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Astromania eyepieces

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#1 John Fitzgerald

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Posted 07 December 2022 - 05:16 PM

https://www.amazon.c...ct_details&th=1

 

These look exactly like the BST Planetary eyepieces.  The focal lengths are very close.  Is the 7.5mm in the link really 7.5mm, or is it the same eyepiece as the 7 or 8, except for labelling?  The difference seems very, very small.  Same with the 4.5mm.


Edited by John Fitzgerald, 07 December 2022 - 05:21 PM.


#2 CowTipton

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Posted 07 December 2022 - 05:25 PM

I believe they're rebranded TMB II eyepieces.

I have no opinion on the quality though.



#3 Sky Muse

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Posted 07 December 2022 - 07:33 PM

The Astromania and BST planetaries are the same as these TMB clones that I have...

 

4mm & 6mm2b.jpg

 

No matter which you have, if you want to get the most out of it, the interior of the barrel and the edges of the lenses round should be ultra-flat blackened.



#4 pj_thomas

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Posted 08 December 2022 - 11:10 AM

I believe they're rebranded TMB II eyepieces.

I have no opinion on the quality though.

From agena:

"Please Note: While these eyepieces look similar to the TMB / TMB II ED eyepieces (and are also sold by some other sellers incorrectly under the TMB label), they are not the same as or copies of the 6-element TMB eyepieces. The factory making these eyepieces just uses the same external housing for the eyepieces."


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#5 John Fitzgerald

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Posted 19 December 2022 - 06:26 PM

I got the Astromania 7.5mm Planetary eyepiece.  At f/8, my particular sample is very nearly the equal of a Delite.  It's shockingly good for its cost.  I paid about $44 including tax.  I haven't tested it at lower focal ratios.  I suspect it might falter at f/5.



#6 great_bear

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Posted 19 December 2022 - 07:09 PM

I got the Astromania 7.5mm Planetary eyepiece.  At f/8, my particular sample is very nearly the equal of a Delite.  It's shockingly good for its cost.  I paid about $44 including tax.  I haven't tested it at lower focal ratios.  I suspect it might falter at f/5.

I’ve had a few of these “clones” over the years, including the Sky-Watcher version of it. 
 

They are in fact, very good at F5, and present a very nice view with a crisp field-stop and (in my scopes) very even illumination, but they do have the following two issues:

  1. Serious glare issues on bright targets
  2. When pushing a scope to its maximum, present a rather “mushy” view
    (fuzzy diffraction spikes around bright stars)

So whilst a casual glance at a star field might present a Delite-like view, I would expect that performing a Luna comparison at the edge of the scope’s limit will provide a view that’s very much inferior to a Delite. 


Edited by great_bear, 19 December 2022 - 07:12 PM.

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#7 John Fitzgerald

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Posted 19 December 2022 - 07:24 PM

I’ve had a few of these “clones” over the years, including the Sky-Watcher version of it. 
 

They are in fact, very good at F5, and present a very nice view with a crisp field-stop and (in my scopes) very even illumination, but they do have the following two issues:

  1. Serious glare issues on bright targets
  2. When pushing a scope to its maximum, present a rather “mushy” view
    (fuzzy diffraction spikes around bright stars)

So whilst a casual glance at a star field might present a Delite-like view, I would expect that performing a Luna comparison at the edge of the scope’s limit will provide a view that’s very much inferior to a Delite. 

My comparisons were with some close double stars, and Mars.  162x.



#8 great_bear

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Posted 19 December 2022 - 07:29 PM

My comparisons were with some close double stars, and Mars.  162x.

In my experience, it’s once the exit pupil drops below 1mm that the fuzziness on (very) bright stars appears. 



#9 John Fitzgerald

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Posted 19 December 2022 - 07:35 PM

Computed exit pupil for a 7.5mm eyepiece in my f/8 triplet is 0.94mm.



#10 great_bear

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Posted 19 December 2022 - 07:41 PM

Computed exit pupil for a 7.5mm eyepiece in my f/8 triplet is 0.94mm.

Just on the limit there, IMO. 



#11 John Fitzgerald

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Posted 19 December 2022 - 07:44 PM

Even with the stated shortcomings, it's still a very good value.



#12 great_bear

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Posted 19 December 2022 - 08:02 PM

Even with the stated shortcomings, it's still a very good value.

Very much so - I had an 8mm once that I was very fond of and always regretted selling. 




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