Apogee's Alta Cameras: U Series (USB2) versus E Series (Ethernet 100Base-T)
The E Series cameras connect directly to a local network or to a host computer using TCP/IP. They digitize to 16 bits. In the case of the E2V CCDs, this is at 700 kpixels/sec; in the case of the Kodak CCDs, this is at 1 MHz . First the complete image is digitized into camera head memory, and then transferred to the host computer. The TCP/IP transfer rate is 200 kpixels/sec. (So an E2V 1K x 1K for example requires 1.5 seconds to be digitized into the head, and another 5 seconds for transfer to the host computer.) In contrast, the U Series cameras have dual digitization, 12 and 16 bit. The E2Vs still digitize at 700 kpixels in 16 bit mode, and 2 MHz in 12 bit mode. The Kodaks digitize to 16 bits at 1 MHz, and from 5 to 10 MHz in 12 bit mode, depending on the specific CCD. (See the individual data sheets.) The 12 bit mode is intended primarily as a focus mode. In contrast to the E Series cameras, digitization and transfer to the host computer are the same step. So an E2V 1K x 1K transfers to the host in 1.5 seconds in 16 bit mode, for example.

If the reason for considering an E Series camera is the cable length restrictions of USB2, there are USB1 and USB2 extender solutions available. Our cameras are USB2, but they automatically adapt to USB1, at the lower USB1 speeds (which is 500 kpixels/sec, still much faster than the E Series considering the E Series two-step readout process). There are USB1 extenders, both using Cat5 cable or fiber--for up to 100m. For USB2, there are extenders for up to 50m, for example, the Icron Ranger 140, as well as fiber extenders to 10 kilometers: Apogee Accessories