William Optics Apochromatic Refractor AP 108/518 UltraCat WIFD

    Petzval optical design with integrated corrector
Color-pure and sharp images up to full-frame sensors
Focusing by William Optics Internal Focus Design (WIFD)
Includes rotator and tilt flange
Camera-side mount: M68, M54, M48

The Astrograph Ultra-Cat 108 represents the culmination of a long and highly successful development!

It is a 108mm apochromatic refractor designed for demanding astrophotographers. It features 5-element Petzval optics with special low-dispersion ED optical glass and a fast aperture ratio of f/4.8 – perfect for capturing large-format skyscapes and landscape photography.

Advanced 5-element Petzval design: Eliminates field curvature and delivers sharp, flat images without the need for an additional flattener.
WIFD (William's Internal Focuser Design) The patented focuser is located inside the tube. This allows precise focusing and prevents tilt, even with heavy cameras. The focusing is EAF compatible.
Temperature-stable lens cells minimize thermal expansion and contraction and ensure perfect optical alignment in any environment.
On the camera side, the tube is equipped with a rotator and a tilt flange. The former allows the camera to rotate for perfect alignment of the subject on the sensor, while the latter prevents distortion that can occur if the camera sensor is not aligned flush with the image plane.
The telescope comes with a Bahtinov mask, conveniently integrated into the lens cap. This mask assists with focusing.
The patented handle allows for stable attachment of accessories.

Technical Specifications
Optics
Type
Refractor
Design
Apochromat
Aperture (mm)
108
Focal Length (mm)
518
Focal Ratio (f/)
4.8
Resolution (arcseconds)
1.28
Limiting Magnitude (magnitude)
12
Light Gathering Power (x of a 7mm pupil)
240
Maximum Useful Magnification (x)
216
Tube Weight (kg)
7.8
Tube Length (mm)
618
Transport Length (mm)
513
Tube Material
Aluminum
Dew Shield Diameter (mm)
80
Lens Design
Triplet
Corrected Field of View (mm)
60
Coating
Multiple
Focuser
Design
Internal
Tilt Flange
Yes
Connection Thread (Camera Side)
M68, M54 M48
Rotatable
Yes
Mount
Design
OTA
Mount type
No mount
Included accessories
Dew shield
Yes
Carrying case
Yes
Dot rest
Vixen-style
Corrector
Integrated
Focusing aid
Bahtinov focus mask
General
Series
Cat
Areas of application
Astrophotography
Yes (very good)
Moon & planets
Yes
Nature observation
No
Nebulae & galaxies
Yes
Sun
Yes (only with a suitable solar filter)
Recommended for...
Beginners
No
Advanced users
Yes
Observatories
No


Product safety
Manufacturer: William Optics Co. Ltd, TW, info@williamoptics.com