Cat 91 WIFD

Nov 20, 2024 by WO Team

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Specification

Lens Type
5 Elements Advanced Petzval Design
Focal Length
448 mm
Diameter
91 mm
Aperture
f/4.9
Image circle
55 mm
Focuser
WIFD R&P Focuser (Compatible with EAF)
Adapter Included
Tilt Adjuster / Rotator / M63 → M54 Adapter / M63 → M48 Adapter
Optional Flattener
No Flattener Required
T-rings Supported
Canon EF, RF | Nikon F, Z | Sony E | Pentax K | MFT (M4/3) | FUJI X
Camera Format
Medium Format (needs additional adapter) / Full Frame / APS-C / M43
Tube Length
556 mm
OTA Weight
4.72 kg / 10.41 lbs
Total Weight
6.3 kg / 13.89 lbs

Diagram Reports

Spot Diagram

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Longitudinal Aberration

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Size Diagram

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Parts

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  1. Front Bahtinov Mask Cover
  1. Lens Cover with Bahtinov Mask How to focus with the Bahtinov Mask ?
  1. Dew Shield
  1. WIFD Focuser How to adjust Focuser Tension?
    1. Focus ruler scale Window
    2. Two Speed 1:10 Ratio Fine Knob
    3. Fine Knob Protecting Cover
    4. M4 Screw Holes for Finder Bracket
    5. Focuser Knob with Temperature Gauge ( Can be removed to attach EAF. How to install EAF? )
  1. Tilt Adapter How to adjust Tilt Adapter?
    1. Tilt Adapter Protecting Cover
  1. Camera Angle Rotator (CAA)
    1. CAA Locking Knob
  1. M63 → M48 Adapter with M48 Filter Thread How to install a Filter? ( M63 → M54 Adapter interchangeable )
  1. M48 ( M54 ) Rear Dust Cap
  1. Handle Bar with Mini Vixen-style Mounting Base
    1. M4 Screw Holes For Locking Screws
    2. Mounting Base Locking Screws (M4)
    3. M6 Screw Holes
  1. Mounting Ring
    1. M6 Screw Holes for Finder Bracket
    2. Mounting Ring Knob
  1. Vixen-style Dovetail Plate
 

Operation Guide

Focuser Tension Adjustment

There’s two side to build WIFD focuser tension:

BUTTON / Rack & Pinion Gear

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  • Quick tension adjustment knob
  • Smoothness adjustment - Pull in (3mm Hex)
  • Smoothness adjustment - Push out (2mm Hex)
  • Please Don’t Touch
 

TOP / Focuser Draw Tube

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  • Focuser Draw Tube Tension Screws Please Don’t Touch
  • Guider/Finder bracket mounting screws (2.5mm Hex)
 
⚠️
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, be sure not to over-tighten the tension screw, as this could damage the focuser. Consider it like driving a car while pressing both the gas and brake pedals simultaneously. Just as this could harm your car's systems, over-tightening the tension screw can compromise your telescope's focuser functionality.

Camera Tilt Adjustment

Where is the tilt adjuster?

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  1. Remove the rotator knob.
 
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  1. Remove the ring cover.
 
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  1. The tilt adapter is inside.
 

Adjusting Instruction

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Installing EAF

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  1. Turn the telescope over and remove the Tension screw.
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  1. Remove the top cover screw near the temperature gauge with 2mm Allen key.
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  1. Release (don’t remove) two inner knob screws.
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  1. Remove the temperature gauge knob.
 
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  1. Find the flat side on the shaft and turn it to face the hole.
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  1. Put the 5-6mm Flexible coupling on the shaft and lock the two inner screws.
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  1. Put the EAF body on and lock the two inner screws.

On Step 6 & 7:

Please make sure one of the screws is lock on the flat side

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  1. Align the screw holes.
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  1. Lock the four M4 bracket screws.
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Installing Filter

Only applies to the M48 camera adapter ( There are no filter threads on the M54 adapter, filter wheel is used instead )

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  1. Lock the Rotator
 
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  1. Take off the M48 adapter
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  1. Lock the filter ( male thread ) inside the M48 adapter ( female thread )
  • It is recommended to apply some lubricating oil on the threads first to avoid being permanently tightened.
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  1. Put the adapter back

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