The Eagle Nebula – Part 3 of 3


narrow-band 673nm filter (Click to Enlarge)

With processing the image of the Eagle Nebula, I start out with the grey scale looking image of the nebula taken in 3 different exposures. Depending on what you are targeting, you may actually have more exposures to chose from. For example, you might want to use a filter looking at infra-red or there may be a filter which handles the luminiscence of the object.

In the case of the Eagle Nebula, I am using only the 3 base exposures of red,blue and green. However, personally I would have liked an exposure for luminiscence in this case as it would have given me more options in the result of this image.

The picture above is the narrow-band 673nm filter ([SII] which as mentioned in the previous posts is red. Now I use this exposure as the starting point and use it to make sure that the other exposures are perfectly aligned with this one. Let us say the camera had moved or was taken with a delay and all 3 pictures were not perfectly aligned with each other. It would make the resulting Eagle Nebula picture a very messy picture.

So I use the exposure as shown above to help align the remaining exposures with each other.

Red and Green Exposures Merged (Click to Enlarge)

The next step is to add a little more color …. and here I look at the green exposure which you would have seen in the last post. Using Photoshop, I go through a procedure which will allow me to merge together both the red and the green exposures. As you can see in the picture on the left, now we are starting to get somewhere.

A fairly interesting picture and much better than the one in complete red at the top of the post. But there is something missing.

As mentioned in the last post, the blue exposure when compared to the red and green exposures looked a little drab. But this is where the blue exposure comes in to importance. The final step of producing the completed picture of the Eagle Nebula is to take the combined exposures of red and green and merge in with them the blue exposure.

Once you do that and have all 3 exposures merged together, then you come up with an even better looking picture. The result is shown at the end of the post.

One can spend hours working on just one picture as you can modify the different settings for each of the 3 exposures and come out with completely different looking pictures which look better as you go along. It really comes down to your artistic talents or your opinion of how the Eagle Nebula should look like. And depending on your settings, you may bring out more details in a part of the object that you are interested in. For example, you may want to highlight the gas clouds a little more .

As mentioned a few days ago in the first post of this series of posts, I will be demonstrating this technique on February 23rd, 2010 at the Northern Sydney Astronomical Society and invite any of you who are interested to attend the New Astronomers Group session. The main topic of the night will demonstatrate  how you can come up with your own professional looking astro-photography….. all without a telescope or camera of your own.

Details can be found at

During this week I will show a few more results of this processing technique.

Final Result Eagle Nebula

~ by sydneystargazers on February 15, 2010.

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