Askar M54/M48 Adjustable Extension Tube 16–20 mm

Askar M54-to-M48 Backfocus Adjuster

The Askar M54-to-M48 Backfocus Adjuster provides continuously adjustable spacing between a telescope or corrector and the camera train. It has an M54×0.75 female telescope connection and an M48×0.75 male camera connection.

Adjustment range and scale

The nominal thickness is 18 mm, with ±2 mm adjustment for a 16–20 mm range. The printed scale is graduated in 0.05 mm increments so a spacing setting can be recorded and repeated. Rotating the body changes the effective separation.

Installation

The CNC-machined assembly has two fixing-screw holes. Use it as part of the total camera-spacing arrangement for the particular corrector, including other adapters and filters. The manufacturer also offers an M54-to-M54 version; this record describes the M54-to-M48 version.

Optical-train fit

Match both thread pitches and genders to the adjoining equipment. The 16–20 mm figure describes adjustable thickness, rather than a clear aperture or a two-axis dimension. Weight, load capacity and a verified clear-aperture value are not published in the checked manufacturer text and are not invented.

Askar manufacturer documentation

Compatibility notes

This record is the M54×0.75 female telescope to M48×0.75 male camera version, as identified in the existing store technical record and model title. The separately offered M54-to-M54 version is not substituted. Adjustment range is a range, not a 16 × 20 dimension.

Additional specifications