Top 3 criteria for choosing an eyepiece

[Saganite]

1.Optical quality

2. Eye relief

3.Price.

[Littleguy80]

My eyepiece collection has turned into 100 degree eyepieces and orthos. Opposite ends of the AFOV spectrum. Being relatively new to astronomy, I’ve had the benefit of a lot of experienced astronomers right here on SGL. That experience led me to the following three criteria.

1. Price. There’s always so much to buy that being strategic with how much you spend on individual eyepieces allows you to get a lot for your money. Buying secondhand makes a whole lot of sense. Pretty much every one seems to take care of their equipment. This is why I have orthos, inexpensive but excellent quality. The law of diminishing returns is why I bought APM HDC’s instead of Televue Ethos. 

2. Optical quality. This feels like the most obvious criteria. It’s got to look good when you look through it! The sharpness of the orthos is a big reason that I find it hard to resist them when they come up. The APM HDC’s are similarly excellent but not quite as sharp as the orthos when comparing like for like focal lengths.

3. AFOV. A nice widefield eyepiece and a manual dob is a match made in heaven. Lots of sky leads to minimal nudging. My 20mm APM HDC is a dream to roam the skies with. An ortho makes an superb high power eyepiece. The small AFOV focuses the eye on small targets like planets, doubles and planetary nebulae. It’s matching the eyepiece to the target. 

I’ve been very pleased with my choices and this feels like a good opportunity to say thank you to the folk of SGL for sharing your wisdom with me and the rest of the community!

[scarp15]

Planning my observations for specific subject matter, would constitute considering this three point criteria;

Function - Exit pupil size, true field of view.

Performance - Comfortable eye placement, contrast.

Design - Glass element composition.

[cv01jw]

I have recently had to decide on my top three as I have a new dob which is too fast for most of my current EPs.

For me, the first thing was usability with a fast scope as there is not point otherwise.  After that, it was quality and then price.

I chose to forego field of view in order to maintain decent quality and reasonable price.

[John]

57 minutes ago, cv01jw said:

....I chose to forego field of view in order to maintain decent quality and reasonable price.

Thats a very sensible approach. If you go for lower cost wide fields the outer parts of the field won't be well corrected so you might as well follow Al Naglers maxim "Show no field unless it's sharp"

[mark81]

32 minutes ago, John said:

Thats a very sensible approach. If you go for lower cost wide fields the outer parts of the field won't be well corrected so you might as well follow Al Naglers maxim "Show no field unless it's sharp"

That's an interesting point, but how do you determine what falls into the brackets of lower cost? Do you go by reviews alone?  For example, I just read a review about an Explore scientific 62 degree (£80) and how the sharpness seems to fade slightly at the outer edge and then I saw one for the Baader ortho  (£49) which is 50 degree and remains sharp all the way across...?

It can be very confusing when your ready to click the 'add to basket' button...

[Stub Mandrel]

Comfortable to use.

Either not a focal length I have or better than one I already have.

Affordable.

[Charic]

53 minutes ago, mark81 said:

........... how do you determine .........

It can be very confusing when your ready to click the 'add to basket' button...

Click that button and find out for yourself.

Often that's the only way to see if a certain eyepiece becomes compatible for your requirements?  Its all so easy to say that 'X' eyepiece works better on 'Y' scope, but unless you trial them, you'll never know. 

I got rid of my BCO's in favour of my Astro's. I don't recall the BCO's being any better, otherwise I would have kept them, but thats not to say their bad, look at the reports, there mostly favourable, they just did not do it for me.

[Louis D]

1 hour ago, John said:

Thats a very sensible approach. If you go for lower cost wide fields the outer parts of the field won't be well corrected so you might as well follow Al Naglers maxim "Show no field unless it's sharp"

Which I think is a disservice when buying a lowest power, widest field "finder" eyepiece.  Even if the outer field is astigmatic, you can still tell if Jupiter, a bright star, or the moon is either in the field or just outside the field allowing the user to center it.  I made do with a 38mm Rini modified plossl for years for this purpose.  I still have it, and when I pop it back in the focuser, I can't believe I was able to stand using it for so many years.  However, I was helping to raise three little kids on one smallish income, so a 35mm Panoptic (the 41mm wasn't available yet) wasn't in the cards.

[John]

15 minutes ago, Louis D said:

Which I think is a disservice when buying a lowest power, widest field "finder" eyepiece.  Even if the outer field is astigmatic, you can still tell if Jupiter, a bright star, or the moon is either in the field or just outside the field allowing the user to center it.  I made do with a 38mm Rini modified plossl for years for this purpose.  I still have it, and when I pop it back in the focuser, I can't believe I was able to stand using it for so many years.  However, I was helping to raise three little kids on one smallish income, so a 35mm Panoptic (the 41mm wasn't available yet) wasn't in the cards.

Do you mean Al's statement or mine is a "disservice" ?

Most of use have been on a limited budget at one time or another Louis

[Louis D]

4 hours ago, John said:

Do you mean Al's statement or mine is a "disservice" ?

