DFK 21AU04.AS vs SPC900NC: how much better do pictures get

[michael.h.f.wilkinson]

I have been pondering getting a DFK camera or similar to replace the SPC900NC that I have. Am I right in getting the impression that the DFK series gets better results than the SPC900NC or will the difference be minimal?

[Trull]

I think you'll benefit from lower noise and hence be able to take longer exposures. The IS cams are nicely engineered - pays yer money...

[pete_l]

The sensor used in the DFK is the ICX098BQ, which is the same one used in Philips' PCVC740, which has been around since 2004.

The spec. for the DFK's says they will send you uncompressed (i.e. lossless) video. I don't believe the Philips webcams can do this at rates above 5 FPS.

So with a DFK you'll be able to fill your disk up much quicker.

[riklaunim]

Old DBK/DFK21 are quicker (up to 30 FPS free of artifacts) and use no compression. Newer DBK/DFK21AU618 use a newer CCD which is much more sensitive allowing either lower exposures or lower gain recordings.

For low altitude targets like Saturn every color camera will be limited by atmospheric dispersion (either a corrector or workarounds required).

[jgs001]

It's not the same thing... but I noticed a big improvement when I got my QHY5v (CMOS sensor guide camera) over my SPC900. The 5v is mono and USB2.

[rwg]

The sensor used in the DFK is the ICX098BQ, which is the same one used in Philips' PCVC740, which has been around since 2004.

The spec. for the DFK's says they will send you uncompressed (i.e. lossless) video. I don't believe the Philips webcams can do this at rates above 5 FPS.

So with a DFK you'll be able to fill your disk up much quicker.

Even at 5fps the SPC900 has to compress the data significantly...

640 pixels width * 480 pixels height * 5 frames per second * 8 bits per colour * 3 colours = 36864000 bits per second

USB1.1 supports up to 12 megabits per second, so only a third of the bandwidth required for uncompressed 5fps.

If the SPC900 sent raw data to the PC and then debayered on the PC it could work at very low compression, but experience of the device in 'raw' mode indicates that it doesn't work that way.

Robin