William Optics

USED RedCat 51mm f/4.9 Petzval Astrograph & erect prism 90-deg Diagonal


  • Sale
  • $698.00
  • Regular price $846.00

 ✔ Staff Pick

Available to Order, usually 7-10 days to ship.


CONDITION:  Lightly used, scratches on the rear rotator ring (see photo).  Optics look brand new. Includes William Optics erect prism 90-degree diagonal for visual use with standard 1.25" eyepieces. 

Probably the very sharpest 250mm camera lens you will find! 

  • 51mm Doublet ED APO f/4.9 (250mm fl)
  • FPL53 & FPL51 glass 
  • 3.2 lbs tube weight.
  • 44mm imaging circle with a flat field edge to edge for full-frame sensors
  • Dual Vixen and Arca Swiss Dovetail
  • M48 thread to accept wide t-rings/t-mounts

 

The best value, highest quality 250mm lens you will find for your camera.

51 mm lens, in a sleek Petzval design, using Synthetic Fluoride (FPL53 and FPL51) glass for a full-frame flat field image. The optical quality provides exceptional performance at a fast focal ratio of f/4.9. 

Filter Adapter allows use of 48mm filters. Focusing is made easy with a bahtinov mask integrated into the lens cap. 

 

Aperture 51 mm (2")
Camera/Eyepiece Connection Male M48x0.75
Dawes Limit 0.46 arcseconds
Focal Length 250 mm
Focal Ratio f/4.9
Glass Type FPL-53 and FPL-51
Highest Useful Magnification 102x
Light Gathering Power 53x
Limiting Magnitude 12.3
Optical Design Petzval
Tube Color Red
Tube Diameter 51mm
Tube Weight 3.2 lbs

 

  • RedCat 51mm Telescope
  • Bahtinov Mask
  • 210mm Dovetail
  • Mount Ring
  • Soft Carry Case

 

SKU: UL-RC51Ix
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