Which are the best 2in Wide Field Eyepieces, avoiding excessively Big and Heavy Eyepieces.

[John]

I think peoples tolerance of optical issues varies a lot person to person. What one person finds annoying might not bother another observer at all.

 

 

 

[Don Pensack]

21 hours ago, vlaiv said:

It is exit pupil - which is related to focal length and aperture.

With increased telescope focal length - magnification is increased and for the same aperture - brightness of background sky goes down, but if F/ratio is maintained, then larger aperture offsets effects of increased magnification and brightness remains the same.

Since all of these quantities are tied together in one way or another - we say that exit pupil is thing that governs background sky brightness but in reality it is aperture + focal length or magnification used.

You forgot to point out that increased focal length only leads to increased magnification and reduced sky brightness background if the eyepiece stays the same.

If you maintain the same magnification, the exit pupil and sky brightness remain the same at all f/ratios in the same aperture.

[Don Pensack]

2 hours ago, johnturley said:

I wasn't looking for an eyepiece with a smaller exit pupil, I already have a 24 mm Explore Scientific 82 degree eyepiece, just eyepieces around 50mm and 35mm to provide a wider field and/or less aberrations than my existing Meade 56mm Plossl and Baader 36 mm Aspheric.

I thought at first that the 50 mm StellaLyra Superview eyepiece with a stated APFOV of 60 degrees might provide an improvement over the 56 mm Meade, and although the level of aberrations appeared acceptable, it turned out that the actual APFOV was only around 48 degrees or less, giving a resultant actual field of view that was significantly smaller than both the Meade 56mm Plossl and Baader 36 mm Aspheric. There does not appear to be much available around 50 mm that might be better than the Meade, the Masuyama 50 mm might be slightly better, but at £499 it is a high price to pay for something that at best would only be marginally better.

At around 35 mm, there are more options, the Masuyama 32 mm looks good on paper, but it appears that the 85 degree APFOV from a 5 element design will result in a lot of aberrations towards the edge of the field, especially in a f5 instrument. The 35 mm Aero according to some reports might be an improvement over the 36 mm Baader, and at a relatively modest price of £105, or the 30 mm APM Ultra Flat, although the actual field of view of the latter will be significantly smaller than the 36 mm Baader.

John 

If you are looking for an inexpensive wide field eyepiece good at f/5, you will buy a lot of different eyepieces to discover that such an eyepiece doesn't exist.

Cheap---well corrected in the outer field---wide field.  Pick any two.

A couple candidates for you: TeleVue 41mm Panoptic, Pentax XW 40mm for maximum field with good correction.

[John]

1 minute ago, Don Pensack said:

If you are looking for an inexpensive wide field eyepiece good at f/5, you will buy a lot of different eyepieces to discover that such an eyepiece doesn't exist.

Cheap---well corrected in the outer field---wide field.  Pick any two.

 

I nearly posted that maxim a while back in this thread. I've been thinking hard over whether things might have changed a little lately making it less relevant, but I don't think they have really

[vlaiv]

5 minutes ago, Don Pensack said:

If you are looking for an inexpensive wide field eyepiece good at f/5, you will buy a lot of different eyepieces to discover that such an eyepiece doesn't exist.

Cheap---well corrected in the outer field---wide field.  Pick any two.

A couple candidates for you: TeleVue 41mm Panoptic, Pentax XW 40mm for maximum field with good correction.

Would that still hold at F/7 and could we possibly add another criteria - light weight - what would be options then?

[johnturley]

5 minutes ago, Don Pensack said:

If you are looking for an inexpensive wide field eyepiece good at f/5, you will buy a lot of different eyepieces to discover that such an eyepiece doesn't exist.

Cheap---well corrected in the outer field---wide field.  Pick any two.

A couple candidates for you: TeleVue 41mm Panoptic, Pentax XW 40mm for maximum field with good correction.

Thanks Don

The trouble with the above is that they are both big heavy eyepieces which I was trying to avoid due to balance issues with my scopes.

John 

[Don Pensack]

2 minutes ago, vlaiv said:

Would that still hold at F/7 and could we possibly add another criteria - light weight - what would be options then?

Light weight implies fewer lenses and poorer correction, or smaller eyepieces with reduced field.

Some candidates for the latter would be the 30mm XW or the 30mm APM UFF or the 35mm Panoptic.

But if those are too heavy, then sticking to narrower fields is the best choice for good correction in the outer field at f/5.

At f/7, the criteria get a bit easier, but most of the inexpensive widefields are based on the Erfle design, which is not good below f/8 or so.

