Starfish Camera Competitive Comparison

Competitor #4 - 'CamD' Specifications

The fourth camera used in the Starfish competitive camera shootout is a camera that we designated 'CamD'. This camera was designed as an purpose built guide camera by a manufacturer of mid to high end astro-imaging cameras. It is a departure from the CCD type of image sensors being used by the manufacturer in their imaging camera line using a Kodak CMOS image sensor.

The design concept for the camera is great. It has one of the smaller enclosures and is one of the lightest of the guide cameras tested. It also has a case design that is long and narrow with the image sensor at one end. This might prove very convenient in tight optical setups. In actual practice, however, this camera falls short in terms of image sensitivity and readout noise. The images produced by this camera are so poor in fact, that it is hard to believe it can be used on anything but the brightest of stars. Refer to the example test images. The Kodak image sensor used has a QE specification of 27% which is less than half of that of the sensor used in the Starfish camera and less than a third of that of CamE. The read noise from the camera was also 5x greater than that of the Starfish. It was this high read noise that made it hard to even see most guide stars dimmer than about magnitude 6-7 even with a fast f/5 guide scope.

The camera's manufacturer recommends that exposures of 2s to 5s are optimal for the camera. However, at least with the software drivers we tested with, you had to fiddle with camera settings (ADC major, minor offset) each time you changed the exposure time making imaging very tedious.

The camera also had a problem with the levels of the guide relay outputs. In our tests, it was the only camera that would not fully drive the relay outputs to the ground reference point. It always had a minimum level of around 0.8V. We did not actually try to guide with CamD but are concerned that some telescope mounts would not reliably register guide commands because of this offset.