I still remember the first time I watched a Nick Page tutorial on how to create a focal length blend. Considering I was beginning my studies as a journalist, I felt like I was lied to visually. I found out some of the best photographers were creating seemingly other-worldly scenes that were so epic that they couldn’t possibly be real places on earth.
As it turns out, I was half right. The photos were of real places, but they weren’t photographed in a straightforwards photojournalistic style as I had hoped. It was both appalling and fascinating to me as I had never even pondered the possibility of shooting a scene with different lenses, only to stitch them together in Photoshop later.
Nick Page not only introduced me to the technique, but he forced me to start analyzing the work of my favorite photographers. I wanted to determine who else was using that method. Eventually, my curiosity and urge to create led me to begin attempting focal length blends myself.
It started with a single landscape photo but eventually led to me buying mid-length primes for night photography, with the goal to create epic nightscapes with an impossibly huge Milky Way filling the sky.
What is a Focal Length Blend?
Focal length blending is a creative technique that requires both in-field and in-computer work to achieve. But before we get heavily into it, you need to know the difference between a single exposure, a blend, and a composite photograph.
As the name suggests, a single exposure is a single frame.
In the world of Milky Way photography, a single exposure is generally a single shot focused on the stars and exposure set for the sky. The foreground can be a silhouette, lit by starlight, moonlight. Or it can be artificially lit with dynamic lighting, like light painting, or with a static lighting setup like low-level lighting.
The above image is an example of a single exposure set up. I used one low-level light to illuminate the scene and capture a properly exposed Milky Way and foreground in a single frame. In my workflow in Photoshop, I double-processed the image. That is, I split the image and processed the sky and foreground separately, but using data from the single frame.
Simply put, a composite is the result of the sky and foreground photographed at different times, or even at different places, and combined later into a single frame.
A composite is essentially the polar opposite of a single exposure.
The above image is a composite of a sky and foreground taken from the same area, but at different times and in different directions. The foreground was shot early during blue hour, while the sky was shot later in the night.
In the case of my image above, the sky and foreground were shot at different locations. Because the moon was so bright on that particular night, I didn’t end up photographing the Milky Way at the same time as I shot the foreground, which was lit by moonlight.
Instead, I created a composite. I used a photo of the Milky Way core from a nearby location shot on a darker, clearer night, but shot in the same direction as my foreground, making the composite.
In night photography, a true traditional blend is simply a blend of a sky and foreground taken from a single position without moving the camera, tripod, or changing the focal length.
The examples below are a sky exposure, a foreground exposure, and the final blended shot. All were taken from a single location without moving the camera or changing lenses or focal lengths.
These blends are very common in night photography. When shooting with fast f/1.4, f/1.8, or f/2.8 lenses, the depth-of-field, or total in-focus area of an image becomes very small, even with wide-angle and ultra-wide lenses. So, to get both the sky and the foreground sharp, we often need two or more separate images.
Another reason blends are common are because we do exposure blends for different reasons.
A shot of the Milky Way core may only be a few seconds long. To see detail in the black, underexposed foreground, you will need a very long exposure. Sometimes exposures are as long as half an hour. That much time may be needed to capture the very dim starlight cast on the landscape, depending on your ISO and aperture.
Opposite that, you may be shooting a foreground with artificial lighting to get short exposures of a few seconds or minutes at lower ISO numbers to get cleaner images.
You may also be tracking the sky, which would result in a blurry foreground since the Milky Way is continuously moving. That means you will have to blend your foreground and sky in post-production.
Now, on to focal length blending.
Focal Length Blend
Focal length blending is roughly similar to a traditional blend. It involves shooting a foreground and sky from a single position, but with different focal length lenses.
A common technique I use is to shoot the foreground with a wide-angle or ultra-wide lens, like my 15-30mm f/2.8. Then switch to a less wide or even mid-length lens, like a 35mm or 50mm. This changes and exaggerates the size of the Milky Way in the sky.
Who Can Do This?
Now let’s get into the who, when, why, and how.
Who can do this technique? Anyone!
As long as you have access to processing software or apps that will allow you to cut the sky out of your night image and blend in another exposure, then you can create a focal length blend. I’ll show how I make focal length blends in Photoshop later in this article.
When Should You Do This?
“When” is considerably less difficult to determine as you can create a focal length blend at any time. What to include in your blended photo does depend on the time of year. To keep your image a blend and not a composite, create your focal length blend with two photos taken from a single location on a single night.
During the winter (November to early February), several large Deep Space Objects (DSO) like the Orion Nebula or Andromeda Galaxy are visible. You can also capture a lot of interesting nebulosity in the winter portion of the Milky Way.
During March to October, the Milky Way core is the obvious main attraction at night.
Why Would You Do This?
Focal length blending is purely a creative choice than anyone can make. But I have two main reasons to create a focal length blend.
