Dark Clear Skies M54M to M42M Back Focus Spacer – 2mm wide field telescope Calcium K-Line and Calcium H-Line

Calcium K-Line and Calcium H-Line in one dualband filter

while the extended drawer handle makes pulling the filter slider smooth and effortless

Black anodized finish

this adapter is commonly used in advanced astrophotography setups involving reducers

With a range of up to 1640 ft in open areas and multiple notification modes

Dark Clear Skies M54M to M42M Back Focus Spacer – 2mm wide field telescope Calcium K-Line and Calcium H-LineThe Dark Clear Skies M54M to M42M Fine Back Focus Spacer (2 mm) is a precision machined spacer designed for accurate fine adjustment of back focus distance in astrophotography imaging trains. Purpose & Use Many telescope reducers and field flatteners require very precise back focus spacing to deliver optimal star shapes and edge correction. Small spacing errors of just a few millimetres can noticeably affect image quality, particularly when using fast