Paracorr Telescope Accessories > Paracorr > "is" Adapter 3"
Big Paracorr
3" BIG Paracorr Type-2 with "Imaging System" Accessories

The Tele Vue Visual / Imaging System Adapter to allow for the use of the Tunable Top and Tele Vue Imaging System accessories on the 3" BIG Paracorr is no longer available - but a substitute can be ordered from Note that the 3" BIG Paracorr has an external flange that screws onto the body - this is removed for the adapter installation. Proceed as follows to have an adapter made:

  • Aim your browser at
  • Select Tele Vue on both sides of the Build-An-Adapter screen.
  • Click [Next].
  • On the left side select "TV Paracorr BIG (VIP-3010) M73.5" (careful! version with flange is also listed).
  • On the right side select "TV Paracorr Type-2 Tunable Top".
  • In the center enter 0.48" as the Effective Length (make sure the "in" radio button is selected).
  • Click [Build]

This is Your Adapter box appears on the bottom left. An image will show which external threads are found on each side of the body. Below that is a clickable 3D view of the adapter so you can see what the finished product is like. On the right is the ordering information.

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Check wording on either side of the adapter to make sure the right threads are used. Image courtesy of

You can image through the adapter by adding our 1/4" Imaging System Spacer (TLA-0250) and then additional Imaging System spacers to achieve a 55mm backfocus from the TLA-0250 to the image sensor. For DSLR cameras, this simply means attaching our Canon EOS Wide T (CWT-2070), Nikon F-mount Wide T (NWT-2073), or your camera T-Ring mated to our Standard T Adapter (TRG-1072) onto the TLA-0250 and connecting the camera.

<span class='caption... Adopting 3" BIG Paracorr for visual and imaging usage.

If you employ a Tunable Top (ATT-2125) on your custom Visual / Imaging System Adatper for visual usage, make sure your low-power eyepiece doesn't reveal the secondary shadow in the field of view. Keep exit pupils smaller than about 7.5mm to avoid this by using our Eyepiece Calculator (mobile site) to verify your exit pupil. For example, with a 16", f/3.5 scope (f/4.0 with Paracorr), your maximum field of view will be attained using our Tele Vue 21mm Ethos (1.3° at 78x) that produces an exit pupil of 5.2mm.  The spot size diagram for this focal length at the field stop edge is under the Airy Disc radius.

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