With Milky Way season starting up, many of us will be spending a considerable amount of time out there away from the city lights. Part of the fun of these outings is including the landscapes we visit in our shots of the night sky. It also presents a few challenges, like getting those foregrounds sharp.
…what you may not know is just how easy it is with an Irix lens.
Focus stacking is a great method for achieving the maximum depth of field throughout a landscape shot. That’s probably not news to most of our readers, but what you may not know is just how easy it is with an Irix lens. That’s what I’m going to show you over the next few paragraphs.
Why Do You Need To?
Now, I know that some of you are wondering why you’d need to bracket the focus with an ultrawide-angle lens. After all, the depth of field is already immense at these focal lengths, right? Besides, Irix lenses have that cool hyperfocal scale that lets you set the focus for the maximum DoF for your aperture setting in a snap.
You’re right, of course. In the photo above, the photographer combined a single long exposure of the foreground with a shot of the Milky Way. Even with the aperture on the Irix 15mm wide open, the depth of field is sufficient.
On the other hand, it’s worth trying focus bracketing and stacking to see the difference, especially when you have objects in the near foreground that you want sharp. It’s a technique that I think everyone ought to try at least once. Even better, with the depth of field scale on your Irix lens, it’s just, plain simple!
How to Bracket Your Focus
You don’t have to guess and you don’t have to measure.
Alright, so I sort of gave away the secret in that last paragraph. Having a depth of field scale is what makes this work. You don’t have to worry about how many focus changes to make. You don’t have to guess and you don’t have to measure. All you have to do is use the scale.
- Use Aperture Priority or Manual exposure mode so that your aperture setting remains constant.
- Use a remote shutter release or your camera’s shutter delay timer to avoid vibrations.
- Save your images as RAW files.
Step 1: Set your camera up on a stable tripod and compose your shot.
Step 2: Select your aperture setting. We’ll use f/8 on the Irix 11mm f/4 for this example.
Step 3: Set the focus to infinity. (Easy as pie – just feel the click!)
Step 4: Shoot.
Step 5: Note where the distance scale lines up with the number 8 on the left side of the DoF scale. This is your near limit:
In the photo above, it’s about 1.8meters. (It doesn’t matter whether you read meters or feet – just notice where the limit falls.)
Step 6: Move the focusing ring so the near limit lines up with the number 8 on the right side of the DoF scale. This is your new far limit.
Step 7: Shoot.
Step 8: Note the new near limit and move the focus ring to make it the new far limit:
Repeat steps 6 – 8 until you reach the stop on the lens, then take the final shot.
Remember – it’s not important to read the distance scale accurately. It’s only important to move the right spot to the far limit each time. When in doubt, turn the focusing ring just slightly to the left, so your new area of sharpness overlaps the previous one.
When you’re done, you should have a set of images with bracketed areas of sharpness stretching from infinity to the closest focus distance of the lens.
How easy was that?
This method works for any aperture setting that’s indicated on the DoF scale. Just be sure to use the numbers that correspond to the aperture you’re using. As you’d expect, the wider your aperture, the more shots you’ll need to take to cover the entire focus range.
I’ll go ahead and mention that there’s one drawback with the Irix 15mm f/2.4: The depth of field scale only goes down to f/8. There simply isn’t enough room on the lens barrel for the other aperture settings. If you need to bracket your focus at wider apertures, you’ll have to do a little guesswork when moving the focus ring on the 15mm. In these cases, a greater number exposures is always better than fewer.
Stacking the Images
The final step in the process is to blend the bracketed images. There are several applications you can use, but I’ll cover the procedure in Photoshop here. I’ll also note that not everyone will proceed exactly the same way. This is a very basic overview of the process, so feel free to adapt it to suit your workflow.
If your images are saved as RAW files (and they should be), start by making your overall edits like lens correction, etc. You can sync the edits in Lightroom or Adobe Camera RAW. Once you’ve got them looking the way you like, you can save them as TIFF files, or open the RAW files directly in Photoshop as outlined below.
Now you’re ready to load the images into a stack and blend them:
- Open Photoshop and select File/Scripts/Load Files into Stack.
- Click the Browse button and select all the files you want to use, then click OK.
- When the script completes, select all the layers.
- Select Edit/Auto-Blend Layers.
- Check the Stack Images button.
- Check the Seamless Tones and Colors box.
- Click OK.
When the process completes, you should have a mask on each of your original layers and a merged layer of the result on top. If you’re happy with the results, you can save the new layer in whatever format you intend to use. If not, you can close the file and start again or use the history to go back and try checking/unchecking options in the process.
This should work well for most focus-bracketed landscape images. Do keep in mind that major changes between exposures, such as wind, flashes of light, etc. can create problems. There are a number of good tutorials out there about manual blending, which is beyond the scope of this article.
How It Works with Night Sky Shots
In case you’re wondering how this is going to help you with those Milky Way shots, it’s like this:
If you shoot a single, long exposure image of the stars that includes the foreground and the results are sharp enough to satisfy you, then this probably won’t help you.
If you’d like to explore some other methods for night landscapes and astrophotography, this is one of a few techniques you should try. For instance, there’s a way to use stacking to reduce noise and sharpen up your Milky Way shots.
A tutorial on image stacking will be coming up very soon, with an emphasis on astrophotography. I touched on it in an earlier tutorial on shooting time lapses and star trails in one session, but the next one will be about increasing the detail in your star shots, rather than creating motion.
Stacking night sky images with the foreground in the shots can be problematic because of the rotation of the earth. To get the best results and a super-sharp landscape to go with your super-sharp Milky Way, you can process your sky stack, then add in your focus stacked landscape with a mask. You can even take your focus stacked foreground shots at different settings than your sky. You can even get really creative with light painting and other fun stuff with those multiple exposures.
Summing it all Up
Focus stacking isn’t everyone’s cup of tea, particularly many landscape photographers. Many would rather simply take advantage of the extreme depth of field wide-angle lenses like the Irix 15mm f/2.4 and 11mm f/4.
It also isn’t ideal for every situation. For those who’d like to expand their arsenal of techniques, however, focus bracketing and blending may be worth taking the time to learn. It’s a solid method of creating maximum sharpness throughout a landscape photo.
This technique is especially useful in situations where standard focusing can be difficult, such as during the evening or nighttime hours. It’s a great way to ensure sharp landscapes to combine with your wide field astrophotography shots.
Best of all, with a depth of field scale like the ones on Irix lenses, it’s incredibly easy to bracket your focus. Give it a try!