Friday, November 21, 2008

Last One!

Just one more picture to show from Tuesday. It needs more work (read: needs more exposure!), but thought I would show it anyway. A couple weeks ago someone on an astrophoto list showed an incredible shot of Taurus near the Pleiades (will show it if I can get close to his effort). What is interesting to me is that, for an area far from the Milky Way center, there is an abundance of dark clouds. To me, these clouds of dust and unilluminated gas are fun to hunt down, visible only because they block the light of more distant clouds of stars. Some of them are readily visible through a telescope when they lie in front of bright Milky Way star clouds. The dark clouds in this exposure (over-stretched a bit to show them better) I was not aware of... This effort is a stack of 18 minutes total exposure with an 85mm lens stopped down to F/4. I need to go a little wider to still keep the Pleiades in the shot, and I'd also catch the California Nebula just off the field to the north. So will likely drop the focal length to 50mm next time with a couple HOURS of exposure!

What is also interesting, while shooting this one stopped down a little, is that the 6-bladed iris gives a pretty diffraction effect around the brighter stars of the cluster. Sometimes called the 7 Sisters, the Pleiades (known in Japan as Subaru!) has hundreds of stars, but with good vision and a reasonable sky, you can see about 7 of them, rising as a small cloud in the east in the early evening this time of year. More later as I collect more photons!


Andrew Cooper said...

I would call the lens a keeper, fairly nice! Looks like some gradient across the image, light pollution from Tucson? May try removing the gradient, several software tools like MaxIm offer a gradient removal function, very useful in wide field work.

Dean said...

Hi Andrew-
Not sure which of the images you were referring to - by the end of the Cygnus sequence, parts of it were getting close to airglow above horizon. The Taurus shot also had a little Tucson, but also Gegenshien was near the Pleiades!