Takahashi FOA-60Q User manual

Instruction Manual
TAKAHASHI

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Thank you very much for your purchase of the TAKAHASHI FOA-
60Q. The original FOA-60 is provided with the objective with almost
no color aberration accomplished by exquisitely correcting a high
order of the spherical aberration. The FOA-60Q has the extender
1.7XR built into the FOA-60. When the extender is removed, you
can use the telescope as the original FOA-60.
This telescope offers a wide variety of visual/imaging applications
with a wide selection of optionally available optical parts. In order to
use your telescope to its highest possible capabilities, please read
this instruction manual very carefully and familiarize yourself with all
of the functions that your telescope o󰀨ers.
All telescopes have been strictly inspected before shipment. If there
is anything wrong with your telescope when unpacked, please
contact your authorized Takahashi distributor for proper care.

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WARNING
CAUTION
WHEN THE TELESCOPE IS DIRECTED TO
THE SUN, ITS LIGHT AND HEAT ARE BOTH
INTENSE AND DANGEROUS. NEVER TRY
TO VIEW THE SUN. DOING SO WITHOUT
PROPER EQUIPMENT MAY CAUSE
PERMANENT BLINDNESS.
DANGER
◆ When attaching the telescope on the mount, take care not to
drop it or to be pinched, causing unexpected injuries.
◆ Never place the telescope on uneven place to prevent it from
falling or dropping, which might cause injuries.
◆ Do not place the telescope in direct sun light. The light
concentrated at the focal point is so intense that it might cause
a re.
◆When focusing the telescope, be careful not to pinch your
nger.
◆ Be careful that children do not swallow small parts such as
button battery, eyepiece, etc.
◆ Flammable materials such as Styrofoam are used for packing
material. Do not place it near a re. Keep children away from
the large vinyl bag to avoid risk of su󰀨ocation.
Warning & Caution

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Table of Contents
Warning & Caution ----------------------------------------- 3
Table of Contents ------------------------------------------ 4
Specications ----------------------------------------------- 5
Tube Assembly Layout ----------------------------------- 6
Set Up Procedures ---------------------------------------- 7
Focusing ---------------------------------------------------- 10
Finder Adjustment --------------------------------------- 11
Observation ----------------------------------------------- 12
Accessories ----------------------------------------------- 13
What is Fluorite? ----------------------------------------- 19
Care & Maintenance ------------------------------------ 20
Additional Precautions ---------------------------------- 20
System Charts -------------------------------------------- 21
Version 1.00

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Specications
Conguration --------------------------- Fluorite Ortho Apochromat
2-group 2-element + 2-group 4-element
E󰀨ective Aperture --------------------- 60mm all surfaces hard-multi-coated
E󰀨ective Focal Length --------------- 900mm
E󰀨ective Focal Ratio ----------------- 1:15.0
Resolving Power ---------------------- 1.93”
Image Circle ---------------------------- φ88mm (60% illuminated)
φ44mm (100% illuminated)
Limiting Magnitude ------------------- 10.7
Light Gathering Power --------------- 73X
Diameter of Main Tube -------------- 68mm
Total Length of Tube Assembly ---- 705mm
(645mm when dew shield retracted)
Weight of Main Tube Assembly ---- 2.4kg(about 4.8lbs) w/6x30 Finder
Finder Scope --------------------------- 6x30 (optional)
Accessories ---------------------------- Warranty Card, Instruction Manual,
Hex Wrench (4mm)
When the Extender 1.7XR is removed
E󰀨ective Focal Length ------------- 530mm
E󰀨ective Focal Ratio ---------------- 1:8.8
Total Length of Tube Assembly -- 570mm
Weight of Tube Assembly --------- 2.1kg (about 4.2lbs) w/6x30 Finder
▼The Extender 1.7XR
The Extender 1.7XR has been built into the FOA-60. It is 2-group 4-element and built-in
the light pass in between the main tube and the focuser unit di󰀨erent from the conventional
extenders. This will extend the original focal length and further improve the center
aberration as well as the aberration near the edge, improving atness across the entire eld.
With the Extender 1.7XR, the e󰀨ective focal length of the FOA-60 is extended to 900mm
(f/15.0). This combination will produce the ultimate optical performance of all Takahashi
telescopes. Over the visible light transmission area and across full format cameras, its
Strehl ratio will be over 99%.

