76 replies to this topic

[Doug Culbertson]

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 anal 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.

[Eddgie]

I am so pleased that you are happy with your decision to take the jump!

 

 I was happy to help.  I felt personally invested in your success and I am very anxious when someone jumps in without experience, but you already had experience with the Collins so less of a risk for you.

 

Put that lanyard on as soon as you can!

 

Looking forward to your hearing your ongoing explorations!

 

[outofsight]

Doug, may I recommend canned air. Compressed air is the best for chunks of dust. I've been through the exact same thing with a new tube. First it was clear, then I had one big blotch, then after clearing that I had several smaller ones. But I immediately realized it was my cleaning process and went back in and looked at the tube under high magnification and it was quite illuminating, several specs of dust. A really black, well defined, blotch is probably something that can be cleaned if you've had no other problems with the tube. A kind of dull gray, amorphous, blotch is probably the tube, at least to my current experience. (But I have seen other black blotches,on another tube, that change shape and position and might be on the inside of the tube, don't know.) Next time you see a spot take the tube out and look at it under magnification. Then use canned air.

 

You can do your own experiment. Put a spec of dust right in the middle of the tube and turn it on and you'll see it. Fortunately these tubes are fairly robust, but try not to drop them (Ed).

 

Glad to see you made it through your first freak out with the tube, Doug. It is a bit daunting when you realize the tube is worth significantly more than all the other parts combined, and then you see spots where you don't want to see spots. And don't worry about the "whining" and stuff, if you get the right (autogated) tube it'll whine for you.

 

Just about everyone who has tried NV for astronomy has been where you're at, but fortunately you have good backup (Ed). 

Edited by outofsight, 20 January 2016 - 01:22 PM.

[Doug Culbertson]

Yes, canned air is what I meant. One of those little cans with the trigger on it that is used for keyboards and optics.

 

Also, I wanted to thank you for your advice via PM as well. I have sent you another PM about one of those.

 

So far I am loving this, but I will be very glad when I receive all of my pieces and parts for using the filters, as well as for use in the telescope!

[GeezerGazer]

So Doug, now that you've made this leap, I am wondering... how much of an investment does this transition require?  And, are you glad you went this route?

 

A few years ago, I purchased an I3 Collins eyepiece but was pretty disappointed and quickly returned it.  I live in the Central Valley of CA, and at the time, observed from home, where light pollution and agricultural dust & moisture conspire to defeat the ostensible benefits of NV.  I no longer observe from home, choosing to drive 45 minutes east into the Sierra foothills to a semi-dark site.  I have been making that journey once or twice a week for 6 years now.  From this site, NV might be of benefit as I rise to a location near the upper strata of particulate pollution  (+\- 1400').  

 

If I understand correctly, your unit can be used visually at 1x or can be inserted into your telescope's optical path so that the image is magnified.  Whereas the I3 was limited to the telescope's FL and the I3's built in eyepiece.  Using NV for very low mag 1-5x  (with or without an Ha filter) seems very appealing.  I have read many of the NV posts by Eddgie and others here all of whom make a compelling argument in favor of NV.  But the financial investment based on new prices, looks like it can quickly jump into many thousands of $.  

[The Ardent]

My friend who has the Collins I3 for fifteen years never had an H-a filter. I had him try mine back in October. He was very impressed with nebulas even in his slow SCT. All the times before the I3 was just a novelty for him (and us) Just something to try when bored.

My opinion: H-alpha filter is essential to enjoying night vision. Everyone who's looked at Cygnus with 3x and H-a has been really, really impressed with all the nebulosity. Invisible nebulae are visible with only 1 inch of aperture.

[Doug Culbertson]

I agree with Ray regarding the Ha filter. The first time that I looked through the Collins I3 it had a Ha filter and the views were spectacular.

 

As to the investment required to make the leap? I would suggest that, if you haven't already, you read the NV Astronomy article that was posted on CN a couple of weeks ago. There is a wealth of information presented there. Ray, Eddgie and Vondragonnoggin did a great job of spelling out what is needed for low power observing as well as using the NV device with a telescope. You can spend a LOT of money getting into this if you wish.

