Monthly Archives November 2013

M33 – Pinwheel Galaxy

Subject: M33 - Triangulum (Pinwheel) Galaxy
Telescope: Celestron CPC 800 with f/6.3 reducer
Camera: Canon Rebel T1i
Technique: 55 approximately 30 second lights at 800 ISO. Total exposure time of 29 minutes 20 seconds. 8 darks. 50 biases.
Prime focus. Stacked with Deep Sky Stacker. Post-processing in Photoshop.

This image was a bit of a gamble for me. My previous stacks were of higher ISO lights in the range of 1600 to 6400 ISO. Because of the way higher ISO images are taken, they basically increase the gain of each pixel. This results in brighter images at the cost of more noise. For my particular camera, there is a threshold at about 800 ISO where any increase does not add to the amount of photons detected, but simply starts to blow out the image in order to make it brighter...

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