Skywatcher SWA 70 Degree Eyepieces

[John]

Skywatcher SWA 70 Degree Eyepieces: 32mm, 13mm and 5mm

Way back in January, I described the physical attributes of 3 of the eyepieces from this new Skywatcher range. Here is a link to that report:

http://stargazerslounge.com/topic/206241-skywatcher-swa-70°-eyepieces-initial-impressions/

I’ve posted a few more pictures of these 3 eyepieces at the end of this report.

As a reminder, First Light Optics have kindly lent me the 32mm, 13mm and 5mm SWA 70 degree eyepieces to try out and report on.

It’s taken a while for me to get enough chances of using the eyepieces to get a reasonable feel for their optical performance and their ergonomics during use under the stars and a while longer to pull my thoughts together into something approaching a review.

Skywatcher state that the eye relief for all the eyepieces in this range is 20.6mm which, combined with their large eye lenses, all a consistent 30mm in diameter, makes for comfortable use. The large rubber eye cups twist up and down smoothly although the difference between their lowest and highest position is only around 6mm. I found the highest position worked best for me but glasses wearers may well find the opposite.

All the SWA 70’s are stated as having, as their name suggests, a 70 degree apparent field of view and this seems to be confirmed by visual comparison with other 70 degree eyepieces such as my Pentax XW’s. I have not actually performed star drift tests or physically measured the size of the field stops though.

All eyepieces in this range at stated as using an 8 lens element optical design. The 5mm and 13mm examples certainly have the weight as well as physical size to support this however I do have doubts about the 32mm in this respect. It’s a fair bit lighter and physically shorter than the 13mm and 5mm eyepieces and it just does not feel like it has 8 chunks of glass in it.

Currently these eyepiece cost £87.50 each.

These are large eyepieces but their weights are not specified in any data that I could find on them. As eyepiece weight can be important I decided to weigh them myself and these are my figures:

32mm = 530g

13mm = 640g

5mm = 670g

In terms of overall size, all three eyepieces are around 75mm wide at the fattest part of their rubber covered bodies. The 5mm is 160mm tall, the 13mm 130mm and the 32mm comparatively diminutive, for a 2” eyepiece, at 110mm tall.

The 13mm and 5mm are 1.25” eyepieces fitted with a hybrid 1.25” and 2” barrel design. The weight and bulk of these eyepieces mean however that they feel much more safely held in a 2” drawtube though. The 32mm has just a 2” barrel as the field of view could not have been achieved within the confines of a 1.25” barrel.

Due to the positioning of the focal plane within these eyepieces, while not quite par focal, the 3 eyepieces I had been loaned reached focus within a few mm of each other when they were all used in a 2” drawtube.

To use the 5mm and 13mm in a 1.25” drawtube you will need a “high hat” style of 1.25” eyepiece adapter so that it fits up inside the 2” skirt. A set screw is provided to secure the eyepiece in such an adapter (although that would mark the outside of the adapter). This set screw has to be removed to use the eyepieces in 2” mode and that’s just what I did which is why you can’t see the screw in the photos.

When used in a 1.25” eyepiece holder I found that the 5mm and 13mm required quite a bit of inward focuser travel which may well prove difficult to find for newtonians and refractors with limited focuser travel. This was another reason why I used all the eyepieces in a 2” drawtube for the vast majority of the time I had them.

Overall I felt this aspect of the SWA 70 degree design was rather awkwardly implemented and I’d recommend that these eyepieces are used in a 2” focuser only.

I used the 3 eyepieces for sessions in my ED102mm F/6.5  and ED120mm F/7.5 refractors and my 12” F/5.3 dobsonian. As the conditions improved during the period I’ve had these eyepieces I managed to view a range of deep sky objects as well as the Moon, Jupiter and Mars and some reasonably challenging binary stars.

32mm SWA 70 Performance

I’m taking the 32mm 2” eyepiece separately from the other two because, to me, it performs quite differently, almost like an eyepiece from a different range dressed up to match the shorter focal length SWA 70’s !

The eyepiece handles nicely and is reasonably compact and not over heavy for a 2” wide angle eyepiece of this focal length. As I’ve mentioned before, I’m not convinced that this member of the Skywatcher SWA 70 family contains 8 lens elements. It feels and actually performs very much like other sub-£100 32mm super wide angle eyepieces that I’ve used.

