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Takahashi FOA-60Q Review

Takahashi’s original ‘Q’ scope, the FS-60Q, which uses an inline extender/flattener to turn the FS-60 imaging scope into a mini super-apo for solar system work and imaging at larger scales, is one of my favourite small refractors. It’s ideal for eclipses, but makes a great terrestrial telephoto too. The FOA-60Q uses a similar module to convert the FOA-60 into … well, what exactly?

The FOA-60 is already one of the most perfectly corrected refractors, for false colour at least. And unlike the FS-60 it’s already a long focal ratio at F8.8. So, on the face of it, the FOA-60Q is a bit of a puzzle. I’ll let Takahashi explain:

“FOA-60Q has the highest optical performance among all Takahashi optical systems. It boasts the World’s highest level of optical performance, maintaining a Strehl ratio of 99% over the entire visible light range and the entire field of view of a full-size camera.”

Those are quite some set of claims. Indeed, they need to be given that the FOA-60Q is getting on for the price of a Tak’ FC-100DC or a Mewlon 180.

Takahashi go on to add that the FOA-60Q is thus ideal for observations of the Moon and planets, for corona imaging of solar eclipses and as an “ultra-high performance super telephoto lens”.

Two Qs: FOA60Q and FS-60Q.

At A Glance

Telescope

Takahashi FOA-60Q

Aperture

60mm

Focal Length

900mm

Focal Ratio

F15

Length

540mm/600mm dewshield retr/extd

Weight

~2.4Kg incl clamshell

 Data from Me.

What’s in the Box?

Typical nested Takahashi boxes:

Design and Build

The FOA-60Q is based on the FOA-60 and that means it’s a premium Tak’ with a slightly retro vibe:  the tube is the same 68mm diameter as the classic FC-60 and FC-50 (yes, their clamshells fit, I checked) and the tiny cast focuser looks to be the same too. But where the FC-60 had a fixed dewshield, the FOA’s is a sliding affair with a lock screw. Did I mention it looks good, with the long slim tube and proper lens hood? Much better, in my opinion, than the Vixen-FL-like FS-60Q.

The livery is Takahashi’s latest – i.e. bluish green powder coat for the focuser, a slightly off-white gloss tube and a matte silver lens ring.

A note on serial-number plates: you could convert a blue-serial-plated standard FOA-60 by buying the Extender 1.7XR. Alternatively, you can buy the complete FOA-60Q with the module installed, in which case you get a red serial plate, same as other quadruplet Taks (in case you’re wondering, triplets get a green plate).  That’s how I bought the one on test here.

The FOA-60Q is a quadruplet and gets the red plate, same as an FSQ.

Three generations of Takahashi long-focal-length 60mm apochromat: FC-60 (bottom), FS-60Q (mid), FOA-60Q (top, shield retracted).

FOA-60 front-surface fluorite Doublet lens.

Collimation screws on the back of the cell, usually hidden by the lens ring.

Optics

The FOA-60Q claims to be perhaps the most perfectly corrected apochromat ever made. How does it achieve this?

The base FOA-60 is already pretty special. It uses front surface fluorite along with some kind of special low-dispersion glass mating element and a large air gap to create a doublet that’s competitive with their triplet ortho-apochromats (TOA-130 and 150) for chromatic aberration.

The FOA-60 lens cell is large and collimatable (the collimation screws are on the back, hidden by the lens ring). The inside is all ridged and blacked like a premium camera lens.

That’s the base FOA-60. The ‘Q’ then adds in a doublet flattener/extender module – the 1.7XR – to further correct the following:

·        Centre field chromatic aberration

·        Edge chromatic aberration

·        Field flatness and coverage across a full-size sensor

The extender 1.7XR is similar to the Q module for the FS-60Q, but it has an even larger doublet lens (40mm diameter) and a different tube size (68mm vs 80mm). It is also considerably more expensive. As with the other ‘Q’ module, the lens has superb multi-coatings and should absorb very little light.

