StellaLyra · 12-inch f/12 M-LRC Classical Cassegrain
A 304mm Cassegrain for detailed lunar and planetary work.
The StellaLyra 12-inch carbon-truss Classical Cassegrain combines a 304mm aperture with a 3648mm focal length at f/12. It is a substantial optical assembly for a dedicated observing or imaging system, particularly when your subjects benefit from a close view.
Plan the telescope, mount and rear accessories together. Its long focal length and physical size make installation, target acquisition and tracking important parts of the buying decision.
Check the framing before choosing the camera.
At this focal length, even a familiar camera can show a surprisingly small part of the sky. As a calculated example, a 23.5 × 15.7mm sensor covers approximately 22.1 × 14.8 arcminutes at the native focal length. Covering the whole lunar disc would require more than one frame in that example.
This is a geometric field-of-view estimate, not a promise of corrected or fully illuminated coverage. Use your actual sensor dimensions and intended targets when planning a setup. For planets or small lunar regions, tight framing can be useful; larger subjects may call for a mosaic or a different optical arrangement.
Build the installation around the complete load.
The published tube weight is 24kg. Upper and lower Losmandy-style rails provide mounting interfaces.
Include the camera or diagonal, eyepieces, guiding equipment, adapters and other attached accessories when assessing the working load. Check the mount saddle, counterweight requirements and balance range as part of the same decision.
Plan how the telescope will be supported while being fitted or removed. A permanent installation may suit your routine better than repeated transport, but either approach needs enough space to handle the complete assembly securely.
Leave room for the rear equipment.
The focuser, extensions and camera or diagonal project behind the optical assembly. Establish the actual configuration before checking clearance around a tripod, pier or observatory structure.
Balance with the intended equipment attached, then check the pointing range and cable routing. Avoid letting a cable become tight as the telescope moves, and keep connectors accessible for changes made in the dark.
An open structure needs a practical storage plan.
Carbon-fibre truss members connect the optical assemblies. The primary and secondary mirrors are quartz.
Protect exposed parts during storage and transport, and assess nearby lighting when deciding whether additional light control is needed. Anything fitted around the truss must remain clear of the optical path and moving equipment.
Allow the telescope time to approach outdoor conditions before evaluating fine detail. Tube construction does not remove the need to check focus, cooling and alignment during a demanding session.
Useful eyepiece magnifications.
Divide the telescope’s focal length by the eyepiece focal length to calculate magnification. Three examples at the native focal length are:
| Eyepiece focal length | Approximate magnification |
|---|---|
| 30mm | 122× |
| 20mm | 182× |
| 12mm | 304× |
Eyepieces are separate purchases. These figures help plan a set; they do not establish the useful upper power on a particular night. Start lower, centre the subject and increase magnification only while the image remains sharp and informative.
Fine focus with the primary mirror held stationary.
The 3.25-inch dual-speed linear-bearing Crayford focuser provides coarse and fine adjustment while the primary stays fixed.
Support a camera or diagonal while attaching it and check each connection before releasing its weight. Keep cable loads off the focuser and assess the complete train at the pointing angles you expect to use.
For motorised focus, confirm the motor bracket and coupling against the supplied focuser. Focuser diameter alone does not define a safe camera payload, and a saved focus position remains a starting point rather than a guarantee for every session.
Select extensions around the actual accessory train.
Two 25mm and one 50mm extension rings are supplied. Use the combination that positions the focuser appropriately for the diagonal or camera, with useful adjustment remaining.
A visual arrangement and a directly attached camera occupy different optical paths. Establish those connections first rather than automatically installing all three rings. If extra optical elements are introduced, check their spacing requirements separately and record the finished arrangement for repeatable setup.
Make short tests part of the imaging routine.
Practise target acquisition at the native focal length before adding a Barlow. An aligned finder and steady tracking help keep a small subject on the sensor while you refine focus and exposure.
Inspect short test captures before committing to longer sequences. Choose amplification around the camera’s pixel size and the seeing. Investigate soft images methodically: focus, thermal settling, atmospheric steadiness, tracking and collimation each need a different response.
The quoted illuminated field is 55mm across. That describes illumination, not a guaranteed flat, sharp field on every sensor. Check actual corner performance and the clear apertures of the complete accessory train when planning a large-camera setup.
Included and purchased separately
| Supplied with the OTA | Choose separately |
|---|---|
| Carbon-truss Classical Cassegrain and focuser | Suitable mount and tripod or pier |
| Upper and lower rails; finder base | Finder and any guiding equipment |
| 2-inch to 1.25-inch adapter | Diagonal and eyepieces for visual use |
| Two 25mm and one 50mm extension rings | Camera, connection adapters and any amplification optics |
Specifications at a glance
| Optical design / aperture | Classical Cassegrain / 304mm |
|---|---|
| Focal length / ratio | 3648mm / f/12 |
| Published length without focuser | 841mm |
| Additional length of supplied focuser | 133mm |
| Published tube weight | 24kg |
Before ordering
Does the price include a mount or observing accessories?
No. This is an optical tube assembly. Budget for a suitable mount, finder, diagonal and eyepieces or camera, plus the adapters required by the intended setup.
Is the open truss a reason to choose it for regular transport?
Assess the complete weight, size and installation process against your own circumstances. Plan protection for the exposed structure and support during fitting and removal before deciding how often you will move it.
Should I compare it with the 10-inch model?
Compare target framing, total mounting load and the space available for the working setup. The 10-inch carbon-truss Classical Cassegrain is a smaller alternative to include in that decision.
This listing currently has no stock available. Contact Dark Clear Skies for a confirmed availability update and dispatch estimate before planning delivery.