Most of use have been on a limited budget at one time or another Louis

Al's statement.  It might be fine for him as a corporate mantra, but it leads to "field shaming" for those folks on a tight budget seeking a widest field finder eyepiece even if it means living with astigmatism.  Heck, I get exit pupil shamed for suggesting using a 40mm-ish low power eyepiece to get a widest field even if it means giving up some photons to your eye's iris in a sub f/6 scope.  Not everyone can afford a 21mm Ethos or 31mm Nagler to get a widest field while maintaining a sub-7mm exit pupil and excellent field correction.  For me, it's about getting that widest field temporarily while you work to correlate the view through your reflex sight or finder scope with the view through the main scope before swapping out for a higher power eyepiece.  This is especially true in long focal length scopes where it can be time consuming to get everything aligned to within a 1/2 degree every time you reassemble your scope.  This is particularly true if you regularly swap finders between scopes that have slight differences in the alignment of the finder bases with respect to the main telescope's optical axis.

[cv01jw]

Well, I selected a set of BCOs at 6,10 and 18mm which reviews tell me are about as good as it gets for the money.

I have also managed to find 14 and 21mm used Denks which, again from reviews, should be great, and give slightly wider views.

[Stub Mandrel]

6 hours ago, Louis D said:

"field shaming"

No doubt by people who have paid to have their eyeballs multi-coated...

[John]

"field shaming" - well thats one way to put it

I don't think that happens here - we just give our opinions, based usualy on our experiences with various bits of kit. It's all well intentioned

 

2 hours ago, cv01jw said:

Well, I selected a set of BCOs at 6,10 and 18mm which reviews tell me are about as good as it gets for the money.

I have also managed to find 14 and 21mm used Denks which, again from reviews, should be great, and give slightly wider views.

Really good choices in my opinion.

 

 

[Macavity]

Consensus (read LOTS of opinions!) seems to help. That said, people do repeat
"stuff they have heard"... Don't always (completely) understand the appearance
of aberrations they cite to promote/criticise eyepieces. Modest tribalism etc. ?

https://en.wikipedia.org/wiki/Eyepiece (All of them have some compromises)

Never in the market for "premium" eyepieces, I have (ironically!) spent far too
much on buying/selling "medium range" eyepieces. Not unlike buying Guitars...
User Ability? Happy with a "Strat Copy"! Don't need £ N-thousand "Les Paul"? 

I HAD often hoped (perhaps impossible) for an objective (as in eyepiece!) test. ? 

P.S. I have learned to follow advice... Offered in good spirit (SGL notably). Don't
ignore occasional "grumpies" (elsewhere)? Some are VERY knowledgeable... ?

[Ags]

Must be 1.25". Must be 68-82° AFOV. Good at F5. Less than €150.

[mark81]

I came across this Youtube vid by Explore Scientific.  It looked as though it was going to be a promotion of their EPs but it ended up being full of really useful information about choosing EPs.  A lot of you will know all about this but well worth a look..

https://www.youtube.com/watch?v=XmRyGsaM4ws

 

 

[Stub Mandrel]

1 hour ago, mark81 said:

I came across this Youtube vid by Explore Scientific.  It looked as though it was going to be a promotion of their EPs but it ended up being full of really useful information about choosing EPs.  A lot of you will know all about this but well worth a look..

https://www.youtube.com/watch?v=XmRyGsaM4ws

That is really good. A great way of promoting their goods without feeling like advertising. Nothing puts me off more than the articles that say 'only my EPs can give you the ultimate viewing experience'.

Interesting how it said NOTHING about EP design, but just gave the information that matters most.

[JTEC]

Really difficult to do it in 3 ?but perhaps that was part of the point.

Price has to come first, but I see it more as an upfront constraint than a criterion to inform choice. Over the years, I’ve probably wasted more than enough money on whimsically chosen, indifferent, mid-price eyepieces to buy quite a lot of well-chosen, expensive ones.

That said, eyepieces don’t have to be expensive to be good and, as others have pointed out, there is some excellent value to be had out there - the BCOs being a prime example. To my eyes, these are a little way optically behind the BGOs and behind the current Tak orthos but very good value indeed. Just to stir the debate a little, I’d also put in a word for the much chatted about Edmund RKEs. I have some, including a pair of the infamous ‘floating image’ 28mms. They have very good ‘acutance’, to borrow a word Ansel Adams was fond of,  and, at the price, I think they’re worth a look.

Orthos (and short fl plossls) understandably aren’t everyone’s cup of tea though - modest eye-relief, modest AFOV, not exactly optimal for sweeping the Cygnus star-fields. So my second criterion would be suitability for a specific observing application. I suppose you’d have to add, since there can be compatibility issues, ‘in the scope I plan to use’. For me, this means orthos and some plossls for lunar and planetary ‘work’ (I love the way we call it that ?).  This side of things can be covered relatively cheaply.

