photographers taking long exposures of milky way

Photo Pills Guide for Sky/Night Photography

How do you make the leap from your imagination to clicking the shutter and seeing what you imagined appear on the back of your camera? For nature photographers, one bridge is the smartphone or tablet-based photography planning app Photo Pills.

The best landscape images begin as an imaginative flicker in a photographer’s mind. I always tell my students that pre-visualization is the key to truly creative photography. Photographers of all experience levels should think like a painter standing before a blank white canvas: what elements of a scene are they going to put on what parts of the canvas? For nightscape, skyscape, and landscape photographers, Photo Pills is a huge asset.

Before planning apps like Photo Pills became available, a landscape or night photographer with a particular image in mind had to pay close attention to movements of the sun, moon, and stars over long periods of time to understand how the rhythms of these celestial bodies would impact the image they had in mind. This was tedious work, requiring one to return to the same spot and catalog how things changed from day to day, night to night, over months and even seasons. Make an invalid assumption, and you could come up empty-handed by being at the right place but at the wrong time.

I knew a budding photographer who once made the long, treacherous trek through the backcountry of Death Valley National Park to the Racetrack Playa hoping to shoot the Milky Way over the famous Sailing Stones on New Year’s Eve. Of course, this was an impossibility in late December as the core of the galaxy doesn’t rise in the northern night sky until late spring. He came home disappointed and very cold.

Here we’ll learn how to use Photo Pills. First we’ll cover the basic functions of the app – the Planner function (or “pill” to use the maker’s jargon). Then we’ll explore the use of day and night Augmented Reality features and cover more technical and complicated features.

Main App Functionality

The Photo Pills Planner function provides a detailed understanding of the exact location of the sun, moon, and stars (e.g. the center of the Milky Way) in the sky at any date – past, present, or future – from any location on the planet.

Photo Pills Screenshot

The four main screens of the Photo Pills App. “Pills” are the app’s features – things like Planner, Augmented Reality, Time-Lapse, etc.

Using the Planner, you can place a pin anywhere you choose and then dial in the date and time. The pin can be placed by GPS to your current location, or you can drag the map under the pin and place it anywhere on the globe. Once the pin is placed, the Planner then overlays colored lines on the map, emanating from the pin location, showing the azimuth (compass bearing) and altitude (elevation above the horizon) of the rise/set bearings and current positions of sun, moon, and the center of the arch of the Milky Way. You can slide your finger on the colored bar at the bottom to adjust the time, and the positions of the sun/moon/galaxy azimuth lines adjust accordingly.

Photo Pills Screenshot

Day mode (left) and Night mode (right) of Photo Pills’ Planner screen, located at Sugar Pine Point State Park in Lake Tahoe’s West Shore in June of 2020. The thick orange line to the west shows sunset location, the yellow line to the east shows sunrise. Thin lines show the position of the sun/moon at the specified time. The light blue line is moonrise, dark blue is moonset, light grey is Milky Way’s rise, and dark grey is Milky Way’s set. Each can be turned on/off in the app settings.

Between the word “Planner” and the map at the top are ten different areas of information denoted by white dots accessible by sliding the bar between the dots and Planner to the left or right. This is the spot for lots of great information – exact sun, moon, and Milky Way position and twilight times as you swipe through day/night.

Let’s try a few examples.

Suppose you want to make a beautiful image of the full moon setting between the two towers of the Golden Gate Bridge at sunrise, in great blue hour light, surrounded by colorful clouds, and from your favorite spot – Horseshoe Park at the Berkeley Marina. You need to figure out two things to capture this vision (weather notwithstanding). First, from where specifically do you want to shoot it, and second, when should you shoot it? Since the moon is only full one day each month, that leaves 12 possible days annually. If you wanted to try September 2019, a quick check of the “Moon” pill reveals the September full moon occurs on the 13th. But what time does the full moon set if you are standing on the seawall at Horseshoe Park at the Marina?

Using the location chooser on the Planner page to place the pin on the seawall, you see that on September 13, the moon sets at 6:13 a.m., and sunrise is at 6:49 a.m. The timing almost works out for our imaginary photo, but the moonset is slightly too early. And what about the location? Looking at the solid blue line from our pin to the west shows that the location where the moon will set is actually too far to the north on the 13th to give you your photo.

Photo Pills Screenshot

The blue line shows the position of the full moon setting at sunrise as viewed from Horseshoe Park at the Berkeley Marina on September 13, too far to the north of the north tower of the bridge.