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Tube Assembly Layout
Dew Shield Cap
Dew Shield Lock Screw
Dew Shield
Main Tube
Extender 1.7XR
6x30 Finder Scope
Focuser Housing
Drawtube Clamp
Finder Bracket
Focusing Knob
50.8(2") AD Ring (FOA-60)
Drawtube
50.8(2”) Adapter (SKY-90)
50.8(2”) Extension Tube L
50.8(2”) Sleeve
Coupling S
Eyepiece Adapter Cap 31.7(1¼”) Eyepiece Adapte
r

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Set Up Procedures
Hex Wrench
(4mm)
Finder Bracket
Finder Base
Cap Bolt
Washer
Focuser Unit
Finder Bracket
Finder Adjusting Screw
Lock Nut
Lock Screw
6x30 Finder Scope
Groove
◆Attaching the Finder Bracket
Place the finder bracket leg on the finder
base on the main tube and lock it firmly
with two cap-bolts, using 4mm hex wrench
provided. Set the nder scope so that it is as
parallel to the main tube as possible. Failure
to do so can make alignment di󰀩cult.
◆Setting the Telescope on the Mount
Set the tube holder on the tube holder base
with two cap-bolts, and then place the tube
assembly on the tube holder and lock the
tube holder with the clamp after balancing
the tube assembly. The tube holder can be
used with all Takahashi mounts. If using this
equipment for astro-imaging, the heavier
duty the mount, the better.
Tube Holder
Tube Holder Base
Equatorial Mount
Tube Holder
Clamp
Cap Bolt
Hex Wrench (6mm)
◆Attaching the Finder Scope
As illustrated at the bottom, insert the
nder
into the bracket so that the nder lock
screw
presses into the finder scope at the
groove. Set the finder scope in the center
of the bracket and lock it with the adjusting
screws and lock screws. Attach the finder
to a position as parallel to the main tube as
possible.

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◆Balancing
Now that the telescope has been attached
to the mount, it is necessary to balance
the load in the R.A. and the Dec. When
unbalanced, the clamps and the gearing of
the motor drive do not work properly.
▼Balancing the Dec.
1. Unclamp the R.A. and lock it when the
Dec. axis becomes horizontal. If the R.A.
is greatly out of balance and does not
rotate smoothly, rst do a rough balance
of the R.A.
2. Be careful that the package does not
move abruptly. Hold onto the telescope,
and loosen the Dec. clamp to adjust
balance.
3. If unbalanced, loosen the tube holder
and move the tube assembly forward
and backward until it balances. Then,
lock the tube holder. Especially when
imaging package is attached, set the
tube assembly at proper position.
▼Balancing in the R.A.
1. When the Dec. axis is balanced, lock it
rmly with the Dec. clamp.
2. Loosen the R.A. clamp and check
balance of the R.A.
3. If unbalanced, move the counter-
weight(s) until the R.A. is balanced and
lock it.
4. If still unbalanced with the weight fully
extended, add extra weight.
◆Retractable Dew Shield
The dew shield of the FOA-60Q is
retractable. To transport, it can be retracted
and when observing, it can be extended
to stop stray light coming into the tube. To
extend the dew shield, follow the instructions
below:
1. Remove the dew shield cap.
2. Loosen the lock screw.
3. Draw out the dew shield.
4. Tighten the lock screw.
(Note)
When you retract the dew shield, be sure to
remove the dew shield cap rst. Otherwise,
the cap may be forced o󰀨.
Dew Shield Lock Screw Dew Shield Cap