 

So far I have around $2300 invested in the used PVS-7, a 1.25" 620nm filter, a 1.25" 12nm Ha filter, a C mount adapter to convert my PVS-7 to accept C mount accessories, a C mount to 2" adapter (with 2" and 1.25" filter threads), a C mount ENVIS objective, an adapter to allow fitting 1.25" filters into the objective, and a 3x magnifier. Some of it was found on Ebay, and other stuff I had to do a bit of shopping around.

 

While that's a lot of stuff, some of it is for low power use with the NV device by itself, and may or may not be needed depending upon your intended use of the NV device. In the 6 days that I have had the PVS-7, I have been out 4 of those nights just sweeping the sky with the objective. Since I am still waiting for the filter adapter to arrive from RAFCamera in Belarus, I have not been able to try low power filtered views of the sky. In spite of that I could clearly make out faint nebulosity around Alnitak where the Flame and HH nebulae are located, as well as the Heart and Soul Nebulae.

 

So, would I do it over again? I believe that given the fact that this device will serve as a grab and go rig all by itself, and that I can also use it in my 11" dob (or other scopes), I would definitely do it again. FWIW, I will most likely sell off my refractor and mount to recoup some of the money spent on the PVS-7 as it's just not enough aperture, and the PVS-7 with 3x magnifier and filters is far easier to haul out and start using than the refractor.

 

If you decide to make the leap, ask questions here on CN, and ask a lot of questions of the sellers of these devices. When I determined that I was going to go with the PVS-7 rather than the NVD Micro due to budget constraints, I found several on Ebay that I was interested in, and I asked a lot of questions of each seller. The seller that had the one that I bought turned out to be an amateur astronomer himself, and assured me that I would be happy with the tube in this PVS-7. He was also the only one who was able to provide the exact specs for this tube.

 

That is just my experience so, since I am new to this, take it for what it is worth. There are people on this forum who can provide much better and more detailed information!

[Eddgie]

 I will most likely sell off my refractor and mount to recoup some of the money spent on the PVS-7 as it's just not enough aperture, and the PVS-7 with 3x magnifier and filters is far easier to haul out and start using than the refractor.

 

 

This was the message I was giving in my early reviews.  When people have telescopes that they don't use, it does not matter at all how good they are.    

 

Many people would be shocked to know that I sold a 6" Astro-Physics refractor to buy night vision.   This was a big scope that required a big mount and a lot of dedication to use.   And when I used it, I struggled to see things that were bright and easy in my 12" dob, which was much easier to use.

 

So, I had an expensive scope that got almost zero use, and I sold it to buy something that I use pretty much every night that there are stars to be seen.

 

 The NVD Micro fits in a shirt pocket, and the 3x mangifier will fit in a jacket pocket.  both will fit in a smaller space than a 31mm Nagler. 

 

The PVS-7 with a 35mm to 105mm f/2.8 SLR lens gives a 28 degree true field at the 35mm setting, and a 9.5 degree field at 105mm setting. 

 

 

This entire setup can be put together for well under $2000 including all adapters and lens pictured.  I see used PVS-7s selling for $1500 or less on a regular basis.

Edited by Eddgie, 22 January 2016 - 10:28 AM.

[Eddgie]

Also, a good NV device can make a smaller telescope perform like a larger one.   How is it possible to value something like that?

 

Using my NVD Micro or PVS-7 in my 140mm f/3.7 Comet Catcher lets me see stars, nebula, and galaxies that I struggle to see in my 12" dob and a conventional eyepiece.

 

I live in very light polluted skies.

 

This past summer, I would sometimes sit in a patio chair with the Comet Catcher in my lap and a NV device in the eyepiece and just scan around the sky.

 

It was like hand holding a 12" dob.   Wicked cool.  

 

I stood in the street in front of my house because trees blocked my western sky in the back yard where I would normally have to use a conventional telescope, and I viewed the Lagoon Nebula using the Comet Catcher cradled in my arms, and had the best view of the Lagoon in my life.  

 

As they say in the commercial:  " Priceless "

Very difficult to say what it is worth because it does things were value is hard to measure, from giving "Big Field" observing that is not possible with any other kind of instrument, to boosting performance of existing telescopes.  It could be argued that traditional ways to measure the reasonableness of a purchase are difficult to apply to night vision gear.
 

