In daily astronomical shooting, the Back focus will have an influence. Astronomical photographers are often frustrated by the change of Back focus due to various reasons such as refraction of filters or when using some products with sensitive Back focus. To solve this problem, ASKAR launched the Back focus adjuster, (providing the adjustment range from 16mm-20mm), which can be adjusted ± 2mm of the Back focus. We offer two specifications for the Back focus adjuster, the camera side adapter M54 and M48, which are convenient for users to choose from. The M54 Back focus adjuster's front telescope interface is female thread M54x0.75 and the rear camera interface is male thread M54x0.75, the overall thickness is 18mm and offers ± 2mm adjustment range. The M48 Back focus adjuster's front telescope interface is female thread M54x0.75 and the rear camera interface is male thread M48x0.75, the overall thickness is 18mm and offers ± 2mm adjustment range. The Back focus adjuster is CNC machined. Each unit is a 0.05mm precision adjustment, the surface is printed with a scale for easy adjustment and to save the position. There are two holes for fixing screws, which make the adjuster easy to use with different products. By rotating the Back focus adjuster, it can be adjusted between ±2mm to match the Back focus requirement, and to solve the various imaging problem caused by the Back focus. Users just need to choose according to their product's rear adapter. Product Size Diagram M54/M48 Back focus Adjuster Installation
