WILLIAM OPTICS FLT91 Apochromatic Refractor Fluorostar Instruction Manual

: June 19, 2024
: WILLIAM OPTICS

Table of Contents

FLT91 Apochromatic Refractor Fluorostar
SPECIFICATION
PACKAGE CONTENTS
PARTS
TELESCOPE DIAGRAM
OPERATION GUIDE
ACCESSORIES MAP
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FLUORO STAR 91
MANUAL

FLT91 Apochromatic Refractor Fluorostar

Warning
Never aim your telescope or finder scope at the Sun without proper Solar filters installed on the front of the telescope. Doing so for even a moment may permanently damage your vision. Proper Solar filters consist of filters made by reputable manufacturers, designed to fit tightly over the front of the dew shield. Solar eyepiece filters are not considered safe, and should not be used. With proper front mounted Solar filters, the telescope will not be harmed by viewing the Sun.

SPECIFICATION

$WILLIAM OPTICS FLT91 Apochromatic Refractor Fluorostar - Fig 1$

Focal Length : 540mm
Diameter: 91 mm
Aperture: f/5.9
Focuser: 3.3″ R&P Focuser
Image Circle : >43mm
Retracted Length : 44 1 mm
Extended Length : 51 0mm
Dew Shield Circumference : 383mm
Dew Shield Diameter : dl 2 2 mm
Weight : 9.1 Bibs / 4.165kg (OTA only)
12.29Ibs / 5.575kg (OTA with ring, dovetail and saddle)

Spot Diagram

$WILLIAM OPTICS FLT91 Apochromatic Refractor Fluorostar - Fig 2$

Longitudinal Aberration

$WILLIAM OPTICS FLT91 Apochromatic Refractor Fluorostar - Fig 3$

NOTE:
We are using a new lens cell design that includes FP53 glass in the WO triplet series (GT and FLT series). This design is perfect for temperature compensation to better prevent pinched optics, that can occur in cold weather conditions.
Before storing your telescope, you must leave it uncovered, with the tube opened for enough time to allow it to adjust to the room temperature. You must make sure the telescope is completely dry of any dew or moisture before it can be safely stored.
The telescope should always be stored in a dry location, with a consistent temperature.

PACKAGE CONTENTS

$WILLIAM OPTICS FLT91 Apochromatic Refractor Fluorostar - Fig 4$

A. Bahtinov Mask
B. OTA
C. 120mm Saddle Handle Bar
D. Visual Extention Tube
E. 2″ Rotolock Visual Back Adapter
F. Long Version Vixen-style Dovetail Plate
G. Soft Carry Case

PARTS

$WILLIAM OPTICS FLT91 Apochromatic Refractor Fluorostar - Fig 5$

A. 2″ RotoLock Visual Back Adapter
B. Visual Extention Tube
C. Camera Angle Rotation Locking Screw
D. Dual Speed 3.3″ R&P Focuser
E. Focuser Rotation Locking Screw
F. Mounting Rings/ Knobs
G. 120mm Saddle Handle Bar
H. Dew Shield Locking Screw
I. Dew Shield| J. Lens Cover with Bahtinov Mask
K. Camera Angle Rotator
L. 10:1 Ratio Fine Knob & Cap
M. Long Version Vixen-style Dovetail
N. Locking Screws on Saddle Handle Bar (M4)
0. M4 Screw Holes
P. M6 Screw Holes
Q. Focuser Adjusting Knob with Thermometer
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TELESCOPE DIAGRAM

$WILLIAM OPTICS FLT91 Apochromatic Refractor Fluorostar - Fig 6$

$WILLIAM OPTICS FLT91 Apochromatic Refractor Fluorostar - Fig 7$

$WILLIAM OPTICS FLT91 Apochromatic Refractor Fluorostar - Fig 8$

R & P GEAR SPACING SCREWS
Adjustment Screws (3 mm Allen Key) – Pull Screw
Adjustment Screws (2 mm Allen Key) – Push Screw
Can be Removed to Attach the Electronic Motorized Device such as EAF (Please refer to the instructions on page 12
Tension Screw (Please refer to Note 2)
Do Not Touch

IMPORTANT NOTE:

The focuser smoothness adjustment ONLY when necessary by progressively push & pull screws until you reach the desired smoothness.
When using the telescope with the motor, please ensure that the tension screw is not over-tightened. Over-tightening the tension screw may cause damage to the focuser.
Think of it like driving a car and pressing the gas pedal while also pressing the brake simultaneously. Just as this action could harm your car’s systems, over-tightening the tension screw could compromise the functionality of your telescope’s focuser.