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Review: Celestron 15mm Spotting Scope Eyepiece/ 12mm Angel Eyes

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#1 RLK1

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Posted 09 May 2023 - 02:28 PM

My impressions:

First, I have to say how shocked I was on how good the $12.00 Celestron 15mm spotting scope eyepiece turned out to be. Frankly, for what it is, I think you'd be hard pressed to find something much better. 

Being a spotting scope eyepiece, and described as a wide angle ocular, it's quite user-friendly with ample eye relief with the stated specs of 20mm and an AFOV of 52 degrees. However, I peg it at 18mm at around 60 degrees AFOV based upon my comparos with my pentax eyepieces of the same-specced eye relief but without any tendency of either blackouts or sensitivity to head placement. I compared it to a vintage Celestron Ultima 15mm wide angle ocular with an AFOV of 70 degrees and an Antares elite 15mm 5 element plossl with a 50 degree AFOV, both of which are Japanese manufactured pseudo-Masuyama eyepieces.

I ran comparos of the eyepieces, with and without a paracorr, in my 16" f4.5 astrosystems dob last night in front my my moderately light polluted home (SQM 19.13). I had good seeing conditions and reasonable transparency along with moderate dew formation. 

My first target was Venus and my observations were essentially a bit limited because I chose to view it during twilight since its too bright for me to take under darker conditions. That said, you will likely see flare and a bit of light fogging in the eyepiece with some of it bouncing off your cornea. Still, the planet was reasonably viewed in all three eyepieces, with the best edge correction noted in the lesser AFOV Antares eyepiece. Without a paracorr, the spotting scope eyepiece shows chromatic aberration at about 75% out from the center and about 85% out from center with a paracorr. Similar findings were noted with the Ultima wide angle eyepiece. 

My second target was Arcturus and I noted astigmatism in the spotting scope eyepiece, with a similar presentation out from the center of the field as noted above on Venus. The wide angle Ultima also exhibited some stig but not as pronounced as in the spotting scope eyepiece. I did not notice any SAEP or any brightening at the edge.

Where the spotting scope eyepiece hit the sweet spot for me was in the observations of DSOs. I suspect it matched my exit pupil nearly perfectly under my light polluted conditions. Viewing various springtime galaxies with different eyepieces, I was, again, shocked on how well this eyepiece performed. With a paracorr in place for all observations,  the "pup" in the whale and the pup appeared the brightest in the spotting scope eyepiece, with or without a broadband UHC filter, as compared to the 12mm Angel Eyes wide angle eyepiece or my 10.5mm pentax ocular. Of these eyepiece, the hockey stick appeared the brightest with the spotting scope eyepiece. Additionally, the large galaxy near the hockey stick, NGC 4631, appeared to seemingly fill almost two thirds of the AFOV. I was stunned by the view. Lower contrast galaxies, like NGC 3628, the dimmer member of the Leo trio, and the Siamese twins in Virgo, were identified in short order, despite the level of light pollution. I don't attribute the successful observations to this ocular being some super-duper eyepiece but, again, it apparently matched my exit pupil and observing conditions splendidly for me. 

Although I didn't do any day time observations with it, I'd expect it to perform well since it's designed for use in spotting scopes and these are typically used during the day. 

When I ordered it, my guess was it probably would be a plossl design but after using it, I suspect it's a repurposed binocular eyepiece, and a relatively good one at that, and my estimation is it's probably a modified erfle of some sort.

Finally, the eyepiece, along with the others I'm describing, does not approach the spot image diameter, quality and contrast and resolution of my 10mm Ethos. I suspect the 15mm spotting scope eyepiece would not fare all that well in one of Ernest's bench tests. Still, based upon what I saw last night, it'll be a go to eyepiece for various DSOs under my observing conditions. I'll reserve judgment on how well it does under dark sky conditions later in the month. Speaking of the latter, I feel it's interesting to note that the moon, at only a few days past full and at more than 90% illumination, didn't rise until 11:30pm and I couldn't see it until nearly midnight and when it did rise, it was well over to the southeast.  Contrast this with one of the months that the moon rides the highest in the sky but nobody seems to notice, probably because of the holidays or inclement weather, that being the month of December. So, if the weather is decent in May, I should have quite a few nights of dark sky observing available to me, unfettered by the moon...

PS: The Celestron spotting scope eyepiece currently sells for $12.00 via a vendor on Aliexpress or $42.00 from vendors on ebay.

Turning now to the Angel Eyes 70 degree AFOV 12mm eyepiece, I found its AFOV to be closer to Ernest's measurement of around 60 degrees AFOV with about 12mm or so of useable eye relief. It would likely be tight for an eyeglass wearer. It has a funke blue border around the edge of the field of view, probably because of the barrel, and I call Ernest saw a blue border in his sample as well. My experience with edge performance was similar to that of the 15mm spotting scope eyepiece described above but with less edge aberrations. Contrast was relatively good on m51and m53. It was easier to spot the black eye in m64 and the dark lane in the large edge on galaxy, NGC 4565, than in the Celestron spotting scope eyepiece, probably because the increased magnification darkened the background a bit more. 

