StellaLyra · 12-inch f/8 M-LRS Ritchey–Chrétien
A 300mm RC for a dedicated long-focus imaging rig.
The StellaLyra 12-inch M-LRS combines a 300mm aperture with a 2400mm, f/8 optical system in a solid metal tube. It is a substantial optical assembly for an experienced imager planning detailed work on targets that suit a narrow field.
Choose it as part of a dedicated system with the mounting capacity, handling arrangements and camera equipment already considered. Its potential is best assessed against your actual targets and observing conditions.
See what the focal length means for your camera.
A longer focal length gives the same target more room on the sensor and narrows the surrounding field. That is useful for some projects, but it can turn a large nebula into a mosaic.
As a planning example, a 23.5 × 15.7mm sensor at the native focal length covers approximately 33.7 × 22.5 arcminutes. This is a geometric field-of-view estimate, not a claim that every part of that sensor will be fully corrected or illuminated.
Check your actual camera dimensions and target framing before buying. Pixel size and local seeing also matter: a very fine image scale makes tracking and focus errors easier to see without necessarily recording more resolved detail.
An RC optical system for a planned imaging train.
The Ritchey–Chrétien design corrects coma, while the primary stays fixed during focusing. This provides a useful starting point for a dedicated camera setup.
Coma correction does not guarantee a flat image plane across every sensor. Select any flattener or reducer for the RC design, the intended camera and the required connections. A Newtonian coma corrector is not a substitute simply because its barrel fits.
Choose the mount for the whole working assembly.
The published tube weight is 24kg. Add the camera, filters, guiding equipment, correction optics and attached accessories before assessing the working load. Check saddle fit, counterweight requirements and the complete system’s balance as well as the mount’s payload specification.
A larger tube changes the practicalities of installation as well as tracking. Decide how it will be supported and secured during fitting and removal, and whether a permanent installation would better suit your use. Do not assume an existing mount is suitable because it can physically carry the bare tube; consider the complete imaging load and intended exposure lengths.
Plan the installation before the first clear night.
Upper and lower Losmandy-style rails provide mounting interfaces, and the telescope includes a cooling-fan system.
Check saddle engagement before releasing the tube. Fit the complete imaging train before balancing, and make sure cables remain free throughout the intended pointing range. Leave clearance for the rear equipment near a tripod or pier.
Allow cooling time before judging star shape. Use the interval for balance, cable and guiding checks, then take short test exposures before beginning a long sequence.
Fine focus and a secure camera connection.
The rotatable 3.25-inch dual-speed linear-bearing Crayford focuser provides coarse and fine manual control.
Support the camera while attaching it, secure every joint and check the train at different pointing angles. Keep cable weight off the focuser. If you intend to automate focus, establish the correct motor bracket and coupling for the supplied focuser before ordering.
Record a useful starting position, but recheck focus as conditions change. The apparent size of the focuser alone does not specify a safe camera payload or corrected sensor coverage.
Get extension and sensor spacing right.
The supplied rings let you position the focuser to suit the assembled camera train. Use the combination that brings the system to focus with adjustment remaining, rather than fitting every ring automatically.
A reducer or flattener introduces a separate requirement: its specified distance to the camera sensor. Count the sensor recess, adapters and filter equipment in that measurement. Establish those optical distances first, then confirm that the complete arrangement reaches focus.
Check the field before committing to a night’s imaging.
Inspect short exposures at the centre and corners. If star shapes differ across the image, investigate focus, tracking, camera tilt, spacing and collimation methodically.
Use an alignment procedure appropriate to an RC, with a star-field check as the final assessment. Change one factor at a time and keep notes. This makes it easier to identify the cause of a problem and return to a known arrangement after transport or an accessory change.
Included and purchased separately
| Supplied with the OTA | Choose separately |
|---|---|
| Metal-tube RC optical assembly and focuser | Tracking mount and tripod or pier |
| Upper and lower rails; cooling fans | Camera, filters, guiding and power equipment |
| Two 25mm and one 50mm extension rings | Camera adapters and any RC-compatible correction optics |
| 2-inch holder and 1.25-inch adapter | Diagonal and eyepieces for visual use |
| Finder base; primary and secondary dust covers | Finder and transport protection if needed |
Dimensions for installation
| Published tube length | 864mm |
|---|---|
| Published outside diameter | 361mm |
Allow additional room for the rear imaging train, cables and access to the controls. Tube dimensions alone do not establish the clearance needed for a complete mounted system.
Before ordering
Is this ready to take photographs on its own?
No. It is an optical tube assembly. Budget for the mount, camera, adapters, guiding and any correction optics as a complete system. The mount in the photographs is not supplied.
Will a larger camera need a flattener?
Assess the specific sensor and your expectations for the image corners. RC optics correct coma, but field curvature and mechanical alignment still matter. Confirm the proposed combination before buying correction optics or adapters.
Can I also use it visually?
With suitable separately purchased accessories and a mount, visual observing is possible. Check the diagonal, eyepiece and extension arrangement reaches focus. Choose this telescope principally around the imaging work you intend to do.
Availability reflects supplier stock and may change. Contact Dark Clear Skies to confirm dispatch timing if you need the telescope for a particular date.