Takahashi FS-60C and
FS-60CB Review
FS-60CB with 6x30 finder.
FS-60C with 5x25 finder. Note the slightly longer tube.
I have a real weakness for tiny, high-quality refractors like
Takahashi’s FS-60: super portable, rugged and fast cooling,
they are ideal for travel and quick looks. There is a more serious side to
small refractors though – very wide-field astro-photography,
with better correction than a typical camera lens.
So what value does Takahashi’s premium FS-60
add, now that small apochromatic refractors are common? You can build a complete multi-role
observing/imaging system around it. Takahashi make a host of reducers,
flatteners and extenders to change the optical parameters of the FS-60,
including the ‘CQ 1.7x Module’ which turns an FS-60C into an FS-60Q, a micro
super-APO for the Moon and planets (I reviewed the FS-60Q separately here).
At A Glance
|
Telescope |
FS-60C |
|
Aperture |
60mm |
|
Focal
Length |
355mm |
|
Focal
Ratio |
F5.9 |
|
Length |
29cm min,
35.5cm incl 1.25” VB |
|
Weight |
1.5 Kg incl clamshell |
Data from Tak/Me.
What’s in the Box?
The logoed carton is typical Tak’, but smaller!
FS-60 alongside the FOA-60.
Design and Build
The FS-60 is the last of Takahashi’s line of FS refractors
that also included 3”, 4”, 5” and 6” models, all now long-discontinued.
Takahashi have made other 60mm fluorite refractors over the years, including
the earlier F8 FC-60 (reviewed here) and the current F9 FOA-60,
a specialist tiny planetary refractor, (reviewed here).
Optics
The ‘FS’ stands for front-surface fluorite: these doublets (all
made by Canon/Optron in Japan) have a fluorite crown element
at the front, something which I think adds a bit to contrast, because fluorite
scatters light less than any optical glass.
Borg is now using front-surface-fluorite Optron
lenses in its recent small refractors like the 71Fl and 90FL, whereas Takahashi
have reverted to putting the fluorite at the back in a Steinheil
configuration for the newer FC-76 and FC-100 models. However, Takahashi’s
latest FOA-60 does also use a front surface fluorite design to achieve its near
perfect correction.
One possible disadvantage
to putting the fluorite up front is that fluorite degrades in damp conditions,
but I’ve never seen this, even in an FS-102 which I
bought that had spent years in a damp observatory.
Unlike other telescopes in the FS series, which were all F8
and primarily designed for visual use (especially planetary and Lunar), the FS-60
is F5.9 (355mm F.L.) and aimed at imagers. Another difference is that the
larger FS-series lenses can be collimated with push-pull screws, whilst FS-60
lens, like other recent Tak’s, cannot.
On the first FS-60 I owned and originally reviewed - a 2009
model FS-60CB - the lens coatings were not as good as the larger FS models and
looked suspiciously like ‘China’ green multi-coatings. This appears to have
been a blip: my earlier 2006 FS-60C has proper broadband multi-coatings and
later ones appear to as well. But compare the
super-transparent coatings on an FS-78.
FS-60CB lens from 2009 – China Green coatings?
FS-60C lens from 2006 – quality multi-coatings.
FS-78 objective with very high quality
multi-coatings and adjustable cell.
Fluorite, air gaps and chromatic aberration
A quick comment on chromatic aberration is in order. The
FS-60 is known to be less than perfect in this respect and has a similar level
of false colour to an F6 ED doublet like a TeleVue
TV-60.
This seems odd, because fluorite generally allows for
slightly better correction than ED glass and indeed the FS-102 has much lower
levels of chromatic aberration than the TV-102. Why should this be?
The answer might be in the mating glass used for the flint,
but is probably just the simple design of the FS-60 objective, with little or
no air gap. The TV-60 has a large air-gap allowing for better correction, as do
some Borg fluorite doublets (see below).
Laser test on FS-60C objective clearly shows the laser
disappear in the fluorite element (fluorite, unlike glass, doesn’t
scatter a laser).
The Borg 67FL has a significant air gap between the elements;
the FS-60 appears not to have.
Two Optron objectives: Borg 67FL
and FS-60. Borg cell is larger, more sophisticated, more like larger Taks.
Tube
The FS-60 tube is 80mm in diameter, like a Borg Series 80,
but note that the threads are different, so you can’t
interchange with Borg objectives. Some older small Takahashis
(the FC-60 and FC-50) and the new FOA-60 have a narrower tube at 68mm diameter.
External finish is the usual Takahashi off-white tube and
green enamelled focuser. Note that since 2016 the green focuser enamel has been
a slightly bluer shade that doesn’t match older
components. The FS-60CB tube has no internal baffling, just flat-black paint,
whilst FS-60C has a single baffle.
The FS-60 dew-shield is the same diameter as the tube,
reminiscent of a Borg or a late Vixen FL. On the FS-60CB the dew-cap was
low-rent black plastic but the older FS-60C has a Takahashi-green pressed steel
item like recent Takahashis. The most recent FS-60s
have logoed dew-shields like classic Takahashis.