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◆Attaching an Eyepiece
Remove the eyepiece adapter cap and
loosen the compression ring by turning it
counter-clockwise. Then, insert a desired
eyepiece or 31.7mm(1¼”) diagonal prism into
the adapter, and tighten the compression
ring by turning it clockwise.
◆Takahashi Eyepiece
A wide variation of eyepieces are available
from Takahashi.
▼LE Series
Standard type, wide view field and high
magnication range available in:
・31.7mm (1¼”) barrel
LE5mm - 30mm
・50.8mm (2”) barrel
LE40mm & 50mm
◆Attaching Accessories
Adapters and rings are attached on the visual back to attach various accessories. Please
check the system charts and attach the desired accessories correctly. Standard connection
is as follows.
▼TAK-UW Series
Ultra-wide angle with apparent field of 90
degrees designed to get sharpest star
images with a at eld telescope, available
in:
・31.7mm (1¼”) barrel
TAK-3.3UW - 10UW
▼Abbe Series
Simple 2-group 4-element eyepiece with
high contrast, less expensive with high
performance, available in:
・31.7mm (1¼”) barrel
Abbe 4mm - 32mm
▼Ere
With 3-group 5-element optics, 60 degree
apparent field of view, almost no flare and
ghost, available in:
・31.7mm (1¼”) barrel
Er-28mm
▼TOE Series
Long eye-relief and wide view field, most
suitable for planetary observation with high
magnication, available in:
・31.7mm (1¼”) barrel
TOE-2.5mm – 4.0mm
Compression Ring
Plastic Ring
Eyepiece
50.8(2”) Extension Tube L
50.8(2”)Sleeve
Coupling S
31.7(1¼”) Eyepiece Adapter
Eyepiece
M55.9x0.75 50.8mm (2”) 50.8mm (2”)
M43x0.75
M36.5x1.0 31.7mm (1¼”)
50.8(2”) Adapter (SKY90)

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Focusing
◆Focusing System
The FOA-60Q uses a rack-and-pinion
focuser. This focuser enables the observer
to focus rapidly. Turning the focusing knob
clockwise will move the drawtube out, while
turning it counter-clockwise will move the
drawtube in.
Afte r inser t ing an e yepi e ce int o t he
telescope, it is necessary to achieve
the best possible focus. Remember that
the atmosphere will limit the highest
magnification that can be used on any
given night. Using the lowest power
eyepiece, focus the image and increase
the magnification by using shorter and
shorter focal length eyepieces until the
desired magnification is reached. This
procedure allows the centering of an object
at high magnification. Please familiarize
yourself with the following items so that
you can always get the best focus in your
observation.
Drawtube
Drawtube Clamp
Focusing Knob
Drawtube will be moved out by
turning the knob this direction.
◆Focusing Process
Remove the dew shield cap and the
eyepiece adapter cap. Insert the diagonal
prism into the compression ring adapter.
Carefully tighten the compression ring until
it begins to make contact with the barrel
of the diagonal prism. It is not necessary
to overtighten the ring to hold the diagonal
prism.Then insert the eyepiece into the
compression ring of the diagonal prism,
repeating previous process. Be careful not
to overtighten the compression ring.
Begin the focusing process by choosing a
bright star in a convenient position of the
sky. When you think that you have achieved
the best focus, move the focuser inside and
outside of what you think is the best focus.
This will conrm the critical procedure.
Begin with a low power eyepiece and then
proceed higher and higher until the desired
magnication has been achieved.
When the best focus at high magnification
has been achieved, the observer may notice
a bright and dim ring around the star. This is
not a defect but rather a diffraction pattern
which is an indication of the diffraction
limited optics.
◆Drawtube Clamp
The drawtube clamp is provided to lock the
drawtube when the best focus is achieved.
In visual observation, clamping the drawtube
is not necessary, but in astro-imaging, the
drawtube will move when a heavy package
is attached so it is necessary to firmly
clamp the focuser to keep the package from
moving and spoiling the image. Don't forget
to loosen the clamp when finished to help
prevent damage to the gears.

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Finder Adjustment
In the view field of a telescope, the image
is seen highly magnified so it is so difficult
to get a desired object in the field of view.
Also when photographing an object with a
camera, the image of the object on the focal
plane is so dark it makes it di󰀩cult to center
in the eld of view. A nder is a useful tool. It
permits the precise centering of an object in
the eld of view. The wide eld of the nder
can find an object easier in the view field.
Therefore, it is important that the nder and
the telescope be in alignment.
◆Focusing
When you see some objects far away, if the
finder is not focused, adjust the finder as
follows.
1. Loosen the lock ring.
2. Viewing some objects far away, hold the
eyepiece and focus the nder by turning
the eyepiece clockwise and counter-
clockwise.
3. When focused, tighten the lock ring.
◆Finder Alignment Procedures
1. Set up the telescope for visual use
according to the system chart and attach
a low power eyepiece. Then, select a
clearly noticeable object far away and
center it in the view eld.
2. Then, change the eyepiece to a high
power one and again center the object in
the view eld. Then, lock the telescope.
3. Looking through the finder, move the
finder with the following method and
adjust it so the object is centered at the
crosshair.
4. Turn all the lock nuts until they reach the
head of the adjusting screw.
5. In order to move the crosshair in the
direction of the arrow, first loosen the
screw (a) and tighten (push) the finder
with the screw (c). Next loosen the screw
(b) and tighten (push) the nder with the
screw (c). This procedure will move the
crosshair in the desired direction. The
top of the nder will move in the opposite
direction and the object will move in the
direction of the smaller arrow.
6. Turn all the lock nuts until they reach
the nder bracket and lock the adjusting
screw.
a
b
c
Field of View of the Finder
Crosshair
Field of View of
the Main Telescope
Finder Bracket
Finder Adjusting Screw
Lock Nut
Focus Lock Ring
Eyepiece
Lock Screw
Finder

