William Optics SpaceCat 51 APO f/4.9
William Optics SpaceCat 51 APO f/4.9William Optics SpaceCat 51 APO f/4.9William Optics SpaceCat 51 APO f/4.9
William Optics SpaceCat 51 APO f/4.9William Optics SpaceCat 51 APO f/4.9William Optics SpaceCat 51 APO f/4.9

William Optics SpaceCat 51 APO f/4.9

  (1 Review)
✓ 2 year warranty


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About this product

Model:  wo_spacecat_51
Part Number:  L-RC51TG

New Limited Edition SpaceCat v1.5 51 / 250mm f/4.9 Apo

This NEW limited edition SpaceCat features an integrated camera sensor tilt adjuster, an updated mounting ring with longer dovetail (easier balancing) and a new focusing index. An optional saddle handle-bar is also now available. 

The William Optics RedCat 51 APO is a 51mm f/4.9 Petzval refractor that features synthetic fluoride (FPL53 and FPL51) glass elements for a full frame, flat field image.

Provides high resolution images when used for astrophotography or wildlife photography.

Its fast f/4.9 focal ratio and compact size makes it ideal for convenient wide field astrophotography or piggybacking. 

Incorporates a smooth helical focuser, a field rotator graduated by degree, a slot for 48mm filters and a reversible dovetail for either Vixen style* or Arca-Swiss mounting. 

Telescope Field of View Simulator

What's in the box

  • SpaceCat 51 f/4.9 scope
  • Soft Carry Case
  • Patented Bahtinov Mask


Aperture 51mm
Focal Ratio F/4.9
Focal Length 250 mm
Objective Type Petzval (4 elements in 3 groups) and Ohara FPL 53 ED element. 
Image Circle Φ 44mm (Full Frame)
Focuser Helical
Dimensions 225mm x 80mm x 80mm
Tube Weight 1.47kg

Customer reviews

Average Rating (1 Review):  
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Fantasic for the big Deep sky objects
Monday, 4 November 2019  | 

Purchased one of these, after some help from FLO, got all the parts needed to attach this to a Star Adventurer, and my Canon 70D. First light on Andromeda Galaxy from Kielder. Using the built in bhatinov mask, I was able to get focus quickly and very precisly. Had a few teething problems at the beginning, but this was human error, FLO very very helpful in helping me solve the issue. And I managed to get 120 * 1 min subs on Andromeda at ISO12800! The scope kept focus throughout, and the image processed extremely well, I took darks, flats, bias to compliment the lights, and it worked superbly. Very impressed with the scope and the build quality. The focuser is easy to move and the graduations on the side (with I didn't see at first) seem to be spot on for getting infinity focus, so a great starting point for that DSO. From now on, this scope is my goto travel scope.


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