The Baader 2" Maxbright Diagonal can be attached to your SCT telescope in a semi-permanent fashion. However, attaching the diagonal directly on to the SCT's rear 2" 24 TPI male thread is bound to result in an odd and inconvenient orientation of the diagonal for virtually all telescopes when the diagonal is fully screwed on. However, this problem can easily be solved with the use of Baader's SCT Lock Ring.
How to use the Baader SCT Lock Ring:
1. Screw this lock ring completely on to the male SCT thread on the rear of your scope by turning it clockwise.
2. Screw on the diagonal clockwise as far as it will go. In this position, the diagonal will come to rest at an odd orientation.
3. Unscrew it slightly in the counter-clockwise direction (by less than one full turn) till it points correctly upwards.
4. Finally, turn the SCT Lock Ring in the counter-clockwise direction by the same amount till it stops turning against the diagonal and will not turn anymore. At this point, the diagonal is locked in against the lock ring in the correct orientation!