While close, this won’t deliver exactly what you want, so what about October? Savvy night photographers know that the moon sets more to the north each month as we go from fall into winter, and the moon rises later with the seasons as the earth revolves around the sun. Sure enough, October’s settings are the opposite of what you want, since moonrise will be later and even more to the north. But in August, from your chosen location, the full moon is the 15th. It sets at 6:25 a.m., and sunrise is at 6:24 a.m. This is perfect. And where does the moon set? It perfectly splits the towers of the bridge from ~6:10 to 6:25 a.m.

Photo Pills Screenshot

The position of the setting full moon at sunrise on August 15 if viewed from Horseshoe Park at the Berkeley Marina in San Francisco Bay. Shows the blue line between the towers of the bridge.

Of course if you wanted to shoot the full moonset in September between the bridge towers, you could just adjust your location and move to the south in the Marina to put the blue line of the moonset’s azimuth between the bridge’s towers. You can also check if the moon will be high enough to be above the deck of the bridge with other more advanced features of the app, which we’ll explore later.

What about using Photo Pills to plan for shooting the Milky Way? Let’s look at the Death Valley Sailing Stone failure we started with. Using the Planner, you can easily determine that on New Year’s Eve, the Milky Way core does not rise at all in the night sky above the Racetrack.

Note the visibility of the Galactic Center is “always invisible” from this location on the Racetrack at the specified date and time of New Year’s Eve. I wonder who the budding photographer was that came home empty handed?

Summer months are prime time for Milky Way shooting in the northern hemisphere, so let’s look at June 2020 for our next trip to Death Valley. I am imagining a Milky Way shot in a dark black sky with no moonlight, so I can shoot one frame for the sky, and one frame for the stones with a very long exposure illuminated by starlight. Others may prefer trying this in one frame with a LED light panel to paint the stones.

Photo Pills Screenshot

The moon “Pill” feature of the app.

A check of the Moon tab in the app shows the new moon in June 2020 is Saturday the 20th. Sliding the screen across the top of the planner to the Milky Way information shows the center of the galaxy is visible from 10:04 p.m. to 3:41 a.m. This should allow plenty of time to try a variety of techniques and compositions. You may even be able to make a photo like this one:

Grant Kaye photo example of Milky Way

Milky Way in the sky over the famous Sailing Stones of Death Valley’s Racetrack Playa. Note that the noise levels in this image aren’t great due to my pushing the sensor of a relatively antiquated Canon 5D Mark III camera in 2012 when the image was taken. Also note that the quality of this image was intentionally reduced further for faster web loading.

Photo Pills Screenshot

The position of the Milky Way in the sky above if you were standing on the Racetrack Playa in Death Valley on June 20, 2020. Think of the white dots as the arch of the galaxy above you, with the thickest white dot (and the white line) as the azimuth or bearing towards the center of the galaxy.

If I happened to physically be at the Racetrack, I could even use the Night Augmented Reality feature and my phone’s camera to predict what my Milky Way photo would actually look like. Stay tuned for that later on. For now, consider what you can gain as a landscape photographer by mastering even just the Planner feature of Photo Pills! You can now accurately forecast the position of the sun, moon, or Milky Way in the sky at any spot on our planet, at any date in the future. This enhances your full creative potential as a photographer. Better planning means stellar photographs!

Advanced Features

While the aforementioned functions are the “meat and potatoes” of Photo Pills, the app is capable of many additional functions to help photographers achieve their best image. So what else can this app do for us?

Photo Pills can help you plan time-lapse shoots, calculate depth of field and hyperfocal distances with virtually any camera/lens combination, estimate the size of tall objects in your frame based on lens selection and distance, estimate the length of star trails in very long exposures, and even enhance the basic functionality of the Planner by including the application of geodetics, which accounts for actual terrain between your location and the horizon when looking at sun/moon/Milky Way positions and visibility.

We’re going to look at a few of these additional features now: Augmented Reality, Exposure, and Star Trails/Spot Stars. These are the ones I use regularly in my night photography planning work.

Augmented Reality

The Augmented Reality (AR) features of Photo Pills are amazing: by using your phone’s GPS to locate yourself on the earth, the app then manipulates your phone’s camera and your specified date/time settings to display live on your screen where the sun, moon, or Milky Way center will be at a future time you choose, superimposed in real time on the image you are looking at on your screen.

Carefully calibrated, you can use this feature to see a close approximation of what your photo will look like at a time in the future from the same location, in either Day AR mode, which shows the positions of the sun and moon and ephemera (arc through the sky), or Night AR mode, where you will see a representation of the actual Milky Way’s core live on the screen.

