Ultra-low power widefield EP recommendation

[badhex]

Hello!

After an extremely long hiatus of nearly 5 years, I'm back in the game and observing again! My first couple of return sessions were at a reasonably dark sky (supposedly Bortle 5 but I think maybe better than that) with an on-the-fly purchase of a celestron travelscope 70, but as the mount is complete and utter rubbish the experience was a pretty frustrating at times. That said, it reminded me how much better my experience would be once I got back home and dug out my SW ED80! Having now had a session or two with my ED80, I'm very happy to be reminded how amazing those widefield views are, and only found myself feeling limited with the 2" 30mm GSO I have (which is great, but the lowest power EP I own), and thought it might be time to buy myself a return-to-astronomy present  

I spent a few days researching, and came to the conclusion that the SkyWatcher Aero ED 40mm would be a good fit for my requirements, and generally gets great feedback... and then found I can't seem to buy the thing anywhere  I guess it's been discontinued.

So, I'd love to hear any recommendations for an alternative to the 40mm Aero. My general requirements are:

• 40mm-ish FL
• Wide FOV
• 2" fitting (obviously required at this point)
• Works well at F7.5 in my ED
• Reasonable size to fit in my EP case
• Budget of 200EUR-ish max

 

TIA! And it's good to be back!
Joe

 

[vlaiv]

Here are a few contenders, but I can't give any more advice since I have not used any of them. Best to get first hand advice or read some reviews

budget:

https://www.teleskop-express.de/shop/product_info.php/info/p1347_William-Optics-SWAN-40-mm-2--Super-Wide-Angle-Eyepiece---72--Field.html

https://www.teleskop-express.de/shop/product_info.php/info/p9299_APM-Eyepiece-UW-30-mm-80---2--barrel-size.html
(might be a budget eyepiece but I think it's rather good - only thing is that it has 41mm field stop - not as large as other eyepieces at 45-46mm - so narrower field of view regardless of the fact AFOV is 80 degrees. However, 30mm might not be a bad thing - darker background sky due to smaller exit pupil)

A bit more expensive:

https://www.teleskop-express.de/shop/product_info.php/info/p9549_Explore-Scientific-62--LER-Eyepiece-40-mm--argon-purged.html
(again, smaller field stop diameter at about 42mm - but this time due to smaller AFOV of 62)

https://www.teleskop-express.de/shop/product_info.php/info/p1754_Baader-Hyperion-Aspheric-36-mm---72--Wide-Angle-Eyepiece.html

Best options (over budget):

https://www.teleskop-express.de/shop/product_info.php/info/p5599_Explore-Scientific-40mm-2--Eyepiece---68----waterproof.html
(out of stock currently)

https://www.teleskop-express.de/shop/product_info.php/info/p1098_Vixen-LVW-42-mm-2---eyepiece---65--wide-angle.html

And finally, I won't even mention TV Panoptic 41mm since it is at least twice the budget that you have

Hope this helps

 

[old_eyes]

How about this?

https://www.firstlightoptics.com/ovl-eyepieces/aero-ed-swa-2-eyepieces.html

I am not sure it is exactly the same (I have an older Skywatcher Aero 40mm and love it), but worth checking out.

[Ruud]

The second best wide field experience I have is from my Maxvision 34mm 68° (5.14° ifield n 430mm refractor). These's also a 40 mm version. Identical optically are ES 68° and Meade series 5K SWA. Only the ES is available new. With a bit of luck the other two can be found used.

I have my very best wide field experience with binoculars:
--  5.5 mm exit pupil with 8x42  (8.1° field)
--  5 mm exit pupil with 4x20     (17° field)

[John]

3 hours ago, old_eyes said:

How about this?

https://www.firstlightoptics.com/ovl-eyepieces/aero-ed-swa-2-eyepieces.html

I am not sure it is exactly the same (I have an older Skywatcher Aero 40mm and love it), but worth checking out.

I have one just like that. I'm sure it is the same as the Aero ED - they have been sold under a number of different brandings.