Reason 1: Exaggerate the Milky Way Size
In the spirit of our website’s name, reason number one revolves around the Milky Way core. (As do all objects in our galaxy!)
The primary reason I, amongst many other photographers, create focal length blends is to make the Milky Way Core a more dominant part of our composition by exaggerating its size.
When shooting with ultra-wide lenses, like in the image below, the Milky Way appears very small in our frame.
Though generally realistic in terms of the way our camera sees, the Milky Way looks bigger through our own eyes when we’re out there. And sometimes, an image just isn’t quite striking enough for our taste. An excellent way to add visual impact is to shoot the Milky Way and foreground with different focal lengths.
The image below used a 15mm and a 50mm lens. The 15mm lens shot the foreground silhouette. And the 50mm was used to shoot a three-panel panorama for the sky exposure.
Clearly, the second image is more visually striking because the Milky Way is so dominant in the frame. The photo also becomes more about the Milky Way itself as it now takes up a majority of the image.
Reason 2: Feature a Deep Space Object
Though not 100% Milky Way Core-related, Deep Space Objects are still a large part of night photography.
DSOs are relatively small in the sky. We need much longer focal lengths to really capture the detail in things like the Andromeda Galaxy or the Orion Nebula (to list just a couple amongst thousands of other DSOs.)
As an example to show how small they can be, the above image of the Orion Nebula. It is a single exposure shot at 450mm and cropped very tight.
In an astro-landscape photo taken at wider than 24mm, the Orion Nebula might appear to just be a large star.
The capture above is of both Orion’s Belt (the three stars on the left) and the Orion Nebula. I shot it at 170mm. It shows that just by going from 450mm to 170mm, you have already lost a lot of detail in the Orion Nebula.
It would take some serious work to capture a landscape with a foreground element in an image at this focal length. (And some have done it, more below.)
To explain the effect simply, a focal length blend can make the Milky Way core and DSOs feel like they are thousands or millions of light-years closer to Earth than they actually are.
How To Make a Focal Length Blend:
The first step is really to shoot the images, and there are different ways to approach the in-field work, but I’ll give you a quick summary of how I shoot.
First, in my in-field workflow, it is merely planning the shot, just like any other shoot. I often scout during the day when the sun is out with the help of PhotoPills or The Photographer’s Ephemeris, or, if for some reason my phone isn’t charged, or neither app is cooperating, basic knowledge of the Milky Way position throughout the year and a compass come in handy.
Once I figure out a composition, my next step is to go back at night and set up.
You set up a focal length blend roughly similar to a single exposure or a blended photo, except for changing lenses. I often start by using a continuous light to let me see my foreground, compose my shot, and to focus. You can use various lighting techniques or rely on a long exposure and starlight to light your foreground.
For the sky, my workflow can vary. When I have a flat horizon line, the workflow is easy. I simply shoot my foreground image, change to a longer lens, refocus, make any needed settings changes, and shoot the sky to be blended later.
In instances where I have a strong foreground subject that partially blocks out the sky or results in no flat horizon line, I have a slightly different workflow.
For example, if I am shooting a lone tree or I’m somewhere like Bisti Badlands or City of Rocks State Park, the tree or various geological formations result in a horizon that can’t be easily be blended if shot from a single spot.
The reason is when shooting your foreground and your sky with a single lens like a 15mm, the silhouettes or the foreground features are the same size. When you photograph the same scene with a 15mm and let’s say a 50mm, that small silhouette becomes 1-3 of the bottom of your image.
You have two options in this case. Option one is to tilt the camera up and shoot the sky without any foreground. But by doing so, you are making the Milky Way seem much lower in the sky than it actually is.
The second option, which I usually use, is to “walk through” my subject. What I mean is I’ll shoot my foreground and then shoot a single exposure at a high ISO to help me roughly line up the shots later. That way, I can place the Milky Way in a realistic and “actual” place it was in the sky.
After that, I will pick up my camera tripod and literally just walk around the subject in my image. Then, the hoodoo or rock I was shooting ends up behind me, but my camera is still facing in the same direction.
The only difference in the image is now there is no geological feature obscuring part of the sky, which makes post-production much easier, as I’m about to demonstrate below.
Now, a quick run-through of how I create a focal length blend using Photoshop. It is only my general personal workflow. There are several ways to do anything in Photoshop.
The two files I will be using are images taken at City of Rocks State Park, New Mexico, on April 13th, 2019. The foreground exposure is the same as used in the blend example above. It was shot at 15mm, f/2.8, ISO 1600, and 2 minutes. I lit it with a warm color temperature, low-level light from camera right.
The sky exposure is a single frame shot with the Pentax D FA* 50mm f/1.4 at f/2.0, ISO 1600. I tracked for 50 seconds using the Pentax Astrotracer feature on a Pentax K-1 Mark 1. I shot in a similar direction as the foreground, as you can see by the angle of the Milky Way core across both frames.
