Nagler T6 help.

[The_bluester]

Does anyone have an exploded diagram of an 11mm T6 nagler?

Mine some time back suffered from horrendous internal fogging (my biggest gripe with it) and I had to disassemble it to let it air dry to clear. My normal routine was just to remove the eye lens from the top as it is a discrete screw in assembly, then the main barrel from the bottom lens assembly, sitting the whole lot upright to dry.

The only section at any risk is the main barrel as the lenses inside are loose, no problem unless someone turns it upside down on you, need I say more? I have not had the chance to use it for some time and worked out tonight that it is not right.

There are two lenses/elements in that section and two spacers, I can probably trial and error re assemble it but every time I take it apart I risk cocking a lens and damaging it or damaging the edge blackening. I have found three alternatives so far that result in not being able to get the edge of the fov in focus! If anyone has an exploded diagram that would be great.

[Larryp]

Maybe contact Televue and ask for their help.

[The_bluester]

From what I have seen in the past they will advise you to send it back to them and they will sort it out.

All very well but with the post two ways and whatever they charge to re assemble it I could probably buy a new one!

Just a pity, I recall a review of the ES line compared to the televues with x ray images (obviously pretty hard to take the sealed ES ones to bits) but I can not find it again.

[mikerr]

Paul, try posting on the "Cloudy Nights" site in the "Eyepieces" forum.
I remember seeing the X Ray pictures that you refer to, and it was probably on that site.

Good luck

Michael.

[casstony]

If you have internal fogging in future you might try sealing the eyepiece inside a zip lock bag with a large quantity of dessicant (eg. Selley's Absorb-it). When not in use I store my eyepieces in an air-tight case with a rechargeable dessicant pack.

[The_bluester]

I might have helped myself out actually. I did some googling after I gave up last night and saw it referenced that the T6 was a 7 element design based off the original Nagler arther than the 8 element design that is more common now. A bit more googling found me a patent filed by Al Nagler himself in the late 70's showing a 7 lens arrangement quite like what mine has.

I will get some cotton gloves and take it apart again and clean it gently while the elements are out and then re assemble matching the arrangment on the patent. That only leaves the spacing up to chance and hopefully I can get it back in order again, there are only two spacers to play with. If that does not sort me I will give Cloudy Nights a try.

It does make me think seriously about the advantages of the ES line being sealed. It would avoid the potential for the internal fogging. The Nagler is the only one that does it, I have a Meade SWA that I bought from another IIS member and a couple of Televue Plossls plus the Celestron Plossl that came with the scope, none of the others suffer the fogging to any great degree and it usually only seems to be the eyelens where the Nagler goes out in the middle of the pack quite early in the night. With all the others the corrector plate is usually gone long before they fog.

The other "Next thing" on the list might have to be a dew heater for the scope with a second belt for the EP to keep it above ambient and keep the mosture at bay.

[The_bluester]

I reckon mine matches the design at the bottom of this image (From Wikipedia)

http://upload.wikimedia.org/wikipedia/commons/6/6c/Nagler_1979_1981.png

[erick]

Yes, heating strap on eyepiece while in use (great when you walk away for a while and forget to cap the eyepiece!

And a heated eyepiece box to store them in: http://www.iceinspace.com.au/forum/showthread.php?t=33500

[The_bluester]

Well, reassembled it going from the info off the net and it seemed reasonable on scenery, very hard to tell as it is a poor eyepiece to use in daylight and very inclined to produce kydney beans and blackouts. Of course now it is cloudy, I will have to wait and see how it goes next time under starlight.

[David Niven]

Put it in a vacuum chamber and it will dry out in no time!

[anj026]

Here is the link to the Ethos 13mm verses Explore Scientific 14mm with x-ray images.

http://www.svenwienstein.de/HTML/es_14mm_ethos_13mm_English.html

[The_bluester]

I acturally re found that last night, it is interesting that the general arrangement is pretty similar to the Nagler, obviously different curvatures and glasses but a pretty similar concept.

Here is hoping that I get to have a peer through it on the weekend and that it performs like it used to. It is a terrefic EP for objects like the Orion nebula and gave great views of areas like the trapezium. I would hate to have to replace it.

I kept thinking that I was imagining things and maybe it does not function well with the 2" diagonal and was showing me an incompatibility with the C925 that was vignetted away with the 1.25" diagonal, but we were at Snake Valley early this year with the 2" diagonal and the EP spent half the night in the scope, most of the other half with the Meade SWA I then bought off an IIS'er in it.