In the central 50 degrees of the field of view, the light transmission seems very good and the stars are sharply defined. Very pleasing. What was less enjoyable though was that, even with my F/7.5 120mm refractor though I could see noticeable astigmatism creeping into the stars in the outer 20% of the field of view. When I used the eyepiece in my faster scopes (F/6.5 refractor and F/5.3 dobsonian) this astigmatism became really quite noticeable. I was rather disappointed with this aspect of the 32mm SWA 70’s performance really although, as I’ve said above, it was about on par for a relatively low cost 2” 70 degree eyepiece, based on others of this type that I’ve used.

I compared the views of the Orion’s Sword area in the 32mm SWA 70 with those delivered by the Vixen 30mm NPL which is a nice 50 degree apparent field of view 1.25” plossl and found that the smaller format Vixen NPL delivered sharp stars over pretty much the same amount of true field that the 2” 32mm Skywatcher did. The extent to which the additional sky that the SWA 70 shows is useful or desirable will I think depend on the focal ratio of the scope being used and the viewers preferences on how sharp they like the outer parts of the field of view to be.

I would expect that the astigmatism that I saw would be much less of an issue, or possibly absent, in scopes of F/10 or slower.

The competition in this price niche includes the Skywatcher Panaview 32mm but unfortunately I did not have one of those on hand to compare with the 32mm SWA 70. There may well be little to pick between them though ?.

13mm and 5mm SWA 70 Performance

These are physically somewhat longer and heavier eyepieces than the 32mm 2” with the 5mm being one just about the largest eyepieces of this focal length that I’ve ever used !.

Located within the 1.25” barrels of these eyepieces is an additional set of lenses which also add to their weight. I feel much more confident that the 13mm and 5mm SWA 70’s do indeed contain 8 elements and, as well as delivering the shorter focal lengths, while maintaining the comfortable eye relief, the additional glass seems to deliver a better corrected eyepiece overall.

The 13mm eyepiece provides a very useful mid range magnification with the scopes I used for these tests that vary between 663mm and 1590mm in focal length. The 5mm is a high power performer giving between 133x and 318x in my scopes, the latter requiring good seeing conditions and a suitable target to take advantage of.

As with the 32mm 2” eyepiece, the transmission of light seemed good with faint deep sky objects showing good contrast and fainter stars such as supernova SN2014J in the galaxy M82, which was between 10^th and 12^th magnitude during this period, being picked out clearly and crisply. The E and F stars in Orion’s Trapezium cluster at the heart of the Orion Nebula were clearly seen on a number of occasions in both my 120mm refractor and the 12” dobsonian with these eyepieces.

Views of Jupiter, the Moon and Mars were pleasing although the 5mm did show some “ghosting” when viewing Jupiter and Mars although this did not seem to interfere with the detail and contrast on the planetary disk. Some light scatter was apparent around these bright objects, more than orthoscopic eyepieces of the same focal length that I compared them with but orthos are particularly good at controlling this so it is to be expected.

When used with the 12” F/5.3 dobsonian, the 13mm and 5mm SWA 70’s showed the stars, planets and lunar features sharply defined across about 80% of the field of view. As the object entered the next 10%, some lateral false colour seemed to creep in tinting the top and bottom edges of the planetary disks in the similar way that atmospheric dispersion can when such objects are viewed close to the horizon. Over the final 10% of the field some astigmatism and a small amount of distortion is added to the mix as well so that is not the part of the view thats going to be used much !

The overall performance of the 13mm and 5mm 70 degree eyepieces is pretty good though, when their cost is taken into account. In my slower scopes, notably the F/7.5 120mm refractor, astigmatism is largely absent although the lateral colour and outer field distortion are still in evidence. So competent performers but perhaps not particularly outstanding for any specific use.

The physical size and weight of these eyepieces can’t be ignored though and while their chunky rubber clad contours make for secure handling, even with gloved hands, their bulk will have balance implications for some setups. This factor plus the positioning of the focal plane of the eyepieces means that, in my view, they really should be used in a 2” drawtube.

