2. Is this bracket similar to the discontinued excellent Celestron 51149A bracket?
The MQR do the same as the Celestron bracket, but are of a different, more sturdy design.
Baader MQR (Multipurpose Quick Release) Bracket
CNC milled, with a sturdy dovetail, comes with a Baader Standard Base to mount it to all telescope tubes with diameters from 100 – 400 mm! The dovetail guarantees a perfectly constant adjustment of the optical axis. You'll surely find cheaper finder brackets, but none that can be removed so easily and that sits as it did before when you put it back- with a precision of up to a hundredth of a millimetre. The mechanical design is so solid that you also can use it as a removable handle for your telescope.
The dovetail fits – even without Baader Standard Base – into almost all finder bases, which are part of the focusers of many telescopes from Celestron, Synta, Vixen and more.
Both the MQR III and the MQR IV finder brackets can be dismantled into their individual parts and configured for other purposes. If for example a finderscope shall be placed very close to the telescope, you can simply remove the 70 mm high center piece and attach the dovetail directly to the finder base. To do this, you need the two M5x12-screws which are included in the scope of supply. If you want to use one of the common red-dot-finders like our Skysurfer III and V, you can remove the upper mounting plate and insert any red dot finder (with Weaver gun rail 11mm standard) into the V-channel at the upper end of the center piece.
The guidescope rings can also be removed from the base plate.