•

## CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

87 replies to this topic

### #76 Procyon

Procyon

Fly Me to the Moon

• Posts: 6,734
• Joined: 23 Feb 2009

Posted 11 May 2020 - 01:40 PM

If it's 90° instead of 100°, the eye lens need only be 40mm wide to have 20mm of eye relief.
A 38mm lens implies, using 90° as the field, an eye relief of 19mm.
It looks like the lens could be maybe 2mm below the rubber surface of the eyecup, so an effective eye relief of maybe 17mm.

Of course, if the apparent field is <90°, the eye relief is longer. If the apparent field is >90°, then the eye relief is shorter.
At a true 100°, the eye relief with a 38mm lens is 15.9mm, making effective eye relief <14mm, so not compatible with glasses.

Hi Don, just measured the ES 25 100 lens and it's 32.5mm wide. It's been said to have an Afov of 103 degrees, eye relief feels like 17mm or more though instead of 14.5mm. How to calculate the eye relief with these numbers? hmmmm.

Edited by Procyon, 11 May 2020 - 01:40 PM.

• 25585 likes this

### #77 Starman1

Starman1

Vendor (EyepiecesEtc.com)

• Posts: 50,714
• Joined: 23 Jun 2003
• Loc: Los Angeles

Posted 11 May 2020 - 03:57 PM

At 100°, the 32.5mm wide lens cannot have an eye relief of more than 13.64mm + the concavity of the top lens.

ES says the eye relief is 14.5mm on that eyepiece, which is consistent with the calculation + 0.86mm concavity.  Likely to be dead on.

The apparent field of 100° is consistent with the quoted 41.0mm field stop and about 6.4% field distortion, which is a bit more than many other eyepieces,

but still not bad for eyepieces overall.  It's about the same as the APM UWA 12.5mm or the Docter/Noblex 12.5mm

I don't think 103° is consistent with any other figures.  In fact, if the apparent field were under 100°, the distortion figures would be lower.

• Procyon likes this

### #78 Jon Isaacs

Jon Isaacs

ISS

• Posts: 92,657
• Joined: 16 Jun 2004
• Loc: San Diego and Boulevard, CA

Posted 13 May 2020 - 05:40 AM

Hi Don, just measured the ES 25 100 lens and it's 32.5mm wide. It's been said to have an Afov of 103 degrees, eye relief feels like 17mm or more though instead of 14.5mm. How to calculate the eye relief with these numbers? hmmmm.

You can calculate the maximum possible eye relief measured at the edge of the eye lens if you know the actual AFoV and the diameter of the eye lens.  It's just trigonometry.  The AFoV forms a isosceles triangle whose base is the eye lens diameter and whose height is eye relief.

The equation:

Eye Relief = (Lens diameter/2) /(tangent (AFoV/2)  = (32.5/2) /(tan(103deg/2) = 12.93 mm

If the AFoV is 100 degrees, then you get Don's numbers.

One can measure the AFoV using what I call David Knisely's projected beam method.

https://www.cloudyni...p/#entry6604421

Jon

• John Rogers and Procyon like this

### #79 naramsin

naramsin

Mariner 2

• Posts: 219
• Joined: 03 May 2016

Posted 13 May 2020 - 10:01 PM

Here's a quickie completely unscientific update on the 21mm MWA. Tonight I focused only on the aesthetics in comparison several other eyepieces. The scope was a 8" f5 Orion Newt with a hybrid focuser upgrade (more on that below) and a GSO Coma Corrector (with appropriate spacer rings for 2" and a tunable top for 1.25"). Targets were Venus, M35, and M13.

The 21mm worked nicely with the GSO. No noticeable coma. Stars were nicely shaped (for a newt) overall. It also worked well with the CC plus a Luminos 2" 2.5X barlow.

