Astro-Physics A3505 2.7inch Thread-on Extension 15.2 mm spacing

2.7" Thread-On Extensions for Astro-Physics Focusers and
Accessories (A3502-A, A3503-A, A3504-A, A3505, A3506, A1008-A)

This series of extensions is designed to utilize the robust 2.7" Astro-Physics thread size, while providing a variety of lengths for use with barlows, telecompressors and camera systems. These extensions can be used in various combinations to achieve the perfect spacing distance for your system.

These extensions thread directly into the drawtube of the 2.7" focuser and into the 4" to 2.7" Adapter (A1024), or its shorter version (A1024-A), which fit the 4" focuser. They feature knife-edge baffles and an interior that is painted flat black to eliminate internal reflections.  Accessories with 2" nosepieces can easily be attached by using the ADA2003A, ADA20132, ADA200 (discontinued), or ADA2013 (discontinued) 2" Adapters with Thumbscrews.

Thread-on Extension with the following applications:

• Achieve proper spacing requirements for your CCD camera system - it can be used in combination with other extensions and with the CCD Adapters for our Prime Focus Field Flatteners.
• Use a combination of the extensions with the 0.75x Telecompressor (27TVPH) to obtain precise telecompression spacing. Reference the Exploded Diagram for placement and see Telecompressor Compression and Coverage for detailed compression calculations.
• Use with the BARADV or BPFFC and the A3511 Internal T-thread System for the ultimate in a rigid, non-flexing setup for high magnification planetary / lunar / solar imaging. See: A3511 System Chart.

The re-design of these extensions include a lip on the outer diameter to prevent the extension from being racked inside the focuser housing.

A3505
2.7" Thread-on Extension
This extension has a net spacing distance of 0.60" (15.2 mm).

A3503-A
2.7" Thread-on Extension
This extension has a net spacing distance of 0.75" (19.1 mm).

A3506
2.7" Thread-on Extension
This extension has a net spacing distance of 0.90" (22.9 mm). 

A3504-A
2.7" Thread-on Extension
This extension has a net spacing distance of 1.25" (31.8 mm).

A3502-A
2.7" Thread-on Extension
This extension has a net spacing distance of 1.75" (44.5 mm). 

A1008-A
2.7" Thread-on Extension
This extension is provided with Astro-Physics refractors that have the 2.7" focuser. It is for use when observing straight-through without a diagonal or when imaging without a prime focus field flattener. [Note that this extension may be too long except for special applications.]
This extension has a net spacing distance of 2.55" (64.8 mm).