The eyepiece currently sells for around $40.00 via a vendor on Aliexpress. I did like it but I was more enamored by the Celestron spotting scope eyepiece. No SAEP or edge of field brightening and no serious faults to speak of. Comparing it to my venerable UO 12.5mm ortho, it falls a bit short on planetary performance on Venus but otherwise it performs well on DSOs. Like the Celestron spotting scope eyepiece, I'll reserve judgment of performance under dark sky conditions at a later time...


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#2 RLK1

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Posted 20 May 2023 - 03:16 PM

I know everybody's been clamoring to know how well the Celestron spotting scope eyepiece performed under dark sky conditions as we know it's on the top of your list. grin.gif

Well, I had an opportunity to check it on a couple of scopes last night under good skies and I'm pleased to report it afforded itself reasonably well. As one amateur put it, it's not as good as a 12mm delight we put up against it (the Delight's contrast was clearly better and it wasn't just the 2 mm of shorter focal length that was accounting for it, either) but the Delight wasn't 20x better, either.

We both felt it was better than a standard plossl eyepiece of similar focal length that is available these days.

Bottom line, if you can find a better eyepiece of comparable cost and focal length, buy it. Otherwise, the 15 mm Celestron spotting scope eyepiece available via a vendor at Aliexpress for $12.00 is bargain-priced diamond in the rough:

https://www.aliexpre...id=0BmKOm1aW0Kz

PS: I just got a second one today for a binoviewer!     


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#3 Sarkikos

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Posted 20 February 2024 - 12:27 PM

I saw this eyepiece on AliExpress today.  I couldn't resist buying a pair for binoviewing.  $25.44 shipped.

 

They had been on sale at Agena Astro for $85.94, original price $109.95.  At that site, they are marked as "discontinued."   https://agenaastro.c...iece-82001.html

 

Mike


Edited by Sarkikos, 20 February 2024 - 12:29 PM.

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#4 Polyphemos

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Posted 20 February 2024 - 02:44 PM

I saw this eyepiece on AliExpress today.  I couldn't resist buying a pair for binoviewing.  $25.44 shipped.

 

They had been on sale at Agena Astro for $85.94, original price $109.95.  At that site, they are marked as "discontinued."   https://agenaastro.c...iece-82001.html

 

Mike

I picked up a pair myself. Shockingly good for $12 each.

 

My only complaint was that the eye protector moved far too easily. A small self-adhesive dot I punched out of flocking paper added just the right amount of resistance and made the action perfect.

 

IMG_2476.jpeg


Edited by Polyphemos, 20 February 2024 - 03:08 PM.

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#5 saemark30

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Posted 20 February 2024 - 03:38 PM

The Celestron spotting scope eyepiece is shockingly good at F6. I haven't measured the fl, so it may be 15mm or 18mm.

I looked at the quarter moon and it was razor sharp. Markly superior to a 20mm XWA 100deg eyepiece.

On deep sky I was pleasantly surprised by the good detail seen in the Orion Nebula with a decent UHC filter.

The open cluster M41 was a fine sprinkle of stars.

It is better than a generic plossl in sharpness.


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#6 Polyphemos

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Posted 20 February 2024 - 04:08 PM

The Celestron spotting scope eyepiece is shockingly good at F6. I haven't measured the fl, so it may be 15mm or 18mm.

I looked at the quarter moon and it was razor sharp. Markly superior to a 20mm XWA 100deg eyepiece.

On deep sky I was pleasantly surprised by the good detail seen in the Orion Nebula with a decent UHC filter.

The open cluster M41 was a fine sprinkle of stars.

It is better than a generic plossl in sharpness.

Nice assessment. I wonder how many lenses it has? Despite it’s apparently wider field of view, edge correction is as good or better than that of my 3, 4, or 5 lens eyepieces.


Edited by Polyphemos, 20 February 2024 - 04:13 PM.


#7 Doug Culbertson

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Posted 20 February 2024 - 04:59 PM

One of my favorite binoviewer pairs. Nice review. 


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#8 Sarkikos

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Posted 20 February 2024 - 07:09 PM

I picked up a pair myself. Shockingly good for $12 each.

 

My only complaint was that the eye protector moved far too easily. A small self-adhesive dot I punched out of flocking paper added just the right amount of resistance and made the action perfect.

 

attachicon.gif IMG_2476.jpeg

I wear glasses, so I keep eye protectors (eye cups) all way down or take them off.

 

Mike


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#9 starfinder123123

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Posted 20 February 2024 - 08:39 PM

It is very good.