Step 1: Open the Files
Start by opening your foreground and background images as layers in Photoshop. I use Lightroom to catalog all of my photos. So for me, Step 1 is as simple as selecting the two files, right-clicking, and choosing to open them as layers in Photoshop. In the layers panel, be sure to place the foreground image at the top of the stack, so it is visible for the next step.
Step 2: Selecting your Foreground
Use either the Magic Wand or Quick Select tool to select your foreground.
When you make your selection, you will see the “marching ants” around your foreground. Everything within this moving dotted line is included in your selection.
With your selection made, right-click in your selected area and choose “Select and Mask…” or choose “Select and Mask…” from under the “Select” tab at the top of your screen.
Step 3: Refining the Mask
Press “B” on your keyboard to select a brush tool. Fix any edges where the selection tool didn’t select all the foreground objects or where it included some of the sky.
I have Photoshop set up to show what is masked out of my image. The area I am selecting appears unmodified. The area that I’m masking out, the rest of the photo, has a semitransparent red tint of it.
The more detailed your foreground, the more time you’ll want to spend doing this to make the blend seamless.
TIP: When shooting in the field, rocky foregrounds with minimal amounts of plants and trees are the easiest to blend with a sky because of their smooth edges. If you have a super-detailed foreground, the Refine-Edge brush tool may help you fine-tune your selection.
Once you are done using a brush and various other tools to perfect your foreground selection, it is time to output your selection to a layer mask.
Step 4: Creating a Layer Mask
At the bottom right of the screen, there is a dropdown menu labeled “Output To:” In this menu, you will want to select “Layer Mask” before you click “OK.” Photoshop will automatically add a layer mask with your current selection to your foreground layer.
Once you are back in the main Photoshop window, you should see a layer mask on your foreground layer. Your selected foreground is white, and the sky masked out with black while leaving your sky layer untouched.
Now you are ready to process your image!
Step 5: Final Processing
Your final step is simply to edit as you usually do.
I would suggest processing your sky and foreground separately using Adobe Camera Raw. Another option is using adjustment layers with clipping masks on the foreground and regular adjustment layers for the sky.
TIP: At this point, with the sky removed from the foreground layer, you can move your sky layer around to be unobstructed or to more closely match the actual location of the Milky Way in the sky, with an exaggerated size.
It can be very simple or it can be a lot of work, depending on your foreground.
Why We Created Focal Length Blends
The image above, notoriously known as the lead photo of my article on Pentax’s Astrotracer feature, was created last year with a particular feeling in mind.
In this case, my simple goal was to make the Milky Way larger than the rocks in the foreground. The stones at City of Rocks State Park in New Mexico are around 35 million years old. Though they are impressive, they aren’t nearly as old as the stars in our galaxy, which are much, much older and larger!
When shot at 18mm, the Milky Way becomes this bright, speckled, sliver going across the frame. Although it might work for some people, it didn’t achieve the narrative I wanted.
I wanted our massive galaxy to dwarf the comparatively tiny rocks of the state park, which dwarf the comparatively small human that was photographing them on this night.
In this particular case, I just wanted to quietly tell the viewer how tiny these rocks and we are compared to our Milky Way.
A Conversation With Marybeth Kiczenski
Below is an image from the Alabama Hills of California by MWP author Marybeth Kiczenski. I asked her a few questions to find out how she went about creating the photo and why.
Aaron: Why did you do a focal length blend, and what led to your decision to make the image?
Marybeth: “I chose to do a focal length blend on this Alabama hills shot to get all the rocks in the frame. Also, with the straight wide-angle shot, the milky way was quite a bit smaller, naturally. I felt that it needed to be more prominent in the scene – something only focal length blending could achieve.”
A: Why not create a composite with a sky from another location?
M: “Although a focal length blend (technically) makes this image a composite, I still feel the emotional connection to this night since both images were acquired on the same night from the same tripod location. I just switched the cameras out to grab the 35mm sky. If I picked a sky from another location, I would lose the connection to the scene. Sounds a little silly, but that is important to me.”
A: Did you plan it before you went out to shoot?
M: “This particular shot was not planned. I set out that night to shoot Mobius Arch, which I did. Then I wandered around and stumbled upon this location. For Mobius Arch, I scouted the location earlier in the day and used PhotoPills to figure out the composition. I took a screenshot for reference, pinned the location and left. Returned after sunset and set up the shot. As for the unplanned one, I did shoot it multiple ways, as I typically do. Started with the tracked sky shots, then the untracked foregrounds, and then a series of single image exposures – for safety. I’ll always shoot single images just in case the tracked shots don’t work out. It wasn’t until post-processing when I looked at the 35mm and the 14mm shot and thought they would complement each other.”
A: Why did you choose the focal lengths you used?