Edited by Eddgie, 22 January 2016 - 11:02 AM.

[Doug Culbertson]

Also, a good NV device can make a smaller telescope perform like a larger one.   How is it possible to value something like that?

 

 

As they say in the commercial:  " Priceless "

 

Exactly! The apparent increase in aperture is hard to explain, and is an often overlooked benefit to NV astronomy, IMO. During that first experience with the Collins I3 that I mentioned earlier, seeing the notch in IC 434 that is the Horse Head through a 4" telescope was amazing. Previously I had only seen the Horse Head as a notch through a 22" telescope using a Hydrogen Beta filter!

[GeezerGazer]

When used with a modest refractor of 4"-5", how does the image of the NVD Micro compare to the I3... Are there differences?

 

Thank you Doug, the NV Astonomy article will be digested carefully.

[Doug Culbertson]

While others on here are probably more qualified to answer your question, it is my opinipon that a thin film version of the I3 would perform very close to the NVD Micro in your TEC 140, assuming that you are using a Ha filter with both. The advantage that the NV devices have over the I3 is that they can be used for low power observing. Looking around my observing field at night is cool too. A few nights ago I watched a pair of foraging foxes keeping close to the edge of the woods. 

[Eddgie]

 

Also, a good NV device can make a smaller telescope perform like a larger one.   How is it possible to value something like that?

 

 

As they say in the commercial:  " Priceless "

 

Exactly! The apparent increase in aperture is hard to explain, and is an often overlooked benefit to NV astronomy, IMO. During that first experience with the Collins I3 that I mentioned earlier, seeing the notch in IC 434 that is the Horse Head through a 4" telescope was amazing. Previously I had only seen the Horse Head as a notch through a 22" telescope using a Hydrogen Beta filter!

 

 

Using the Micro (PVS-7 was on loan at the time but I am positive it would have done as well) and the 12" dob, even from my very light polluted back yard, not only did I see the notch, but the shape of the head, while faint, was clear and well resolved.

 

With respect to the question about whether the cost can be justified, I would say for me it is slam dunk.   I am seeing nebula that I never even knew existed before.    Some of them are so very large that it would be difficult to really see them any other way.   The Angelfish is a great example. 

 

I could not see this from my house, but one night I drove out to the dam (about 20 minutes, and not particularly black skies, but much darker than at my home).   When I saw the Angelfish, I was delighted and really surprised at how large it was.

Then there was Barnard's loop.   What a mind blower!  Talk about huge!!!!!! 

Edited by Eddgie, 23 January 2016 - 09:34 AM.

[Jeff Morgan]

 

Also, a good NV device can make a smaller telescope perform like a larger one.   How is it possible to value something like that?

 

 

As they say in the commercial:  " Priceless "

 

Exactly! The apparent increase in aperture is hard to explain, and is an often overlooked benefit to NV astronomy, IMO. During that first experience with the Collins I3 that I mentioned earlier, seeing the notch in IC 434 that is the Horse Head through a 4" telescope was amazing. Previously I had only seen the Horse Head as a notch through a 22" telescope using a Hydrogen Beta filter!

 

 

Doug, I am following your progress with interest.

 

A quick check of the Zambuto web site shows a price for a 22" mirror at $7,825. That is of course, just the mirror, not all the rest of the scope. One would be challenged just to get a basic working 22" scope together for less than $11,000.

 

In my high desert climate, a 22" would never thermally equalize and be unsatisfactory much beyond 130x.

 

And then there the weight of the scope to consider.

 

The one drawback I see to NV is that you effectively lose the capability of interchangeable eyepieces. As I understand it, when used as a telescope eyepiece, the NV device gives you one effective focal length (and magnification). To change that, it sounds like you need a barlow (increasing the telescope effective focal ratio and decreasing NV effectiveness) or a nearby large scope of the same focal ratio.

Edited by Jeff Morgan, 26 January 2016 - 11:52 PM.

[cnoct]

As I understand it, when used as a telescope eyepiece, the NV device gives you one effective focal length (and magnification). To change that, it sounds like you need a barlow (increasing the telescope effective focal ratio and decreasing NV effectiveness) or a nearby large scope of the same focal ratio.

