Sky Rover Optics 0.8x Reducer for 155GPS (Sky Rover Optics, SKU: 25688) is a dedicated focal reducer designed for astrophotography with the Sky Rover 155GPS telescope. It reduces the instrument’s focal length from 1240 mm to 992 mm and changes the focal ratio from f/8 to f/6.4, providing a wider field of view and increasing the amount of light reaching the sensor per unit of time. The three-element optical system with ED glass produces a 55 mm image circle, allowing the use of full-frame and selected medium-format sensors.

Key features

• design developed and optimized specifically for the Sky Rover 155GPS telescope
• 0.8× reduction factor, resulting 992 mm focal length and f/6.4 focal ratio
• optical system consisting of three lenses in three groups, including an ED glass element
• design optimized for even field illumination and point-like star rendering
• 55 mm image circle suitable for full-frame and selected medium-format sensors
• standard 55 mm backfocus measured from the M54 interface surface
• precise backfocus adjustment using PVC spacer rings
• factory-installed spacers with a total thickness of 1 mm and two additional 0.5 mm spacers
• M92 interface on the telescope side and M92 × 1 and M54 × 0.75 threads on the camera side
• male M54 × 0.75 thread facilitating a short optical connection to the camera
• front and rear protective covers made of aluminium alloy

Set contents

• Sky Rover Optics 0.8x Reducer for 155GPS
• two additional 0.5 mm PVC spacer rings
• aluminium front protective cover
• aluminium rear protective cover

Technical specifications

• manufacturer: Sky Rover Optics
• manufacturer’s product name: 0.8x Specialist Reducer for 155GPS
• SKU: 25688
• type: dedicated focal reducer for astrophotography
• compatible telescope: Sky Rover 155GPS
• reduction factor: 0.8×
• telescope focal length without the reducer: 1240 mm
• telescope focal length with the reducer: 992 mm
• telescope focal ratio without the reducer: f/8
• telescope focal ratio with the reducer: f/6.4
• optical design: 3 lenses in 3 groups
• special glass: ED
• image-circle diameter: 55 mm
• supported sensor format: full frame and selected medium-format sensors fitting within the 55 mm image circle
• telescope-side interface: M92
• camera-side threads: M92 × 1 and M54 × 0.75
• M54 × 0.75 thread type: male
• backfocus: 55 mm
• backfocus measurement point: M54 interface surface
• backfocus adjustment: by adding or removing spacer rings
• factory-installed spacers: 2 × 0.5 mm, 1 mm in total
• additional spacers included: 2 × 0.5 mm
• dimensions: 78 × 116 mm
• front and rear cover material: aluminium alloy
• telescope installation method: after removing the rear 3.7" adapter
• recommended DSLR connection: direct M54–T2 adapter, reducing the risk of exceeding the required backfocus

The combination of a 992 mm focal length, f/6.4 focal ratio and 55 mm image circle allows the Sky Rover 155GPS telescope to be configured for imaging larger objects with large-format sensors.