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#10 RichA

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Posted 20 February 2024 - 10:04 PM

I saw this eyepiece on AliExpress today.  I couldn't resist buying a pair for binoviewing.  $25.44 shipped.

 

They had been on sale at Agena Astro for $85.94, original price $109.95.  At that site, they are marked as "discontinued."   https://agenaastro.c...iece-82001.html

 

Mike

History of eyepiece crossovers.  The 22x wide angle on the Bausch & Lomb Spacemaster was the same eyepiece as the 20mm Meade RG Wide Angle.


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#11 RichA

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Posted 20 February 2024 - 10:28 PM

I picked up a pair myself. Shockingly good for $12 each.

 

My only complaint was that the eye protector moved far too easily. A small self-adhesive dot I punched out of flocking paper added just the right amount of resistance and made the action perfect.

 

attachicon.gif IMG_2476.jpeg

https://www.aliexpre....5067f19cQDQNwX

 

Same FOV as Plossl, interesting though.



#12 Polyphemos

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Posted 20 February 2024 - 11:11 PM

https://www.aliexpre....5067f19cQDQNwX

 

Same FOV as Plossl, interesting though.

I don’t have direct evidence but I think Don measured the apparent field of view to be around 65°.

 

https://www.cloudyni...ssl/?p=12988915

 

Not Don, so second hand, but if true that’s pretty good. Seems to be quite a bit wider than my 15mm Plössl and I can easily believe 60° and possibly 65° just eyeballing it.

 

Perhaps Don will confirm or deny the rumor?


Edited by Polyphemos, 20 February 2024 - 11:19 PM.


#13 RichA

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Posted 20 February 2024 - 11:15 PM

Don’t quote me, but I think Don measured the apparent field of view to be around 65°.

Different.  One of the seller sites spec said 52.



#14 Polyphemos

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Posted 20 February 2024 - 11:23 PM

Different.  One of the seller sites spec said 52.

There was some discussion on the thread from which I pulled the post that the seller was incorrect.

 

https://www.cloudyni...ssl/?p=12988915

 

I really don’t know what the AFOV, but it certainly looks much wider than a Plössl.



#15 CrazyPanda

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Posted 21 February 2024 - 11:54 AM

Placed an order for one of these for $12, and there was also a welcome deal for a 15mm Celestron Omni Plossl for $4.80 (free shipping).

 

Guess I'll be doing a mini-shootout between this 15mm spotting scope eyepiece ($12), 15mm Celestron Omni ($4.80), 15mm Tele Vue Delite ($256), and 15mm Svbony Red Line ($7) :D


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#16 RLK1

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Posted 21 February 2024 - 12:55 PM

Placed an order for one of these for $12, and there was also a welcome deal for a 15mm Celestron Omni Plossl for $4.80 (free shipping).

 

Guess I'll be doing a mini-shootout between this 15mm spotting scope eyepiece ($12), 15mm Celestron Omni ($4.80), 15mm Tele Vue Delite ($256), and 15mm Svbony Red Line ($7) laugh.gif

Bring it on!



#17 Orion68

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Posted 29 February 2024 - 11:12 PM

I just got my $12 Celestron 15mm. Quality is good and came with sturdy box, caps, cloth bag and cleaning cloth. Rain outside so I viewed through the window and saw no obvious issues. Sharp field stop. Looks good to me. Star test will tell for sure. Happy so far.


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#18 CrazyPanda

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Posted 02 March 2024 - 03:04 PM

Mine just arrived today.

 

It's a surprisingly high quality eyepiece for $12. Heavy, very nice deep anti-reflection coatings, perfectly clean optics.

 

The twist up eyeguard mechanically is flimsy but I like the fact that it behaves like a light trap the way Tele Vue DeLites do. The field stop is the sharpest I've seen in any eyepiece (at least during the day anyway), contrast is excellent with zero unwanted light around the exit pupil. I noted some strong field curvature with this eyepiece in my 130mm F/7 refractor. I know the refractor has its own FC, but this eyepiece seems to reinforce it. Pretty substantial difference in focus between center and edge. Edge correction is pretty good overall at F/7, but not perfect. I noted some strong lateral color - a bright white object produced yellow and purple copies of itself near the edge - similar to some other wide angle eyepieces I own like Pentax XWs.

 

Also arrived was the 15mm Celestron Omni Plossl. Most surprising about this Plossl is how good the eye relief is. I have a 20mm TV Plossl which has far less effective eye relief than this 15mm Celestron Omni.The interior of the Omni is very well blackened and baffled. Field stop in the Plossl is also very sharp and contrast is excellent. However, the field falls apart quite quickly as you leave the center, even at F/7. No question that the spotting scope eyepiece has better overall edge performance.

 

I'm looking forward to trying both these eyepieces under the stars and comparing them against the 15mm Red Line and 15mm DeLite.


