This is my first LRGB image blended with narrowband data. In the RGB data, the cluster and stars are quite visible and properly colored. But the nebula is almost invisible to an RGB image. Most of the data on the nebula came from the hydrogen-alpha filter.

The hydrogen-alpha filter is a narrowband light filter that blocks all other light and only allows hydrogen-alpha emmissions past it to the camera sensor.

It's ideal for imaging nebulas like the Bubble Nebula that emit h-alpha light. Because the filter blocks so much other light, the incoming h-alpha image is pretty dim. To compensate for this, a typical h-alpha frame is usually ten to twenty minutes long. A comparable RGB frame would only take two to five minutes.

The h-alpha data on this image was actually a bit short. The individual h-alpha frames are only eight minutes long. Later I found that ten to fifteen minutes worked better with this scope and camera combination. This is also the first usable image where I used the field flattener on the NP101is. It did a very good job of correcting oddly shape stars in the corners and the edges.