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Unusual Vixen 100mm eyepiece

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#51 Astrojensen

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Posted 05 August 2018 - 03:02 PM

Vixen's 100 may just be a shorter FL ep with a barlow, all in one unit. And where is it made?

With a barlow? I think you mean with a compressor. 

 

 

Clear skies!
Thomas, Denmark


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#52 Starman1

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Posted 05 August 2018 - 03:06 PM

31mm Naglers have for me too-short eye relief. The 35 and 41 Panoptics are just OK. Best is my TV 55mm Plossl. This is usable eye relief, not advertised.

 

Takahashi advertise 28mm eye relief for their 32mm Abbe. The eye lens is so recessed usable relief is 17mm. So the advertised amount was not the usable amount. I have read the LE ep is similar.

 

Vixen's 100 may just be a shorter FL ep with a barlow, all in one unit. And where is it made?

The 31mm Nagler has a 19mm eye relief.

But, that's from the glass, which is concave on the eye lens.  And, there is some aluminum height above that and some height to the rubber eyecup above that, even folded down.

So the "Effective" eye relief is more like 15-16mm.

 

For glasses wearers, it is the Effective figure that counts, and it would be an unusual set of eyeglasses that sits so close to the eye that 15-16mm would be enough eye relief, even with the

glasses touching the rubber eyecup.

 

And if you don't want to have your expensive glasses touch the rubber eyecup?

I figure you need to have at least 20mm of Effective Eye Relief to use an eyepiece, and that means the eye relief parameter of the eyepiece should be a minimum of 23-24mm.

I really sympathize for people who must wear glasses to observe.  Not many eyepieces have eye reliefs that long.


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#53 Simon B

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Posted 05 August 2018 - 04:25 PM

https://www.vixen.co...roduct/35203_6/

 

 

The specs table shows 11° AFOV....  what the heck  confused1.gif

 

I just read a blog of someone who had been to the CP+ 2018 Vixen booth and checked out the eyepiece.... he was puzzled by the thing, and said it was extremely narrow, much more so than the typical 40° he was used to, and that one would probably be better off with a 40mm plossl. Also the eyepiece has a crosshair reticle.

 

 

Hey what would happen if I stacked barlows with it lol.gif


Edited by Simon B, 05 August 2018 - 05:05 PM.


#54 Simon B

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Posted 05 August 2018 - 05:00 PM

Okay I did find a little more info..... According to a fellow on Twitter in Japan:

 

Eyepiece is 186mm in physical length. It is just a single lens, it looks uncoated. The crosshair reticle is below the lens, and can be removed if one wished to do so. Upon using the eyepiece, it is rather prone to blackout. With the Mewlon 250, it gives 30x and 0.36° TFOV.

 

 

Okay I think he just calculated the mag. and TFOV based on the eyepiece's apparent specs, I don't think he measured it himself.

 

 

You can see pics near the bottom of the page

 

https://ja.whotwi.co...4/tweets?page=2

 

 

 

Sooo, um, yeah, largely useless it seems



#55 25585

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Posted 08 August 2018 - 01:01 PM

The 31mm Nagler has a 19mm eye relief.

But, that's from the glass, which is concave on the eye lens.  And, there is some aluminum height above that and some height to the rubber eyecup above that, even folded down.

So the "Effective" eye relief is more like 15-16mm.

 

For glasses wearers, it is the Effective figure that counts, and it would be an unusual set of eyeglasses that sits so close to the eye that 15-16mm would be enough eye relief, even with the

glasses touching the rubber eyecup.

 

And if you don't want to have your expensive glasses touch the rubber eyecup?

I figure you need to have at least 20mm of Effective Eye Relief to use an eyepiece, and that means the eye relief parameter of the eyepiece should be a minimum of 23-24mm.

I really sympathize for people who must wear glasses to observe.  Not many eyepieces have eye reliefs that long

Thanks Don. Yes it's, as an understatement, frustrating to find an eyepiece bought on spec, to find its not good enough.

 

My most pleasant surprise has been Baader Morpheus. They are the new Vixen LVW, if not better.

 

That 100mm is a novelty, but it could be Vixen's longest eye relief optic in current production. Cheap enough to experiment with.   



#56 BillP

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Posted 08 August 2018 - 10:19 PM

I'm scratching my head a bit over this one.

 

Why?  Wouldn't everyone want tiny AFOVs with 7.8mm exit pupils when used in the 70mm light bucket of a scope advertised? 


