!
So, if you have made it this far I want to thank those who wrote the excellent article about NV observing, because you guys saved me a lot of leg work trying to figure out what adapters, filters, etc. that I would need to make this work with a telescope. While I have not yet received my c mount adapter, or the filter adapter for the objective lens, I do have the ENVIS lens, filters and the c mount to 2” adapter when they do get here.
Eddgie, my friend, you are the man! Thanks for the endless PM exchanges, listening to my whining, and allowing me to call you at home. You are a wealth of information, and I can’t thank you enough.
Edited by Doug Culbertson, 19 January 2016 - 12:27 PM.