TS-Optics Photon 203 f/4 OTA This PHOTON Newtonian combines a 203 mm (8") aperture with a 800 mm focal length at f/4. Its parabolic primary mirror and fast optical geometry support deep-sky imaging and visual astronomy.
Manufacturer model: TS-Optics Photon 203 f/4 OTA · Specifications checked against manufacturer data on 2026-11-04
This PHOTON Newtonian combines a 203 mm (8") aperture with a 800 mm focal length at f/4. Its parabolic primary mirror and fast optical geometry support deep-sky imaging and visual astronomy.
Optics and illumination
The manufacturer specifies 94% enhanced mirror reflectivity with a protective quartz layer. Secondary-mirror size and illuminated-field figures are specific to this aperture; the table distinguishes fully illuminated field from partial illumination where TS publishes both.
Focusing and tube
The metal tube is fitted with a 2" Monorail focuser, dual speed, adapter to 1.25" and compression rings. Use the published dimensions and assembled-weight configuration when selecting a mount; cameras and other added equipment contribute further load.
Imaging configuration
A suitable coma corrector is optional for wide-field imaging. Native focuser backfocus is available mechanical travel/spacing, not automatically the sensor-spacing requirement of a chosen corrector. Keep primary and secondary collimation aligned for the installed camera train.
Additional specifications
100 illuminated field
25 mm - ideal for APS-C format sensors with suitable coma corrector
90 illuminated field
38 mm - thus suitable also for larger sensors (flats recommended)
Limiting magnitude visually
13.3 mag
Dimensions of the tube
Length 730 mm, diameter 230 mm
57997
Data sheet
Aperture
203 mm (8")
Focal length
800 mm
Focal ratio
f/4
Focuser
2" Monorail focuser, dual speed, adapter to 1.25" and compression rings
Manufacturer listed equipment
TS Photon 8" f/4 Newtonian Tube rings 2" extension tube 35 mm for visual observing Dust cover for the front opening Primary mirror fan with battery holder 8x50 finder with quick release Vixen/EQ5 style dovetail bar - length 335 mm
Manufacturer part number
TPM8F4
Model
TS-Optics Photon 203 f/4 OTA
Primary mirror
Parabolic primary mirror of BK7 with 94% reflection and protective quartz layer
Resolution
0.58 arc seconds
Secondary mirror
70 mm minor axis with 94% enhanced reflection and protective quartz layer
Support surface on the bottom of the tube rings
Flat support surface with an M6 thread
Support surface on the top of the tube rings
Flat support surface with a 1/4? internal thread (tripod socket)
Tube material
Steel
Tube weight
8.4 kg with tube rings and finder
Specific References
MPN
TPM8F4
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TS-Optics Photon 203 f/4 OTA This PHOTON Newtonian combines a 203 mm (8") aperture with a 800 mm focal length at f/4. Its parabolic primary mirror and fast optical geometry support deep-sky imaging and visual astronomy.
Manufacturer model: TS-Optics Photon 203 f/4 OTA · Specifications checked against manufacturer data on 2026-11-04