I find it an excellent "lowest, widest" eyepiece in all my scopes. It's even decently well corrected in my F/5.3 12 inch dobsonian although the exit pupil generated in that scope is rather over-large but that is not the eyepieces fault.

I've been impressed by my 40mm ED SWA 2 inch. My other low / wide eyepieces are the Ethos 21 and Nagler 31 so it's in good company.

 

[badhex]

Thanks all! 

3 hours ago, vlaiv said:

Here are a few contenders, but I can't give any more advice since I have not used any of them. Best to get first hand advice or read some reviews

Thanks for the options. I've been doing a bit of research and have already seen a few of these so will definitely wait and see if anyone has first hand experience of the EPs

3 hours ago, old_eyes said:

How about this?

https://www.firstlightoptics.com/ovl-eyepieces/aero-ed-swa-2-eyepieces.html

I am not sure it is exactly the same (I have an older Skywatcher Aero 40mm and love it), but worth checking out.

Thanks - although I'm a bit confused  - this link *is* for the Aero ED, or are your referncing the 35mm version? Or are there two version of the 40mm, like an older one as you mention? I was looking at exactly this EP but sadly, the 40mm is no longer available from FLO (or anywhere else that I can see) and the 35mm is not a huge difference from my existing 30mm in terms of power. 
 

25 minutes ago, John said:

I have one just like that. I'm sure it is the same as the Aero ED - they have been sold under a number of different brandings.

I find it an excellent "lowest, widest" eyepiece in all my scopes. It's even decently well corrected in my F/5.3 12 inch dobsonian although the exit pupil generated in that scope is rather over-large but that is not the eyepieces fault.

"Lowest, widest" is exactly what I'm going for! Indeed, I'm pretty sure a few of your replies to older threads were what made me think the Aero ED would be the best for my needs! I can't seem to find any of the clones/alternative brandings available for this EP either. 
 

[John]

19 minutes ago, badhex said:

"Lowest, widest" is exactly what I'm going for! Indeed, I'm pretty sure a few of your replies to older threads were what made me think the Aero ED would be the best for my needs! I can't seem to find any of the clones/alternative brandings available for this EP either. 
 

Telescope Services in Germany have them but currently only seem to list the 30mm and 35mm:

https://www.teleskop-express.de/shop/product_info.php/info/p2334_TS-Optics-35-mm-2--UFL-Eyepiece---69--Field-of-View---6-Element-Design.html

 

 

[Louis D]

55 minutes ago, badhex said:

Thanks - although I'm a bit confused  - this link *is* for the Aero ED, or are your referncing the 35mm version? Or are there two version of the 40mm, like an older one as you mention? I was looking at exactly this EP but sadly, the 40mm is no longer available from FLO (or anywhere else that I can see) and the 35mm is not a huge difference from my existing 30mm in terms of power.

The 35mm version has a 71° AFOV (and a 73° effective AFOV due to distortion) and a 44.4mm field stop by my measurements, so it comes pretty close to maxing out the field of view possible in a 2" format (46mm field stop).  It should perform well enough at f/7.5 for your needs.

The 40mm Maxvision/Meade 5000 SWA has the same optics as the 40mm ES-68, so if you can find one used, it's an excellent choice.  It is much better corrected in faster scopes, but also much heavier (30.8 ounces vs. 12.3 ounces for the Aero ED).

Below is comparison image of my widest field eyepieces taken through a field flattened f/6, 72ED refractor.  It should give you some idea of the relative edge correction characteristics of various eyepieces.  The 40mm Meade 5000 Plossl is basically the same as the new 40mm ES-62.  The Baader Scopos is discontinued.

Edited September 24, 2020 by Louis D

[badhex]

9 minutes ago, Louis D said:

The 35mm version has a 71° AFOV (and a 73° effective AFOV due to distortion) and a 44.4mm field stop by my measurements, so it comes pretty close to maxing out the field of view possible in a 2" format (46mm field stop).  It should perform well enough at f/7.5 for your needs.

The 40mm Maxvision/Meade 5000 SWA has the same optics as the 40mm ES-68, so if you can find one used, it's an excellent choice.  It is much better corrected in faster scopes, but also much heavier (30.8 ounces vs. 12.3 ounces for the Aero ED).