Staying with the ‘suitability for task’ criterion, these simple eps, of course, can also perform exceptionally on many DSOs, where wide FOV is not required. But for extended DSOs, nothing does the job like one of the wide-field wonders. Again, to my eye at least, the reverse does not apply. I bought a 13mm Ethos because at the time I’d sold some kit and could afford it and everyone was saying how wonderful they were. It absolutely IS a wonderful piece of design and execution. I’ve read claims, though, that, in addition to providing those astonishing wide views, it’s right up there as a ‘planetary’ eyepiece as well. Nope. Not, in my scopes and to my eye, compared to a good ortho.

And this is where price has to come in. For the observing experience it gives - as someone else pointed out, on this or another forum, it’s nothing like looking out of a porthole of a spaceship, it’s like looking through a very wide field eyepiece on the end of your telescope - the cost is very very difficult for most of us to justify.  I also discovered that I don’t peering around to take in the full, impressively sharp-to-the-edge field of view. I prefer eps up to about 70* AFOV.

So that brings me to my third criterion, and in some respects it’s tricky to specify. Eyepieces don’t just have focal lengths, eye-relief, AFOV, etc. They have character and ‘likeability’. And this is hard to define. It may boil down to individual preference. It might encompass things like weight, bulk, colour cast. An eyepiece might tick all the numerical boxes but ... you might not LIKE it. I have an irrational fondness for my old Meade 24.5mm SWA and a more explainable liking for the crystal views I get from my Tak 9mm in my refractor. Then there’s the funky 28mm RKE ...  You just have to ‘try around’ to answer this one.

So:  1  yes, price.  2  suitability for an observing application.  3  character, appeal (no help to the questioner, I know - sorry!?)

John

TEC140, C11, 360mm Dob, AZEQ6, EQ6 Pro, Baader Zeiss prisms, TV Delos, Ethos, Plossls, Tak orthos, RKEs, QSI 583 with Astrodon filters. Numerous boxes of astrojunk.

 

 

 

[Sagitta]

After years and years of experience and testing and comparing it boils down to

1 > it must be one that does not fall through the focuser down in the tube onto the primary

2 > it must not cost too much

3 > it must look sexy

?

[mikeDnight]

I used to be a big fan of the black and green, and Pentax XW's (still rate the Pentax very highly!), then someone handed me a good quality 24mm plossl to play with. Granted the field was not as wide, but there wasn't that much of a difference, and the edge of field in the plossl was sharper than any of the 70°+ eyepieces, which got me wondering why I was bothering with the wider fields at all? The biggest difference that haunted me for a long time afterwards was the transparent view in the plossl. The peppering of stars in the milkyway were noticeably more obvious in the plossl with an undeniable clarity that was not quite there in the wider field multi element big boys. It was a bit of a sickener really, as I had over £3,500.00 tied up in my eyepiece collection and theyed just taken a slapping from an eyepiece that many today would turn their nose up at. Typically, when I enquired about a set of these plossls I found they had been discontinued in favour of a more complex design that proved not to be in the same league optically. 

Today, I'd happily forfeit a wide field for the ultrasharp transparent/clarity offered by some of the better 50° plossl/Super plossl designs. And I'm now only interested in 1.25" fit eyepieces. In my collection, a black and green will not be seen, and its liberating!

[Ags]

What make of plossl are you referring to?

[John]

40 minutes ago, mikeDnight said:

I used to be a big fan of the black and green, and Pentax XW's (still rate the Pentax very highly!), then someone handed me a good quality 24mm plossl to play with. Granted the field was not as wide, but there wasn't that much of a difference, and the edge of field in the plossl was sharper than any of the 70°+ eyepieces, which got me wondering why I was bothering with the wider fields at all? The biggest difference that haunted me for a long time afterwards was the transparent view in the plossl. The peppering of stars in the milkyway were noticeably more obvious in the plossl with an undeniable clarity that was not quite there in the wider field multi element big boys. It was a bit of a sickener really, as I had over £3,500.00 tied up in my eyepiece collection and theyed just taken a slapping from an eyepiece that many today would turn their nose up at. Typically, when I enquired about a set of these plossls I found they had been discontinued in favour of a more complex design that proved not to be in the same league optically. 

Today, I'd happily forfeit a wide field for the ultrasharp transparent/clarity offered by some of the better 50° plossl/Super plossl designs. And I'm now only interested in 1.25" fit eyepieces. In my collection, a black and green will not be seen, and its liberating!

I keep wondering if the same will happen to me Mike.

So far though, it hasn't happened. I guess having the 12" dob keeps my big complex eyepieces in business here. If I just had the refractors then I might well decide to do without the hyper wides.

One day, maybe

 

[LukeSkywatcher]

Vixen,Vixen,Vixen.

[mikeDnight]

1 hour ago, John said:

I keep wondering if the same will happen to me Mike.

So far though, it hasn't happened. I guess having the 12" dob keeps my big complex eyepieces in business here. If I just had the refractors then I might well decide to do without the hyper wides.

One day, maybe

 

Yes John, I think at least part of my reasoning is based on the fact I'm only using a 100mm scope. I dare say I'd be lured back to the 2" heavyweights if I owned a large aperture, but it just seemed a bit overkill carrying a case of eyepieces that weighed more than my scope.  So the lightweight frac did in part influence my move to a lightweight set of eyepieces.