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Takahashi FOA-60 Review

What is the most perfectly corrected refractor? It’s an interesting question and for some years the answer would likely have been, ‘Takahashi’s TOA-130’. The acronym ‘TOA’ stands for ‘Triplet Ortho Apochromat’ indicating that the TOAs have aberration levels below most catadioptrics and a hundred times lower than many apochromats. They achieve this by using two ED elements, rather than the usual one, along with big air gaps that can be used by designers as ‘virtual elements’ to further control aberrations.

Takahashi have recently extended the TOA concept into smaller apertures to produce the FOA-60. In this case, they have achieved a similar level of correction using a fluorite doublet. But this is not any old fluorite doublet. Not only is it a fairly long focal length at F8.8, it also employs a mating element ‘never used before’ (an ED glass perhaps?), but a big air space as well.

Given that such perfection was never going to be cheap, you might ask, ‘why bother?’ One clue is in the timing: the FOA-60 was launched in time for the best Mars opposition in the current cycle (2018). A really perfect 60mm should work well on Mars; and a perfect, long-focal-length scope with a small aperture stands the best chance of cutting through the poor seeing inevitable when viewing Mars at low altitude. Trouble is, the Red Planet is a tough target for many imperfect scopes that give preference to correcting short wavelengths for imaging, which is where the FOA-60 comes in.

Of course, a really perfect and portable tiny refractor has other uses – other solar system targets, eclipses and high-power terrestrial viewing too. And whilst Takahashi have produced two well-corrected 60mm scopes before (the old FC-60 and recent FS-60Q), neither come close to the theoretical perfection of the FOA-60. Now let’s discover how that putative perfection translates to the real world, how it compares with the FS-60Q and whether it’s worth splashing out for.

Note: I bought this as the complete FOA-60Q with its quadruplet red nameplate; you could buy the blue-plated basic FOA-60 and then add the ‘Q’ module later: the end result is optically identical. I will also review the FOA-60Q separately, as it’s a very different telescope with its own characteristics.

At A Glance

Telescope

Takahashi FOA-60

Aperture

60mm

Focal Length

530mm

Focal Ratio

F8.8

Length

510mm (dewshield retracted)

Weight

1.8 Kg

 Data from Takahashi

What’s in the Box?

Few things in life are better than unboxing a brand new Takahashi

Design and Build

The FOA-60 is classic Takahashi and has styling cues – like the short focuser, super-long draw-tube and slim OTA – from earlier days. This makes the FOA look more like the descendant of an FC-60 than an FS-60, despite the new-style silver lens ring. Build quality is gorgeously high and it has a luxury feel. I would imagine the FOA-60 will be a collectors’ item one day.

Two Takahashi 60s – FS-60C and FOA-60

Lens cell and sliding dew-shield detail

Optics

The old FC-60 had a fairly conventional Steinheil fluorite doublet, but the FOA-60 is quite different. Not only is it a slightly longer focal length at 530mm (F8.8), it also employs a mating element ‘never used before’ (a special dispersion glass of some type). It also reverts to the front-surface fluorite design of the FS-series and has a very large air gap, like the old Sky-90, with a suitably large, collimatable cell.

Takahashi’s published centre spot image and crossings diagram suggest the FOA-60 achieves tighter control than any other Takahashi refractor, even including the outstanding TSA-102, a now discontinued F8 triplet. It significantly out-performs their two best current 4” doublets, the FC-100DL and DZ. This is why the FOA-60 should perform very much better than an F6 doublet like the FS-60C (TV-60 etc), especially at the far ends (red and violet) of the visible spectrum. In theory at least, the FOA really does extend the ortho-apochromat concept into a small doublet.

Bench tests have measured the FOA-60’s real-world Strehl at 99%, literally almost perfect.

Below you can compare Takahashi’s own crossing diagram for their new best 4” fluorite doublet, theFC-100DZ, with the FOA-60. I’ve also compiled spot diagrams for a range of Tak’s best refractors for comparison. On a purely theoretical basis, the FOA-60 reigns supreme!

Tube

The FOA-60 has the usual Tak’ white enamelled tube, but for the FOA-60 it is a slim 68mm in diameter, closer to the style of the old FC-60 (that I loved).

Again, unlike the FS-60C, the FOA-60 has a sliding dew shield that sports the (in more recent models) signature silver ring and a big lock-screw. It has a perfectly fluid action and hits the stop with a satisfying clunk. The lens cap is a black plastic clip-in affair on this one, but I have also seen a silver pressed tin example like you get with an FC-76.