I compared it to a few favorites, the 16mm Meade 3000 (made in Japan version with rubber eye guard), and TV smoothie plössls (10.5mm, 17mm, and 21mm). I threw in an ES 11mm and Meade 5.5mm 82°. They were all great. The plössls generally seemed to have even nicer AND fainter stars and (to my eyes) darker blacks than the MWA. I imagine owing to less scatter, fewer elements, etc. But I'm not dwelling on this aspect.

The 21mm MWA was pleasant to use and wonderful for sweeping the sky, since it provides such a huge 'window.' WIth the barlow Venus was gorgeous with its delicate crescent on the twilit sky. M35 had that painterly effect when the background stars illuminate the blacks. And M13 was resolvable in dozens of stars in my humble newt. It was similar in overall effect to the ES 11mm 82°. The best view of M13 was the Meade 5.5mm though. I thought I saw the dark lanes nicknamed the propeller.....but maybe it was my imagination?

In sum, I enjoy the MWA. In use it does not seem different from the two 82° EPs, probably because it isn't. But for an 80ish 21mm it's not bad. And I found it to be very comfortable, with and without glasses. In fact, the 21mm MWA, 11mm ES, and 5.5mm Meade would make a nice minimalist set.

Focusers: I broke a bearing on the original Crayford focuser that came with the Orion. I have no doubt that I would have broken it tonight with the MWA, CC, and barlow attached. You really want to have a beefy focuser for these moosey EPs! I settled on the Orion Orion 13036 hybrid focuser, which is pretty good overall.

• eros312, Procyon, Magnitude7 and 1 other like this

### #80 MrJones

MrJones

Mercury-Atlas

• Posts: 2,738
• Joined: 15 Sep 2010
• Loc: Indiana

Posted 23 May 2020 - 11:21 AM

Based partly on the review here and also hoping Meade improved the MWA line as this EP come out much later, I now have one of these. I tried and quickly sold the 10mm and 15mm MWAs a few years ago. Here it is between a decloaked Maxvision 40mm SWA and ES68 34mm. The idea was that it would replace my ES68 34mm if I liked it - the Meade is only slightly bigger than the ES 68 34mm.

The outside design is alright, the rubber grip is actually quite nice and the eyecup is very good. The top cap does not fit tight but is not loose either. I find it to be a pretty good looking eyepiece overall in person. That's the quick ergonomic review.

I've not had good nights with it, just a few murky views along with daylight comparisons but thought I'd post what I've learned so far. Testing has been only in my f/7 AT102ED. A little but not a lot of eye position management is needed. I don't wear glasses but it seems like plenty of eye relief to me for them, but it's also not too much for me as I sometimes find. I doubt the 25mm ER claim and would say more like 20mm.

I have to peer far "around the edges" to see the field stop, as with the other MWAs I've used. More so than Ethos EPs require. This means looking in at an almost 45 degree angle from the side. Of course the rest of the field does not look good at this angle. The EP is sharp over most of the FOV at f/7, with no major problems otherwise and no EOFB was seen. It is exceptionally sharp over most of the center actually, with good contrast and no weird glare.

OK so far but then I tried it against my ES68 34mm. The MWA should in theory have a wider FOV than the ES68 but was a little short of it, even with the aforementioned peering from steep angles to see the field stop. If the ES68 34mm is indeed 68 degrees and 34mm, I estimate the Meade 26mm MWA has an 85 degree AFOV. Yikes. This is about +/- 1 degree, it's not even close to 90 degrees if it's 26mm.

However, the magnification difference seemed a little too large going from 34mm to 26mm so I've compared it with my ES68 24mm. This is with the low profile 1.25" adaptor in the GSO 2" quartz diagonal. Magnifications seem very close swapping back and forth with the MWA of course having a noticeably larger AFOV. My conclusion is that this is more like a 24mm 92 degree eyepiece. Maybe 25mm 89 degrees or something in between. I've spent most of the daylight testing time going back and forth between these 2 EPs, mostly because it's not going to replace my ES68 34mm but might still be a keeper for 2" between the ES68 24mm and 34mm. A good test comparison for this EP would be against a TV 26T5, which I used to own. This Meade might actually beat the 26T5 for overall sharpness and contrast across the main FOV - it's really quite good. I have birdfeeders hung with coated copper wire in the backyard and the text on the wires is even clearer in the Meade MWA than my very good ES68 24mm.

