A couple of eyepieces that are great value

[gregbradley]

I have been accumulating good eyepieces lately.

A couple of surprise eyepieces are the TMB Planetary 11's and Edmunds RKE 28mm.

The TMB 7mm costs about AUD $53 on ebay or AliExpress and its a wow eyepiece with a 58 degree field and very sharp, bright, low to no chromatic aberration. Its well made as well. Crazy good for the price.

The other is Edmunds Optics 28mm RKE. I got this from Edmunds direct and I
paid Singapore $90 + shipping.

If you read the thread all time favourite 10 eyepieces I was amazed to see how often the 28mm RKE was listed. I tried mine out last week and was surprised by how nice it was. 45 degree field of view but at 28mm its quite a wide view.

Greg.

[AG Hybrid]

Its the 28mm RKE with its seemingly half meter of eye relief that creates an effect that the image is floating above the eyepiece itself. Its a lot of fun but no body is making any serious observations with it.

[bigjoe]

.
Greg Hi..

Got the 8mm TMB11 from Allie..put it up against my 9mm Nagler and said.."This cant be happening"!..Better Contrast and ALMOST as Clear..Jupiters Belts were Browner and the GRS a darker pink ..prob due to Only 5 Elements versus 7..but still NOT what I wanted to see as the 9mm Nagler is a great EP.
Hope it was due to the slight mag diff in 1800mm scope!

PS: Dont tell Anyone..Shhh!
Bigjoe

[astro744]

The view through the 28mm RKE is unlike any I have seen before and I bought mine simply to experience this view described by others as floating. You don’t get the feel as if you’re floating but instead the view itself appears to float in front of you. It isn’t so much the eye relief of the 28mm RKE although it has been calculated perfectly to match a combination of factors including design of the upper body holding the eye lens which consists of a thin wall beveled at such an angle to match the 45 deg apparent field.

It is as if the walls of the eyepiece simply disappear and the view is simply in front of you superimposed against the background peripheral view. The floating effect of this view is seen just as well the daylight as it is at night in a number of different ‘scope designs.

[GUS.K]

The 9mm Morpheus has the same effect as the 28mm RKE where the eyepiece dissapears ( best seen with the eyecup removed) akin to an infinity pool view. I Have the Edmund scientific 28mm Kellner (RKE predecessor) which has the same floating field characteristic.

[Hemi]

Hey Greg,

Thanks for starting all these EP threads, I’ve been enjoying them immensely. Lots of great info coming out as well.

I had a couple of questions

1. There seems to be a lot of clones/knock off tmb’s on AliE and eBay, prices range from $30 to $70, is there any way of knowing or supplier that you’re getting the right one? Was after a pair of 9mm for binoviewing. In a small frac.

2. What would be your ultimate planetary/ double star ep?

Cheers

[DeWynter]

TMB Planetary Type II eyepieces are not really a clone or knock off of the original TMB eyepieces. And there is no "the right one" - they are made on the same factory. You can get a lemon from any supplier unfortunately as QC is the issue. I can recommend just check the seller's rating to make sure you are buying from a good one.

[gregbradley]

Hi Hemi,

I could find it again on Ebay.com.au but they show up at ebay.com.

They all look like the same eyepiece. I don't for a fact but I am confident there is only one factory and many resellers.

Here is one link:

https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2380057.m570.l1313&_nkw=Telescope+eyepiece+TMB&_sacat=0

The one I have is the 7mm. I have 2 more I bought at the same time that have not yet arrived. This is my first dealing with Aliexpress. I am more confident in Ebay.

I see there is a 7.5, 8 and 9mm as well. Plus a hood that extends the magnification of each X3. I didn't see those on Aliexpress.

I think I ordered the 3, 5 and 7. On Aliexpress most of the vendors do not have the full range and and don't anything above around 5mm.

As far as ultimate planet/double star eyepiece I have limited experience.

What I have is:

Edmunds RKE 8mm 15mm and 28mm. These rate highly in planetary shootouts, in fact did the best out of some very high end eyepieces and they are cheap. There is an article on Cloudy Nights where RKE's beat out everything else including Zeiss Abbes. Mine seem good, very clear. Small field of view though.

