Understanding Image Stacking for Astrophotography
Image stacking is the process of combing two images so that the overall detail is more intense. This effect is most often seen in astrophotography. Astrophotography involves photography items in the sky, including the moon, start clusters and galaxies. Basically, since these images move so slowly, you can take a variety of images of the same item, and then merge them. This makes the final image a lot more eye-popping.
Taking Your Photographs
The toughest part of this project is going to be taking good photographs. The objects that you are filming are very far away so you will need a good telephoto lens. Next, you need to find a place that does not have any light pollution as this will cause your images to be too light.
Now, set your camera up on a tripod, which will eliminate any blurriness. Since you will be zooming into the object, you want the camera to be as steady as possible. Zooming into objects increases the chances of images being blurry. Finally, take as many pictures as possible. You probably want to take individual pictures as opposed to doing time-lapse as you will be merging these images.
Picking a Photo Editing Program
To do this effect, you can use any type of advanced editing program that you already own. Adobe Photoshop will do an adequate job. There is also a free program by the name of DeepSkyStacker, which is almost solely dedicated to stacking images. You should go with the program that you are most comfortable with.
If, however, you do not currently have a photo editor, then DeepSkyStacker will be a good learning tool for you. You just need to download the program, and then use the very intuitive user face. Beginners can quickly learn this program.
Start off by selecting your best image. This will function as your aligning image for the rest of the images. Next, open up your next image, and make it a new layer. Open up the Difference Function. Apply it to the two images, and this will show you the errors in the alignment.
Fixing the Alignment
Select one of the layers, preferably the second layer since the first one is your reference point. Slide the image over until the difference image turns black. You may have to do more than slide the image. If you cannot get the difference image to turn completely black, you should try rotating the image a bit.
While the goal is get the difference image completely black, this may not be possible. Just get it as close as you can.
Changing the Transparency
Now, you want to change the second layer’s transparency to 50 percent. If not, it will completely overwhelm the first image.
You should now repeat the previous two steps for all succeeding layers. The only difference is that you will continue to decrease the transparency for all other layers. The formula for this is N(Layer)=100/N%.
Once you have all your layers added, you simply need to finish tweaking your image.