I'm a little surprised to say it's not an immediate sell for me after finding the TFOV less than that of the ES68 34mm. It's an intriguing eyepiece, especially if you like the no field stop view. It's not what it is advertised to be but a good 24-25mm 90ish degree EP at this price is not a bad thing. More night time testing needed at this point.

#### Attached Thumbnails

Edited by MrJones, 23 May 2020 - 11:27 AM.

• Procyon, faackanders2 and 25585 like this

### #81 25585

25585

Voyager 1

• Posts: 13,089
• Joined: 29 Aug 2017
• Loc: In a valley, in the SW UK. Dark end of the street.

Posted 24 May 2020 - 12:20 AM

Thanks for your review MrJones, I will get one for my birthday maybe.

### #82 Astrojensen

Astrojensen

Voyager 1

• Posts: 14,143
• Joined: 05 Oct 2008
• Loc: Bornholm, Denmark

Posted 24 May 2020 - 03:40 AM

Hmmmmmm. Shapes up to be quite an interesting eyepiece, from these early reviews, even if it falls a bit short of the listed specs.

Clear skies!
Thomas, Denmark

• 25585 likes this

### #83 MrJones

MrJones

Mercury-Atlas

• Posts: 2,738
• Joined: 15 Sep 2010
• Loc: Indiana

Posted 24 May 2020 - 09:52 AM

Thanks. After all that, it was clear enough last night although the sky was bright with humidity and light pollution. I took the setup out for 20 minutes that turned into 2 hours on M81/82, M13 and other globs.

To clarify my eye position management comment, this EP has some SAEP. Hovering just above the eyecup works to give the maximum no-field-stop FOV where I could tilt my view and see more of the field in any direction but pressing my face into the eyecup results in kidney beaning. I would classify it as mild because it's easy to avoid but it's there. I'm also going to say the eye relief could be 25mm after all. It's easily at least 20mm.

Again it seemed to have the same magnification of the ES68 24mm but with an obviously bigger and yes more immersive view. No EOFB at all though and again I found it to be very sharp and contrasty, even against my old favorite the ES68 24mm. Maybe they did update something vs. the rest of the MWA line.

I've bought and sold 2 versions of the APM XWA 20mm, a Luminos 23mm, a Nagler 26T5 and a Pan 27. Could this be the one?

The biggest annoyance with it is putting it away and it still says "26mm 100° AFOV" on the side. Big fat Meade liars. But they didn't get it all wrong and I still don't hate it.

• 25585 likes this

### #84 faackanders2

faackanders2

Fly Me to the Moon

• topic starter
• Posts: 6,843
• Joined: 28 Mar 2011

Posted 24 May 2020 - 11:19 PM

Thanks. After all that, it was clear enough last night although the sky was bright with humidity and light pollution. I took the setup out for 20 minutes that turned into 2 hours on M81/82, M13 and other globs.

To clarify my eye position management comment, this EP has some SAEP. Hovering just above the eyecup works to give the maximum no-field-stop FOV where I could tilt my view and see more of the field in any direction but pressing my face into the eyecup results in kidney beaning. I would classify it as mild because it's easy to avoid but it's there. I'm also going to say the eye relief could be 25mm after all. It's easily at least 20mm.

Again it seemed to have the same magnification of the ES68 24mm but with an obviously bigger and yes more immersive view. No EOFB at all though and again I found it to be very sharp and contrasty, even against my old favorite the ES68 24mm. Maybe they did update something vs. the rest of the MWA line.

I've bought and sold 2 versions of the APM XWA 20mm, a Luminos 23mm, a Nagler 26T5 and a Pan 27. Could this be the one?