Fujiyama 18mm Ortho. This is brand new so I haven't looked through it yet but comes with a strong recommendation from the supplier.

University Optics 12mm Ortho. This gives pleasing views. Again a bit on the narrow side like all these types eyepieces - something in the low 40 degree area.

University Optics 4.6mm - ouch, mainly see defects in my eyes! These eyepieces also show lousy eye relief so you have to get your eye right up to them and keep it very still. Pinhole view.

The TMB Planetary 11 is very comfortable, very bright, very sharp and very low chromatic aberration and a comfortable 58 degree view. Also very cheap eyepiece.

3.5mm Nagler T6. 82 degree field of view is hard to beat and very addictive. I use this one when the seeing is steady. Very nice but it does requrie steady seeing.

9mm Nagler T1 -lousy eyecup (I have ordered some nice looking wing eyecups off ebay). Great views. I used to have the 9mm T6 Nagler. Not sure the views were any better (many years apart) but the ergonomics were. I see detail through this eyepiece I may not in others. Best view of Jupiter was many years ago through a TakFS152 and 9mm Nagler at 2am and very steady seeing.

9mm Morpheus - lovely view, very easy to see the view, very little blackout (the weak spot of the Naglers) and more forgiving of eye position. Very sharp, clear and detailed view. There is a 6.5 and 4.5 Morpheus but I decided (at this stage) to simply use a barlow on the 9 or the 12.5 I have. But this is a stunning eyepiece.

Pentax 7mm XW its on the way to me and will be tested next clear night. the 7 and 10mm XW Pentax topped the list of 10 all time favourite eyepieces thread on Cloudy Nights. Many responded. So I want to see what all the fuss is about. 10mm and below seems to be the specialty of these eyepieces.

TMB Planetary monocentric. I got one or two of these when they first came out about 12 years ago. Sharp etc but I don't like these tiny pinhole views. The FOV is just too small and feels claustrophobic. No need these days as eyepieces have evolved.

13mm Ethos. This was the first in the Ethos line. A beautiful eyepiece but huge and heavy and expensive. Got an amazing view of M42 in my TEC180FL at my dark site one time. I am sure the short focal length versions would be good but now you are looking through a lot more layers of glass so ultimate performance may be lacking. Others should comment here as I am no expert on Ethos, Delos or Delites but they review really well. Delite and Delos around 6mm or so seem to get a lot of recommendations on Cloudy Nights. 6 and 8m Delos comes up a lot in threads.

10mm 85 degree Masuyama. I got the best views from this compared to 9mm Nagler. The Nagler is better corrected all the way out to the edge but the Masuyama central 60% is just sublime. Its subtle but its a more pleasing view. More natural, easy to see, clear, detailed, no flaring - lovely. Eye relief for me without glasses was fine. I am interested in adding either the 26 or 32mm Masuyama at some point. They only have 5 lenses compared to the modern more complex eyepieces which have 9 or more. Each layer of glass takes something away no matter how slight.

Available now for reasonable prices are Baader Classic Orthos ($139.95) - 52degree, Fujiyama Orthos ($149.95) 42 degree view (supposed to be better than the Baaders but 42 degrees isn't easy to live with), these TMB Planetary 11.
Other high end are Takahashi Abbe, TOE, Pentax XW but now prices are much higher. Pentax XW are around $500, Tak Abbe and TOE not 100% sure but I imagine $300-400.

Nagler 3-6mm zoom often is recommended. I had one for a while years ago and it was nice. I have a cheap SvBony 8-24mm zoom and its good (it goes out of focus when you zoom though). The Baader Hyperion 8-24mm Zoom though gets constant good feedback ($389.95 or so).

That's about all I know. You can google best planetary eyepieces and I am sure there would be many threads on Cloudy Nights eyepieces forum about this.

Greg.

