Eyepieces are something of a personal choice. Differences in eyesight and even variations in pupil diameter mean that what works for one person might not work for another.
Every astronomer, however, should have a selection of low- and higher-powered eyepieces in their arsenal.
Masuyama’s offering of 53° eyepieces covers an excellent range, from a long-focal-length 30mm down to a punchy 5mm.
With an apparent field of view of 53°, first impressions were that these should work for a wide range of objects and eyes, but we were curious about field illumination and eye relief versus narrower variants.
Read our guide to eyepieces and how to build an eyepiece collection.
Unboxing
There isn’t an option to purchase all eight eyepieces as a set in an eyepieces case.
Instead, we received them within a single parcel, each individually packaged in smart boxes.
A clear and moonless night presented itself and so, armed with our 81mm refractor, we headed out.
We started with the lowest power, inserting the 30mm for star alignment.
Popping over to Vega, we had our first look and were greeted by a superb field of view that was well illuminated from edge to edge.
How the Masuyama 53˚ eyepieces performed
Alignment completed, we slewed to Albireo with the 25mm and enjoyed exquisite colour contrasts between the gold and blue stars.
This was repeated at 20mm and 15mm, the optics proving flawless.
Next, selecting the Orion Nebula, M42, the 12.5mm eyepiece provided a reasonable 36x magnification and we resolved some lovely detail among the mist surrounding the Trapezium.
Eye relief continued to be excellent through the 12.5mm and 10mm sizes as we finally headed to the Double Cluster in Perseus.
The field of view remained beautifully flat from edge to edge, with no distortions, allowing us to enjoy a pleasingly immersive view for 53°.
As we stepped up the power, we were impressed to discover that the eyepieces appeared to be at least close to parfocal, barely requiring refocus.
Eye relief was less forgiving at 7.5mm, which could be challenging for glasses wearers. However, we didn’t note any aberrations.
The next clear sky was a couple of weeks later, when we brought out our long refractor for another session, this time at a 1,100mm focal length.
The 30mm, 25mm and 20mm eyepieces (now providing 37x, 44x and 55x magnification) proved again to be excellent for star alignment.
We now had the Moon and nearby Jupiter to play with, so popped the 15mm in and started some lunar observing.
Observing the Moon
This is where the Masuyama 53° set really came into its own – the view was exceptional and eye relief was perfect.
We couldn’t resist grabbing our smartphone for a quick picture.
Even at 7.5mm, we were impressed with the lunar details and our view remained sharp even at 148x magnification, although the seeing was undeniably brilliant.
We couldn’t take our eyes off Jupiter as we studied its bands and zones.
Next, we popped the 5mm in. With an aperture of 101mm, the theoretical limit of useful magnification for this focal length is about 200x, whereas the 5mm ortho Plössl pushes beyond this at 220x magnification.
Nevertheless we were curious, given the excellent seeing conditions of the night.
Heading back to the Moon, we weren’t surprised to see our view start to blur, in addition to a minor reflection in our optical train, yet we were still relatively pleased with the results.
Overall, these Masuyama eyepieces did more than impress us.
Even for a seasoned astronomer, it almost felt as if we were viewing each object for the first time.
We found ourselves lost in the moment as we homed in on the Moon and admired its terminator features, including the Apennine mountains and even shadows strewn across crater Ptolemaeus as we progressed to higher powers.
With minimal distortions up to 7.5mm, we knew that this was a set that we would use again and again.
Bearing their cost in mind, these are eyepieces to cherish and not relegate to a forgotten kitbag.
Perfect for outreach events, at-home observation and as a grab-and-go option, these are to be used and enjoyed often.
Ortho Plössl lens design
Each Masuyama 1.25-inch 53° eyepiece combines the best of popular Plössl and classic orthoscopic eyepieces to produce a unique hybrid design.
While standard versions of those types typically consist of four elements across two lens groups, the Masuyama Ortho Plössl (MOP) comprises five multi-coated lens elements across three groups.
This renders these ‘super ortho Plössls’ for maximum control over aberrations, optimal colour correction and sharp views.
Each eyepiece provides a supremely flat field of view from edge to edge with minimal light scatter.
That makes them suitable for a range of different astronomical objects, including the Moon, planets, deep-sky objects and the Sun (only with an appropriate solar filter).
The hybrid design also allows a wider apparent field of view than standard orthoscopic eyepieces, which at 53° strikes an ideal balance between narrow and widefield alternatives.
Best features
Filter screw threads
On the underside of every eyepiece is a screw thread for 1.25-inch filters, such as colour or high-contrast varieties. Such filters can be used to elevate an astronomy session by boosting contrasts and enhancing details, or reducing aberrations if viewing objects close to the horizon.
Lightweight design
Well-designed eyepieces are not just great to look through, but easy to handle with gloved hands or in low light. With weights that range from only 60g to 140g across the set, the risk of dropping them is reduced, while each has a ridge that told us when the eyepiece had fully slotted into our diagonal.
1.25-inch barrels
Each eyepiece has a 1.25-inch chrome-coated stainless-steel barrel that is familiar to all keen visual astronomers. The smooth design allows for easy transition into and out of a 1.25-inch diagonal, making these eyepieces easy to swap out in dark conditions while ensuring they are well secured.
Rubber eye-cups
Each eyepiece comes fitted with a soft rubber eye-cup for maximum viewing comfort. These guide observers to the best resting position, providing an optimised viewing experience. Meanwhile, for the high-powered versions, the cups can be folded down to allow spectacle wearers eye relief.
Dust caps
Keeping eyepieces dust-free is essential to maintaining performance and ensuring you make the most of each observing session. These dust caps are a beautifully simple but effective addition that, provided you replace each cap as your night progresses, allows you to easily swap eyepieces knowing that each one will be free of dust.
Vital stats
- Price: £185 each (for sizes 5mm –20mm), £195 each (for 25mm and 30mm)
- Focal lengths: 5mm, 7.5mm, 10mm, 12.5mm, 15mm, 20mm, 25mm, 30mm
- Lens design: Ortho Plössl
- Apparent field of view: 53°
- Eye relief: 4mm, 5mm, 7mm, 8mm, 9mm, 13mm, 16mm, 19mm
- Optical elements: 5
- Extras: Dust caps, filter thread
- Weight: 60g, 70g, 80g, 90g, 100g, 120g, 115g, 140g
- Supplier: First Light Optics
- Email: questions@firstlightoptics.com
- www.firstlightoptics.com
This review appeared in the April 2024 issue of BBC Sky at Night Magazine
