Losmandy GM8G Equatorial Mount with Gemini 2 GOTO and LW Tripod

Product Overview

The Losmandy GM8G is the lightest German equatorial in Losmandy's GOTO line, supplied with the Gemini 2 GOTO servo system, a counterweight shaft, one 7 lb counterweight and the folding lightweight tripod. Losmandy publishes an instrument capacity of 40 lb for imaging and 55 lb for visual use, on a 21 lb equatorial head. Both axes carry 2.812-inch, 180-tooth 7075 aluminium worm gears running a spring-loaded worm, and uncorrected tracking is rated at ±5 arcseconds or better, with corrected periodic error often at ±2.5 arcseconds or better.

Who It's For

This is a good match if you want Losmandy mechanics and Gemini 2 GOTO in the lightest package they offer, and your imaging train fits inside 40 lb. A 21 lb head is the lightest in the line, which makes this the GM-series mount that travels most easily to a dark site. It suits an observer imaging with a refractor up to about 4 inches plus camera and guider, or doing visual work with something larger inside the 55 lb visual rating.

Key Features & Design

• 40 lb imaging / 55 lb visual instrument capacity on a 21 lb equatorial head — the lightest head in the GOTO range.
• 2.812-inch, 180-tooth 7075 aluminium worm gears on both axes.
• Spring-loaded worm for adjustment-free tracking — the spring maintains mesh, so there is nothing to set.
• Dual-supported, ball-bearing-housed ground high-precision brass worm.
• ±5 arcsecond or better uncorrected tracking, with corrected periodic error often at ±2.5 arcseconds or better.
• Built-in permanent periodic error correction.
• Gemini 2 GOTO: DC servo motor based computerised positioning, accuracy published at up to half an arcminute.
• Folding lightweight tripod, 15 lb, with adjustable legs and 25" between leg centres when retracted but spread.
• Supports altitudes from 0° to 68°, and runs on 12–18 V DC.

Mechanical Design

The GM8G runs the same 2.812-inch, 180-tooth gear on both axes. That is a smaller gear than the G11 family uses, and it is the main reason the head comes in at 21 lb rather than 33 — but the worm driving it is the same dual-supported, ball-bearing-housed ground brass component found across the line, and the published tracking figures are the same ±5 arcsecond uncorrected and ±2.5 arcsecond corrected as the larger mounts.

Both axes use a spring-loaded worm, so worm mesh is maintained by the spring rather than adjusted by the owner. Periodic error correction is stored permanently in the mount rather than re-trained each session.

Recommended Uses

Deep-sky imaging with a small to mid-size refractor, camera and guider inside the 40 lb imaging rating. Travel and dark-sky trips, where a 21 lb head and a 15 lb tripod are the lightest Losmandy combination. Visual observing up to the 55 lb rating. Remote or automated sessions through Gemini 2. A first Losmandy mount, with the option to step up to the GM811G or G11G later.

Compatibility and Accessory Notes

Saddle: the GM8 saddle plate accepts both Losmandy D-series and Vixen-style V-series dovetail plates, and also fits Takahashi mounts.

Counterweights: one 7 lb weight is included, with 7, 11 and 21 lb sizes available separately.

Tripod: supplied on the folding lightweight tripod. The LW tripod spreader is an add-on for it, and the MA tripod/pier adapter fits this mount for pier use.

Axis upgrades: Losmandy sells axes separately — the G11 RA axis is listed for use with a GM8 DEC if you later want G11 RA gearing.

Polar alignment: the iPolar electronic polar scope or the optical polar scope with illuminator, which Losmandy lists for the GM8, G-9 and G-11 mounts.

Good to Know Before You Order

40 lb is the imaging figure to plan against. The 55 lb visual rating is the looser one; a long exposure asks more of the mount than an eyepiece does.

Both axes use the smaller 2.812-inch gear. If RA tracking quality with a heavier train is the priority, the GM811G puts a 5.625-inch G11 gear on RA for a 26 lb head.

The lightweight tripod does not include a spreader — it is available as an add-on accessory.

Tracking figures are Losmandy's published specifications. Balance, polar alignment and seeing all bear on the result.

Frequently Asked Questions

Is it difficult to set up?

No, and this is the easiest Losmandy to handle physically. Tripod, head, shaft and weight, balance, polar align. The spring-loaded worm means no mesh adjustment, and Gemini 2 does the pointing from its hand controller.

What can I image with on 40 lb?

That figure has to cover the telescope, rings, plate, camera, filter wheel, guider and cabling. Send us your intended train and we will add it up with you before you order.

How does it compare with the GM811G?

The GM811G puts a 5.625-inch, 360-tooth G11 gear on RA where the GM8G uses 2.812-inch, 180-tooth on both axes, and its published imaging capacity rises from 40 lb to 50 lb. The head goes from 21 lb to 26 lb.

Can I upgrade the axes later?

Yes — Losmandy lists the G11 RA axis for use with a GM8 DEC, without a motor, so you can keep your existing servo.

Does it need a computer?

No. Gemini 2 runs as a self-contained GOTO system from its hand controller.

Bottom Line

The lightest Losmandy GOTO mount: 40 lb imaging capacity on a 21 lb head, spring-loaded 2.812-inch worm gears, permanent periodic error correction and Gemini 2, on the 15 lb folding lightweight tripod.