With the module in place, we get a quadruplet optical system at F15 (900mm focal length).

The result is a scope that corrects false colour almost to reflector levels. Perhaps more importantly, spherochromatism – variation of spherical aberration, i.e. optical quality, by wavelength - is basically eliminated for all visible light as well.

For imaging, the ‘Q’ module confers a flat and well-illuminated field across a full-frame sensor for virtually the whole visible spectrum. This being Takahashi, they’ve backed those claims up with some graphs and spot sizes that I’ve re-printed below.

To get a handle on just how theoretically excellent the FOA-60 is, I have also collated Takahashi’s published centre spot diagrams for a few of its ‘planetary’ refractors, along with a basic FS-60C for comparison. As you can see, the base FOA-60 – even without the ‘Q’ module in place - achieves tighter control than any other Takahashi refractor, even including the outstanding TSA-102, a now discontinued F8 triplet and the very latest FC-100DZ.

The poly-strehl (spherochromatism) graphs for the FOA-60Q and FC-100DZ are also telling: the ‘Q’ is way better, almost perfect as claimed.

FOA-60 Extender 1.7XR Module with 40mm lens.

Some spot diagrams for Takahashi fluorite apochromats compared.

Spot diagrams for FOA-60 and new FC-100DZ compared.

Poly-Strehl graphs for FOA-60Q and new FC-100DZ.

Tube

The ‘Q’ borrows its 68mm tube from the base FOA-60, which in turn derives it from the old-skool small Taks, the FC-60 and FC-50 (the super-rare FCT-65 too). Physically, you turn an FOA-60 into an FOA-60Q by unscrewing the focuser and inserting the Q extended module between it and the FOA main tube. The threads seem very well machined, but they are fine and would be easy to cross-thread, so I always thread them carefully with the tube vertical.

The sliding dewshield has a large thumbscrew to secure it and runs easily, locks with a satisfying thunk. It’s a generous length and has some micro-ridge baffles at the front – another little premium feature.

Inserting the extender changes the optical character; the physical character too. The FOA-60Q is quite a bit longer than other Takahashi 60s, at 540mm from the 2” VB (the 1.25” insert adds another few cm) with the sliding hood retracted, 600mm with the hood extended.

For a 60mm, it’s quite heavy too at ~2.4Kg including the clamshell. The FOA-60Q is almost as heavy as an FC-100DC, heavier than the FC-76DC. By comparison, the old FC-60 was just 1.5Kg incl. its ring.

The FOA tube has a single knife-edge baffle, one area where the old contrast-monster FC-60 beats it with three.

Dew-shield retracted …

… extended.

FOA-60Q focuser at full extension, showing 2” visual back with slot-in 1.25” adapter.

Focuser

The focuser appears to be the same unit as the old FC-60 and FC-50. It looks tiny, much smaller even than the FS-60s, but it has a full 84mm of travel to accommodate most eyepieces without an extension. For photography, Tak’ provide a quality 2” extension (also useful for Japanese style straight-through viewing).

My FC-60 has the cheapo hollow-plastic imitation focuser knobs, but the FOA gets the proper anodised silver metal ones like other Taks. The other silver knob, on top of the focuser, is the standard Takahashi lock. It is progressive and shift-free.

The focuser tube is the same slim 45mm silver one as the small FCs. Back then, that limited those scopes to 1.25” accessories. But the FOA visual back differs from the FC-60’s - it terminates in an adapter and 2” eyepiece holder. Instead of threading in, the ‘normal’ 1.25” Takahashi visual back just slots into the 2” one. Like all Tak’ 2” VBs, there are twin set-screws, not the lock-ring you get with the 0.965” or 1.25” visual backs. If you did want to go all retro, an old 0.965” FC-60 visual back threads into the adapter.

The focuser tube is all concentric ridges and camera-black inside to kill stray light.

