As I was going through my ep's I found a dark green moon filter that came with a Circle T Celestron Er. 20mm I bought. I don't use filters so I put the filter away. I looked at the Er. 20mm and saw black ridges on the top before. I thought they were there to help with stray light.
Turns out those are threads on top, and the moon filter screws right on. I am curious if all the Circle T Celestron Er. 20mm's are threaded on top for filters.
Gary
Turns out those are threads on top, and the moon filter screws right on. I am curious if all the Circle T Celestron Er. 20mm's are threaded on top for filters.
Gary
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