[DeWynter]

These two are relatively good and well-known stores on Ali with the full range of 2.5/3.2/4/4.5/5/6/7/7.5/8/9mm focal lengths:

https://www.aliexpress.com/item/32790319139.html
https://www.aliexpress.com/item/32889506872.html

[Saturnine]

For a good planetary / double star eyepiece, it is hard to go past either BGO ( Baader Geniune Orthoscopic) or Fujiyama orthoscopics. Compact design, simple lens configuration, only 40 / 45 deg. AFOV but that helps to concentrate on the subject, with a dark contrasting view.
The TMB "clones" are quite good performers as well, with a larger FOV which may help find and frame the target at high magnifications, at quite a reasonable price considering.

[gregbradley]

There are a number of comparisons between the Baader Genuine Orthos (BGO) and the Baader Classic Orthos (BCO).

The BGO's often rate a hair better but on the 18mm the BCO seems to rate better. BCO's have a 52 degree FOV. Depends on your preferences for the size of the FOV. I definitely like a wider view but I am not super experienced here so I may change my mind on that. I just got the 18mm Fujiyama so I can post my impressions about that here next clear night.

What focal length eyepiece and scope do you use?

Greg.

[mental4astro]

I don't know where people get the idea about "clone eyepieces"!

There have never been clones. Ever.

Clones implies that somehow these have been copied or the design stolen. There are only a handful of manufacturers of eyepieces in the world (nearly all of them in China), and there are only a limited number of eyepiece designs. Anyone can go to the right factory and ask for eyepiece X if the design is not under licence and the factory will ask "what casing design will you like and coating specs". That is it. This is why the Baader Hyperions appear re-branded under a number of different flavours. And NO, the Hyperions are NOT a rip-off of the Vixen LVW's. Totally different optical designs with the only similarities being focal lengths and a focal length colour coding system, but they are not rip off copies of anything.

As for the TMB's, they are made in the same factory as when Thomas Black was still alive. When Thomas died the factory dishonoured the contract they had and started making these eyepieces for themselves - and good luck to the TMB estate in making a claim against that factory...

The TMB Planetary Type II's were a revelation when they were released, being relatively inexpensive for the quality of optical performance and inexpensive to manufacture. Without the licencing restrictions on the factory, they could sell the exact same eyepieces at an even cheaper price. HOWEVER, quality control is now not the same :( When you do get a good sample they can be excellent performers. But the failure rate is astronomical!

I bought the entire line from one supplier in order to test them all out in Newts, refractors and Catadioptic scopes, all 10 individual focal lengths. I also had four other eyepieces of these, so I had duplicates which allowed me to verify QC, so 14 eyepieces in total. Of the 14, 4 were totally unusable! These would not even come to focus, just remained a blurry mush. Sadly too is both of the 3.2mm were crap - a real shame as this would have been a good focal length for one of my scopes.

Of the two 2.5mm samples I had, one was rubbish. The other flaming brilliant, going toe to toe with the mystical 2.5mm Pentax XO with both outstanding in Newts and refractors. I was able to pit both EPs against each other. The 5mm TMB is just as good as the 5mm XO in a refractor, but whoops the Pentax's pants in an f/4 Newt - the 5mm Pentax just cannot handle a fast Newt.

Like I said, when you get a good unit these TMB's are excellent. All perform really well in refractors for which these were designed for. In Newts the pick of the crop at the 2.5mm, 4mm, 5mm, 7mm & 8mm in really fast Newts, like f/4, so with slower Newts the other focal lengths are less challenged by coma and perform well.

Curiously, the 6mm was the weakest performer from the Thomas Black era and continues to be. It will still do an ok job, but the other focal lengths are better performers, and you don't want to buy something knowing that it is just ok for the same money.

The pic below shows all the TMB eyepieces I used in my testing. The ones with the white band are the duplicate pieces. The crap pieces were put in the rubbish. I kept 5 of them and sold the others. I often use them with my lunar and planetary sketching and observing.

Also pictured is a 9mm TMB beside a 9mm plossl. The eye relief across all TMB's is the same generous amount as is the same big eye lens size, unlike plossls who's eye relief shortens and eye lens reduces as the focal length gets shorter.

Alex.

PS, I do not sell these eyepieces as the QC is just not good enough. I would only recommend buying them from Ebay because if you do get a poor sample you can get a refund.