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Observation
◆Preparation for Observing
The telescope will take time to temperature
equalize in the cold weather, taking the
telescope from a warm place to the outside.
It is best to take out the telescope about one
hour before observing begins to equalize
with the colder air.
◆Visual Applications
▼Determining Magnication
The magnication of any eyepiece used with
the telescope can be calculated by using
the following formula.
(focal length of a telescope) divided by
(focal length of an eyepiece)
For example with LE-7.5mm
900mm / 7.5mm = 120X
Therefore, the shorter focal length eyepiece
will produce the higher magnification. In
general, the limit of the magnification will
be 20X and lowest 1.4X, respective to the
e󰀨ective aperture (cm). In the case of FOA-
60Q, the highest will be 120X and the lowest
8.4X. Therefore, most Takahashi eyepieces
can be used with FOA-60Q.
▼Diagonal Mirror & Diagonal Prism
When observing the zenith is necessary, it
is advisable to use a high quality 90-degree
prism. The Takahashi 90-Degree Prism is a
quality multi-coated prism, which allows the
observer to easily view the zenith by looking
down into the prism. The diagonal prism
has a 45-degree light pass and produces an
erect, reversed (mirror) image. The diagonal
prism is designed to be used with 31.7mm
(1¼”) barrel eyepieces.
The light pass length through the prism
becomes longer so the drawtube must be
moved a longer distance. In order to achieve
the best focus, please connect the system
parts as instructed.
◆Astro Imaging
▼Prime Focus Imaging
This is the method to take images at the
focal point, just like using a telescope as
a telephoto lens. Since the focal length
of a telescope is far longer than that of a
telephoto lens, even a slight error in guiding
will result in poor star images. Therefore,
a steady mount should be used to keep
images as sharp as possible. A DSLR
camera or a CCD camera can be used for
the prime focus imaging. In order to attach a
DSLR camera, the CA-35 (50.8/2") and the
T-Mount DX-WR are required, according to
the camera model.
▼Eyepiece Projection Imaging
When the FOA-60Q is used to take images
of lunar craters or planets, the TCA-4
eyepiece projection system can be used for
taking magnied images. The magnication
for each eyepiece can be increased or
decreased by moving the sliding tube that
is an integral part of the TCA-4. This device
can be attached to a DSLR camera with the
T-Mount DX-S, which is available for EOS
or Nikon.
In imaging the lunar surface, it is well
illuminated so you can enjoy various images
with various magnifications. For planetary
imaging, make the magnication as high as
possible according to the seeing. When the
seeing is not good, you cannot take good
images either of the moon or of planets.
Check the seeing condition before imaging.

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36.5mm
Length of Light Pass
81.0mm
11mm
Length of Light Pass
106.5mm
Length of Light Pass
63.5mm
Accessories
Takahashi o󰀨ers a wide variation of system parts for the FOA-60Q, including:
◆Diagonal Mirror 50.8 (2")
◆Diagonal Prism 31.7(1¼”) MC
When the Diagonal Mirror or the Diagonal
Prism is used, the light path length will be
longer; so to get focus, you must turn the
focusing knob more. Attach the desired
accessories as instructed in the chart in
order to get sharp focus. The diagrams
shown at the right indicate the light path
length for reference. Please note that
some other 50.8 (2") eyepieces, from
brands other than Takahashi, cannot
focus.
◆4-Turret Eyepiece Holder 31.7(1¼”) D
The 4-Turret Eyepiece Holder 31.7(1¼”) D
is a convenient accessory that allows the
observer to use 4 eyepieces. This turret
allows eyepieces to be changed quickly by
turning it. In addition, this device has a built-
in 90 degree prism that allows the observer
to conveniently view the entire sky.
When using the FOA-60Q be sure to also
use the Extension Tube S to ensure sharp
focus.
Diagonal Mirror
50.8(2")
50.8(2") Adapter (SKY-90) 50.8(2") Extension Tube S
4-Turret Eyepiece Holder 31.7(1¼”) D
Diagonal Prism
31.7(1¼”) MC