 

[vlaiv]

I think I'll just make sensible decision and get TS WA 38 (or rather local supplied clone which somehow looks like TS version but is sold as SkyWatcher brand - don't ask) as this will really be my M31 eyepiece in 4" refractor. For the time being I'll use it at F/10 and after assessing it at F/6-F/7 will decide if I want to keep it when I get faster 4" scope.

If these work well at F/8 - then if I really miss edge performance - I'll make aperture mask for F/7 scope to bring it down from 102mm to ~90mm thus creating F/8 - for those moments when I want to marvel stars at the edge of the field.

In fact, I might keep both F/10 and get F/7. I'm still yet to do all the things that I planed to do with F/10 and once I do Roddier test on it, if it is good in Ha - it will be delegated to Ha Solar role (again at some point in the future).

[Ships and Stars]

1 hour ago, John said:

I think peoples tolerance of optical issues varies a lot person to person. What one person finds annoying might not bother another observer at all.

 

 

 

I've used both the  Baader 31 and 36mm without a coma corrector in a f4 scope. The edges would make a sailor seasick if you were looking at star clusters! But for large nebulae, they will do the trick, assuming exit pupil is optimal for a particular person's observing eye.

At f5 they are passable. but far from perfect. Relatively cheap secondhand however, and light.

I still have the 31mm which I use on occasion, but I'd choose the 30mm APM as I can't afford TV or Pentax now. However, I have the 20mm APM 100deg so the fov is the same as the 30mm APM. 

The only caveat is exit pupil depending on which scope I'm using. For really faint objects I lean towards a 6mm plus exit pupil while my eyes are still capable.

Weight and balance is secondary to me, there's always a way to stick a few hundred grams to offset balance with a big eyepiece, though my solutions have not always been elegant.

I once left my counterweights at home with the 20"dob and strapped a tool bag to the base instead. That was the best alignment I've had! Field expedient method

[johnturley]

2 hours ago, vlaiv said:

Would that still hold at F/7 and could we possibly add another criteria - light weight - what would be options then?

IMHO the 36 mm Baader Aspheric is not bad at all in my f7 Esprit, but not that great in my f5 Newtonian.

Is there any reason why it might perform better in an f7 triplet refractor than say in an f7 Newtonian.

John 

[vlaiv]

1 hour ago, johnturley said:

Is there any reason why it might perform better in an f7 triplet refractor than say in an f7 Newtonian.

I can think of one reason why it might perform differently.

Field curvature of focal planes of both scope and eyepiece. F/7 triplet and F/7 Newtonian are likely to have different radius of curvature (although that depends on focal length of scope and not F/ratio - I'm assuming regular / available scopes that will have somewhere between 500mm and 1500mm of FL in both cases).

In one case field curvature of EP can match that of the scope and as a result - no FC will be present, but that would mean that it won't match the other scope as refractors and newtonians of roughly the same FL will have very different radii (for refractor it is about 1/3 of FL while for newtonian it is equal to FL, if I'm not mistaken).

[Louis D]

8 hours ago, John said:

Having owned a 36mm Baader Aspheric and not found it brilliant even at F/12, I'm a little surprised to read this. The 40mm Aero ED is certainly a much better corrected eyepiece than the Baader Aspheric IMHO.

I was comparing the 35mm Aero extensively last night against other, much better corrected widest field eyepieces such as the 40mm Meade 5000 SWA, and it was pretty poor on the moon in the outer 30% at f/6 even with a CC in comparison.  From online images I've seen, the 36mm Baader seems to be similar.  Even in 2x Barlows, the 35mm Aero would not clean up very well in the outer 20%.  I just didn't want the OP to buy one and be disappointed with it in his 14" Newt.  It would probably be fine in a f/12 to f/15 Mak, though.

[John]

16 minutes ago, Louis D said:

I was comparing the 35mm Aero extensively last night against other, much better corrected widest field eyepieces such as the 40mm Meade 5000 SWA, and it was pretty poor on the moon in the outer 30% at f/6 even with a CC in comparison.  From online images I've seen, the 36mm Baader seems to be similar.  Even in 2x Barlows, the 35mm Aero would not clean up very well in the outer 20%.  I just didn't want the OP to buy one and be disappointed with it in his 14" Newt.  It would probably be fine in a f/12 to f/15 Mak, though.

If I had a choice, I would not choose the Aero ED's (in any focal length) for use in an F/5 14 inch newt. I've not used the 35mm though. The 40mm is certainly better corrected than the 30mm and is possibly the best of this design. Not a particularly useful exit pupil with an F/5 scope though.

