36 replies to this topic

[Mazerski]

Back in 2017 a number of us on CNs purchased PVS7 goggle style, white phosphor with c-mount nosepiece and an ENVIS lens for $100. Then the ENVIS became unavailable and in 2019 or 2020, I spoke to the outfit that sold us the PVS7 and the lead tech said there were a box of ENVIS lenses somewhere in the shop To my knowledge the lenses never surfaced, at least not to Astro users. 
 

The sky condition makes all the difference. The ENVIS has a fast f/# which for me, lets too much light in even with 685nm IR filter. So I don’t do any 1x viewing but if I’m out west in a dark sky, it’s a different ballgame. 
 

I sold 2 ENVIS lenses but still have one, thinking that one day I’ll try afocal but in the multitude of photos posted on CNs, the length of the stack (as it’s called) makes me nervous. Has anyone experienced focuser sag from the weight of the pieces?  I own a NewMoon DOB with the lighter weight Starlight focuser and the TS Boren-Simon with the focuser that comes with scope.

[sixela]

Afocal stacks are usually long but some are not that heavy, though. You should see my 150mm f/4 Newt with the afocal stacks (the most ridiculous one is the one with a Paracorr)...it's ridiculous but it works.

Here's my record stack on my earlier 130mm:



And yes, I did use it, even though I now use another coma corrector that doesn't throw out the focal plane as far as a Paracorr (and also requires more in-travel than the Paracorr).

Edited by sixela, 16 August 2024 - 01:53 PM.

[sixela]

This is the new TV67 stack (with a PVS-14 instead of an OVNI-M):


The one with a Nexus and a 40mm Plössl is even shorter (and even lighter too).

Edited by sixela, 16 August 2024 - 01:55 PM.

[Mazerski]

Thanks for throwing up the photos… that first stack looks radical. How many times did you or friends bang into it with the noggin? 2nd photo: Nexus, is this similar to the TS ASA corrector / reducer? To guess, the stack looks to be the Nexus, spacer/adapter, eyepiece, I assume the smaller 67mm EP that TV sells and connector between EP and I assume the objective of the PVS14. 

[sixela]

Yeah, that second photo is identical with the TS Maxfield, the Nexus or the Skywatcher 0.86x reducer that I got with the scope. Basically: any coma corrector that requires the sensor or eyepiece focal plane to be 55mm above the flange.

And yes, you named all the elements correctly. The TV67 is rather special in that its focal plane position is actually hovering below its barrel on the telescope side, which makes the stack longer (all these extenders between the coma corrector and the TV67 barrel). The TV40+Nexus stack is much shorter.

Of course the stack is also longer because it's a photo-Newton whose focal plane is thrown out roughly quite a bit from the fully racked in focuser. But it's on purpose, to avoid the coma corrector sticking out into the light path at the other end.

Edited by sixela, 16 August 2024 - 02:30 PM.

[Mazerski]

Of course the stack is also longer because it's a photo-Newton whose focal plane is thrown out roughly quite a bit from the fully racked in focuser. But it's on purpose, to avoid the coma corrector sticking out into the light path at the other end.

The Born-Simon is an Astrograph and what you said never occurred to me. Maybe one day I’ll save up for the afocal pieces… using NV in Prime Mode seems a lot simpler. 

[GGK]

The Born-Simon is an Astrograph and what you said never occurred to me. Maybe one day I’ll save up for the afocal pieces… using NV in Prime Mode seems a lot simpler. 

I’ll be using refractors and an SCT, and prime focus definitely looks like a easier compact set-up. But it looks to me like Afocal has a lot of benefits /capability missing in prime, so I’m planning the parts to do both.

 

This thread and the other one I started on the specific parts have been very helpful to me to understand what I need to get started. The component pictures from various users have been very cool and really help me picture the parts coming together into the assembly. 
 

Thanks to all for the input and your comments about your experience. 
 

Gary

[chemisted]

The Born-Simon is an Astrograph and what you said never occurred to me. Maybe one day I’ll save up for the afocal pieces… using NV in Prime Mode seems a lot simpler. 

Mazerski,

 

Save some bucks and contact Gary Russell.  Have him fix up one of his 65mm Plossls with 2" threads at the top and you will be good to go with afocal.  Not only do you save money but weight as well.  His eyepieces are made from Delrin and are much lighter than the TV 55mm.  I have more than one and can attest to the optical quality.

 

Ed

[Mazerski]

Thanks Ed… will do a search on the 65mm // Gary. Stay tuned as I may have questions.

[Jeff Morgan]

ENVIS lenses can still be had if you're willing to do a little horse trading. For example, at this moment there are five M703E ENVIS monoculars for sale on ebay, each complete with its original objective lens. They pop up on ebay quite regularly. Buy one, transfer the lens to your RVM/MOD3C/prime-converted PVS-14, then resell the remaining parts. Or find a standard C-mount lens, like a Computar v2513 or similar, put it back on the M703, and use it for camping or navigating around your dark site or whatever.

 

More than anything else, it is the perception that matters.

 

Those of us with prime focus units know that configuration changes are as simple as opening a jar of peanut butter.

 

However, look at the number of posts and threads here from prospective NV buyers trying to wrap their head around it.

 

Add to that the prospect of having to churn thru many different 1x objectives to find a “good” one, and the entire NV adventure looks expensive and complicated. Who wants to scour eBay for six months?

 

Granted for astronomy I am using more than 1x 95% of the time, but a solid 1x solution is virtually required for terrestrial NV use. Easy availability of an “ENVIS” lens (or close clone) from the manufacturer at time of purchase would encourage the fence sitters.

[chemisted]

Thanks Ed… will do a search on the 65mm // Gary. Stay tuned as I may have questions.

So it looks like his web page is being updated.  Here is his contact information:  https://www.citlink.net/~optics/

 

My experience is that he is delightful over the phone and answered email quickly.  He calls the eyepiece a 65mm Super Plossl and has cut the threads in the top for a number of customers.

[WheezyGod]

More than anything else, it is the perception that matters.

Those of us with prime focus units know that configuration changes are as simple as opening a jar of peanut butter.

However, look at the number of posts and threads here from prospective NV buyers trying to wrap their head around it.

Add to that the prospect of having to churn thru many different 1x objectives to find a “good” one, and the entire NV adventure looks expensive and complicated. Who wants to scour eBay for six months?

Granted for astronomy I am using more than 1x 95% of the time, but a solid 1x solution is virtually required for terrestrial NV use. Easy availability of an “ENVIS” lens (or close clone) from the manufacturer at time of purchase would encourage the fence sitters.

Agreed. The only reason I went Mod3 a couple Dec’s ago was because I reached out to someone selling Envis parts on EBay who said he had 4 Envis objective lens that he was going to sell and told me when he was going to post them on CNs. Without this I probably would have caved for a PVS-14 if nothing popped up after a few months. I wanted the ability to observe in prime and the flexibility of using different lens beyond 1x, but not enough to wait around for an Envis forever. I also didn’t want to deal with the hassle of buying an Envis unit and trying to sell it without the lens.

However, if I was looking to buy now and learned that one of the RVM lens was detachable and equivalent or better in quality/focal ratio to the standard PVS-14 lens, then I would order the RVM. Although it isn’t clear if this is the case or not.