Summary

I found the 2” 32mm Skywatcher SWA marginally disappointing overall in all honesty. It’s a decent enough budget 2” wide field with a distinctive look to it but I’d hoped it might be a little more than that.

The hybrid 1.25” / 2” barreled 13mm and 5mm from the series are really quite nice eyepieces if you can get over their sheer size and weight. They are very comfortable to peer into and offer reasonably well corrected views in scopes down to around F/5.

There are though many other competitors at around the same £80-£90 price point and I cannot help feeling that the novel styling and eye comfort alone are not enough to give these Skywatcher SWA 70 degree eyepieces a clear edge, other than in physical presence in an eyepiece case.

Good but not great eyepieces would perhaps be a fair assessment, overall.

As ever, many thanks are due to James and Steve at First Light Optics for making these eyepieces available to me to try out and report back on.

[YKSE]

Nice work John, a long waited review for some members.

[John]

Nice work John, a long waited review for some members.

Thanks Yong 

[luminova11]

Yes thanks John. I was looking at these to carry on from my MV 68°s for the shorter focal lengths. Do you think they're up to it, or should I stick with my original plan of going with the ES 82°s?

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[John]

Yes thanks John. I was looking at these to carry on from my MV 68°s for the shorter focal lengths. Do you think they're up to it, or should I stick with my original plan of going with the ES 82°s?

Sent from my LG-D802 using Tapatalk

Very difficult to for me to advise on this because I've never used either the MV 68's or the ES 82's. Sorry.

[bingevader]

A fair and excellent report, thanks John. I suppose they were unlikely to be greatly different from the offerings already on the market at that price.

[Damo636]

Another excellent and useful report John, many thanks!

[nicks90]

really glad you posted that review john, as I am still tying myself up in knots over what to do about my eps for the 12" f4.9 dob. Certainly settles for me that there is no point selling my panaviews to buy the 32mm as an 'upgrade'...

although i might be tempted to replace my old 60deg 15mm with the 13mm you reviewed.

[rwilkey]

Yes thanks John. I was looking at these to carry on from my MV 68°s for the shorter focal lengths. Do you think they're up to it, or should I stick with my original plan of going with the ES 82°s?

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The ES82's have shorter eye-relief and take a bit of getting used to if your are familiar with a variety of widefields, however, I think the ES82's will give more satisfactory views than the SW SWA's.  Just a guess as I have only tried the ES's.

[luminova11]

I don't mind the short eye relief, the MV 16mm pretty tight.

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[AlexB67]

Thanks for the report John. Not that I  had the intention of buying one and expecting they would probably be sort of middle of the road and perform not so well in the faster scopes.   My main gripe is the large size though for what could be smaller for the 1.25 inch eyepieces. Without having tried it, I m not keen on the 2 inch design making them that heavy and big somehow. I also wonder how much cost you'd be paying for that extra casing and added stuff as well.  Not the type of thing I'd go for I think. 

[Tiny Small]

An interesting read. I own the 32mm, 22mm and as of earlier this week the 5mm. Your thoughts on the 32mm are absolutely bang on. I use them in my dob and the astigmatism from the 32mm is very bad... but... when used in context it is a perfectly adequate eyepiece. Unfortunately adequate isn't really good enough at that price point I don't think. I haven't had chance to use the 5mm in good conditions yet but initial thoughts are it should be decent. I have a feeling though that the 22mm is going to be the gem of this series. It really is VERY different to the 32mm and is my go to eyepiece even for planetary stuff. Jupiter and Saturn are brilliant through it, even when used with the ED barlow. No noticable astigmatism or coma, very good contrast and colour and resolves a lot of detail. I think the 22mm punches well above it's weight.

Are you going to SGL9? It would be interesting to see what you think of the 22.

[John]

Are you going to SGL9? It would be interesting to see what you think of the 22.

I am indeed 

I'll be there from Thurs - Sun on pitch 115. I'd love to have a look at and, hopefully, through the 22mm 

[Tiny Small]

Im on pitch 37 from Wednesday through to Monday morning so I'll come over to say hello once you're settled.

[alan potts]

John,

Better late than never, a fine well balanced review as ever from yourself. I keep forgetting to check this part of the site and I have a good deal of reading to do, but as the skies here are still awful I guess I have time.

Alan.