FYI.
the Sinarback 23 is discontinued since years, but was one of the most fantastic back, even with its "only" 6 MPx sensor. It existed in 2 version: the SB 23 L (Light = only 1-shot), and the SB 23 HR (High Resolution = 1-, 4- and 16-shot modes).
It is still in use in many places, sometimes in combination with the Sinar Macroscan adapter, which allows to produce automatic stitches (the back is positioned automatically by very precise motor drives) in all directions with automatic stitching software integrated in Sinar Captureshop, leading to files to up to 450 MB in 16 bit.
This back was only available with a Fiber Optic interface with a PCI card, making it difficult to use it on current Macs since the technology changed to PCI Express in the G5 (
www.magma.com. does however have a soltution). But G5s with PCI Extrem can be used.
From time to time one can find such a SB 23 on eBay, and I can only recommend to take, if it happens.
I hope this helps.
Best regards,
Thierry