This is a clamping adapter that allows you to provide a male T2 thread on the end of any suitabley sized eyepiece that does not feature a thread. The adapter features an internal compression clamp that is rubber coated to prevent scratching of the eyepiece barrel.
The internal depth of the D42 clamping adapter is 20mm with an initial 5mm gap before the start of the compression ring. The internal diameter allows it to be fitted on to eyepiece barrels up to 42mm in diameter. Included with the clamping adapter are some self adhesive rubber strips in 1,2 and 3mm thickness. These can be inserted inside the clamp to pack it out allowing its use with barrel sizes down to as little as 30mm diameter.
This clamp allows you to use any suitabley sized eyepiece for digiscope or projection photography, night vision eyepieces and also optical testing on artificial stars.
We recommend this particular adapter for Night Vision applications using the Televue 55mm Plossl. For this application the upper part of the 55mm eyepiece that is for adjustment of eye relief should be unscrewed completely. This reveals a smaller section that the D42 clamp fits perfectly.