Let’s look at an example of the night AR mode to test its accuracy. I taught a Milky Way photography class at the (gorgeous) Sugar Pine Point State Park on Lake Tahoe’s west shore in July 2019. How could I be sure I could guide students to actually shoot the Milky Way? Before I scheduled the class, I made a daytime visit to the park in June and used the AR feature of Photo Pills to pick the date and time of my class.

Below is a screenshot of the Night AR feature from Photo Pills as I was standing on the dock at the park looking south in the daytime in June.

Photo Pills Screenshot

Screenshot from Photo Pills’ Night AR feature at the location where I was planning to do my Sugar Pine Point Milky Way photography class the following month.

And here is an actual photo taken during the class, on July 23rd at 11:15 pm:

Grant Kaye's Photography Students on Dock Shooting Milky Way

Students in my Milky Way photography class at Sugar Pine Point on Lake Tahoe’s West Shore in July 2019. Quality intentionally reduced for faster web loading.

The app accurately represented the real conditions my students would see during my July workshop. This Night AR feature is useful at any location when you are searching for a good composition and strong foreground at night.

The Day AR mode works much the same: it overlays the position of the sun/moon onto your screen, allowing you to see where these objects will be in the sky at your location at a time in the future. I’ve made extensive use of the Day AR feature in my commercial and architectural photography planning, since the sun’s position can be a critical part of lighting on your subject, and timing is often critical. Note: this could also prove a useful feature for natural-light-only portrait photographers.

Photo Pills Screenshot

Photo Pills’ Day AR feature showing the position of the sun from my office window.

Exposure Calculator

A technique I employ frequently in night photography is to shoot two separate frames and blend them together in Photoshop: one “short” (25-30 seconds) exposure for the sky and one for the foreground. This is often referred to as “multiple exposure blending” or just MEB and I discuss this in more detail in my article High Dynamic Range vs Multiple Exposure Blending Editing for Photographers. For the foreground, I shoot a very long exposure in Bulb mode (or “Time” on Nikon) to gather enough starlight to properly illuminate the landscape, often up to several minutes.

Upper Sardine Lake by Grank Kaye

A panoramic view of Upper Sardine Lake and the Sierra Buttes shot in August 2019, created by blending panoramas shot at differing exposure values – short 20-second exposures for the sky, and long two-minute exposures for the foreground.

The MEB method can be tricky, especially in pitch dark, as most of us don’t have reciprocity tables memorized and would have no idea how long the foreground exposure needs to be to achieve the proper exposure level.

Photo Pills offers an easy way to figure this out with its Exposure feature (or Exposure “Pill” in the app’s terminology). You begin by guessing at a test exposure until the desired illumination is reached. This is done by cranking the ISO of your camera to its maximum level (ISO 25,600 or even 102,400) and guesstimating moderately-long shutter speeds (5, 8, 20 seconds…). Shoot and adjust until, upon review of your histogram, you’ve achieved the proper level of illumination in this throw-away file. Remember, this is obtained when the image’s histogram is clear of the left edge (no areas in pure shadow – RGB 0, 0, 0).

Once you have the value of the desired test exposure set, you can input those values into Photo Pills’ Exposure calculator, and the app uses reciprocity tables behind the scene to determine how long an equivalent foreground exposure needs to be at a very low ISO, so you can lower your ISO and keep noise in check in your useable image. Remember that very long exposures in bulb will be inherently noisy, even at your lower ISO values, so don’t forget your dark frame!

Photo Pills Screenshot

Photo Pills’ exposure feature showing the equivalence in illumination (exposure) of two photos taken at different settings.

Spot Stars

Another Photo Pills feature I use is the Spot Stars calculator. This Pill allows you to input your camera and lens combination and it will determine how long of an exposure you can take before the stars in your photo’s center portion will transition from dots to lines (i.e. when you start to get star trails). Because of the earth’s rotation and the distance we are from the stars we see, long night time exposures will eventually shift the shape of all of the stars in the frame from dots to streaks.

If you are hoping for a star trails image, this can be used to your advantage. But if you are trying to create an image of the center of the Milky Way you might want the trillions of stars in the galaxy to be as close to dots as possible and to look like they actually appear to us.

Some Behind-the-Scenes Math

Here’s a summary of how the math behind this stuff works using the NPF rule as an example. If I point my Canon 5D Mark IV at the sky and attach my Rokinon 20mm f/1.8 lens, I can shoot a frame for 10.56 seconds using the NPF rule, or 25 seconds for the “500 rule”. The NPF rule is much more accurate, and uses the following (simplified) formula:

(35 x Aperture + 30 x Sensor Pixel Pitch)/Focal Length of Lens = number of seconds the shutter can be open.

