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22mm Vixen LVW question !!!

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#1 Scanning4Comets

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Posted 11 February 2013 - 03:59 PM

Can the bottom half of the 22mm Vixen LVW be taken off, (unscrewed), and a Baader fine tuning ring be added in between to make it a shorter FL eyepiece? I am just curious as to what it would perform like with the Baader 28mm FTR in between the two parts. :question:

Thanks in advance!

#2 Starman81

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Posted 11 February 2013 - 05:05 PM

Can the bottom half of the 22mm Vixen LVW be taken off, (unscrewed), and a Baader fine tuning ring be added in between to make it a shorter FL eyepiece? I am just curious as to what it would perform like with the Baader 28mm FTR in between the two parts. :question:

Thanks in advance!


Too scared to try on your own LVW 22? :lol:

#3 jjack's

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Posted 11 February 2013 - 05:12 PM

I Don't recommand to unscrew and dismantle these kind of eyepiece.
It is made with a sort of barlow in the barel that focus near the lens in the core. My friend do th with its Hyperion and some subtle dusts were put on this internal lens. We never could remove the totality of that dust. Now his eyepiece is usable for deep sky, but on the moon we see a lot of pinpoint microscopic dust and that's bother a lot.
take care !

#4 Scanning4Comets

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Posted 11 February 2013 - 07:23 PM

You're darn right Syed! Not going to risk messing mine up, when I can see if someone else has done it to their's first, HAHA! Good points on the dust, which I did think about as well.

I haven't removed the bottom half at all as of yet, and I don't think I will now! I don't even think the bottom of the 22mm Vixen LVW has a "smythe" lens anyways, unless I am wrong ?

Cheers,

#5 SeattleScott

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Posted 11 February 2013 - 08:19 PM

I have a few LVW's and got curious about this once, but upon inspection I really didn't get the impression the LVW's were designed for this, and felt it was a bad idea and didn't try it. Good point about the dust, all the more reason not to try it.

#6 Phillip Creed

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Posted 11 February 2013 - 10:38 PM

One thing I would be curious about, too, is what happens if you machine out the field stop (~25mm) to the max 27mm for a 1.25"-EP, effectively making a 22mm 70-deg EP.

Again, not something I'd *recommend* doing, but it'd be interesting to see what happens.

Clear Skies,
Phil

#7 jjack's

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Posted 12 February 2013 - 03:35 AM

One thing I would be curious about, too, is what happens if you machine out the field stop (~25mm) to the max 27mm for a 1.25"-EP, effectively making a 22mm 70-deg EP.

Again, not something I'd *recommend* doing, but it'd be interesting to see what happens

You can got two things :
-larger field but with more degraded stars.
-you can loose the sharp field stop and get something like vigneting and loose the resale value.
not recommanded too.

#8 iluxo

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Posted 12 February 2013 - 04:42 AM

Yes, the LVW22 does have a 2-element Smythe lens. And yes, the Smythe lens is mounted in the 1.25" barrel and can be removed, as this unscrews from the 2" barrel section.

What you then have is a 2" barrel containing a longer focal length eyepiece with shorter eyerelief and no field stop, and the remaining lens elements are mounted in an inner sleeve approx 30mm diameter. Optically it's not good without the Smythe lens.

With respect to the other Vixen LV and LVW's, all the smaller ones from LV25mm (LV) and the LVW22 have a Smythe lens.

The 30mm NLVW and 50mm LV do not, no real surprise.

I don't have a 42mm LVW but I'd expect it is similar to the 30mm (ie no Smythe lens).

As for removing the field stop this is a rather poor idea as most eyepieces have aberrations that get extremely bad just outside the field stop so you'll see LOTS OF COMETS, and you're ruining what was a fine eyepiece. You won't improve an eyepiece by such crude measures.

If you want a different focal length or ultra wide field go buy another eyepiece rather than ruin a very nice one.


#9 Phillip Creed

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Posted 12 February 2013 - 10:33 AM

I'll take apart my 22mm LVW right around...never.

Clear Skies,
Phil

#10 Scanning4Comets

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Posted 12 February 2013 - 12:50 PM

:funny:






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