For inexpensive eyepieces, these are really outstanding. QC lets them down though.

PPS: There is a way to tell if the TMB is from the time of production when Thomas Black was alive - those particular EP's have the focal length engraved as "mm". With the current, post Thomas Black, fabrication, the focal length is engraved as "MM" and the box they come in does not carry TMB branding.

PPPS: These TMB's are also available rebranded too! There is nothing exclusive about this design either.

[FlashDrive]

Thanks Alex for your report ..!!

Col.

[gregbradley]

Wow, thanks for the post Alex. Poor Thomas Back, he got shafted a few times.

So its like buying the cheaper Samyang lenses?

Or the more reason as you say to buy on Ebay so you can return them.

I guess the old "you get what you pay for" rule applies.

Greg.

[mental4astro]

Col, your signature also brings up another aspect of this "clone" eyepiece business.

You list a 35mm Orion Ultrascopic plus a 30mm and 25mm Parks Gold Series pair. These are the same as the "original" Masuyama line. Celestron I believe also released a similar line as did one or two other brands. Difference being they were manufactured AFTER the master optician Masuyama died and the licencing restrictions ended on the eyepiece designs.

There are some manufacturing differences, including QC, case design and coating specs. When pitted against original Masuyamas, these differences are noticeable, but the glass inside the casings are exactly the same - no "clones". There was a premium to pay for the original Masuyamas at the time as they were the best at the time. Still bloody good today too, when used in slower refractors as they were designed for, NOT Newtonians and not for f5 fracs.

I have a 35mm Masuyama - damn nice eyepiece too. But exclusively with my refractors. This 35mm EP is not well suited for Newts.

[mura_gadi]

Bugger,

Here I was thinking about a 6mm TMB for my F6 dob to do star testing/collimation with and someone helps out with "a weakest in the line up" comment. (helpful yes...) TMB II's are currently going for under $40 AUD with free postage at aliexpress(The Outdoor Movement Store) - I'm hoping for Chinese New Year specials - But the APM 30mm UFF is not budging atm...

Any pro's or con's about using a eyepiece/barlow combo to collimate against star tests? (like adding extra plumbing from a cheap barlow is not the best idea?)

Well, I'm still on a high as I have found someone to try and get my 8" glass blanks cut with at less than half the price of other quotes. Just dropped of the slab of glass half an hour ago. Fingers are crossed they don't shatter under the water jet.


Steve

[Hemi]

Thanks Greg: a lot of info and experience to ponder there. I might try the TMBs, that got me posting on this thread. And great value for pairing in Bino’s.

Thanks DeWynter, very helpful, i purchased a couple of TMBs from one of your links on AliE. Fingers crossed Alex that I get a good example.

Thanks Saturnine: so many designs! I haven’t tried any orthoscopics so far, never thought I had a use case that differentiated them significantly from my plossls, but I’m still a relative novice with a very small collection, and will surely try at some point. I’m a fan of Baader!

Thanks Alex: these TMBs certainly have an interesting back story. I don’t think that the term clones necessarily implies any skull duggery. There are lots of re badged, housed, rebranded Astro stuff. All legitimate, and all clones. The sky watcher Az eq6, Orion Atlas pro, Saxon AZEQ6 I would describe as the same mount or clone. :)

[mental4astro]

Steve, you will best served with a 5mm TMB for your dob! I have one and frequently use it in my f/4 Newts to observe with, not just star test. :thumbsup:

You can use a barlow if you like. However, Barlows are not a "neutral" optical element, and can actually exacerbate aberrations if the eyepiece is not an optical match with the scope. Really, it is just easier to have one EP that you star test with, even if you don't use it any other time, than use a barlow/EP combo... But you may be lucky with the barlow/EP combo you have and it may work just fine :D

Alex.

[astro744]

I think the term clone is used loosely and perhaps a more accurate term would be to mimic or imitate.

I recall seeing the early Tele Vue ads in the astronomy magazines of the mid to late 1980s offering a range of 50 deg Plossl, 65 deg Wife Field and 82 deg Nagler in various focal lengths only to be pipped by ads from Meade offering the same or slightly different focal lengths in 52 deg ‘Super’ Plossl, 67 deg Super Wide Angle and 84 deg Ultra Wide Angle.

