Love my Denk's but with multiple set-ups, newt, Tak and Cat, power switch was kinda out. Tak users with 2.7 focusers can go straight in the back for no mag viewing, it is great, but adding barlow's required screwing extensions on,(I hate screwing and unscrewing, extensions or OCA's), Siebert optics made me this cool little 3X OCA you just pop in, minimal back focus, now I have ultimate low power and pop in high power. It works great, the GRS was nice at 200.
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