The slim tube and beautifully executed sliding shield, together with the diminutive focuser, do give the FOA-60 a more premium look and feel than the FS-60C/Q if that matters to you. That makes sense – this is a very expensive 60mm refractor.

Focuser

The biggest problem with my other favourite Takahashi 60mm – the FS-60Q – is a serious lack of focus travel at just 25mm. This is all that the original short focal length FS-60C needs, but isn’t really enough with the Q module in place.

By comparison, the focuser on the FOA-60 has no such trouble. Its drawtube is slightly narrower at a bare 50mm, but has a whopping 85mm of travel to accommodate any eyepiece you could think of. And with the supplied extension, straight through viewing Japanese style is easy too, as is imaging.

At first the focuser seemed frankly a bit stiff. But after a few months of light use it freed to give an oily smooth and superbly precise action, virtually free of image shift and up to the task of minute adjustments at high power. Full marks.

Again, in line with the FOA-60’s premium price tag, the focuser has the proper metal silver wheels in place of the plastic imitations some entry level Takahashis get.

Mounting

Unlike the longer and heavier FOA-60Q, the basic FOA-60 has a short light tube that works on the lightest mount. But given the high magnifications the FOA-60 can take, it benefits from a slightly beefier mount than the SP. The FOA-60Q meanwhile needs the size of mount you’d use for a typical 4” doublet.

Accessories

A note on colour. Think Takahashi think lime green. But that hasn’t always been the case. Takahashi has changed the colour of its focuser and accessories a few times, to include black and brown. It’s recently done it again. Now the lime has a bluish tinge. I like it. Trouble is, it doesn’t match the old colour – take care when buying accessories if a perfect match matters to you.

The FOA-60 comes with one of Tak’s beautiful-but-heavy extension tubes for straight through viewing or imaging. A 2” visual back with twin lock-screws is supplied (again, the draw-tube is narrower than the FS-60C’s, so its visual back won’t fit), along with a nice 1.25” adapter that ends in Tak’s characteristic silver twist-grip.

The obvious finder is Takahashi’s peerless 6x30 unit, but you could fit a 7x50 with an illuminated reticle, or indeed the tiny 5x25 if you can find one: the finder-ring mount on the focuser is standard.

The FOA-60 has a dedicated cast clamshell – an expensive thing of beauty. At 68mm I.D., it’s closer to the old 65mm FC-60 rather than the 80mm tube of the FS-60C. That means the clamshell for FS-60C definitely won’t fit, but the FC-60’s just might.

The elephant-in-the-room accessory for the FOA-60 is of course the ‘Q’ module, that screws into the OTA in front of the focuser. The Q module increases the focal length by 1.7x to make the FOA-60 into a 900mm/F15, flattens the field and takes out the remaining aberrations. You can either buy the module as part of a package – in which case you get a red quadruplet-style serial number plate (which is how I bought the scope reviewed here) - or as a separate item.

The ‘Q’ module changes the scope so utterly, both physically (it’s much longer and heavier) and optically, that it gets a separate review. Suffice to say it is of marginal use visually, because the FOA-60 is already very well corrected (unlike the FS-60C which really benefits from its dedicated Q module). But don’t dismiss the FOA-60Q, because it does deliver very impressive results photographically.

The FOA-60Q is longer and heavier and needs a beefier mount

This APS-C daytime image through the base FOA-60 (no Q) is sharp to the edge and free of false colour

In Use – Daytime

The basic FOA-60 makes an excellent daytime spotting and birding scope because it remains sharp and false-colour free at powers (100x plus) at which ordinary birding scopes just don’t work. Daytime photos are excellent too, but the quality falls off in the corners, especially at full-frame.

Terrestrial photography is perhaps where the Q module makes most sense, as a 900mm telephoto lens which is sharp and bright across a full frame sensor and free of false colour in the most demanding situations. Want to image a rocket launch against a bright sky? Or raptors nesting a hundred metres away? Here you go.

In Use – Astrophotography

The FOA-60 delivered excellent lunar images, but again this is where the FOA-60Q with its extender module fitted shows its advantage: more image scale of course, but incredible resolution for a 60mm scope. If you want a compact scope for lunar imaging (collecting phases, for example), the FOA-60Q is the one. Similarly, the FOA-60Q might be the best portable eclipse imager available.

The base FOA-60 shows dramatic off-axis curvature on a full-frame sensor and this is where the Q module again shows what it’s for. Sure, it’s slow at F15, but the pay off is an extremely wide and flat field. Apart from a touch of vignetting in the very corners (that might be due to my cheap T-ring; a big-aperture Borg one would be better), the ‘Q’ is flat and perfect edge-to-edge.