I think this could have started the ‘clone’ industry in eyepieces but I agree clone is not a good description so perhaps the imitation industry is a better choice if words. Have a look at the report on the Company 7 site; scroll down to “Mine is better than yours...”.

http://www.company7.com/meade/history.html

Company 7 mention that fans were loyal to Al Nagler for being a true innovator as opposed to following a company for being a true imitator by the fact that Meade took the Tele Vue concepts and designs from the US Patent Office. It is mentioned that some of the Meade offerings were quite good but they were an attempt to copy another product and market it as being and improvement on what others had, (namely Tele Vue). At the end of the day they were an attempt to make a better copy. Call it clone or imitation but the former rolls off the tongue easier and this is where I believe the term clone started amongst the amateur astronomy community.

[mura_gadi]

Hello,

I have just placed an order for the 5mm TMB II, toes crossed(fingers already in use) it is a good one, though the "Outdoor movement store" does offer free returns at least.

I seem to remember reading that star tests should use an EP that is the same FL as the F ratio of the scope. That's why I was fixating on a 6mm a bit, at 240mag the 5mm may be seldom used though. Was $38.xx plus the 10% GST added on at the checkout.

Any truth(or weight) in the statement that the best marriage for ep's is, if you have a convex objective, you should go for concave EP' tops and visa-versa?


Thanks
Steve

[mental4astro]

No. Many EPs have a flat eye lens, and then what? Plus with many other EPs the reflections seen through the eye lens may not allow you to determine the shape of the eye lens top surface. Many retailers would not be able to answer that question for you either as they will be most reluctant to open a factory sealed EP.

Unfortunately it is a case of reading LOTS to work out what is what. While most people who write "reports" about eyepieces don't understand optical matching, what they write can be used as a tool to help you work things out. Most people will use ONE eyepiece in a given scope, say for this purpose a Newt. Forget their opinion that the EP is crap... What is important is to try to work out what aberrations they recognise.

The one single most important aberration to recognize for Newts is astigmatism! This will appear as little seagulls all concentric to the optical axis. Astigmatism does not mean a poor eyepiece for your scope though. If it appears slight and right at the very edge of an 80deg AFOV, then for my money this is a good eyepiece if it is at a good price! :D NO ONE does any observing right at the very edge of the FOV. NO ONE. You may look at the edge to see what it says, but when you are actually observing YOU DO NOT LOOK ALONG THE EDGE OF THE FOV - you will move the scope.

But for some people this is just not good enough, and good luck to them :thumbsup:

Field curvature is unavoidable, especially with faster focal ratios, and not something that should concern you unless it is really grotesque. Then this could be more of a symptom of a mismatch than anything else.

Reading what people write between the lines is your best friend, as will be your tolerance to certain aberrations. And DO NOT MAKE A PURCHASING DECISION BASED ON ONLY ONE EYEPIECE FROM A WHOLE LINE THAT WAS USED IN ONE SCOPE TYPE, ESPEICALLY IF IT IS NOT THE FOCAL LENGTH EYEPIECE YOU ARE KEEN ON!!!!!!! Contemporary EP design is just too complex and involved and to pass judgement on a whole eyepiece line based on one individual focal length in just one scope only shows the ignorance of the author.

Alex.

[Saturnine]

Greg
I have a pair of 12mm BGOs' that are mainly used my 5" f7.5 apo (950mm ) and 5" f9.4 (1200mm ) achro for lunar and planetary. Using the binoviewer in the 10" newts is problematic because of the weight and balance issues and also focuser position when the newts are EQ mounted. I have 1.6X and 2 X OC to use in the binos, allowing a for range of magnifications, 121X & 152X in the apo and 153X & 192X in the achro and they give nice crisp images in both scopes, the image in the apo is better colour corrected of course but the achro is quite acceptable, when teamed with a Baader Semi Apo filter.
Have never looked through the BCOs' so can't add anything there but the wider FOV does make them more desirable for some. I also have an 5mm TMB which is a good performer in the fracs and the newts and also several Circle T volcano top orthos', 25, 18, 9 & 7mm. The early volcano tops are fine eyepieces but suffer a little from internal reflections and narrow fov of 40/42 deg.

