ZWO Seestar S50 Pro
Illustration — drawn from the published dimensions. Not a photograph.
What it is
The Seestar S50 Pro is a smart telescope: the optics, the camera, the mount and the computer are one sealed 2.8 kg unit. You give it a target and it finds it, tracks it, and stacks a long series of short exposures into a single deeper image — the work that used to take a pier, a laptop and a cold night.
Its 50 mm aperture and 260 mm focal length give a wide, fast view. That makes it well suited to large, faint things — nebulae and nearby galaxies — and poorly suited to small, bright ones. Its dual-band filter is the reason it can work from a site with any light pollution at all.
Specifications
As published by ZWO for the S50 Pro. The plain S50 and the S30 Pro are different instruments with different figures; nothing here is taken from either.
Optics
- Aperture
- 50 mm (telephoto)
- How wide the light-collecting opening is. Wider gathers more light, which is what lets a faint galaxy show up at all.
- Focal length
- 260 mm telephoto · 6 mm wide-angle
- Roughly how much it magnifies. A short focal length gives a wide view of a large nebula rather than a close-up of a small one.
- Focal ratio
- f/5.2 telephoto · f/1.75 wide-angle
- Focal length divided by aperture. A smaller number collects light faster, so exposures can be shorter.
- Optical design
- Four-element apochromatic lens including ED glass
- A lens design that brings different colours to the same focus, so bright stars do not come out fringed with purple.
- Equivalent focal length
- 880 mm telephoto · 35 mm wide-angle
Camera
- Telephoto sensor
- OmniVision OS08B10 · 1/1.2 in · 2.9 μm pixels · 8.3 MP
- The chip that records the image. Larger pixels collect more light each, which helps in the dark.
- Wide-angle sensor
- Sony IMX586 · 1/2 in · 1.6 μm pixels · 8.3 MP
- Resolution
- 2160 × 3840 pixels
- Field of view
- 2.8° telephoto · 63° wide-angle (portrait)
- How much sky fits in one frame. The full Moon is about half a degree across, so 2.8° is a generous view around it.
- Filters
- UV/IR-cut on both lenses · dual-band OIII 30 nm / Hα 20 nm on the telephoto
- The dual-band filter passes only the two colours most nebulae glow in, which cuts through light pollution.
Mount and control
- Mount
- Alt-azimuth, with equatorial mode supported
- Alt-azimuth swings left–right and up–down. Equatorial mode tilts the whole mount to follow the sky’s rotation on one axis, which allows longer exposures.
- Slew rate
- 1× to 1440×
- Mounting thread
- 3/8-16 inch
- Automation
- Plan Mode with multi-target continuous shooting; mechanical home position
- The instrument can work through a list of targets on its own overnight, which is what makes remote operation practical.
Storage, power and connectivity
- Storage
- 128 GB eMMC (about 100 GB usable)
- Connectivity
- Wi-Fi 2.4 / 5 GHz · Bluetooth · USB Type-C
- Battery
- 10,000 mAh, up to 9 hours
- Charging
- USB Type-C, 5 V/3 A or 12 V/3 A
- Weight
- 2.8 kg (main unit)
- Folded size
- 140 × 149 × 268 mm
What it is good at
- Large emission nebulae, where the dual-band filter does its best work.
- Nearby galaxies and galaxy groups that fit a 2.8° field.
- Open and globular clusters.
- The Moon, which is bright enough that a dark sky is not needed.
What it is not good at
- Planetary detail. At 260 mm a planet is a few pixels across — this is a wide-field instrument, and no smart telescope of this size resolves cloud belts or polar caps the way a long-focus telescope does.
- Small, faint galaxies, which need more aperture than 50 mm.
- Anything requiring very long single exposures on an unguided alt-azimuth mount.
Solar observing is not offered
ZWO supplies a magnetic solar filter with this instrument. Mary Astronomy does not offer solar targets and will not accept a plan for one: the policy layer refuses them before any hardware is consulted, whatever filter is fitted.