Maybe your 36mm Baader Aspheric is better than the one that I had ?. I was rather shocked to see astigmatism in the outer field in a 150mm F/12 refractor I must say

For a 14 inch F/5 dob I'd get the counterwieghting sorted out and and go for a 21mm Ethos or 20mm APM XWA and soak up the fabulous views 

I might not even bother with a longer FL eyepiece.

Edited November 25, 2020 by John

[Louis D]

4 minutes ago, John said:

Maybe your 36mm Baader Aspheric is better than the one that I had ?. I was rather shocked to see astigmatism in the outer field in a 150mm F/12 refractor I must say

I never said I own a 36mm Baader Aspheric, but based on everything I've seen and read online, it performs similarly to the 35 Aero in that it is an improvement over the Erfle design, but not corrected to the level of a Panoptic or XW.

[Louis D]

9 hours ago, vlaiv said:

Problem is of course that I keep reading: "It is ok in F/7" and "It is not good even at F/7" - all over the place . I'm fairly sure it will be acceptable at F/10, and I'm also aware that Aero ED will be better corrected - problem of course being that Aero ED is no longer available in 40mm FL - only 35mm and that has 10% smaller FOV if I'm not mistaken - about 42-43mm, right?

I've measured my 35mm Aero ED to have a 44.4mm field stop.

[John]

14 minutes ago, Louis D said:

I never said I own a 36mm Baader Aspheric, but based on everything I've seen and read online, it performs similarly to the 35 Aero in that it is an improvement over the Erfle design, but not corrected to the level of a Panoptic or XW.

Apologies Louis - I misinterpreted your post.

I did own a Baader Aspheric 36mm, but not for very long. I've not owned the 35mm Aero ED though.

 

 

[Louis D]

I just remembered I had taken images through my 127 Mak of most of my eyepiece AFOVs, but haven't had the chance to composite them yet, so I went ahead and did the 32mm to 42mm group and posted it in my thread below:

Follow the link above and have a look at the changes going from an f/6 AT72ED to an f/12 127 Mak.  It includes both the 35mm Aero ED and 40mm Meade 5000 SWA as well as some modified Plossls and a true Erfle (three achromat variation) for comparison.  I think it supports my position that the 35mm Aero ED lies between a modified Plossl or Erfle and a Panoptic type design.  I don't have a 36mm Baader Aspheric to test to see if it falls into the same category, but I'm certain it probably does.

[Victor Boesen]

I've been following along with this thread since its first post which was conveniently posted while I was considering a new widefield eyepiece for my two refractors. I currently have an Explorer scientific 82 degree 24mm eyepiece which I really like in my 102mm f/7 refractor (haven't tried it yet in my Evostar 72ED), but I would like something slightly wider for darker skies when observing the Veil complex or perhaps even the North american nebula.

I've looked at the Explorer scientific 30mm 82 degree since my eyepiece collection only consists of these 82 degree eyepieces and it wouldn't cause trouble with my OCD with one eyepiece standing out form the others😅 At the same time I don't want to pay overprice if I could purchase the TS-optics 38mm 70 degree eyepiece that @vlaiv mentioned which also looks very promising (and very reasonably priced!) and not as heavy! My only concern is the exit pupil when using it with faster scopes and the magnification becomes vey low through both my refractors.

Does anyone have experiences with any of the eyepieces?

Thanks in advance, Victor

[vlaiv]

3 hours ago, Victor Boesen said:

I've been following along with this thread since its first post which was conveniently posted while I was considering a new widefield eyepiece for my two refractors. I currently have an Explorer scientific 82 degree 24mm eyepiece which I really like in my 102mm f/7 refractor (haven't tried it yet in my Evostar 72ED), but I would like something slightly wider for darker skies when observing the Veil complex or perhaps even the North american nebula.

I've looked at the Explorer scientific 30mm 82 degree since my eyepiece collection only consists of these 82 degree eyepieces and it wouldn't cause trouble with my OCD with one eyepiece standing out form the others😅 At the same time I don't want to pay overprice if I could purchase the TS-optics 38mm 70 degree eyepiece that @vlaiv mentioned which also looks very promising (and very reasonably priced!) and not as heavy! My only concern is the exit pupil when using it with faster scopes and the magnification becomes vey low through both my refractors.

Does anyone have experiences with any of the eyepieces?

Thanks in advance, Victor

I think that you'll find Evostar 72ED very demanding on eyepieces. This is not as much due to being faster scope at F/5.8, but because of very short focal length. Such a short focal length will produce very curved field and not many eyepieces can deal with that.

