提上来回答 器材+科普 问题

Fellow photographers asked a few questions concerning the equipment, etc at:

Andromeda

Here are the answers:

Camera: Apogee AP 42, 4MP, 1x1 sensor (used in 50% crop mode)

Lens: custom, approximately 6-7000mm f/8

The camera is black and white. To get a color photo, pictures were taken with red, blue and green filters, and later combined to produce the color photo.

The Andromeda galaxy is quite bright, and signal to noise ratio is quite good. But the Orion Nebula is quite dim.

There are additional steps for calibrating the camera (such as subtracting dark noise and pixel sensitivity). It takes about 4 hours for those 2 photos: 2 hours for camera calibrations, and 1 hour for each photo.

Note: Modern digital camera is much better than film. The saying is: one minute exposure with a modern digital camera produces a photo as good as 1 hour exposure with film.