Despite its small size, the focuser takes larger eyepieces fine and remains smooth and shift free with a camera. It started out a bit stiff, but accurate and with no slop. It has gradually eased up to become a typically butter-smooth Tak’ focuser, although still stiffer and less fluid than the identical unit on my 30 year old FC-60, which has probably the smoothest focuser I have ever tested (yes, even smoother than a Feathertouch).

Mounting

Though the FOA-60Q is well within the weight limit for the miniature Takahashi equatorial mounts, the Teegul or PM-SP, it is long, which means it vibes a lot more than an FS-60C or even an FC-76DCU. For high power use as designed, you need a heavier mount. Much of my testing was done on a Vixen SX2.

FOA-60Q on Vixen SX2 (no need for a counter-weight).

Takahashi’s excellent 6x30 finder.

6x30 finder view: sharp, flat, wide and with loads of eye relief.

Accessories

Nowadays, Taks are starting to come with a 2” visual back as standard, so at least you won’t have to spend extra for one.

The other accessory you’re likely to get with the package is Taks’s excellent 6x30 finder. If you hate optical finders this unit will change your mind with pin-sharp optics, a huge field and loads of eye relief.

Unlike the FC-60, the finder mount is the standard one, so alternatively you could go the whole hog and buy the 7x50 unit with the illuminated reticle. Yes, it’s the price of a decent small Chinese apo, but it’s only money, right?

As I noted already, the FC-60 and FC-50 68mm clamshells fit fine, but the ‘proper’ one is a little different, having mounting holes on top for the GT40 guider. But the base is the same – twin M8 holes at 35mm separation like always (except now there is another pair at right angles for side-by-side on a big plate).

In Use – Daytime

Weird. Almost supernatural. I mean, look, when I reviewed Swarovski’s state-of-the-art 15x56 HD binos I marvelled at the sharp false-colour-free views of silhouetted feather and branch … at 15x. Now with the FOAQ you can multiply that by ten to create a kind of long-distance microscope.

Viewing birds, berries, leaves or whatever, highlighted against a sunny sky at 150x with an Ethos 6mm eyepiece, the view is totally sharp – like being a few centimetres away. What’s more there is no hint of false colour, none: not in focus, not focusing through.

Consider that my usual apochromat test is viewing silhouetted branches at 100x; most refractors fail it, some extravagantly. Indeed, anyone who has used a normal spotting scope will appreciate how extraordinary viewing in crystal clarity at 150x plus really is. Photos can’t convey that perfection, but I’ve tried with a snap taken with my phone through the Ethos 6mm.

Ordinary views not in silhouette are just as sensational. I watch flies crawling across a trunk 200m away in close-up HD. And the view is sharp and colour free right to the edge. But you do need a superb eyepiece like the Ethos (£500 each) to do this – my Naglers just won’t cut it at this magnification during the day.

Practically, though, there is another problem – the FOAQ is big for a spotter already and at those magnifications you need a very stable mount. You could take the FOA-60Q out for nature photography, but you’d a big tripod and cine-head.

Snap of needles 200m away at 150x with FOA-60Q, taken through Ethos 6mm eyepiece with an iPhone camera.

Prime focus with FOA-60Q as a 900mm telephoto lens and 100% crop of corner. Straight from Fuji X-Trans camera.

Prime focus shot of berries. Again, Straight from Fuji X-Trans camera.

Crow in flight with FOA-60Q: no false colour.

In Use – Astrophotography

An aperture of 60mm at F15 doesn’t sound promising for astro-imaging, but with a very flat field, wide coverage, minimal violet bloat and large image scale, the FOA-60Q has some real applications. Below are some sample subs straight from the camera to show what’s possible. As expected, images of the Moon and planetary nebulae are particularly good.

Coverage would likely be even better with a Takahashi (or Borg) wide-T mount.

M1 at full-frame: 180s at ISO1600 with Canon EOS 5D and FOA-60Q.

Crop of Moon with FOA-60Q: slightly increased contrast, otherwise un-retouched.