Good thing being that you are still young, if I remember correctly - most people start having trouble with not being able to adapt to shifts in focus position after age of 50 or so. This means that your eyes will compensate for most of field curvature. Other way of dealing with that is of course use of field flattener. Though these are mostly used for imaging - some people use them on short focal length scopes to get flat field.

Not sure if you should select your eyepiece to work with both scopes - maybe aim just at 4" F/7. At 420mm - Evostar already offers quite wide views and if you want to get widest possible view at 70mm of aperture - to go "ultra wide" - there is a cheaper solution, get one of these:

https://www.teleskop-express.de/shop/product_info.php/info/p2005_TS-Optics-11x70-LE-Porro-Prism-Binoculars---perfect-for-twilight-and-night.html

although you already have 15x70 - that is just a tad smaller FOV.

[vlaiv]

On a slightly different note - I just realized there is this eyepiece:

https://www.firstlightoptics.com/astro-essentials-eyepieces/astro-essentials-super-plossl-eyepiece.html

56mm 2" Plossl.

I know that it is not wide eyepiece - but it is wide field eyepiece - it will show you as much of the sky as any other 2" eyepiece.

How much of a problem is this focal length?

Again, at F/10 - it will be ok with 5.6mm but at F/7 it will provide 8mm of exit pupil and that is wasted light for most people. Also, I'm guessing that eye relief will be too much?

[Victor Boesen]

Thanks @vlaiv! An eyepiece working with both scopes would be a plus, but my priority is the 4" F/7;)

I think I will think about this a little more since the ES 30mm is quite pricey compared to the TS 38mm. I would, however, prefer sticking to the 82 degree series since I really like them, and I have no doubt that I will also be using it with future scopes, maks, dobs and fracs... I have seen mixed reviews on the 30mm ES eyepiece though, but I think some of them may be their original 30mm eyepiece which I assume won't have the same performance.

[vlaiv]

3 minutes ago, Victor Boesen said:

Thanks @vlaiv! An eyepiece working with both scopes would be a plus, but my priority is the 4" F/7;)

I think I will think about this a little more since the ES 30mm is quite pricey compared to the TS 38mm. I would, however, prefer sticking to the 82 degree series since I really like them, and I have no doubt that I will also be using it with future scopes, maks, dobs and fracs... I have seen mixed reviews on the 30mm ES eyepiece though, but I think some of them may be their original 30mm eyepiece which I assume won't have the same performance.

Here is alternative to consider.

I have some of the 82° range (11mm, 6.7mm) but also a little bit less wide line - 68° 28mm. I prefer less wide eyepieces for wide field. I'm ok with 82° being planetary eyepieces in my dob - gives you more "drift" time before nudging the scope.  Overall, best AFOV size for me is in 60°-70° range.

If you decide to mix eyepiece, then alternative to 30mm 82° in terms of sky it will show would be this one:

https://explorescientificusa.com/collections/62-series-eyepieces/products/62-40mm

It has 42.2mm of field stop (43mm for 30mm 82° - so very close) and it is relatively light weight compared to others at 670g. Not sure about edge performance in 40mm, but I do have 5.5mm and it is nice eyepiece that is easy to use and good sharp performer in the center of the field (I used it as planetary EP and did not pay much attention to edge of the field).

[John]

Another alternative is the Nirvana / UWA 28mm 82 degrees:

Old design:

http://www.opticalvision.co.uk/astronomical_accessories-eyepieces/nirvana_uwa-82_28mm_high-performance_eyepiece.html

New version:

https://www.teleskop-express.de/shop/product_info.php/info/p2757_TS-Optics-2----28-mm-Ultra-Wide-Angle-Eyepiece---82--Field.html

These compare well with premium 2 inch wide fields. I did a comparison a few years ago:

They are quite heavy but so is the ES 30mm 82 !

Edited November 27, 2020 by John

[pregulla]

I have the 35mm Aero ED and very happy with it in my F/5 scopes. It is not perfect, but for given size and weight (350g) I don't think you can get any better. It is a compromise I am willing to make. I also own ES82 30mm and even though it's better corrected and offers wider AFoV I just don't use it that often because of it's size and weight (over 1kg - almost exactly 3x Aero ED weight) . Another 2" eyepiece in that range I have owned was SW SWA70 32mm and it performed significantly worse at 8" F/6 (what I had back then).

[Highburymark]

Panoptic 27 is a light and very well corrected 2”. It’s the only 2” EP I still have since I moved away from heavy eyepieces.