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◆31.7(1¼”) 2X Barlow Lens
This can extend the focal length of the
FOA-60Q by 2X in visual use, keeping
the aberration to a minimum. Barrel size
is 31.7mm (1¼”) and it can be used with
the Diagonal Mirror 50.8 (2") by way of the
Adapter (DM).
◆T-Mount DX
In order to attach a DSLR camera and TCA-4
Projection Device, the T-Mount DX-S is used.
For imaging with the Flattener 0.93X,
the T-Mount DX-60W is required. When
the Flattener 0.93X is used as a 500mm
telephoto lens, the Extender 1.7XR must be
removed. For the other imaging at the prime
focus or with the extenders, the T-Mount
DX-WR is used. The T-Mount is available
for EOS or Nikon.
Caution
Be careful of scratches and dirt on
the T-Mount. These could cause
misalignment of the camera, resulting
in poor quality star images.
T-mount DX-WR
T-mount DX-60W
T-mount DX-S
TCA-4 DSLR Camera
DSLR Camera
DSLR Camera
CA-35 (50.8/2”)
Flattener 0.93X
31.7(1¼”)
Eyepiece
31.7(1¼”) Eyepiece
50.8(2”) Extension Tube L
31.7(1¼”)
Eyepiece Adapter
Coupling S 31.7(1¼”) 2X Barlow Lens
31.7(1¼”) 2X Barlow Lens
31.7(1¼”) Adapter(DM)
Diagonal Mirror 50.8(2")
50.8(2”) Adapter (SKY90) 50.8(2”) Sleeve

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◆CA-35 (50.8/2")
For imaging at the prime focus, the CA-
35 (50.8/2") is required to attach a DSLR
camera. It can be attached with the 50.8
(2") Adapter (SKY-90) to connect a DSLR
camera by way of the T-Mount DX-WR.
T-mount DX-WR DSLR Camera
CA-35 (50.8/2”)
50.8(2”) Adapter (SKY90)
◆TCA-4 Eyepiece Projection Device
This device allows the observer to change
observing mode simply and quickly from
visual to magnied mode.
You can easily change the eyepiece for
magnified imaging, and can also simply
adjust the magnifying rate, as you like, by
sliding the magnifying tube. You can use
any standard 31.7 (1¼”) eyepieces with this
device. To attach TCA-4 to a DSLR camera,
the T-Mount DX-S is used according to the
camera model.
Caution
When magnified imaging, the tube
assembly will be apt to be out of
balance. So, rebalance it according
to the instruction of the Takahashi
mounts. If the Dec. clamps are
loosened carelessly, the tube assembly
may turn abruptly and dangerously.
When the clamp must be loosened,
do so slowly and carefully, holding the
imaging package with one hand.
DSLR
Camera
TCA-4
T-mount
DX-S
50.8(2”) Extension Tube L
31.7(1¼”)
Eyepiece
50.8(2”) Adapter
(SKY90) 50.8(2”)
Sleeve
A PC camera or a CCD camera
with 31.7(1¼”) sleeve can be
attached to the TCA-4 with the
31.7(1¼”) eyepiece adapter.

