What is the primary purpose of the Baader 80mm M68 Extension Tube?
The primary purpose of the Baader 80mm M68 Extension Tube is to add exactly 80mm of fixed, rigid spacing to an imaging train while maintaining perfect optical alignment. It is designed to be part of a larger M68 threaded system to prevent flexure, which is critical for astrophotography and spectroscopy.
How does the Baader M68 Extension Tube prevent imaging train flexure?
It prevents flexure by replacing standard slip-fit or compression connections with a direct, large-diameter M68 threaded connection. This creates a solid, metal-on-metal lock between components, eliminating the possibility of tilt or sag that often occurs when heavy cameras or long accessories are attached to a telescope.
Is this 80mm M68 tube compatible with other thread systems like M48?
Not directly. This tube features M68 x 1mm threads on both ends. To connect it to a different thread standard like M48 or T-2, you would need a specific Baader M68 adapter. Baader offers a comprehensive system of adapters to step up or down between various thread sizes.
When would I choose the 80mm Baader M68 Extension Tube for my SCT setup with a telecentric system?
You would use the 80mm M68 tube in a Schmidt-Cassegrain Telescope (SCT) setup when your telecentric system or other correctors require a precise and rigid 80mm of back focus. For high-magnification solar or planetary imaging with a telecentric, maintaining rigidity is paramount to prevent image shift, making the M68 system an ideal choice over less stable connection methods.
Can I stack multiple Baader M68 Extension Tubes for longer distances?
Yes. The M68 system is designed to be modular. You can thread multiple Baader M68 extension tubes of different lengths together to achieve any required distance with exceptional rigidity. For example, combining this 80mm tube with a 40mm tube would give you a solid 120mm extension.
How does the Baader 80mm M68 Extension Tube help when imaging faint objects like the Cygnus Loop (NGC 6992)?
For faint, extended objects like the Cygnus Loop, maximizing contrast is key. The Baader 80mm M68 tube's interior is treated with a matte black, anti-reflection finish. This acts as a baffle, trapping stray light from bright stars or local light pollution that might enter the optical tube, ensuring a darker background and allowing the faint nebulosity to stand out more clearly in your final image.
