History of Long-Range Photography in Astronomy

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Correlated Double Sampling

Virtually all serious imaging systems employ this technique in various manners.

Correlated double sampling yields the best representation of the true charge associated with each pixel.

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Other Factors

Weight

Electronics Modules

Surface mount technology

Stay away from cameras with bulky external control boxes

Number of camera connections

Camera start-up procedures

Peltier Cooler

Starlight Xpress – just plug in he camera

SBIG – Controlled by software

Cooling Fans

Can induce vibrations

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Other Factors

Is the software user friendly

Drop-down menus

Dialog boxes

Keyboard shortcuts

Learning curve of the camera

Large instruction manuals

Using your camera should be an enjoyable experience

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Basic Imaging Concepts

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More “Buzz” Words

Bias Frames

Light Boxes

T-Shirt Flats

Flat Fields

Dark Frames

Raw Imagines

Calibrated Image

Signal vs. Noise

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Bias Frames

Astronomers make bias frames to capture the bias level.

Bias frames represent noise levels that occur on a CCD detector when placed in total darkness with an integration time of zero.

These frames represent the minimum noise generated by the camera electronics as pixel values are read from the CCD array.

This bias level can fluctuate because of things that happen every time the CCD is read out or because extraneous signals are added to the bias level. These un-patterned events can originate in power supplies, nearby electronics, motors, and radio-frequency interference from computers and monitors.

The noise in these bias frames is extremely low; so many CCD imagers do not bother to apply them to their images.

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Why take Bias Frames?

They give you a history of your cameras operational functionally.

Noise level changes

Interference

They are needed if you intend to do astrometry, photometry or to get the best results from your images.

NOTE: SBIG cameras add a 100-unit pedestal to each Bias, Dark, Flat-

Field, and Light frame. This pedestal value is subtracted by

CCDSoft during the data reduction process. This will need to be

subtracted manually with other IP programs.

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