13 replies to this topic

[woody wood]

Not too familiar with this eyepiece but I found it in my drawer of goodies. Used it once but not 100% sure of its performance. Maybe I didn't let it acclimate to the weather or maybe I was expecting too much from it visually but it's not terribly clear. I managed to point it at M51 and an unidentified nebula. Greenlight surrounded by bright stars but not sharp. Appeared to sharpen as I backed off of the eyepiece. Quick snapshots with my iPhone through a 4" SCT at F/6.3. I've also tried using it with a 60 mm refractor. What if any experiences have been had out there with this particular eyepiece. I don't know if this is something I want to continue playing with or if perhaps somebody might be interested in taking it off my hands I'd be willing to sell it. I guess I'll make a decision based on the responses I get from this topic. 

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Edited by woody wood, 05 July 2024 - 01:40 PM.

[chemisted]

To get sharp stars you need to adjust the diopter.  Did you do that? If not, loosen the retainer ring at the eye lens and adjust by rotating the eye lens assembly.

 

That is the first version of the I³ that predates the current thin film Gen III devices but can still give creditable results.  The best deep sky objects to show its superiority to glass are globular clusters. Now is a good time to give them a try. 

Edited by chemisted, 05 July 2024 - 02:02 PM.

[TOMDEY]

I had one of those long ago. It was good, albeit unnecessarily heavy and clunky. My newer Night Vision ITT Gen 3 are more user friendly, lighter, and especially with better eyepiece on the tail end. I was involved on the evaluation end of these at work. The best field use devices are quite amazing.    Tom

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[Jeff Morgan]

Grab yourself a h-alpha filter - doesn't have to be tight, 12nm will do - and prepare to see the Milky Way like you have never seen it before.

[Jeff Morgan]

 

That is the first version of the I³ that predates the current thin film Gen III devices but can still give creditable results.  The best deep sky objects to show its superiority to glass are globular clusters. Now is a good time to give them a try. 

 

For sure. In my 130mm f/7 refractor, every glob I observed resolved into many dozens of stars. Even the faint NGC ones. Usually too many to hope to count.

[woody wood]

Is this the ring you're talking about?

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[Highburymark]

For sure. In my 130mm f/7 refractor, every glob I observed resolved into many dozens of stars. Even the faint NGC ones. Usually too many to hope to count.

Even with a smallish TV85, the only summer glob I struggle to resolve at my Bortle 4-5 holiday site is M107. Love globular clusters with an image intensifier.
I’ve never used an l3, but it would be fun to try one. A piece of history.

[chemisted]

Is this the ring you're talking about?

Yes, that's it all right.  Judging from my I³ you probably need to screw your eye lens out a fair amount.  I got mine in 2002 and it still sees a lot of regular use even though my other NVDs might be described as 'more powerful'.

 

Here it is paired with an equally vintage TeleVue refractor:  https://www.cloudyni...0109-135342576/

Edited by chemisted, 05 July 2024 - 06:46 PM.

[Eddgie]

The key to getting the best performance from these eyepieces is to use filters.

 

An IR long pass filter (650nm or longer, down to 690nm) will block the vast majority of light pollution. Since the device is very sensitive to red light, you don't need the wavelengths that are typically associated with artificial lighting.  This will turn a suburban sky into a dark sky for observing purposes.

 

The second filter has already been mentioned, and that is a narrow band Hydrogen Alpha filter. This filter will only pass the a narrow range of wavelengths around 654nm.  This suppresses both light pollution and the all of the infra-red sky glow, and makes it possible to see even faint nebula from bright skies. 

 

Have an epic day!

[csrlice12]

Of course they're no longer being made, so if something fritzes out, it's a paper weight.  Those early tubes aren't known for their longevity.  Nice piece of eyepiece history though.  Used to live not far from where the shop was.

[chemisted]

Of course they're no longer being made, so if something fritzes out, it's a paper weight.  Those early tubes aren't known for their longevity.  Nice piece of eyepiece history though.  Used to live not far from where the shop was.

The Gen III tubes in all I³ devices have a nominal life of 10,000 hours - the same as today.  Mine is 22 years old and operates as if it were brand new.

 

Bill Collins was a true pioneer in this niche of the hobby.  I treasure the conversations that I had with him.  Much later in life I moved to Evergreen and was a member of DAS for a few years.  I asked the club president if they had ever had Bill in to give a talk.  He replied that they had not.  I think that was a real opportunity lost.

[Jeff Morgan]

Correct me if I am wrong, but isn't the intensifier in the i3 the F9800 - still being made?

[noisejammer]

I find the B+W 091 (roughly the same as as Wratten #29) filter works really well. It passes H-alpha so that emission nebulae are visible. I got mine in 48mm off the shelf but I think this is now a special order.

 

Globular clusters are great. Other objects emit a lot of light at a part of the spectrum that is outside the photocathode's response.

 

My experience is there is very little light pollution longer than ~600 nm. Presumably this is because it doesn't make much sense to illuminate things with light humans can't see.

[chemisted]

Correct me if I am wrong, but isn't the intensifier in the i3 the F9800 - still being made?

All of Bill's tubes were from ITT and they were the F9800 series which has the green phosphor screen (P-43).  I have a tube from one of his last devices for which he provided a summary data sheet.  He labeled the tube 'F9800 Select +Thin Film, No Export'.  It is really a wonderful performer.

 

Whether or not these green phosphor tubes are still being made is an open question.  I talked with Malcolm at Night Vision Devices a few months ago and came away with the impression that the military is not ordering them anymore and consequently the manufacturer was not expected to switch over their production lines from the F9400 series (P-45) to make the F9800 in the future.