Finderscope magnitude

Without use of any lens, Uranus at 5.7 and its current companion at magnitude 6.7 are easily visible in dark skies (Milky Way skies).

The  6x30 right finder cannot see the Ring Nebula at magnitude 9.5. I found the 6x30 can just see HIP110169 a small magnitude 7.9 star directly below Neptune in Aquarius. The star itself is 607 ly away. So I put the upper limit of the finder at 8. But (happiness expressed here) the 127mm Mak-Cassegrain can see up to 10.5 (my last test with the Mak was with M57 at magnitude 9.5) since it easily resolved TYC5810-701-1 at magnitude 10.56 -- one of 2 tiny stars to the left of Neptune and above HIP110169.

I'm going to see if I can see the 3 very faint magnitude 10 stars TYC6861-1787-1, TYC6861-2115-1 and TYC6848-2970-1 from Kaus Borealis to M28 (magnitude 10.5) with either my finder scope and the Mak Cassegrain.
TYC6861-2412-1 is exactly 10.0 and directly above Kaus Borealis and should be a good test for testing magnitude capability of both finder scope and Mak.