In Use – The Night Sky

General Observing Notes

Visually, even the brightest O-A stars like Vega and Sirius show no false colour, none at all, even in the star test. This is a truly chromatic-aberration-free refractor. It’s almost odd. It’s also chastening to consider how far you have to go (a fluorite/ED quadruplet 60mm F15!) to get a refractor to do what comes naturally to mirrors.

With a perfectly corrected eyepiece like an Ethos (or even Nagler), the FOA-60Q delivers beautifully pin-point and aberration free stars right across the field; this is unusual and again a little unnatural.

One really striking feature is the FOA-60Q’s ability to cut through bad seeing. On one night I was enjoying a setting first quarter Moon only 10-12° above the horizon. The FOA-60Q was delivering super-sharp and detailed views at 100x with 9mm Nagler; I easily resolved Hyginus crater and caught glimpses of the rille. But turning to my other scope, the Moon was a mess of boiling air.

Cool Down

All that glass means cooldown is noticeably a bit slower than a doublet, but still fast compared to other types. It’s usable straightaway, but actually only delivers its finest views after perhaps ten or fifteen minutes. This was apparent when I tried splitting Epsilon-Lyrae straight from the house.

Star Test

Independent bench tests have measured a random sample of the base FOA-60 lens at 99% Strehl. However, the ‘Q’ star test, like the FS-60Q, was slightly off – quite under-corrected. Complex optical systems with aspherical surfaces can show this in the star test. In practice, there’s no question this is an outstanding optic.

The Moon

The FOA-60Q delivers the coldest hardest whitest Moon you’ll ever see (in a refractor anyhow). No false colour anywhere. You don’t notice this in an image, but you do visually. There is no smear of lilac around highlit peaks or shadowed craters at all. Focusing through the bright limb of a nearly full Moon – centre field to avoid eyepiece effects – yields no trace of colour at 180x; an FC-60 alongside generates the merest hint of gold and dusky-rose either side of focus.

A 3-day crescent Moon fills a 7mm Nagler Type 6 at 129x. The Moon is low and from my other scopes I know seeing is poor, but the FOA-60Q still gives a good view, confirming that long f-ratios do work better in turbulent seeing. Mare Criseum looks really involving and mysteriously explorable, even at this tiny aperture – impressive.

At 180x with a 5mm Nagler, examining Mare Imbrium and Theophilus on a different night, there’s no sense that this is more power than the Q can handle. Swapping to the same magnification but with a 10mm Zeiss Abbe Ortho in the Zeiss 2x barlow definitely sharpens things up and reveals more detail. I notice how little light bleed there is off the limb into black space.

Dropping back to 69x with a 13mm Panoptic give a real wow moment, a stunning view of the whole Moon with Propus in Gemini hanging a firey orange just off the limb. The view reminded me of my TMB175 with a 13mm Ethos – a perfect hard white and grey orb in miniature, full of sharp detail. One of the finest views of the whole Moon I’ve ever had.

One frosty November morning of excellent (8-9) seeing gave me a last quarter Moon, high in the sky just off the meridian, with Albategnius on the terminator. The ‘Q’ was in its element. A 5mm Nagler giving 180x showed a wealth of sharp detail. I could make out the craterlets like a string of beads along Rima Hyginus, normally the preserve of larger scopes. The view was just like a good 100mm apochromat, reminding me of a similar morning with an FS-102 years ago. Incredible for a 60mm.

Traversing the terminator, I wanted to forget the review and just view. Mons Piton alone in the mare, bathed in evening light. The sharply defined peaks of the Apennines. Rima Ariadaeus full of shadow and running off into the lunar night. Alphonsus with its offset central peak and hummocky ridge, where Ranger 9 impacted in 1965. The Straight Wall and its odd arrow-head at one end. The slumped walls of Tycho in extraordinary detail. Clavius and its arc of craters.