M: “The 14-24mm and the 35mm are not too far off from each other. The results are pretty “natural” feeling. Most people I have shown it to were not aware that two different focal lengths were used! So, this allows for the more detailed milky way to compliment the wide-field view quite nicely – without being too obvious.”
Arguments AGAINST Focal Length Blending
I reached out to New Mexico photographer, Paul Schmit, to ask if he utilizes the technique in any of his work. I also wanted to know why he did or didn’t create focal length blends. Here is his response:
“I actually never blend focal lengths in my shots, even my deep-sky astrolandscapes. I just can’t get behind an image-making method that presents sky and foreground out of proportion with one another. Instead, I bend over backwards to find real compositions at fixed focal lengths that afford unique views of sky and foreground in proper position and proportion. This applies to my Andromeda nightscapes as well as the recent image I released featuring Rho. (Rho Ophiuci.)”
Paul Schmit’s Insight
Paul was also kind enough to give some basic insight about how he works in the field.
“During a shoot, my tripod never moves, and I don’t touch my camera either. For example, if I’m shooting an astro feature rising behind a mountain, tree, etc., I set up in position, collect untracked foreground data while the sky slides into place, and simply turn on my tracker to freeze the sky in position at a predetermined moment.”
Paul ended our conversation with some personal words about how he feels about the technique and how he works to avoid it.
“The bottom line is that with a bit of additional work prior to going into the field, you can capture true-to-experience astro-landscapes at these longer focal lengths while retaining most of the qualities of fixed-focal-length astro-landscapes that people have become familiar with (largely at wider angles). The biggest challenge at these longer focal lengths is finding compelling scenes with adequate depth and the correct orientation relative to the sky, which really constrains the planning process.”
Paul’s image, “Galaxyset” is one of several images he’s taken using the technique he described.
You can learn more about “deepscapes” by reading our article, “Deepscapes: Leave the Wide-Angle Lens at Home,” by Scott Aspinall.
Paul also has a detailed tutorial on Capturing Galaxyset on his website.
Focal Length Blends – Ethical Concerns
Both Paul and Marybeth brought up some interesting points in their discussions.
The technique, though it can create fascinating and beautiful images, is purely an artistic choice that can only be considered semi-realistic at best.
These types of images are only blends because the skies and foregrounds are shot at the same time and place. However, the images aren’t true blends and they don’t fit the standards many magazines uphold to depict images taken in a photojournalistic, or generally realistic, style.
New Mexico Magazine’s rules for their yearly contests state, “All photographs should accurately reflect the subject matter and the scene as it appeared. With the exception of the Mobile Category, photos that have been digitally altered beyond standard optimization (cropping, spotting for dust, reasonable adjustments to exposure, color and contrast, etc.) will be disqualified.”
National Geographic guidelines on blends and composites are simple. “Composites are allowed… To be eligible for publication in National Geographic Magazine, the images must be combined parts made at the same time.”
“At the same time,” means back-to-back, without the long pause necessary to change lenses, refocus, and recompose.
As Marybeth pointed out, all focal length blends are technically composites because the foregrounds are not shot with the same gear as the sky.
Along with the magazines above, many photographers, “can’t get behind an image-making method that presents sky and foreground out of proportion with one another,” to repeat the words of Paul Schmit.
By using different focal lengths, the photographer creates a scene that would be very difficult, even impossible to create with a single lens.
As with landscape photos that are focal length blends to make mountains larger, sunsets feel closer, create images more epic and appealing, focal length blends in nightscapes present the viewer with a fantastical interpretation of the scene that is often far beyond reality.
Despite the intent behind the images, the ethical concerns surrounding focal length blends come down to a single simple fact. Presenting a scene with unrealistic proportions gives the viewer an inaccurate view of the world and the night sky.
Considering my background education is in journalism, the images I’ve included in this article were some of the last focal length blends that I made. The image created in the “how-to” portion of the article is purely an example to show you how to blend the images.
In 2019, I even withheld what I then considered some of my best night images from being used because I could not, with a clear conscience, enter images that were not “real” into contests meant to reward photographers, not digital artists.
As of writing this article, I have not published or made any images created from frames shot with different focal lengths. Instead, I will be sticking to blends and single exposures from now on. (And maybe a very clearly labeled composite here and there to quench my thirst for wanting to be artistic.)
That does not mean I am bashing the technique. If you are a photographer that likes creating other-worldly images, or just have a joy for creating art, then focal length blending is a challenging, fun technique. It can astonish your viewers and help you hone your post-production and shooting skills.
- Pentax Astrotracer Guide – 2021 Edition: What it is and How to Use it - January 21, 2021
- What’s In My Camera Bag #3 – Milky Way Edition - September 22, 2020
- Learn to Shoot the Night Sky with Sigma Ambassador, Babak Tafreshi - August 16, 2020