Fisheye & Allsky Lenses

Selecting an appropriate optical lens requires matching the lens projection circle diameter to the physical sensor dimensions of your camera.

If the lens image circle is smaller than the sensor, the full circular fisheye horizon is visible with black margins surrounding the circle. If the image circle is larger than the sensor, the view will be cropped to a rectangular field of view.

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Lens Specifications & Sensor Pairing Matrix

Lens	Field of View (FoV)	Focal Length	Focal Ratio	Aperture	Image Circle Diameter	Ideal Sensor Format & Cameras
ZWO 2.1mm	$150^\circ$	2.1mm	f/2.0	1.05mm	6.7mm	1/3" & 1/2.8" (ZWO ASI120, ASI224, ASI290, ASI462)
ZWO 2.5mm	$170^\circ$	2.5mm	f/1.2	2.08mm	6.7mm	1/3" & 1/2.8" (ASI224MC, ASI462MC, ASI662MC)
Arecont 1.55mm	$180^\circ$	1.55mm	f/2.0	0.78mm	4.8mm	1/2.3" (Raspberry Pi HQ / IMX477, IMX378)
StarDot 1.55mm	$185^\circ$	1.55mm	f/1.5	1.03mm	4.8mm	1/2.3" (Raspberry Pi HQ / IMX477)
M12 1.7mm	$180^\circ$	1.7mm	f/2.0	0.85mm	5.6mm	1/2" – 1/1.8" (ASI178, ASI678MC, ASI676MC)
M12 1.8mm	$180^\circ$	1.8mm	f/2.0	0.90mm	6.9mm	1/1.8" (Sony IMX178, IMX678, IMX676)
Meike 3.5mm f/2.8	$220^\circ$	3.5mm	f/2.8	1.25mm	12.5mm	1" & Micro Four Thirds (MFT) (ASI183, ASI294, ASI533)
Camera Module 3 Wide	$120^\circ$	2.75mm	f/2.2	1.25mm	Full sensor	Raspberry Pi Camera Module 3 Wide (IMX708)
Camera Module 3 Standard	$75^\circ$	4.74mm	f/1.8	2.63mm	Full sensor	Raspberry Pi Camera Module 3 (IMX708)
Hawkeye 64MP AF	$84^\circ$	5.1mm	f/1.8	2.83mm	Full sensor	Arducam 64MP Hawkeye

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Mount Considerations

• M12 Mount (S-Mount): The standard thread for embedded camera boards and security lenses ($M12 \times 0.5$). Requires an M12-to-CS or M12-to-C adapter ring when used with standard astronomy cameras.
• CS-Mount: Back-focus distance of 12.526 mm. Used natively by the Raspberry Pi HQ Camera and many industrial CMOS housings.
• C-Mount: Back-focus distance of 17.526 mm (5 mm deeper than CS-mount). C-mount lenses attach to CS cameras using a 5 mm spacer ring.