This is great, thanks for the comparison image! I'd love the Maxvision/Meade 5000 as I have two from the wider lineup already in 1.25 format but as you said, much heavier and hard to get hold of. I could plump for the ES 68 but it's over my budget and again we come back to the size issue. It looks to me that apart from some softening around the edges, I'd be getting a pretty good deal going with the Aero ED 35mm - and from what know the softening should be much less obvious at F7.5 as you've mentioned.

[Louis D]

15 minutes ago, badhex said:

It looks to me that apart from some softening around the edges, I'd be getting a pretty good deal going with the Aero ED 35mm - and from what know the softening should be much less obvious at F7.5 as you've mentioned.

At 71° AFOV, if you concentrate on the center, the fuzzy parts are mostly in your peripheral vision where they are harder to perceive.

I forgot to add my ~30mm line-up which includes the 30mm ES-82, 30mm APM UFF, and 30mm 80° WideScan clone.  None of which will show as much sky (TFOV) as the Aero ED 35mm, though.

The WideScan clone suffers mostly from massive field curvature which the cell phone camera suppresses with its depth of focus, so be aware it actually looks worse to the human eye which has less depth of focus.  Make no mistake, it also has edge astigmatism, but it improves quite a bit by refocusing for the edge.  If the design had a field flattening element or two ahead of the field stop, it would have a massively improved reputation.

[John]

I use the Aero ED 40 in my F/7.5 ED120 refractor and it's pretty much sharp right across the field of view.

 

[badhex]

1 hour ago, John said:

I use the Aero ED 40 in my F/7.5 ED120 refractor and it's pretty much sharp right across the field of view.

Good to know. Can I safely assume that the 35mm will be the same though? I'd love to see a direct comparison of the 40mm and 35mm.

One other question springs to mind - why did they discontinue the 40mm? Is it just lack of interest in those long focal lengths or some other reason?

[badhex]

2 hours ago, Louis D said:

At 71° AFOV, if you concentrate on the center, the fuzzy parts are mostly in your peripheral vision where they are harder to perceive.

I forgot to add my ~30mm line-up which includes the 30mm ES-82, 30mm APM UFF, and 30mm 80° WideScan clone.  None of which will show as much sky (TFOV) as the Aero ED 35mm, though.

Thanks for the additional lineup! Very helpful to see those differences.

[Louis D]

2 hours ago, badhex said:

Good to know. Can I safely assume that the 35mm will be the same though? I'd love to see a direct comparison of the 40mm and 35mm.

One other question springs to mind - why did they discontinue the 40mm? Is it just lack of interest in those long focal lengths or some other reason?

I'm guessing the manufacturer is just waiting for someone to pony up enough money for another full production run.  These Chinese factories that supply the rebranding market don't generally start a production run unless they have a paying customer ordering a large enough quantity to make it worth their while.  I've heard you have to order 300 to have you brand printed on them, but I don't know how many to actually restart a sold-out production run.  I'm guessing well over 1000.

Edited September 24, 2020 by Louis D

[John]

2 hours ago, badhex said:

Good to know. Can I safely assume that the 35mm will be the same though? I'd love to see a direct comparison of the 40mm and 35mm.

One other question springs to mind - why did they discontinue the 40mm? Is it just lack of interest in those long focal lengths or some other reason?

Good question. I have the 30mm and 40mm of this line and they do vary in optical performance. The 40mm is a better corrected eyepiece in scopes faster than around F/8. I've not used the 35mm so I can't comment on how that compares with the 30 and 40mm.

@johninderby may well be correct on why production of a specific focal length has stopped.

 

[Louis D]

2 hours ago, badhex said:

Good to know. Can I safely assume that the 35mm will be the same though? I'd love to see a direct comparison of the 40mm and 35mm.