Full frame (EOS 5D) image of M42 with FOA-60 shows lots of curvature towards the edges

With the ‘Q’ 1.7x extender module in place, the same full frame image is flat to the edges

Cropped image of the Moon with the FOA-60 – sharp and detailed

With the ‘Q’ 1.7x extender module, the FOA-60Q produces superb images of the Moon, showing stunning detail for a 60mm

In Use – The Night Sky

General Observing Notes

The FOA-60, mounted on Takahashi’s sadly-discontinued PM-SP mount, was particularly easy and relaxing to use. The short tube vibes much less than the longer, heavier FOA-60Q and the balance point near the focuser means the eyepiece doesn’t change height much, always giving an easy viewing position, from horizon to zenith.

The focuser is easy to use and smooth, with minimal focus shift even at high power. The focusing sweet spot is long enough to make finding it easy and the low vibes help too. There’s enough travel for every eyepiece I tried.

High powers with flat-field eyepieces deliver a completely flat FOV, but low powers with Plossls show just a bit of curvature.

The perfect (really) optics give wonderfully sharp and bright stars with saturated colours and no flare at all, making the FOA-60 an unexpected pleasure on the deep sky.

Cool Down

Cool down seems instant, with a perfect image minutes from a warm house.

Star Test

The star test is effectively perfect, with identical crisp diffraction rings either side of focus, even illumination and tight in-focus diffraction pattern.

The Moon

The Moon is the obvious favourite subject of a tiny, perfect apochromat, so let’s consider it in detail through the FOA-60.

On a night of ordinary seeing, the Moon looks much like it does through any small apochromatic refractor. But on a really steady night, with slight haze dampening convection, I got stunning views of a 6-day Moon at 151x with a 3.5mm Type 6 Nagler. Masses of detail was visible for a 60mm scope - the shadow of Albategnius’s pyramidal central peak and its knotted rim on the terminator; small craters and rays in Mare Serenitatis. I don’t generally reckon on finding rilles with scopes this small, but Rima Hyginus and Rima Ariadaeus were sharply defined with changes in width clearly visible, maybe Rima Triesnecker in deep shadow too.

A three-day crescent Moon in good seeing showed surprising detail. This is a difficult phase of a lunation: often low down in the twilit sky and lacking contrast. But the FOA-60 revealed the embayments around Mare Criseum in enough detail to really explore, all picked out in icy whites and hard greys. The low sun highlighted crater Yerkes with its ‘winged’ shape; Swift, Peirce and Picard too. The rille in Petavius was clear and distinct. Taruntius right on the terminator was broodingly full of shadow, showing its inner ring of hills, central peak and crater Cameron (astronomer, not the execrable British Brexit politician) on the rim. Meanwhile nearby Mare Fecunditatis was full of subtle shading and shadowed wrinkle ridges.

One particular feature of the FOA-60 is lack of light bleed-over from the Lunar limb. Even at 151x with a 3.5mm eyepiece, the transition to black space is stark and it was possible to see a mag 7.5 star right close in

The Moon is of course delivered with perfect sharpness and absolutely no false colour or flare, as you might expect given the FOA-60’s optical quality and correction.

Venus

On a warm spring evening, with bats flitting the air and a crescent Moon nearby, Venus is bright and lovely in the western dusk sky. Also, it’s my wedding anniversary (cue the strings). How romantic.

The Goddess of Love thing fails with most refractors, even ‘apochromats’, because Venus’ natural platinum gets ringed with false-colour: amethyst or emerald. With the FOA-60 there is none of that – Venus presents as a perfect brilliant gibbous planet with <almost > no false colour, even out of focus. I say almost, because at 180x the focused image is still perfectly sharp and clean, but there is the merest hint of amber in the out-of-focus blur.

I labour this to make a point about the FOA-60Q: that last faintest hint of CA outside focus at ultra-high power on the brightest subjects is what its superlative correction removes. Normally though, for visual astronomy at least, the base FOA-60 is false-colour free in any situation.

The summary here is that for visual you just don’t need to further correct the FOA-60 with the Q module.

Mars

Mars just after the 2018 opposition (i.e. large at 24.2” but very low in the sky) showed a bright full disc with no false colour. I could make out Syrtis Major and a hint of polar cap at 108x with a 5mm Nagler.

Later in the year, with Mars much smaller (9”) but higher in the sky, 180x with the 3mm setting on a Nagler zoom gave an excellent view with the dark equatorial band of Tyrrhena, Hesperia and Cimmeria running out from the centre of the gibbous limb.