The objective threads off for fitment of the CQ module or an
FC-76 objective unit (both sold separately).
The OTA itself is very short (for back-focus and compactness)
and will need extensions to come to focus in some cases. Two slightly different
models exist, as I have said. The original FS-60C has a slightly longer tube
than the later FS-60CB which was introduced to give more in-focus for imagers
(to repeat myself, the 2006 model in the photos is an FS-60C; the 2009 model is
an FS-60CB). You can convert an FS-60C into an FS-60CB just by buying a new
barrel.
The standard visual back is 1.25”,
but you can fit a 2” as an accessory. Doing so yields a staggeringly wide
maximum field-of-view for fans of extended DSOs and star fields: 7.4° at 9x
with a 40mm Pentax XW, almost identical to the latest Swarovski EL 8.5x42
binoculars, but with much more light gathering power.
Focuser
The rack-and-pinion focuser is reassuringly familiar: the
usual Tak’ green enamelled casting, the familiar
silver knobs and oversized tensioner. But unlike the
larger FS models, the focuser on the FS-60 has a very
short body for compactness, a bit like the one on the Sky-90, but with a
smaller (~55mm) diameter drawtube.
Two of the three FS-60s I’ve owned
have had excellent focusers – creamy smooth, precise and free of image shift,
with a progressive and shift free lock. In comparison, the FS-60CB I tested was
much sloppier, with noticeable image shift on changing focus direction or when
using the lock. What’s going on? Is this just
variation between samples? I don’t think so. You see,
many FS-60s end up with big CCD cameras hanging off that compact focuser and I
reckon after while it causes wear and play. This isn’t
really a criticism: expecting a small focuser to handle several Kgs of CCD is
asking a lot. But it would explain why the Taks I
have seen with image-shift problems have been imaging models. Either way, check for image shift before
buying used.
FS-60 focuser with optional 2” VB.
Mounting
It goes without saying that the FS-60 is very compact and
light-weight. Any small photo tripod would take it and it needs just the
smallest counterweight on an equatorial.
Takahashi once sold a tiny equatorial mount for the FS-60 –
the Teegul Sky Patrol – ideal for eclipse chasers.
The Teegul was marketed specifically for the FS-60
and it makes a surprisingly stable and solid platform for it. The Teegul/FS-60 rig can work in one of two modes: as a true
German equatorial or as a half-fork. I have posted a full review of the Teegul here.
The FS-60 has a dedicated tube ring that is offset towards
the objective end to allow better balance with a heavy camera (or eyepiece).
The ring fits the standard Tak’ 2-hole pattern, but
also has a central 1/4-20 thread for a photo tripod. This ring also gives
much-needed extra clearance on the Teegul.
FS-60C on Teegul SP2 in German
equatorial configuration.
FS-60C on Teegul SP2 in half-fork
configuration.
Latest version with blue enamel and logoed dewshield on a photo tripod.
FS-60 mounted atop my big scope to let the mount find targets
and track them for some astrophotography.
Accessories
Like BMW, Takahashi really start fleecing you on the optional
extras. A raft of tasty bits-and-bobs are available for the FS-60, including a
flattener, a reducer, a version of the extender-Q, a camera rotator and more
besides.
For wide-field imaging, the flattener looks like a bargain:
it extends the f-ratio slightly to F6.2, but gives a flat field across
full-frame (44mm image circle) and is pretty cheap
compared to the reducer.
One of the most interesting accessories is the CQ 1.7x module
I mentioned that turns the FS-60 into the FS-60Q (also available as a complete
scope: check-out my separate FS-60Q review).
Some desirable FS-60 accessories: Flattener, camera rotator,
2” visual back, FQR finder dovetail.
Flattener configuration – note the extension and rotator in
front of the flatener, both required for correct
spacing.
Another FS-60 accessory, the CQ 1.7 extender module, turns it
into a flat-field F10 super-APO.
Finder
In theory any Takahashi finder will bolt on, but the FS-60 is
usually found with the excellent 6x30 unit. My second FS-60 happened to come
with the rare 5x25 finder that I think suits it even better. Either finder has
a wide field, sharp optics and lots of eye relief.
In Use – Daytime
It isn’t waterproof, but otherwise
the FS-60 makes a great daytime scope – it is light weight, sharp and doesn’t
generate too much false colour. Wide-field Tele Vue eyepieces, like Naglers, give wonderful daytime views that beat just about
any spotting scope.
The FS-60 makes a great telephoto
lens, especially with a flattener: sharp to the edge and with minimal
vignetting, even at full frame.
My usual test of viewing branches against the sky at ~100x
yields just a trace of violet in focus and an over-exposed daytime branches
image shows just a small amount of violet:
In Use – The Night Sky
The FS-60 is typical FS-series in many ways. Cool-down is
very fast and benign and the views are very sharp and high-contrast. Optical
quality is excellent and the FS-60 takes high magnifications easily. Focus snap
is precise.
As discussed in the ‘optics’ section, the FS-60 is not ‘visually
CA-free’ like the slower FC-60 and FOA-60 models. Chromatic aberration is not a
problem on most visual targets, but at 100x on a bright Moon
you can see it as you focus through the limb.