The biggest annoyance with it is putting it away and it still says "26mm 100° AFOV" on the side. Big fat Meade liars. But they didn't get it all wrong and I still don't hate it.

Makes it really hard to compare eyepiece when specifications are wrong!  Meade used to be better than this.

• John Huntley and MrJones like this

### #85 MrJones

MrJones

Mercury-Atlas

• Posts: 2,738
• Joined: 15 Sep 2010
• Loc: Indiana

Posted 25 May 2020 - 09:10 AM

Unfortunately it gets worse - I may have overestimated this one.

I got up at 3:30AM and took the setup out to a glorious summer Milky Way with nearby Jupiter and Saturn side by side.

Paying a little more attention I have to say the SAEP is fairly intrusive. I would get a something nicely framed then immediately get  kidney beaning as I explored the FOV. I also finally evaluated astigmatism and quickly noticed the stars were not pinpoints across the view at all. In fact they are noticeably larger at about 50% then nice seagulls by the edge. I still didn't hate it because it's so sharp and transparent in the center and there's no EOFB or other weird glare. Open clusters like M25 that I admit I often skip over were stunning.

But then I tried to put a 2" UHC filter on it. The diameter of the threaded bottom of the barrel is too large and the filter just fell out. Same with my OIII and H-beta. These filters fit all of my current 2" eyepieces and I'm pretty sure any that I've ever put them in.

That's a deal killer.

p.s. I apologize for any slight of the 26T5. Although it didn't wow me \$600 worth it certainly had none of these problems.

• eros312 and 25585 like this

### #86 25585

25585

Voyager 1

• Posts: 13,089
• Joined: 29 Aug 2017
• Loc: In a valley, in the SW UK. Dark end of the street.

Posted 25 May 2020 - 02:55 PM

That is a shame. And a deal killer. Better to have the same TFOV & less magnification or vice versa.

• MrJones likes this

### #87 Miranda2525

Miranda2525

Gemini

• Posts: 3,031
• Joined: 12 Jul 2016

Posted 25 May 2020 - 03:46 PM

Unfortunately it gets worse - I may have overestimated this one.

I got up at 3:30AM and took the setup out to a glorious summer Milky Way with nearby Jupiter and Saturn side by side.

Paying a little more attention I have to say the SAEP is fairly intrusive. I would get a something nicely framed then immediately get  kidney beaning as I explored the FOV. I also finally evaluated astigmatism and quickly noticed the stars were not pinpoints across the view at all. In fact they are noticeably larger at about 50% then nice seagulls by the edge. I still didn't hate it because it's so sharp and transparent in the center and there's no EOFB or other weird glare. Open clusters like M25 that I admit I often skip over were stunning.

But then I tried to put a 2" UHC filter on it. The diameter of the threaded bottom of the barrel is too large and the filter just fell out. Same with my OIII and H-beta. These filters fit all of my current 2" eyepieces and I'm pretty sure any that I've ever put them in.

That's a deal killer.

p.s. I apologize for any slight of the 26T5. Although it didn't wow me \$600 worth it certainly had none of these problems.

SAEP is a big deal for me as well. Thanks for noting this and letting all of us know. Big deal-breaker for me also, so I would not be interested. Looks like the tolerance for the barrel diameter is off, which is a HUGE deal breaker.

Edited by Miranda2525, 26 May 2020 - 05:11 AM.

• MrJones and 25585 like this

### #88 Starman1

Starman1

Vendor (EyepiecesEtc.com)

• Posts: 50,714
• Joined: 23 Jun 2003
• Loc: Los Angeles

Posted 06 June 2020 - 01:09 PM

In depth review of this 79-83° eyepiece:

https://stargazerslo...wa-26mm-report/

• John Rogers and eros312 like this

## Recent Topics

 Cloudy Nights LLC Cloudy Nights Sponsor: Astronomics