I use the SPC900NC/27 web cam and, like others, find it an excellent tool for planet imaging.

The Philip web site has full specs on both, and a quick comparo shows the 1300 has higher pixel density and faster USB 2.0 connetivity, etc. The 900 has lower light requirements (<1 vs <5), and Philips makes a point of this feature. I do not know the advantages of the CMO based chip on the 1300 vs the CCD based chip on the 900.

Victor.