Edited by CrazyPanda, 02 March 2024 - 03:08 PM.

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#19 RLK1

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Posted 02 March 2024 - 03:12 PM

Mine just arrived today.

 

It's a surprisingly high quality eyepiece for $12. Heavy, very nice deep anti-reflection coatings, perfectly clean optics.

 

The twist up eyeguard mechanically is flimsy but I like the fact that it behaves like a light trap the way Tele Vue DeLites do. The field stop is the sharpest I've seen in any eyepiece (at least during the day anyway), contrast is excellent with zero unwanted light around the exit pupil. I noted some strong field curvature with this eyepiece in my 130mm F/7 refractor. I know the refractor has its own FC, but this eyepiece seems to reinforce it. Pretty substantial difference in focus between center and edge. Edge correction is pretty good overall at F/7, but not perfect. I noted some strong lateral color - a bright white object produced yellow and purple copies of itself near the edge - similar to some other wide angle eyepieces I own like Pentax XWs.

 

Also arrived was the 15mm Celestron Omni Plossl. Most surprising about this Plossl is how good the eye relief is. I have a 20mm TV Plossl which has far less effective eye relief than this 15mm Celestron Omni.The interior of the Omni is very well blackened and baffled. Field stop in the Plossl is also very sharp and contrast is excellent. However, the field falls apart quite quickly as you leave the center, even at F/7. No question that the spotting scope eyepiece has better overall edge performance.

 

I'm looking forward to trying both these eyepieces under the stars and comparing them against the 15mm Red Line and 15mm DeLite.

I'd like your estimation of the AFOV of the spotting scope eyepiece. I recall one poster drift timed it at 58 degrees and essentially the same as my estimate of 60 degrees.



#20 CrazyPanda

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Posted 02 March 2024 - 03:15 PM

Yeah about 60 degrees is my estimate as well.



#21 Polyphemos

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Posted 03 March 2024 - 02:07 PM

I'd like your estimation of the AFOV of the spotting scope eyepiece. I recall one poster drift timed it at 58 degrees and essentially the same as my estimate of 60 degrees.

Speculation on the AFOV has been all over the place, ranging for the same as a Plössl to 70°.

 

Measuring the AFOV using a flashlight, tape measure, and some high school trig seems simple enough, and I’ll look into my eyepiece when I return from vacation in a couple of days. If anyone want to get a head start, here’s the techniques I’ll employ:

 

https://www.cloudyni...ent/?p=11923517



#22 RLK1

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Posted 03 March 2024 - 03:51 PM

Speculation on the AFOV has been all over the place, ranging for the same as a Plössl to 70°.

 

Measuring the AFOV using a flashlight, tape measure, and some high school trig seems simple enough, and I’ll look into my eyepiece when I return from vacation in a couple of days. If anyone want to get a head start, here’s the techniques I’ll employ:

 

https://www.cloudyni...ent/?p=11923517

I hadn't seen any estimates at 70 AFOV and I'd consider that to be wildly inaccurate.

There are several methods of determining AFOV but I don't know if one is really more accurate than the other or, more importantly, if they've been been compared in a rigorous manner to determine reliability. 

But, I'd prefer not to go off on a tangent on methodology so we will see what you get and add it to the mix... 


Edited by RLK1, 03 March 2024 - 03:51 PM.


#23 Polyphemos

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Posted 03 March 2024 - 05:17 PM

For those who are interested in measuring the AFOV of the subject eyepiece or any other, here’s an easy and repeatable method:

 

https://www.cloudyni.../#entry10394414

Here’s an interesting measurement setup in a post by Jon:

 

https://www.cloudyni...view/?p=7916259

 

In essence the most popular techniques for measuring AFOV are deviations of the same general method with allowances made for what’s at hand for a light source and eyepiece stand. They’re all pretty simple and easy.

 

 


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#24 Sarkikos

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Posted 03 March 2024 - 05:26 PM

The easiest way to determine the AFOV is to hold the eyepiece up to one eye and compare the field of view to another eyepiece held up to the other eye.  Superimpose the two fields and see how they compare. 

 

No math, flashlights, tripods, rulers, clocks or other equipment necessary.  This method is dependent, though, on having a range of eyepieces with known AFOV's close to the AFOV of the eyepiece whose AFOV you don't know.   

 

I just now compared the AFOV of the Celestron 15mm to a DeLite 7mm.  The Delite's AFOV is 62 degrees.  The two fields appear the same when I superimpose them.  If it isn't 62 degrees, it's really close.

 

Mike


Edited by Sarkikos, 03 March 2024 - 05:38 PM.

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#25 CrazyPanda

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Posted 04 March 2024 - 08:15 AM

Just compared the fields of the 15 DeLite with this spotting scope eyepiece. The field stops overlap, so I'd say 62 degrees is pretty accurate.


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