In stock & shipping from Oregon. New: Wanderer Astro Filter Cube baseplate for existing 90 mm cages →
In stock & shipping from Oregon. New: Wanderer Astro Filter Cube baseplate for existing 90 mm cages →
At f/2 your focus tolerance is about 11 microns. The Photon Cage gives you 4-corner tilt, independent backfocus and a removable filter slider in one device. It mounts to your camera, not the scope, so it works on any telescope.
Optical path used. Replaces the 5 mm stock tilt plate on most cameras, with ample room to tilt and adjust backfocus.
Independent tilt adjusters that map to the corners Hocus Focus reports.
Fine-pitch threads, about 0.21 mm per turn, for micron-level control.
M54×0.75, 62 mm 6-bolt EFW and ASG 5-bolt slider patterns as standard.
Your critical focus zone shrinks with the square of the focal ratio. At f/2 it’s roughly twelve times shallower than at f/7. If the sensor is tilted even a few microns, one side of the frame drifts out of focus and the stars there turn to commas.
Fast optics deliver spectacular data in a fraction of the time, but only when the sensor is square to the light cone and sits at the correct backfocus. That’s the job the Photon Cage was built to do.
Total critical focus zone, 4.88·λ·N² at 550 nm. A human hair is about 70 µm thick.
Tilt and spacing errors look different. The Photon Cage fixes both, independently.
We build every unit and have tested every design. Not sure which fits your train? Tell us your setup →
The original manual cage: 4-corner tilt, independent backfocus and an optional removable filter slider, for 78 mm and 90 mm cameras. It mounts to your camera, so it works on any telescope: RASAs, SCTs, Epsilons, refractors, Newtonians and more.
Four motors adjust tilt and backfocus from your PC or NINA, so remote rigs stay in focus.
Cage plus M68 PRO slider for unmounted 50×50 filters, rotator and RASA 11 camera mount.
Cage, custom RASA 8 filter slider and camera mount for 90 mm cameras.
We built the Photon Cage because no single device did 4-corner tilt, removable filters and independent backfocus together. It mounts to your camera and moves with it, so your settings stay put between sessions.
Each corner has its own 120 TPI adjuster and lock screw. The adjusters map one-to-one onto the corner readout in NINA Hocus Focus or ASTAP.
1/32 turn ≈ 2.9 µm at a full-frame cornerA push-pull outer ring moves the sensor in and out without disturbing your tilt. Dial in the spacing your corrector actually wants.
≈ 5 mm of travel
Swap filters in seconds with magnetic sliders for 2″ mounted filters or the PRO M68 system for unmounted 50×50 filters at f/2.2.
Standard 11 mm · PRO 11 mm + 4 mm M68M54 female threads, the 62 mm 6-bolt ZWO/QHY filter wheel pattern and the ASG 5-bolt slider pattern all come standard. Baseplates are available in 42, 48 and 54 mm.
3 mm baseplate · M54×0.75The sensor corners sit closer to the pivot than the adjusters do, so every turn is scaled down at the sensor.
120 TPI adjusters on a 100 mm circle · 211.7 µm per turn
| Turn | At adjuster | Corner vs center | Corner to corner |
|---|---|---|---|
| 1 turn | 211.7 µm | 91.6 µm | 183.2 µm |
| 1/2 | 105.8 µm | 45.8 µm | 91.6 µm |
| 1/4 | 52.9 µm | 22.9 µm | 45.8 µm |
| 1/8 | 26.5 µm | 11.4 µm | 22.9 µm |
| 1/16 | 13.2 µm | 5.7 µm | 11.4 µm |
| 1/32 | 6.6 µm | 2.9 µm | 5.7 µm |
A 1/32 turn moves a full-frame corner about 2.9 µm.
Four motors, 1.8 µm full steps on a 110 mm circle
| Motor | At adjuster | Corner vs center | Corner to corner |
|---|---|---|---|
| 1 step | 1.8 µm | 0.71 µm | 1.4 µm |
| 2 steps | 3.6 µm | 1.4 µm | 2.8 µm |
| 5 steps | 9.0 µm | 3.5 µm | 7.1 µm |
| 10 steps | 18.0 µm | 7.1 µm | 14.2 µm |
All four motors together move backfocus 1.8 µm per step.
Four motors adjust tilt and backfocus from the ASG Windows app or the NINA plugin. Remote and observatory imagers never have to touch a hex key.
“What used to take 20 minutes you can now do remotely in about 2 minutes.”Typical result in our domes: tilt down to about 1–2 µm.
It allowed me to finally get round stars to the edge of my 6200mm sensor.
I am able to tune tilt and backfocus to a few microns from scratch in 30 minutes… Josh and team provide excellent support and are very responsive.
It’s so much less hassle than fiddling with manual tilt adjustments.
Astro PM is astrophotography project management software for Windows. Plan targets, track every exposure by filter, grade your subs and push the night’s plan straight to N.I.N.A.
Windows 10/11 (x64 & ARM) · 3 PCs per licence · Free Android & iOS companion apps
Practical, tested write-ups on tilt, backfocus and fast-optics imaging, plus the processing workflow behind our gallery.
Collimation, then backfocus, then tilt, in that order, with NINA Hocus Focus, ASTAP and our three-part video series.
M54 vs M68 trains, filters and where spacing changes the math.
We build all our units, and every design is tested in our dual-dome observatory on RASAs, refractors, Newtonians, RCs and more.
Send us your gear. We set it up, tune and test it under real skies, then crate and ship it anywhere.
CAD, CNC, 3D printing and observatory software for your one-off parts and projects.
Tell us your scope and camera and we’ll recommend the exact cage, baseplate and slider for your optical train.