[Saturnine]

Thanks Saturnine: so many designs! I haven’t tried any orthoscopics so far, never thought I had a use case that differentiated them significantly from my plossls, but I’m still a relative novice with a very small collection, and will surely try at some point. I’m a fan of Baader!

Thanks Alex: these TMBs certainly have an interesting back story. I don’t think that the term clones necessarily implies any skull duggery. There are lots of re badged, housed, rebranded Astro stuff. All legitimate, and all clones. The sky watcher Az eq6, Orion Atlas pro, Saxon AZEQ6 I would describe as the same mount or clone. :)[/QUOTE]

Good quality Plossls should not be left out of the mix, with their simple design and less glass for the light to pass through, they provide great views, with 50 / 52 deg FOV. Like the orthos', unfortunately as the focal length gets shorter say from 7mm down, so does the eye relief which makes them difficult if not unusable for old eyes.

[N1]

Yes but that's hardly unique to the 28 RKE. Serious observations are now done by camera. Unless something serious happens to be going on and no camera is handy. Then an RKE might provide a serious advantage over a non-observation. Seriously :P

[mura_gadi]

Hello,

When I first went looking for ep's I read many a forum trying to find out about eps' and light cone angles, lenses, groupings, designs and such. So many pretty bling things to read about and ponder. While doing so I saw a pair of knight owls(?) at 30mm and 15mm on ebay going for a song - no bidders, zero interest.

Off to research said ep's and man did they ever get bagged out, both here and at cloudy nights. My favourite quote which has stuck in my head was along the lines of "there not seagulls at the edge, or even eagles but screaming pterodactyls". But not to be put off I kept searching for an article to reinforce my idea of getting them - as you do, read the stuff that you already agree with/reinforces your opinions.

Eventually I found a high school grade author who pointed out at F6 and above there not the worst ep you could get, but a little scratchy at the edges. As a novice I am more into the view at the center of the ep anyway and was keen to get a cheap wide field to try (still on my x2 ep's as supplied with the scope at that stage).

$50 later I had both ep's with my 2" barlow I had 30/20/15/10 and 7.5mm in an 80 degree field. I won't say there the best ep I own now by a long way, but at F6 there are useable to a newb and his dob and I would say a 6" F8 dob they would be very useful for a novice, or those with a limited budget wanting extra wide FOV. (But get the 20mm it has a removable x1.5 barlow and gets you a 30mm too boot)

These ep's are still sold off very cheaply and if you have a slower scope and a tight budget, I'd say get them if they're as cheap as mine were(up to $40 a pop maybe for the 20/30mm anyway). I'm still looking mostly at the center of FOV at the object of interest and even with adverted gaze the edges really aren't a big worry for me, or that bad imho.

Too many people want to defend spending what amounts to a decent second car for most family's on a set of premium ep's. If you get a slower scope (F6+) and are new to this hobby, cheap eps are fine if you do a little research, and very good if your not chasing extra wide FOV's ep's. After you have spent a few hours out in winter at sub zero temperatures, you'll know if your a keen observer and can look at migrating up after that.

Blessed be the astronomy club that lets you try all these ep's first!


Steve
Ps. I have wanted to try and capture the images from my 30mm knight owl's (read apm cheapest wide field "clone/replica") and the images from my Tele Vue 32mm wide field I was donated.

The 30mm knight owl shows far more nebulosity on M42 than the older Tele Vue 32mm does, but I am assuming that due to scatter control or a lack of it. The Tele vue image is 60/70% of the nebulosity but has a lot nicer blackness within the cloud for contrast, something that is almost absent in the knight owl.

But till I got a better ep, I was none the wiser, and for M42, I tend to use the knight owl over the older style Tele Vue anyway as I want to see nebulosity in my clouds even if I only get 3 stars in the Trapezium Cluster.