According to Ernest in Russia who tests many eyepieces on his optical test bench, the 35mm falls somewhere between the 40mm and 30mm.  You can look on his summary page for United Optics, ED toward the bottom of the table.  I've tried to repeat it below.  The numbers reflect the size of the blur spot of an artificial star at center/70%/98% to the field stop using an F4 and an F10 lens.  He moves the eyepiece to center the area of interest over the center of the lens image to eliminate lens aberrations influencing the results.  The actual full report page is here.  Try using Chrome browser to translate them.

	FL	AFOV	F4	F4	F4	F10	F10	F10	List of
Eyepiece	mm	°/deg.	centre	zone	edge	centre	zone	edge	rest aberrations

United Optics, ED	40	64	5	18	25	<5	12	20	Ast.,FC
United Optics, ED	35	70	5	20	35	<4	12	20	Ast.,FC
United Optics, ED	30	66	5	20	40	<4	11	22	Ast.,FC

[vlaiv]

40 minutes ago, Louis D said:

According to Ernest in Russia who tests many eyepieces on his optical test bench, the 35mm falls somewhere between the 40mm and 30mm.  You can look on his summary page for United Optics, ED toward the bottom of the table.  I've tried to repeat it below.  The numbers reflect the size of the blur spot of an artificial star at center/70%/98% to the field stop using an F4 and an F10 lens.  He moves the eyepiece to center the area of interest over the center of the lens image to eliminate lens aberrations influencing the results.  The actual full report page is here.  Try using Chrome browser to translate them.

	FL	AFOV	F4	F4	F4	F10	F10	F10	List of
Eyepiece	mm	°/deg.	centre	zone	edge	centre	zone	edge	rest aberrations

United Optics, ED	40	64	5	18	25	<5	12	20	Ast.,FC
United Optics, ED	35	70	5	20	35	<4	12	20	Ast.,FC
United Optics, ED	30	66	5	20	40	<4	11	22	Ast.,FC

Very interesting methodology for testing out eyepieces. This gives me all sorts of ideas.

Maybe MTF graphs could be used, or at least artificial star images?

[Louis D]

38 minutes ago, vlaiv said:

Very interesting methodology for testing out eyepieces. This gives me all sorts of ideas.

Maybe MTF graphs could be used, or at least artificial star images?

I think he uses a microscope of sorts with a reticle eyepiece to precisely examine the aerial image of the eyepiece.  This allows for fairly accurate measurements of blur spots.  The problem comes in with irregularly shaped blur spots.  I get the impression that they're sometimes really diffuse or asymmetrical.  He uses an artificial star to the best of my knowledge.  He also tries to use them under the stars in actual telescopes as well to give his impressions of real world usage.

[LDW1]

12 hours ago, badhex said:

Hello!

After an extremely long hiatus of nearly 5 years, I'm back in the game and observing again! My first couple of return sessions were at a reasonably dark sky (supposedly Bortle 5 but I think maybe better than that) with an on-the-fly purchase of a celestron travelscope 70, but as the mount is complete and utter rubbish the experience was a pretty frustrating at times. That said, it reminded me how much better my experience would be once I got back home and dug out my SW ED80! Having now had a session or two with my ED80, I'm very happy to be reminded how amazing those widefield views are, and only found myself feeling limited with the 2" 30mm GSO I have (which is great, but the lowest power EP I own), and thought it might be time to buy myself a return-to-astronomy present  

I spent a few days researching, and came to the conclusion that the SkyWatcher Aero ED 40mm would be a good fit for my requirements, and generally gets great feedback... and then found I can't seem to buy the thing anywhere  I guess it's been discontinued.

So, I'd love to hear any recommendations for an alternative to the 40mm Aero. My general requirements are:

• 40mm-ish FL
• Wide FOV
• 2" fitting (obviously required at this point)
• Works well at F7.5 in my ED
• Reasonable size to fit in my EP case
• Budget of 200EUR-ish max

 

TIA! And it's good to be back!
Joe

 

Have a look at the 2” WO 40mm, 72°, its a great ep, I get some great views with my f6, f6.25, f6.6 and also my f11.4 refractors. The last I looked they were about $125 US at Agena Astro out of California, hopefully they are available your way maybe under a different brand ! And it barlows (2x) very well also.