Though it's a method I'm always hesitate to suggest, afocal mounting is an option. In instances where higher magnification is desired, afocal mounting produces better results than barlow. For best results, when mounting night vision in an afocal configuration, stick with simple eyepieces that have a focal length of less than 21mm.
 
There's a bit of feedback regarding afocal mounting of NV in this post (digiscope mount)

Here's a purely demonstrative photo depicting a night vision device in an afocal configuration...

[Doug Culbertson]

But, a barlow can be used, yes? As I recall from one of Ray's (The Ardent) posts, he uses a 2x Powermate. I also have a 2x Powermate and was planning to utilize it for extra magnification as needed.

 

Also, in the case of the PVS-7, does this device act as a 23mm or 26mm eyepiece? I was thinking 23mm.

 

Jeff, obviously I am unsure as I have not yet had the chance to use mine in my telescope.

[cnoct]

Sure, a barlow work, not ideal but neither is afocal mounting but that's just me wanting to tap directly into the flux of electrons, maximizing efficiencies.

There are DSO's which respond well and require more magnification than the prime system offers, in these cases either using a barlow, teleconverter or afocal mounting will give just that, a bit more magnification.

If one goes by the public specs, the PVS-7 would be equivalent to an eyepiece with a FL of 26mm. In reality, it's a touch over 26mm so to be safe just figure it lies between 26mm and 27mm.

Edited by cnoct, 27 January 2016 - 10:32 AM.

[Doug Culbertson]

Thanks, that's good information.

[Doug Culbertson]

The adapter to allow use of a 1.25" filter on the ENVIS objective arrived today, allowing a session with the 12nm Ha filter at 1x tonight. Holy cow! The California Nebula was easy and huge. Bernard's Loop was there, the Flame, a notch of the Horse Head, and the Rosette were all easy targets. Heart an Soul nebulae looked amazing.

 

I believe that I am hooked. 

[cnoct]

 It's a real   when, in an instant, the invisible hydrogen alpha regions pop into view. Like one walking into a living celestial museum, H-a splashed art splashed all over the dark canvas.

The existence of other dimensions is all the more tangible when one has this revealing H-a experience.

[Eddgie]

The adapter to allow use of a 1.25" filter on the ENVIS objective arrived today, allowing a session with the 12nm Ha filter at 1x tonight. Holy cow! The California Nebula was easy and huge. Bernard's Loop was there, the Flame, a notch of the Horse Head, and the Rosette were all easy targets. Heart an Soul nebulae looked amazing.

 

I believe that I am hooked. 

 

Wonderful.  So happy that your parts are all coming together!  

 

You can see why I have taken to calling it "Big Field" observing.  Far bigger and richer true field than can be obtained visually in just about any other way.

 

I now do the very vast majority of my own observing at 1x or 3x.  Even with a 40 degree apparent field, there is a Majesty to the sky that I never got from a Nagler eyepiece in a 4" Apo.   We live in a galaxy that I have recently learned is far more amazing than I ever realized.    

Thee more you view at these low powers, the more I think you will enjoy it.   

 

Thanks for sharing and looking forward to your continued reports.

[The Ardent]

Maffei 2, barely seen with my 18" dob and PVS-7.

In the city. In the glare of streetlights.

After 12 years of unsuccessful trying with normal eyepieces. "Drops mic like Neil Degrasse Tyson"

http://www.spitzer.c...e-Hidden-Galaxy

[Eddgie]

Wow!   Good stuff!

 

I had not really considered that there would be galaxies that were more visible in IR than in white light.

 

Did you detect any structure, or just the center?

 

 

Amazing to hear this.   

[The Ardent]

Just a uniform dim round glow, just barely seen over the background with averted vision.

Position and field stars verified with SkyTools planetarium software.

Averted vision with night vision!

[Doug Culbertson]

Maffei 2, barely seen with my 18" dob and PVS-7.

In the city. In the glare of streetlights.

After 12 years of unsuccessful trying with normal eyepieces. "Drops mic like Neil Degrasse Tyson"

http://www.spitzer.c...e-Hidden-Galaxy

 

Very cool! Probably out of reach for my 11" but, like Eddgie, I hadn't considered galaxies in IR.