Astro-Physics 2" Advanced Convertible Barlow

Astro-Physics 2" Advanced Convertible Barlow
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  • This 2-element 2" Advanced Convertible Barlow from Astro-Physics was designed to match the characteristics of small-to-medium size CCD sensors (like the popular 8300), but it is also a great accessory for high power visual observing as well as lunar, planetary, and solar photography.
  • The large flat field optic eliminates vignetting, even with f/6 telescopes.
  • Use as a conventional Barlow or separate the optics from the 2" locking adapter and screw directly into your camera's faceplate for a flexure-free fitting.
  • Includes both 42mm and 48mm threads for versatility.


Astro-Physics 2" Advanced Convertible Barlow…

The Astro-Physics Advanced Convertible Barlow has a unique design that provides several configurations to increase the focal length of your telescope. It was designed to match the characteristics of small and medium size CCD chips. It is also ideal for high-power visual observation and lunar-planetary-solar photography.

The AP 2" Advanced Convertible Barlow can be used conventionally by inserting an eyepiece or a camera’s nosepiece into its 2” locking adapter. Alternatively, the optic section can be separated from the 2” locking adapter and screwed directly into a camera’s faceplate, a threaded nosepiece, or extension tubes for a flexure-free fitting. It has both 42 mm and 48 mm threads for versatility.

Advanced Convertible Barlow Features…

  • Flat field for imaging and visual
  • Very effective high-tech coatings eliminate ghost images
  • Screws into front nosepiece of cameras and diagonals
  • Ideal for medium size CCD sensors
  • Greater than 98% light transmission
  • Large field optic eliminates vignetting even with f/6 optics

This redesigned optic features a flatter field, allowing it to be used for deep-sky photography when increased magnification of smaller objects is desired. Naturally, additional exposure time will be required. Changing the spacing distance will change the magnification of the Barlow (90 mm back spacing is ideal, yielding 2.0x magnification). The “sweet spot” of the flatter field is between 1.8x and 2.5x.

The 2-element design of the AP 2" Advanced Convertible Barlow preserves the fine color correction of the main objective. The optical elements are precision ground and polished to insure that no aberrations are introduced into the system. The Barlow focal length is -102 mm which is longer than conventional types. This minimizes the divergence of the edge rays and therefore reduces the apparent vignetting common in many eyepieces. The Barlow features a brass locking ring that clamps eyepieces and accessories securely, yet will not mar their fine surfaces.

The Advanced Convertible Barlow’s flat field is optimized for APS-C and smaller sensors (such as the 8300 and 3200 sensors). Using this Barlow with an f/8 refractor provides round stars over 90% of the field, and over 80% of the field with an f/6.3 refractor.

Note the following positions and resulting magnifications (Distance from rear of Barlow to focal plane, measured from 2" barrel):

  • Minimum recommended mag: 1.8x, 70 mm back focus distance
  • Normal magnification: 2.0x, 90 mm back focus distance
  • Maximum recommended mag: 2.5x, 134 mm back focus distance
Additional Information

Additional Information

Barrel Size 2"
Magnification 2X
Manufacturer Astro-Physics
Warranty Limited Warranty
Included Items

Included Items

  • 2" AP Advanced Barlow
Questions & Answers

Product Questions

I usually do imaging with a Canon T3i DSLR at prime focus. Can I use Barlow between my diagonal and the camera to increase magnification?
Is this compatible with a Nikon D 610? 
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