Many times it is better to increase the ISO to make sure you have information in the shadow areas of your Milky Way foreground blend images. I use two techniques to tame the noise in my images. One for the sky and another for the foreground.
Milky Way capture
Let’s start with the capture of Milky Way images. Think of the image in two pieces (which is why this article is split into two parts). You need one exposure for the stars which is relatively short to avoid stars trailing. If there is no light pollution or moonlight to illuminate the foreground that will fall into silhouette. While that can be fine for the occasional photo having a recognizable foreground sets one Milky Way photo from another.
Stars focus
Stars need to be in focus. You will have people suggest that you set your lens to the infinity mark. While this can get you close, please only consider it as a starting point. Variations in lens construction and ambient temperature can change where the actual infinity focus is in your lens. You can zoom in with manual focus and rack the lens back and forth a tiny bit at a time until there is the smallest circle if your camera has live view. Make a photo. Review the resulting image zooming in as far as possible. If you see a magenta fringing when you zoom in your focus is too far away. Conversely, a green fringe means you are focused too close.
Focus Peaking
Many cameras today have a feature brought over from the video world. It’s called Focus Peaking. Focus Peaking when activated shows a sharp color where the focus is. You can choose the color when activating this feature. Usually red is the chosen color as bright as possible. Settings in various cameras will be found in your menu system. Look in your camera manual for proper activation.
Starry Sky Autofocus
If you are working with an Olympus or OM System camera you can ignore all of the advice above. Newer models have Starry Sky Autofocus. This mode is activated if the camera indicates you are in focus. You are done. Activate using the AEL/AFL button and you’ll see the message Starry Sky Autofocus is running. The camera then begins to look to lock onto the stars. If there’s not a bright enough star in your field of view, or you don’t have enough focus points activated, you may not get a lock. Check your focus points or point your camera to a brighter star or planet. After achieving focus you can recompose. Here’s an article I wrote about pairing Starry Sky Autofocus and Live Composite which only adds new light to the image capture leaving the shadow areas. Handy for catching star trails.
I use back-button-focus (BBF) with my OM-1 so that activating the shutter doesn’t look for focus again. I also use BBF for my wildlife photography for the same reason. BBF can take a little getting used to, but once you’ve made it muscle memory you won’t go back!
Cameras that have the Starry Sky Autofocus are the OM-1 and OM-1 Mark II, OM-5, & OM-D E-M1 Mark III (available used).
Noise handling
Once you have the proper capture set for your camera make multiple exposures. I recommend between eight and twenty and will often use ten images for noise reduction. I’m on a MAC so I purchased Starry Landscape Stacker for aligning and kicking down the noise automatically. Starry Landscape Stacker goes for about $39.99. You can also align the stars using Adobe Photoshop but it’s time intensive. Starry Landscape Stacker is well worth the money. Here’s an article on using Starry Landscape Stacker.
PC users have a similar program that is no charge in Sequator.
Next time, we’ll describe the process of using Photoshop to handle foreground noise.
As always put your questions or thoughts in the comments below.
Yours in Creative Photography,
Bob