End Caps and Flanges

Flanges, Terminations and Protective Caps

This collection covers three distinct jobs: mounting a focuser to a tube, terminating a drawtube in a usable thread, and sealing an opening when the equipment is not in use.

• Telescope-specific mounting flanges: Machined plates matched to a particular tube's bolt pattern, which is what allows an aftermarket focuser to be fitted squarely.
• Drawtube end terminations: Convert a focuser's native output to a standard thread such as M48 or M68, giving you a clean starting point for an imaging train.
• SCT and rear-cell flanges: Adapt Schmidt-Cassegrain rear cells to threaded standards for focusers, reducers and cameras.
• Threaded dust caps: Seal a threaded port when a camera or eyepiece is removed, keeping the interior of the drawtube clean between sessions.
• Objective and aperture caps: Full-aperture covers, including sub-aperture stops used to reduce light for lunar viewing.
• Blanking plates: Cover unused ports on filter wheels, focusers and rear cells to prevent stray light entering the train.

Why Choose David Astro for End Caps and Flanges

These parts either fit exactly or do not work at all, so the value is in correct identification rather than selection.

• Model-specific identification: Tell us the telescope and focuser and we will name the flange, rather than asking you to match a bolt circle from a photograph.
• Squareness is critical: We advise on flanges that hold a focuser perpendicular to the optical axis, because tilt introduced here shows up as one-sided star elongation you cannot process out.
• Genuine manufacturer parts: Authorized dealer supply with full warranty and verified authenticity.
• Replacement caps for older gear: We can often source a lost cap for a discontinued telescope through dealer channels.

End Caps and Flanges in Canada: Frequently Asked Questions

How do I identify the flange my telescope needs?

By telescope make and model rather than by measurement, since bolt circles that look similar are often a few millimetres apart. Send us the model and the focuser you intend to fit and we will specify it.

Does a flange affect image quality?

Indirectly but significantly. A flange that holds the focuser slightly off-square tilts the whole imaging train, producing elongated stars on one side of the field regardless of how well the optics perform.

Are dust caps really necessary?

Yes. Dust on an interior surface is far harder to clean than dust on an objective, and moisture that condenses inside a sealed tube takes a long time to clear. Capping every open port between sessions is cheap insurance.

Do you stock these in Canada?

Yes, anything marked in stock is held in our Canadian warehouse.

Need a specific flange?

Send us your telescope and focuser model and we will identify the exact part. Canadian stock, fast domestic shipping.