Following the Test Report in the October issue of the Sky and Telescope, Simon Kidd of Welwyn in the United Kingdom has written to us (and to the magazine) pointing out an error in the article.

Simon Kidd writes:

The Dynamics of Dynamic Range

I enjoyed Sean Walker’s review of the Imaging Source DMK 21AF04.AS camera (October issue, page 36). But near the end he implied that a camera’s dynamic range - its ability to record detail in faint and bright areas of a scene at the same time - is determined by the number of bits used in digitally sampling the image.

Not so!

The number of bits (often 8 or 12) determines only the resolution of the sampling, that is, the number of gray levels between pitch black and pure white.

Dynamic range is determined principally by the well depth and readout noise of the camera’s pixels, both measured in numbers of electrons.

This misconception reminds me of the Spinal Tap guitarist who thought his amplifiers were of superior power because the controls went up to 11 rather than the usual 10!

Our thanks go out to Simon for taking the time to point this out.

We are delighted to announce that Caley Monk has just won one DMK 21AF04.AS.

Congratulations!

We have just sent him an e-mail confirming his win and asking him to send us his full postal address, so that we can dispatch his prize as soon as possible!

Judging by his e-mail address, I would guess that he is based in the UK.

The Astronomy Cameras Competition is a monthly event, meaning that you can now enter again for this month’s prize. Even if you participated in last month’s competition, you may enter again this month. This month, we are again offering one of our most popular astronomy cameras - DMK 21AF04.AS.

Entering the competition is completely free of charge.

Enter the competition now! Good luck!

UPDATED November 06, 2007: Caley’s prize was dispatched yesterday afternoon. It should be with him in the United Kingdom by Thursday this week.

UPDATED November 09, 2007: I just received the following message from Caley:
Hi Jonathan, I received the camera yesterday - thank you. Its great!!! Kind Regards, Caley