Side by Side

Carrying Two Instruments Properly

A side-by-side arrangement moves mass away from the mount's axes in a direction that a standard dovetail does not, which changes the balance problem.

• Lateral balance adjustment: The plate must allow each instrument to slide sideways so the combined centre of mass sits over the declination axis.
• Plate thickness and stiffness: Deflection scales sharply with thickness, and a plate carrying two telescopes at their extremes is under considerable bending load.
• Total payload: Both instruments, both cameras, all cables and the plate itself count against the mount's rating, which is easy to underestimate.
• Moment arm: Keeping the two instruments as close together as possible reduces the rotational inertia and improves how the mount responds to corrections.
• Dovetail standard: Plates come in Vixen and Losmandy patterns on both the mount side and the instrument side, and these do not have to match.
• Differential flexure: If one instrument guides for the other, flexure between them corrupts the correction, which is why stiffness matters more here than anywhere else.

Why Choose David Astro for Side-by-Side Plates

Two instruments on one mount is a rigidity problem before it is a payload problem.

• Stiffness prioritized: We recommend plates substantially built for your payload, since a flexing plate makes guiding worse than a single instrument would be.
• Total payload calculated: We add both instruments, cameras, cables and the plate itself, then check against your mount's imaging margin.
• Guiding arrangement advised: If one instrument guides the other, we will discuss whether an off-axis guider on the main scope is the safer approach.
• Authorized dealer: Genuine hardware with manufacturer warranty, in Canadian stock.
• Ships from Canada: No duties or brokerage fees for Canadian buyers.

Side-by-Side Plates in Canada — Frequently Asked Questions

Can my mount carry two telescopes?

Only if the combined weight sits within its imaging payload margin, which is roughly 50 to 60% of the visual rating. The plate itself is not light and must be included.

How do I balance a side-by-side setup?

Slide the instruments laterally until the combined centre of mass sits over the declination axis, then balance in right ascension with counterweights. Both axes need attention.

Can one telescope guide the other?

It can, but any flexure between them corrupts the guiding. For long focal length work, an off-axis guider on the imaging telescope is considerably more reliable.

How far apart should the instruments be?

As close as they physically fit. Wider spacing increases rotational inertia and the bending load on the plate, both of which degrade guiding response.

Running two instruments?

Tell us both payloads and your mount and we will recommend a plate. Authorized dealer, Canadian stock.