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#57 Simon B

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Posted 21 August 2018 - 01:26 AM

I received mine a few days ago.... here are a few details and pictures

 

 

Vixen Finder Eyepiece 100 (1)

 

 

Vixen Finder Eyepiece 100 (2)

 

 

Vixen Finder Eyepiece 100 (3)

 

 

Vixen Finder Eyepiece 100 (4)

 

 

 

Haven't taken the lens assembly apart but apparently it's an uncoated singlet - can't confirm but it certainly looks that way to me. You can see in the last image the crosshair at the field stop. It's a very delicate crosshair, made of thin foil or something... you can probably easily remove it by peeling it off, but it's made of rather flimsy material so I don't know if you'd be able to glue it back on. If you remove it it's probably a one-way procedure

 

 

I tested it briefly in my Starblast 62. Based on some rough measurements and calcs:

 

 

Field stop:   20mm

 

TFOV (520mm FL):   ~2.2°

 

Max TFOV (520mm FL):   ~3.1°

 

AFOV:   ~11.5°

 

 

 

My determined AFOV seems to match with Vixen's specs (11°)

 

 

 

All in all a very odd eyepiece. If it had closer to max. field stop (~27mm), then it could be useful, otherwise I see no real use for it. I'll keep it around as a strange novelty piece, but I doubt I'll ever use it


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#58 Starman1

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Posted 21 August 2018 - 10:22 AM

Apparently, as Vixen describes it, its purpose is to replace the finder scope with an eyepiece that essentially turns the eyepiece into a finder scope, yielding, perhaps an 11° field at 6x magnification or something similar.

It's oriented to smaller refractors and the idea is to allow the scope owner to search for something using an eyepiece instead of a finder scope.

So there was some rational thought behind its creation.

Maybe.


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#59 25585

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Posted 22 August 2018 - 05:07 AM

Apparently, as Vixen describes it, its purpose is to replace the finder scope with an eyepiece that essentially turns the eyepiece into a finder scope, yielding, perhaps an 11° field at 6x magnification or something similar.

It's oriented to smaller refractors and the idea is to allow the scope owner to search for something using an eyepiece instead of a finder scope.

So there was some rational thought behind its creation.

Maybe.

Smaller refractors may have the 100 instead of a pea shooter finder in future. Could be cheaper for Vixen.



#60 Astrojensen

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Posted 22 August 2018 - 08:08 AM

Smaller refractors may have the 100 instead of a pea shooter finder in future. Could be cheaper for Vixen.

A 6x30 RACI is only something like $15 more expensive and is infinitely more useful. 

 

 

Clear skies!
Thomas, Denmark


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#61 Simon B

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Posted 22 August 2018 - 08:31 AM

A 32mm plossl would make a better finder....

 

 

 

 

Heck, even a 25mm plossl would make a better finder grin.gif


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#62 25585

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Posted 22 August 2018 - 11:47 AM

OK. What TFOV do you get from your current finder ep for any particular scope? To me finders are for zoning in - RDF (Telrad) to finder to main scope.



#63 faackanders2

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Posted 26 August 2018 - 12:06 PM

Apparently, as Vixen describes it, its purpose is to replace the finder scope with an eyepiece that essentially turns the eyepiece into a finder scope, yielding, perhaps an 11° field at 6x magnification or something similar.
It's oriented to smaller refractors and the idea is to allow the scope owner to search for something using an eyepiece instead of a finder scope.
So there was some rational thought behind its creation.
Maybe.

I would rather have a 24mm 68 AFOV Panoptic, 18mm 82 AFOV ES or a 2" 40mm 70AFOV UO MK70 Koenig eyepiece as finder eyepieces for my ST80 finder (or on my 17.5" f4.1 Dob main scope).

#64 faackanders2

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Posted 26 August 2018 - 12:11 PM

I received mine a few days ago.... here are a few details and pictures
Haven't taken the lens assembly apart but apparently it's an uncoated singlet - can't confirm but it certainly looks that way to me. You can see in the last image the crosshair at the field stop. It's a very delicate crosshair, made of thin foil or something... you can probably easily remove it by peeling it off, but it's made of rather flimsy material so I don't know if you'd be able to glue it back on. If you remove it it's probably a one-way procedure
I tested it briefly in my Starblast 62. Based on some rough measurements and calcs:
 
 
Field stop:   20mm
 
TFOV (520mm FL):   ~2.2°
 
Max TFOV (520mm FL):   ~3.1°
 
AFOV:   ~11.5°
 
 
 
My determined AFOV seems to match with Vixen's specs (11°)
 
 
 
All in all a very odd eyepiece. If it had closer to max. field stop (~27mm), then it could be useful, otherwise I see no real use for it. I'll keep it around as a strange novelty piece, but I doubt I'll ever use it


11 deg AFOV is this a record for smallest AFOV?
What was Vixen thinking?