The NPF rule was derived by a French photographer and each letter in the this rule represents a variable: N = aperture (typically represented by the letter N in optics), P = pixel pitch, F = focal length. Sensor Pixel Pitch is the center-to-center distance between individual pixels, measured in microns. Generally speaking, a larger pitch is better because it means less noise in the image – think of bigger buckets stacked in a grid being able to catch more falling ping pong balls (photons of light).

To find your camera sensor’s pitch, you can look it up or use the formula to find it manually: take the width of sensor in mm (such as 35mm) and divide it by max image resolution width in pixels and times that by 1000. Here’s a little bit of a breakdown:

Finding Sensor Pixel Pitch

(35/width of sensor in pixels) x 1000 = Sensor Pixel Pitch

Let do this together using the Sony a7 III:

The sensor width is 35.6. The max sensor resolution width is 6026:

(35/6026) x 1000 = 5.91

Your Sensor Pixel Pitch for the a7 III is 5.91.

Finding Max Sensor Resolution Width

If you’re wondering where to find your max sensor resolution width (that 6026 number), you can either look it up or – if you enjoy this sort of thing – do it manually. To find it manually, you’ll need to know your sensor width and effective megapixels. This part you simply have to look up in the specs for your camera. In this example, it’s 35.6 and 24.2. Now that you have this much, you can begin calculating…

Step One: Sensor Resolution = 35.6/24.2, which gives you an answer of 1.5

Step Two: Now that we have our 1.5 ratio, let’s find our vertical resolution. Take 24.2 (our effective megapixels for the a7 III which we simply looked up in the specs) and times that by 100,000 then divide by 1.5. You’ll get a very long result of 16133333.333333333333333. You need to find the square root of that answer. I just used an online square root calculate to get 4017 (or 4016.6320883712183).

Step Three: We have the vertical resolution and now to find the horizontal resolution we just take 4017 x 1.5  to get 6026.

The sensor resolution of the a7 III is 6026 x 4017, slightly larger than the maximum file image resolution of 6000 x 4000.

a7 III Pixel Pitch and NPF Example for Exposure Calculation

Now that we have our pixel pitch of the a7 III, which is 5.91, here is how you can use it. Remember, this is how the simplified NPF formula goes:

(35 x Aperture + 30 x Sensor Pixel Pitch)/Focal Length of Lens = number of seconds the shutter can be open.

Let’s say I want to shoot at an aperture of f/2.8 using a 24mm lens.

(35 x 2.8) + (30 x 5.91) / 24

35 x 2.8 = 98
30 x 5.91 = 177.3


98 + 177.3 = 275.3


275.3/24 (our lens length) = approximately 11.5 second exposure is needed. It is after this amount of time where your star “dots” will start to transform into star “streaks”.

500 Rule

The 500 rule came from the days of film and, while not nearly as accurate as the NPF rule above, still provides a good ballpark for how long your exposures can be. It’s easier than the above: just divide 500 by the focal length of your lens (or the length you’re shooting at). Using our 24mm lens as an example, this means at approximately 20 seconds your star dots become streaks. As we already know using the more precise NPF calculation, this is very likely way too long of an exposure for maintaining “dots” – especially when looking at the image close up. The only real way to know is to shoot and carefully examine your image, both in the center and at the corners. What is acceptable to one photographer may not be to another.

You can explore this further on Photo Pills’ site.

Photo Pills Screenshot

Use of Photo Pills’ Spot Stars Calculator to determine longest acceptable shutter speed when aiming to shoot stars as dots instead of trails with a Canon 5DIV and 20mm lens.

The app offers two choices: “Default” for barely noticeable trails or “Accurate”, which is useful for large prints. This choice accounts for the fact that very large prints will enhance trails due to magnification – in other words, slight streaks will simply be more noticeable in a big print vs just a web-sized image.

Give Photo Pills a try this coming year. This app majorly enhances a your planning skills. You may return from your next photography adventure with a memory card full of exactly the images you imagined. You’ll also feel more connected to your environment.

Born in Hawaii, educated in New Zealand, and now living in Lake Tahoe, Grant Kaye specializes in landscape, night-sky photography, motion-controlled time-lapse, and creative filmmaking. His clients have included Red Bull, MSNBC, Yahoo, and many others. See more of his work on his website or join him for a workshop.

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