Pps. I still troll pictures of M42 trying to find out what it should look like, but with AP you get so many options, not just based on scope, aperture and camera settings but post processing and such its hard to know what a "true image" looks like, even at grey scale. The Knight owl best duplicates sites such as "astronomy.tools" FOV calculator image imo.

[mental4astro]

Steve, those Knight Owl eyepieces that you mention and your reading about them are exactly what I mean about "reading between the lines" when it comes to figuring out optical matching of eyepieces.

That people were describing "pterodactyls" to me says they were using those eyepieces in fast Newts/dobs. WRONG scope for those eyepieces. And you then use them in a slower Newt/dob, and this astigmatism aberration is milder, still there but far less aggressive.

Put those eyepieces into a refractor, especially a slow refractor, and they will perform much better. Won't be "perfect" but much improved.

The GSO SuperViews are similar in that way. Inexpensive but for value for money very good. They do show astigmatism in Newts, and the faster the Newt the more significant the seagulls will be. In an f/5 Newt, this aberration may well be just fine for an individual person :) In refractors and SCTs they still do show tangential astigmatism rather than sagittal (seagulls), and the slower the frac the less significant is as well.

One thing I really like with these SuperViews is they are excellent for novices/newcomers to astro as they are so easy to use. I bought the 30mm and 15mm more than 12 years ago, with the 30mm being my first 2" eyepiece. In the subsequent years I have bought and sold on soooo many eyepieces but I have NEVER even considered selling my two SuperViews. I don't use them for my own observing, but they are my EPs of choice for outreach.

I came across a picture that demonstrates what is mean by "seagulls" as a symptom of astigmatism due to a mismatch between eyepiece and scope. In "Astronomical Optics", Bruce MacEvoy has a picture that shows the different appearance between Sagittal astigmatism (seagulls) and Tangential astigmatism. The page that deals with aberrations seen at the eyepiece is highly recommended. You can follow the maths or you can just keep it simple with reading and following the diagrams. Understand the appearance of these different aberrations will go a long way to help you finding the better eyepieces for YOU. I have my own set of preferences in what I look for in eyepieces, and it would be wrong of me to insist that MY preferences are the "right" ones. I am not you, nor am I in charge of your purse strings. All I can do is show you what things are through the eyepiece and you can then make your own choices.

Astronomical Optics - Optical Aberrations (https://www.handprint.com/ASTRO/ae4.html)

Alex.

[N1]

The tangential astig looks pretty radial to me. What's the tangential aspect of it?

[mental4astro]

Mirko, I agree that the effect looks more radial, but it relates to how this particular type of astigmatism is produced. See the actual astigmatism section of the article:

Astronomical Optics: optical aberrations - astigmatism (https://www.handprint.com/ASTRO/ae4.html#astigmatism)

[gaseous]

That's a terrific resource Alex, thanks for sharing. 99% of it is well above my pay grade to comprehend, but it's great to have a definitive list with diagrams of all the types of aberrations out there.

[mental4astro]

One thing about aberrations - their presence/appearance does not necessarily indicate that there is something wrong with a given eyepiece. Instead their presence is an indicator of many different conditions predicated by the scope-eyepiece-eyeball combination at play.

Some aberrations are unavoidable, such as coma in Newts, and eyepieces will be able to deal better or worse with it. How severe the coma is is also a function of the focal ratio of the primary mirror, and coma correctors are optimized for specific focal ratios, say centred around f/4 or f/5, with a half f/stop either side. So an f/5 corrector in an f/4 Newt won't clean up all the coma present. Like wise an f/4 corrector will over correct in an f/5 Newt.

Other aberrations will be noticeable as a result of an excessively fast focal ratio that is beyond the design parameters of the EP.

Aberrations do not indicate a poor eyepiece either. What it can do is offer really good value for money if what aberrations are visible are totally acceptable to YOU. A wee amount of astigmatism along the very edge of the FOV of an 80° EP is no real problem as you do not ever do any observing along the very edge of such an EP. You don't. You move the scope. So such a $250 EP may be an absolute bargain for you :) And if you rather drop $1000 on an EP, great too :thumbsup:

Alex.