I don’t generally use high powers, but the ‘Q’ could clearly take more. So, I upped to a 3.5mm Nagler, giving a ridiculous (for a 60mm) 257x. Yet the view remained incredibly sharp, with no break up or softening, the kind of ‘Lunar Module porthole’ view I have only experienced in much larger scopes. I spent ages flying over the rugged shadows of the terminator, struggled to quit the eyepiece in the end. Takahashi promised the ability to take exceptionally high magnification; they delivered.

The FOA-60Q is a fabulous lunar scope for its aperture.

Jupiter

At 150x in a 6mm Nagler zoom, Jupiter showed an excellent image with absolutely no false colour and no softness or stray light. But then I swapped to a Zeiss Abbe Ortho’ 6mm. Usually the difference would be very subtle; but in this case, Jupiter sharpened considerably with more contrast and detail, revealing NEB and SEB, polar hoods and hints of darker storms – impressive detail for a 60mm.

Mars

A low and tiny Mars, at just 13 degrees altitude early in an opposition year is nonetheless a hard, tight ball with no softness or CA. I’ll update this review once I get a get view of the Red Planet during the loftier 2020 opposition (the Fates willing, obvs).

Deep Sky

At 129x in with a7mm Nagler, the Double Double was the easiest and cleanest of splits I’ve seen in a small scope, in decent seeing just after dusk.

Whilst slow focal ratios mean longer exposures, it’s a myth that slower scopes are dimmer for visual. In fact, the FOAQ’s ultra-high strehl should mean tighter brighter stars and that’s how it seems to work out. With plenty of field width in a 32mm Plossl to accommodate them, the Pleiades are especially brilliant and diamantine, shining in a silvery mist of nebulosity.

I find the Ring Nebula, swap to an 18mm Takahashi MC Orthoscopic and … wow! I can’t remember seeing the Ring so clearly defined, like floating smoke, through a small aperture before. I hunt down the Dumbbell and it seems even more so, hanging with an almost 3D solidity and separation in black space. The 18mm MC Ortho quickly became my favourite deep sky eyepiece in the FOAQ, with loads of eye relief, no blackouts and incredible transparency and contrast.

Next up are two bright globular clusters – M15 in Pegasus and M13 in Hercules. M13 in particular seems brighter than I’ve ever seen it in a 60mm refractor and with averted vision I can start to resolve the mass of outer stars. M15 is smaller and dimmer, less resolved, but looks good too.

The FOA-60Q’s good deep sky performance (for a 60mm obviously, this is no Big Dob!) is notable, likely down to its tight star images, flat field and top-quality coatings.

Summary

When I started work on this review, I’ll admit I was pretty sceptical. Why would anyone want that level or perfection when the basic FOA-60 is already very good, as is the cheaper and lighter FS-60Q? Now I’m converted, excuse the pun.

Sure, it’s only a 60mm refractor, but there is no other telescope I know of that will do what the FOA-60Q can do. Perfect views of birds roosting hundreds of metres away at 150x is extraordinary. Views and images sharp to the very edge are amazing too. Ditto sharp lunar views still sharp at 257x (!)

Most amazing of all is that, visually and for daytime telephoto at least, this is truly an ortho-apochromat, with no discernible false colour at all under any circumstances.

Who but Takahashi would dare build such a thing and sell it to the public? App-driven automated imaging scopes are one type of progress; pure optical innovation like this is another. But I fear that if we lose the high-end manufacturers like Takahashi, the latter will stop.

Of course, whether you need the singular optical wizardry of the FOA-60Q is up to you. In ordinary circumstances for astronomy you will notice no difference compared to other fine 60mm apochromats. But on the right occasion with perfect seeing the FOA-60Q has the power (literally) to amaze. Or if you need a terrestrial super-telephoto at sensible cost, this is a serious option. I certainly intend keeping mine long term.

The FOA-60Q is certainly a specialist telescope, but it’s far from a pointless exercise as I had feared. For specific uses and connoisseurs of fine optics, the FOA-60Q is highly recommended.