Edited by faackanders2, 26 August 2018 - 12:16 PM.

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#65 Astrojensen

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Posted 26 August 2018 - 12:19 PM

What was Vixen thinking?

I have no idea. This thing isn't even remotely useful. 

 

 

Clear skies!
Thomas, Denmark


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#66 BillP

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Posted 26 September 2018 - 08:02 PM

I have no idea. This thing isn't even remotely useful.

 

Well...it might be some internal wager at the company...seeing if a product would sell even if it was totally ridiculous...because when it comes to people in this hobby suckers are not born every minute, but every arcsecond  lol.gif

 

Would it even be possible to find anything in a tiny 11 degree AFOV? 


Edited by BillP, 26 September 2018 - 08:11 PM.

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#67 dothead

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Posted 27 September 2018 - 04:16 PM

The 100 mm eyepiece would be very useful for this 8 inch F/225 aerial refractor, yielding a magnification of 457 x (exit pupil of 0.44 mm), with a TFOV of 87 arcseconds - which would frame Jupiter just perfectly ! A superb planetary eyepiece !

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#68 dothead

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Posted 27 September 2018 - 04:33 PM

And before anyone dares to ridicule this setup:

Using this refractor, Hevelius created the most accurate maps of the moon up till then, he detected the moon's libration and made the most advanced observations of sunspots.

 

And Cassini, using the refractors pictured below, made stunning discoveries about the Saturnian System.

 

Nowadays, we amateur astronomers have all become girlie men !!!

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Edited by dothead, 27 September 2018 - 04:36 PM.

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#69 faackanders2

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Posted 29 September 2018 - 04:39 PM

Well...it might be some internal wager at the company...seeing if a product would sell even if it was totally ridiculous...because when it comes to people in this hobby suckers are not born every minute, but every arcsecond  lol.gif
 
Would it even be possible to find anything in a tiny 11 degree AFOV?

Maybe it was made for the giant observatory scopes. but the mrket is small

#70 luxo II

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Posted 03 October 2018 - 02:02 AM

According to the Vixen website its purpose was to be used used with small refractors to provide an 8X magnification as a "finder" view. Never mind that the exit pupil is hopelessly wrong.

 

Bear in mind in Japan the most popular telescopes sold there are small refractors typically 80-100mm f/7 - not 8" SCTs or big dobsonians - and with small refractors it would actually work well enough as a finder.


Edited by luxo II, 03 October 2018 - 02:04 AM.


#71 25585

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Posted 03 October 2018 - 07:40 AM

Its AFOV being only 11 degrees is small, but so is the magnification.

 

In a 900mm refractor, that is 9x, a finder magnification figure. The TFOV would be smaller than a 9x50 finder, but say using a 9x100 finder, the extra detail for star hopping in its view would be useful.

 

For 500mm, 5x magnification - maybe too small. Just over 2 degrees TFOV. Could work for scopes without 2 inch capability such as spotters. The Japanese never really adopted 2 inch for visual use, hence the extra plumbing needed on Vixens, some Taks.

 

Maybe its just for jokes. "Is that an eyepiece in your pocket, or....." 



#72 dothead

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Posted 03 October 2018 - 02:53 PM

Maybe its just for jokes. "Is that an eyepiece in your pocket, or....."

No, it's for 45,000 mm aerial refractors ...


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#73 ultraclassic1

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Posted 04 November 2018 - 06:03 PM

I just got the Vixen Finder Eyepiece 100 Item #35203 somewhat by mistake. Thought I would do a review for it on my YouTube channel before it gets returned. This is the link: https://www.youtube....BE9kJXEwk&t=43s

 

Thanks Tony


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#74 Peter Besenbruch

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Posted 05 November 2018 - 08:43 PM

Nowadays, we amateur astronomers have all become girlie men !!!

And some of us may be girlie girls. ;)



#75 scopeboy42

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Posted 16 December 2018 - 06:41 PM

Since this only has a single lens do you think it might work as a solar projection eyepiece? Just wondering if there could actually be a use for it.




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