The FS-60C focuser is very smooth and accurate, like most
Takahashi’s, but on the 2009 FS-60CB there was a problem with image-shift – see
above in the ‘focuser’ section.
The Moon
I have always loved the view of the Moon through FS scopes.
There is something about the contrast between the brilliant limb and black
space, with very little unfocussed light, that makes the FS-series special.
Perhaps it’s because fluorite scatters so little (back
to that laser result again).
The Moon at 100x with the 3.5mm Nagler
was spectacular for a small scope with surprising detail.
Jupiter
If you imagine that a tiny, fast APO can’t
do planets you’d be wrong. At 100x with a 3.5mm Nagler
the FS-60 showed an impressively sharp and detailed view of Jupiter, with four
belts, polar hoods and some cloud belt detail, plus
the Great Red Spot. On the night, I thought it provided a view of Jupiter every
bit as good as the nearby Zerodur Duplex Questar I
also had on test, but did so much more quickly from a warm room.
Mars
Mars is a tough object for many refractors: small and low in
contrast, but also because of its colour. Most short focal length doublets
suffer spherochromatism in the red. In other words,
their optical quality takes a dive at longer wavelengths.
The FS-60 illustrates this point: it gave a slightly soft
image of Mars with some red blur, just like other F6 doublets (the TV-60
included). For Mars, an FOA-60 or older FC-60 give a sharper view.
Venus
A small, full-disk Venus showed some violet blur in focus and
wasn’t as sharp as through a longer focus 60mm
fluorite doublet.
Deep Sky
The FS-60 is ideal for very large DSOs and I really enjoyed
using it on the Andromeda Galaxy and the North American Nebula, neither of
which fit in most scopes’ FOV.
Of course, it’s only a 60mm ‘scope,
but the FS-60 pushes the limits. I managed to split the double-double (2.3”)
without difficulty, Rigel too. Many DSOs – M13, the Dumbbell, M42, M56 – looked
better than they had any right to in such a small aperture, with the superb
contrast and perfect optics helping out.
In
Use – Astrophotography
The FS-60 has the potential to take great images of extended
objects. To give you an idea of what’s possible, there
follow a couple of single frames straight from the camera. The first is an APS-C
DSLR frame of M31. Note the field curvature: you would need a flattener or some
serious cropping. The second image is full-frame and the curvature gets quite
extreme in the corners. In all cases violet bloat is quite well controlled.
As noted above, you can get a cheap full-frame 1.05x
flattener for the FS-60 without splashing out for the full-on reducer. This actually extends the focal length slightly to 372mm at F6.2,
but the results are excellent, as you can see from the images of M45 and M42 taken
with it below.
Note that for the F6.2 flattener you may need an adapter (e.g. Borg’s Camera Mount Adapter part 7000) to connect to a
camera T-mount and the rotator and extension to get proper spacing (see above).
Note that coverage is good, but might have been even better with a wide T-mount
(Tak’ and others make them).
As always, these are single frames straight from the camera, with
no stacking and no processing, just reduced in size.
M31: 130s ISO 800, Nikon 5100 APS-C DSLR.
M36: 70s at ISO 1600 with Canon EOS 5D full-frame DSLR.
M45: 88s ISO 1600 with Canon EOS 5D DSLR plus F6.2 Flattener
M42 (some sky glow): 121s ISO 1600 with Canon EOS 5D DSLR plus
F6.2 Flattener.
The FS-60 has too short a focal length to be ideal for solar
system imaging (which of course is where that CQ module comes in), but photos
of the Moon taken with it have the same qualities that the view does: super
sharp and high contrast. In the photo below that wide field enabled me to
capture a close approach of the Moon and Jupiter. Interestingly, the FS-60
gives sharper Lunar images than the more extreme F4.5 Borg 67FL.
The Moon and Jupiter (top left) with FS-60: super sharp and
wide.
Summary
The FS-60 is another excellent
Takahashi: tiny and light, yet well-made, razor sharp, with do-anything optics.
It has modest false colour on most things and takes high powers well. However,
though it is very sharp on-axis, it
really needs a flattener for APS-C, let-alone full-frame.
Perhaps the best feature of the
FS-60 is its unrivalled flexibility, thanks to the thoughtful native design and
copious accessories. Unscrew the objective and plug in the CQ module and it’s a mini planetary scope. Attach the reducer and it’s a 250mm F4 telephoto lens.
Am I just imagining it, or is
there something about FS-fluorite lenses that gives images with contrast
nothing else can quite match? And let’s face it, the
FS-60 is cheap for a Takahashi (the next one up – the FC-76 - is over double
the price).
Note: The 2009 FS-60CB showed
evidence of cost cutting compared to both the earlier model and the recent
FS-60C I owned.
The FS-60C is very highly
recommended and is one of my all-time favourites, but it’s
possible the focuser wears badly if subjected to big CCD cameras, so check for
image shift if you’re buying used. Expect to buy a flattener for imaging if you
want to make the most of that wide field.