2" Adapter to use SCT accessories - for 2.7" drawtubes (ADA204)

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If you have thread-on accessories for an SCT and own one of our refractors, a Ritchey-Chretien with an Astro-Physics focuser or built your scope with our 2.7" focuser, you will appreciate this item. This adapter threads into our drawtube and has SCT threads on the accessory side.

For owners of larger Meade SCT's with the 3.25" rear cell, simply thread this adapter into our ADASCTLM27 or ADASCTLC27 and you no longer need your Meade or Celestron 2" visual back.

The ADA204 is also popular with owners of Finger Lakes Instrumentation CCD cameras. It can be used with several configurations of Astro-Physics CCD Adapters and 2.7" Extensions to reach proper backfocus distances for the particular combination of components you are using.

This adapter has a net spacing distance of 0.3" (7.6 mm).

The following adapters can be used to step down from the 2.7” thread of the appropriate extension to the threads of your camera or filter wheel:

          ADA27-42,  step down to 42 mm threads, net spacing distance: 0.2” (5.1 mm)

          ADA27-48,  step down to 48 mm threads, net spacing distance: 0.2” (5.1 mm)

          ADA27-54, step down to 54mm threads net spacing distance: 0.2” (5.1 mm)

          ADA27-68,  step down to 68 mm threads, net spacing distance: 0.2" (5.1 mm)

          ADA27-2156,  step down to 2.156” threads, net spacing distance: 0.2” (5.1 mm)       

          ADA204, step down to 2” SCT threads, net spacing distance: 0.3” (7.3 mm)

Our 2.7” Extensions (EXT27-) and Spacer Rings can be combined with the above adapters to help you meet optical spacing distance requirements. Each has a different net spacing distance. In May 2021, we changed our part # system so that you can determine what you need more easily.

          EXT27-15.2, (former part # A3505), net spacing distance: 15.2mm

          EXT27-19.1, (former part # A3503-A), net spacing distance: 19.1mm

          EXT27-22.9, (former part # A3506), net spacing distance: 22.9mm

          EXT27-27.0,  new in 2021, net spacing distance: 27.0mm    

          EXT27-31.8, (former part # A3504-A), net spacing distance: 31.8mm

          EXT27-44.5, (former part # A3502-A), net spacing distance: 44.5mm

          EXT27-64.8, (former part # A1008-A), net spacing distance: 64.8mm

          SRSET-27, set of three 1mm thick spacer rings. 

It may still be necessary to use a custom adapter to complete the connection, but using combinations of the above adapters will greatly reduce cost by eliminating the need for multiple and costly custom adapters.

Diagram and Instructions