Edited September 24, 2020 by LDW1

[John]

22 minutes ago, LDW1 said:

Have a look at the 2” WO 40mm, 72°, its a great ep, I get some great views with my f6, f6.25, f6.6 and also my f11.4 refractors. The last I looked they were about $125 US at Agena Astro out of California, hopefully they are available your way maybe under a different brand ! And it barlows (2x) very well also.

Do you mean the WO SWAN ?:

https://www.firstlightoptics.com/william-optics-eyepieces/william-optics-swan-eyepiece.html

I bought the 33mm (pre-owned) for my astro society and it works very well in their 12 inch Meade ACF LX600 F/8.

When I compared it with the 30mm Aero ED in my scopes I thought they were corrected to a similar level.

I've not used the 40mm SWAN though.

 

 

[LDW1]

4 minutes ago, John said:

Do you mean the WO SWAN ?:

https://www.firstlightoptics.com/william-optics-eyepieces/william-optics-swan-eyepiece.html

I bought the 33mm (pre-owned) for my astro society and it works very well in their 12 inch Meade ACF LX600 F/8.

When I compared it with the 30mm Aero ED in my scopes I thought they were corrected to a similar level.

I've not used the 40mm SWAN though.

 

 

Yes I do, sorry to confuse, lol !

[John]

27 minutes ago, LDW1 said:

Yes I do, sorry to confuse, lol !

No problem

[badhex]

12 hours ago, Louis D said:

According to Ernest in Russia who tests many eyepieces on his optical test bench, the 35mm falls somewhere between the 40mm and 30mm.  You can look on his summary page for United Optics, ED toward the bottom of the table.  I've tried to repeat it below.  The numbers reflect the size of the blur spot of an artificial star at center/70%/98% to the field stop using an F4 and an F10 lens.  He moves the eyepiece to center the area of interest over the center of the lens image to eliminate lens aberrations influencing the results.  The actual full report page is here.  Try using Chrome browser to translate them.

This is great - thanks! Definitely bookmarking his site, the reports are helpful. 
 

10 hours ago, LDW1 said:

Have a look at the 2” WO 40mm, 72°, its a great ep, I get some great views with my f6, f6.25, f6.6 and also my f11.4 refractors. The last I looked they were about $125 US at Agena Astro out of California, hopefully they are available your way maybe under a different brand ! And it barlows (2x) very well also.

I can't find it now but I'd thought I'd read in a thread somewhere that a few people had had issues with the 40mm SWAN, glad to hear that's not the case for you! Perhaps a dodgy one slipped through the QA or something (or could be I'm confused and thinking about a different EP!)


Thanks everyone for all the advice so far. It's nice to know that even after 5 years SGL is still the super helpful, friendly place I remembered! Ultimately I'm still thinking about that Aero 40mm! My only concern with buying the 35mm at this point is that it's not very different from (although better quality and somewhat wider FOV than) my GSO, and if the 40mm decides to make a comeback I'll be kicking myself I didn't wait. Might be worth me contacting FLO and a few other suppliers to see if they know anything...?

[Pete Presland]

I owned a Vixen 2" 42mm LVW, it was a good performer in my C9.25. Nice and lightweight, pretty sharp across most of the field of view.

I have replaced with a 35mm Televue Panoptic, which is quite a bit more expensive and substantially heavier.

[old_eyes]

21 hours ago, badhex said:

Thanks - although I'm a bit confused  - this link *is* for the Aero ED, or are your referncing the 35mm version? Or are there two version of the 40mm, like an older one as you mention? I was looking at exactly this EP but sadly, the 40mm is no longer available from FLO (or anywhere else that I can see) and the 35mm is not a huge difference from my existing 30mm in terms of power. 
 

Apologies. This is labelled OVL rather than skywatcher, but I assume it is the same. Yes, I thought I had clicked on 40mm to check availability, but I must have missed. I would email FIrstLight Optics and see what they say. Lots of items have gone onto long back order due to COVID19, but will be supplied in future (I am currently waiting for a NB filter that is delayed until at least November).