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◆Extender ED 1.5X
◆Extender Q 1.6X (50.8/2")
The focal length of the FOA-60Q is as
long as 900mm. In order to get high
magnifications, eyepieces with shorter
focal lengths must be used. Generally,
the eye-relief of the eyepiece with shorter
focal length is short, so it is apt to make
observers tired in a long observing session.
The Extender ED 1.5X can extend the focal
length of the FOA-60Q by 1.5X to 1350mm
(f/22.5) and the Extender Q 1.6X(50.8/2")
can do so by 1.6X to 1440mm (f/24.0)
respectively. So, by using these extenders,
optionally available, you can comfortably
do the highly magnied lunar and planetary
observations using eyepieces with long
focal lengths.
These extenders can be easily attached
with the 50.8 (2") sleeve system.
Extender ED 1.5X
Extender ED 1.5X
Extender Q 1.6X(50.8/2")
Extender Q 1.6X(50.8/2")
The T-Mount DX-WR is required to attach a
DSLR. Use the T-Mount optionally available,
according to the camera model.
▼Imaging System
with the Extender ED 1.5X
E󰀨ective Focal Length : 1350mm
E󰀨ective Focal Ratio : f/22.5
▼Imaging System
with the Extender Q 1.6X (50.8/2")
E󰀨ective Focal Length : 1440mm
E󰀨ective Focal Ratio : f/24.0
Caution:
Do not attach a filter when the 50.8(2")
Extension Tube or the CA-35 (50.8/2") is
connected to the Extender Q 1.6X (50.8/2").
The lter will touch the lens of the extender.
50.8(2”) Sleeve
T-mount DX-WR
DSLR Camera
CA-35 (50.8/2”)
50.8(2”) Adapter
(SKY90)
50.8(2”) Adapter
(SKY90)
31.7(1¼”)
Eyepiece
50.8(2”) Extension Tube L
31.7(1¼”)
Eyepiece Adapter
Coupling S

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◆Removing the Extender 1.7XR
The Extender 1.7XR is 2-group 4-element
built into the FOA-60 in between the tube
and the focuser unit. There is no need
to remove it for visual use, or magnified
imaging for the moon and planets. However,
when the Flattener 0.93X is used as a
500mm telephoto lens, the Extender 1.7XR
must be removed. Then, it becomes same
to the FOA-60.
▼How to remove the Extender 1.7XR
1. The Extender 1.7XR can be removed as
seen below. The black part of the tube
center is part of the Extender 1.7XR so
this must be removed together.
At first, remove the main tube. Holding
the main tube and the Extender 1.7XR
by hands, turn the main tube counter-
clockwise to remove.
2. Next, remove the Extender 1.7XR from
the focuser unit. Holding the Extender
1.7XR and the focuser unit, turn the
Extender 1.7XR counter-clockwise
to remove. Be careful not to touch
the focuser handle. When the excess
pressure is applied to the focusing
handle, the focusing will be performed
not smoothly.
3. Connect the main tube to the focuser unit
by turning it clockwise to the end. When
connecting these parts, be careful not to
cross thread. If cross threaded, unscrew
them and start it again. Be careful not to
drop these parts when connecting.
(Note)
When the main tube and the focuser unit
are too tight and can be not removed, have
two people hold these parts, turning them
with even power to remove.
1
2
3
Main Tube
Main Tube
Focuser Unit
Focuser Unit
Focuser Unit
Extender 1.7XR
Extender 1.7XR

- 18 -
Caution:
Do not use the Flattener 0.93X
and the Extender 1.7XR together.
Use just one at a time.
◆MEF-3
The Micro Edge Focuser, MEF-3, is an
optionally available fine focus attachment
that permits 8 to 1 focus for critical focusing
for imaging or highly magnied viewing.
◆Cautions for Imaging
▼Sharp Image
Use a 3-4 magnitude star in order to achieve
sharpest focus of an image. Do trial shots
with a DSLR camera to determine the best
focus of the image. You can use the "live
view" function of the camera to focus on a
star.
▼Trial Shots
Before heading to a remote place to find
darker skies, it is recommended that you
take some trial shots in your backyard. Even
in the light polluted city area, you can take
images with an exposure of one minute
or so. This will allow you to confirm the
procedures that will achieve the sharpest
images for your equipment.
▼Guided Imaging
The quality of the image will depend on
guiding. Little or no guiding error in the
process of imaging will produce very sharp
images. Play or misalignment will ruin longer
exposures. Please use a very rigid guide
scope system for long exposure imaging.
MEF-3
T-mount DX-60W
◆Flattener 0.93X
When the FOA-60Q turns into the FOA-
60, the Flattener 0.93X, 2-group 2-element,
can be used. Keeping the center image
sharp as in the FOA-60 and improving the
edge aberration at the prime focus, this
can reduce a bit the focal length to 495mm
(F/8.2).
Using the Flattener 0.93X, the focal length
will be darker (f/8), but it can produce the
10 micron image (RMS-SPOT) across the
eld, suitable for deep sky imaging as well
as imaging the outer corona of the total
eclipse. At the same time, it can be used
as a 500mm (f/8) telephoto lens suitable
for imaging birds and lands. To attach the
Flattener, the 50.8mm(2") is used for quick
change from visual use to imaging mode.
▼Imaging System
with the Flattener 0.93X
E󰀨ective Focal Length : 495mm
E󰀨ective Focal Ratio : f/8.2
Image Circle :φ44mm
DSLR Camera
Flattener 0.93X
50.8(2”) Adapter (SKY90)

