M42

Hi all,

The last time I posted a deviation was in September 2003. It was an image I threw up in Photoshop.

Here, today, 2.5 years later, I'm posting the real thing.

This is a composite of approximately 100 images stacked manually in Photoshop CS2. I could have used IRIS, Registax, or the other usual suspects, but decided to become a glutton for punishment.

As I didn't have an equatorial wedge for my Meade 8" LX90 LNT (F/10) at the time, I ended up with quite a lot of field rotation as the images were 15 second exposures with a five second gap until the next exposure (thank you DSLR Focus). You can imagine, that after 100 x 20 seconds, I had quite a lot of field rotation. So, the glutton for punishment part here was manually de-rotating each and every image in Photoshop. It took a lot of time, but was worth it.

The featured image has been processed in varying stages. Firstly, each image was dark frame calibrated via subtraction of a master dark. They were then stacked in Photoshop; the first image remains at 100% opacity, the next image is stacked at 50% opacity, the next at 33% opacity and so on (inverse relationship). The aim of this, of course, is to increase the signal-to-noise ratio and as a result, lower the noise.

Photoshop functions of particular use were exposure, brightness and contrast, hue and saturation, levels, curves and channel mixing. Various layer masks were utilised in order to bring out the detail in the central Trapezium area. Most times you see photographs of this nebula with the Trapezium area saturated and as a result washing out any detail in the central area. No noise reduction was carried out in this image; it would be rather pointless as I shot these images in the smallest resolution mode of my Canon EOS-350D (Digital Rebel XT). Next time I attempt this beauty, I shall shoot in large RAW mode.

So, finally, the particular details once again:

Telescope: Meade 8" LX90 LNT (F/10) Schmidt-Cassegrain astronomical telescope
Mount: Altitude/Azimuth
Camera: Canon EOS-350D (Digital Rebel XT) at prime focus (F/10)
Exposures: unguided, 15 seconds each with five second gaps until next exposure
Location: my backyard in western Sydney
Date: 10th January, 2006
Software: DSLR Focus (for focusing metrics and image capture) and Adobe Photoshop (processing/post-processing)

Regards,
H