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0.6 mm washer for Celestron RASA

Additional filter slider designed for Astrodevice filter drawers. Slider accepts standard 2″ threaded astrophotography filters.

The slider comes in two variants, differing minimally in size. The first variant works with drawers FD 900 M87 and FD 900 M42 and the second with drawers FD 860 M87 and FD 860 M42. Depending on which drawer you have, choose the appropriate slider variant.


When placed on the front of the telescope, this shim allows you to add 0.6 mm to the effective length of the optical path. This can prove particularly useful when adjusting backfocus or investigating the causes of optical distortion in an image.

This washer is also used on adapters with Front Tilting Mechanism, such as accessories for Canon or Sony cameras.

Thanks to its specially designed shape, the shim does not slip off the tube when attached. To use it, it is necessary to unscrew the glass window from the front of the telescope.

The base of the product are 3D printed elements made of PET-G CF filament (polyethylene terephthalate glycol-modified reinforced with carbon fiber).

Note: In the sensor tilt adjustment mode, so when working with the attached washer, the outer diameter of the 2″ filter housing must not exceed 50.7 mm.

For filter drawer model

FD 900 M87 or FD 900 M42, FD 860 M87 or FD 860 M42

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