- 19 -
What is Fluorite?
In 1979, Takahashi became aware of
the superior optical performance of a
telescope that used a fluorite element
so Takahashi started development of a
90mm uorite telescope in 1979. FOA-60Q
is a doublet apochromatic refractor that
makes the best use of its fluorite element.
With less curvature and high resolution,
its focal length can be changed freely by
dedicated reducer and extender. As shown
below, its transmission area and ratio are
outstandingly large. In addition, multi-coated
element can produce rich illumination
from short wave to long wave. Different
from reectors, there is no light loss by the
secondary, FOA-60Q can produce brighter
images even with f/8.8 optical system,
which will enable viewing and imaging faint
objects.
The fluorite element with its excellent
performance is used in various high quality
objective. Chemically the uorite element is
as hard as optical glass and can be multi-
coated for long time use. The focal length
can change with uctuating temperature. So
it is advisable to take the telescope out at
least 30 minutes before using it to allow it to
equalize with the temperature of the outside
air to produce stable images. It is good to
refocus with a temperature change of 3
degrees C.
The uorite lens of FOA-60Q is multi-coated
to harden the lens surface to protect it
scratched and is placed at the rear. So there
is little chance to get scratches on the lens.
Wave Length
(nm)
Focal Length
(mm)
Comparative Color Aberration Curves
CaF2
BK7
FK01
A’ (768.2)
C (656.3)
d (587.6)
e (546.1)
F (486.1)
i (365.0)
h (404.7)
g (435.8)
-1 -1 012345678910
Wave Length
Light Transmission
Comparative Diagram (non-coated)
CaF2 (t=10mm)
BK7 (t=10mm)
0.20.40.60.81
100
80
60
40
20
02345678910μ
%

- 20 -
Care & Maintenance
Additional Precautions
▼Minimize large uctuation in temperature
around your telescope. When the
telescope is brought out from a warm
room to colder air, dew may form.
▼Store the telescope in a cold dry
environment. Any dew should be removed
by blowing it with a hair dryer with the
heat element turned o󰀨, which means the
air will be at room temperature. This ow
of room temperature air will dry the dew
and not leave a residue. Additionally, it is
a good idea to store the telescope with a
drying agent near the objective to prevent
moisture issues.
NEVER USE ALCOHOL TO CLEAN
THE LENS. IT WILL DESTROY THE
COATING.
▼Under no circumstances should the
lenses be disassembled. The lenses have
been properly aligned and set in place by
a skilled optical technician with special
tools. Movement, removal or disassembly
of the lenses will void any warranty on the
tube assembly.
▼Optical Axis
Before shipment, the optical axis of your
telescope has been precisely adjusted
and in normal use it should not require
adjustment. On occasion, however,
damage or rough handling during
transport may cause alignment issues.
If there is an abnormal star image visible
with your telescope, immediately contact
your local distributor.
▼Care for the Lens
If the front lens of the objective has dust
or dirt particles on it, use a large hand-
powered blower to remove the particles.
Under no circumstances should dust be
removed by any other means. Rubbing
the surface will cause scratches. If the
lens must be cleaned, be certain that all
dust and particles have been removed by
using a blower.
Then using cotton swabs slightly
moistened with telescope lens cleaner,
dab the surface, changing cotton swabs
often until the objective is cleaned.
If any questions arise during this process,
immediately contact your local distributor
for help. Under no circumstances should
the surface ever be rubbed.
REMEMBER, DO NOT USE ANY FORM
OF CANNED AIR TO REMOVE THE
PARTICLES.
Canned air is very cold and could harm
the front lens of the objective. Be certain
that the dew cap is removed before
attempting to clean the objective. Use
the procedure above, if the front and rear
surfaces of the objective must be cleaned.