Jupiter

The FOA-60 gave a perfect view of Jupiter at 132x with the 4mm setting on a Nagler zoom, but the best view was at just 108x with a 5mm Monocentric. In excellent seeing, I could make out fine bands in the polar hood, the delicate-pink GRS just coming around the limb and thickening and swirls in the NEB and SEB. I also watched a shadow transit of Europa.

Saturn

On a cold evening in early October, with a clear dusk sky but surprisingly good seeing, Saturn is at only 13 degrees altitude, just above the trees opposite my balcony: a long way from opposition and just 16.8” in size. The circumstances are hardly ideal. Nonetheless, the FOA-60 gives an excellent view.

The 5mm Monocentric giving 108X looks good, but I sense the FOA-60 will take more and I’m right: the 4mm Zeiss Abbe Ortho yields my favourite view, noticeably brighter than the 3-6mm Nagler zoom. This is where minimalist eyepieces like the Mono and the Abbe Ortho come into their own. The FOA has superb optics and can take high powers, but then gets quite dim and benefits from the very best light throughput.

Saturn through the Zeiss Abbe at 132x is that Cassini-in-miniature view that I love: perfectly crisp with all the major stuff on show. Part Cassini division, planet obscured by the rings, shadow of the planet on the rings and both a hint of a band and the polar hood. Through a 60mm! Again, the only problem is that it’s easy to want more, forgetting this isn’t an FS-128.

The FOA-60 is, in very good seeing, a better planetary scope than a 60mm has any right to be.

Deep Sky

I hadn’t really been looking forward to testing a 60mm F8.8 scope on deep sky, but on a dark clear night of good seeing in February, I had great fun with it.

At 59x with a 9mm Nagler, M42 looked better than it had a right to, with knots in the nebulosity, the extended arms and dark lane all clearly visible, the Trapezium nestling within, bright stars like Nair Al Saif with not a trace of false colour or flare. A great view which I lingered over.

Open clusters – M35, M36-38 in Auriga and the Double Cluster – looked particularly beautiful through the FOA-60, perhaps due to the super-tight PSF delivered by such perfect optics. Stars are such pinpoints that the faintest ones are just the tiniest pin-points of light in dense black. The shape of the Starfish Cluster, its arms of stars, were easy with direct vision. The Pleiades had that misty sparkle that only fine refractors give.

Fainter Messier objects like M1, the Crab Nebula, were a bit dim but still easy to pick out from perfectly black space.

Rigel and Castor were both an easy split.

Later in the season, I had a wonderful view of M3 – much more than just a fuzzy star, I had fun trying to start to resolve it at 58x with a 9mm Nagler.

In case all this deep sky goodness was a moment of madness, I repeated it. And again. No, the FOA-60 really is a very nice small refractor for deep sky.

Summary

In no way could you call Takahashi’s superb little FOA-60 good value. But if you like perfect small refractors then you will probably want this one. Making negative comparisons with a similarly priced Dob’ is a bit like pointing out that a Nissan GTR is faster than a Morgan; so I won’t.

There’s not much else to say, because this is as close to a perfect 60mm aperture as you will ever find. It has clearly (and nowadays unusually) been designed with visual use in mind. As such, it does a surprisingly good job on the Moon and planets, but you need good seeing to realise why it really is better than any other 60mm apochromat. It also exudes a certain gorgeous hand-built retro charm, a refractor-guy’s Questar, maybe.

True, in most circumstances an FC-76 is a better choice and will show you more. It also has to be said that an FS-60Q is in many ways a more adaptable telescope and gives just a little away to the FOA-60 at high powers.

The only caveat that I must mention is that I have seen one with a trace of mis-collimation, just like the old Sky-90 often had (the lens and cell design are similar). The FOA-60 may not be a particularly robust travel scope, then. And make sure you test it thoroughly or can return it if there’s a problem.

But in the end, the FOA-60 has that magic exoticism and perfection which neither the fC-76 or FS-60Q can match. Plug in the Q module and it delivers aberration-free lunar and terrestrial photos at full-frame like almost nothing else.

In the end, I’d be quite happy, stuck on a desert island with clear skies and only the FOA-60 to explore them; and you can’t say fairer than that.

As an irrational fan of tiny refractors, I absolutely love the FOA-60. It reboots the classic style of the FC-60 with the latest tech’. But for practical purposes, apart from terrestrial (or lunar) imaging, I would strongly advise you to buy an FC-76 or FS-60Q instead. You want one anyway? Me too.

 

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