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Astronomy > Telescopes > William Optics > Cat > William Optics Apochromatic refractor AP 51/250 SpaceCat 51 OTA

Product description

More about the series Cat...

The AP 51/250 refractor is an impressive combination of compact size, attractive price and outstanding optical quality which is suitable for all astro- and nature photography. At the heart of the optical set-up is the Petzval design comprising four elements in three groups in which FPL53 and FPL51 glass has been utilised. The result is a colour-rich corrected image field with a diameter of more than 44 mm - perfect for full-frame cameras. The fast focal ratio of f/4.9 allows short exposure times.

For camera connection there is a M48 thread. Appropriate T2 adapters can be found under “recommended accessories”. Focusing is helical - so by twisting the textured ring on the telescope body even heavy cameras are no problem.

The 110mm long dovetail bar offers three connection alternatives; screw connection with a photo thread, Arca Swiss or Vixen standard fittings. With these three options it should be no problem to connect this telescope to all the usual photo tripods, photo mounts or astronomical mounts.

Not only is a protective nylon carrying case included, but also a specially devised Bahtinov mask. This mask helps with focusing and is built into the lens cap.

A telescope such as the RedCat 51 is ideal for photographers who are interested in the night sky and also animal photography.

With the RedCat 51 you are not only investing in impressive optical performance, but you will also be thrilled by the durable and beautiful finish William Optics has achieved.

It not only matters which telescope you buy but also where you buy it. Our additional services:

  • We are a leading telescope dealer and know the devices we sell. Our customer service team will gladly help you after your purchase if you have problems with assembly or operation.
  • We provide a copy of the 80-page Telescope ABC beginners handbook with every telescope.
  • We also provide an edition of the exciting astronomy magazine, “Sterne und Weltraum” with each telescope.

Specifications

Optics


Type
Refractor
Type of build
Apochromat
Aperture (mm)
51
Focal length (mm)
250
Aperture ratio (f/)
4,9
Resolving capacity
2,71
Limit value (mag)
10,3
Light gathering capacity
50
Max. useful magnification
102
Tube weight (kg)
1,5
Tube length (mm)
225
Tube material
Aluminium
Coating
multiple
Tube construction
Full tube
dew cap diameter (mm)
80
lens design
Quadruplet

Focuser


Tilting Adaptor
yes
Type of build
Helical
Connecting threaded socket (camera-side)
M48
Backfocus (mm)
59,7
Free aperture (mm)
44
Rotating
yes

Mount


Type of build
OTA
Mounting type
no mount

Included accessories


Dew Shield
yes
Carry case
yes
Miscellaneous
Bahtinov focus mask
Prism rail
Arca-Swiss & Vixen-Style
Corrector
integrated

General


Series
Cat
Colour
silver

Area of application


Astrophotography
yes (very good)
Moon & Planets
yes
Nature Observation
yes
Nebulae & galaxies
yes
Sun
no (Only with appropriate Sun filter)

Recommended for


Beginners
no
Advanced
yes
Observatories
no

Recommended accessories

Media (3)
Star chart

Omegon Star chart Planisphere

$ 14.90*
Outdoor (2)
Headlamp

Omegon LED headlamp

$ 13.90*
Solar Observation (2)

Baader Sun filter foil 20 x 29 cm

$ 31.90*
Maintenance & Cleaning > Lens cleaners (3)

Omegon 7-in-1 lens cleaning set

$ 19.90*
Maintenance & Cleaning > Other (2)

Omegon microfibre cleaning cloth 20cm x 20cm

$ 4.90*
Miscellaneous (1)

Star In A Star Moon Hat

$ 17.90*

*All prices include VAT plus shipping costs.

William Optics Apochromatic refractor AP 51/250 SpaceCat 51 OTA
Carrying case included.
William Optics Apochromatic refractor AP 51/250 SpaceCat 51 OTA
Focusing Mask
William Optics Apochromatic refractor AP 51/250 SpaceCat 51 OTA
Original William Optics
William Optics Apochromatic refractor AP 51/250 SpaceCat 51 OTA
Field rotator & tilting mechanism
William Optics Apochromatic refractor AP 51/250 SpaceCat 51 OTA
Focusing
William Optics Apochromatic refractor AP 51/250 SpaceCat 51 OTA
Prism rail

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