Unmodded Canon 5D III, with 600mm f/4 L II lens. A big part of getting this kind of result is the software I use to process: PixInsight. Powerful, powerful tool.Hi,
I use an Atlas EQ-G tracking mount, along with a specific set of rings and dovetails to hold the lens onto the mount. I'll post some photos of my current setup in another thread, so those of you interested in getting started can get an idea of where I'm at, and what options there are at a lower cost.
Your sky must be very good to get that result...
Actually, it's pretty bad. :\ I'm on the border between a red and orange zone. Sometimes the skies are really bad, sometimes they are fairly decent and I can just barely, faintly see the milky way.
I just integrate like a nutcase.
And I think the brightness of the Pleiades stars brightens the nearby dust enough for me to pick it up. Man, it would be so amazing to image this under blue zone skies.
By the way, you said you previously use the Astronomik CLS filter, how to you solve the colour shift issue?? Last time I use the CLS filter as my area light pollution is very serious, but had big problem solving the colour shift issue...
The CLS doesn't necessarily cause a color shift. It blocks certain frequencies of light, so they simply are not in the data to start with. Color in astrophotography is a rather fluid thing. There are all kinds of light sources out there, not just stars, but various kinds of gasses, each of which emit light in different very narrow bands.
I use the CLS when I'm imaging nebula. Most nebula, gaseous emission nebula, emit light in several primary narrow bands, depending on the composition of the nebular clouds. There is Hydrogen, Oxygen, Sulfur, Nitrogen, and a few other gasses. Hydrogen and Oxygen are the most prominent, Hydrogen by far the most prevalent in the skies overall. When you use a CLS filter, or an IDAS filter, or something like that, your blocking out the frequency bands that include light pollution (primarily, sodium and mercury vapor lamps), and passing the blue and red ranges that include H-alpha, H-beta, O-II O-III, N-II & S-II. That lets you pick up the nebula, and when your imaging nebula, that's what you want.
I imaged the Pleiades without the filter, because the nebula around those stars is a reflection nebula. It's not emitting light, it's reflecting light. The CLS filter would have blocked out a good chunk of that light in the greens, which would have resulted in a "color shift". I was able to get away with not using a filter thanks to some of the advanced processing features of PixInsight. It has background extraction capabilities, which I can use to identify any excess light introduced by light pollution, and remove it. It can be extremely difficult to do, especially on an image like my Pleiades...you have to make sure you sample true "background sky", and not any nebula, otherwise that part of the nebula will be factored into the extraction and likely eliminated. It took me a couple days of fiddling to finally extract the background sky well enough for the dust to show...and I'm still not happy with it.