Monday, September 2, 2013

Apps for the Landscape Photographer

I recently acquired some iPhone apps that may prove useful for landscape photography. I have yet to field test them, so the following are only first impressions after some playing around. I’m planning several photo trips starting next month and I’ll update this blog if my opinion changes with actual field use. The apps are: PhotoPills, The Photographer's Ephemeris (TPE), CameraAngle, and Pocket Light Meter. TPE is available for all platforms, including desktop, while the rest are iPhone only.

PhotoPills and The Photographer’s Ephemeris (TPE)

The essence of these two very similar apps is to indicate the sun and moon coordinates during any time of day at any global location. TPE has been around for some time and most photographers are probably already familiar with it. PhotoPills is a new challenger that adds some impressive features. PhotoPills is $10 while TPE is free for desktops, $5 for Android and $9 for iOS. Note that PhotoPills' iPad version is just a ported iPhone version and doesn’t utilize the larger screen.

Update: TPE for desktop is no longer available. It has been replaced by a web-based application. Click here to access the new app. Click here to read more why the desktop app was discontinued.

The screenshot below of TPE (iPad version) shows the purpose of these apps. I placed a red pin on one of my favorite spots to photograph the Court of the Patriarchs in Zion National Park, specifically the Abraham Peak with the Virgin River in the foreground. The direction of the rise and set of the sun and moon are shown by the radiating lines from the red pin for the selected date of 19-Nov-2013. Orange is sunset, yellow is sunrise, dark blue is the moonset, and light blue is the moonrise. Moving the time scale below rotates thin yellow (for the sun) and blue (for the moon) lines to show their position anytime during the day. All the ephemeris data is displayed in the bottom panels. I also placed a grey pin on Abraham Peak to determine its distance and elevation, which is indicated in the lower right panel. The grey pin aids in determining if and when either the sun or moon is at some desired coordinate relative to a landmark.

PhotoPills does essentially the same thing and additionally throws in extra tools relating to depth-of-field, exposure conversion, star trails, and time-lapse photography to name a few. Beside the extra frills, what PhotoPills really brings to the table is its superior search capability for determining when (and if) the sun or moon is in a particular coordinate. If you ever had a favorite site that you always wanted to photograph with a full moon precisely positioned within the scene, then this is the must-have app.

PhotoPills, being a first version, does have some drawbacks. One is its location database and search engine. While most major landmarks can be found, it’s hit-and-miss on lesser ones. For example, TPE had no problem finding two popular state parks along Lake Tahoe (Sugar Pine and Sand Harbor). PhotoPills couldn't find them. This is most frustrating when, say, you’re at a particular location and trying to “pin” a nearby landmark to assess elevation and distance, but PhotoPills can’t find it. Instead, you have to try to pin the landmark using the satellite imagery, which can be difficult (if not impossible). The iPhone-size screen and other interface annoyances only compound the frustration. Presently, I see PhotoPills more a long-range planning tool while TPE is better for everyday field use.

Example using PhotoPills
I live near a 19th century lighthouse that I would someday like to photograph with a long lens capturing the upper portion of the lighthouse with a full moon next to it. (See my blog post, Moonshot, for more info on shooting the moon.) The free TPE desktop version lacks any automatic search for a predetermined sun or moon position. Instead, you have to manually hunt for it. The tablet versions have a search capability, but only in the azimuth direction that doesn’t include elevation. Though finding a predetermined position is easier with the tablet version, you still are left with some manual hunting to find the desired elevation. However, if you can accurately find and “pin” your desired shooting spot as well as whatever landmark you’re aligning to, then PhotoPills is the perfect tool.

In the PhotoPills screenshot below, the red pin shows my intended shooting location. I placed the black pin (equivalent to the grey pin in TPE) to trace the line-of-sight I want the full moon to be, which is slightly to the right of the lighthouse. Also, for the moon to be in proper alignment with the lighthouse, its elevation needs to be about 10-degrees. How did I know that? I’ll explain that when I get to the CameraAngle app. Usually, you can place the black pin on a landmark (a mountain peak for example) and the app indicates the elevation angle and distance (same as TPE’s grey pin). But building heights are not in the database and must be determined separately.

Now, based on the black pin’s position, I have PhotoPills search when the moon will be at that azimuth and elevation. I can control the search window size to as much as ± 5-degrees in either azimuth or elevation. In this example, I set the search field from 9 to 13 degrees elevation and ± 2 degrees in azimuth. PhotoPills then lists all the moon phases for that coordinate. You can sort the listing and show all the full moons first. The listing is color coded to indicate if the moon is at night, during the day, or during the golden hour. I want it during the golden hour since that's the most photogenic time and the contrast issues with the moon are minimal. From the screenshot below, you can see that the next best opportunity isn’t till May 2015. In the above screenshot, notice that the full moon (thin blue line) on 2-May-2015 aligns both in azimuth and elevation with the dotted black-pin line at 7:37pm, which is exactly at sunset–perfect! (To see the black pin's coordinates you  finger-swipe the top banner showing the sun and moon's rise and set times.) If you can tolerate more slop in the moon’s position, then widening the search area will yield more results that may occur sooner.

TPE is the must-have field tool that should satisfy 99% of your needs. I feel that for determining routine sun and moon ephemeris data, TPE is more user-friendly and the larger screen support (for tablets and desktops) is one main reason why. The free desktop version is sufficient by itself, but if you don’t carry a laptop out in the field, then you’ll need the tablet or smartphone app. To be fair, if you are relying only on a smart phone in the field, then PhotoPills may be a better choice (if you have an iPhone). The reason is TPE was also annoying to use on a small-screen phone. And if establishing a precise sun or moon position in your compositions is an important part of your photography, then PhotoPills is the best tool for that job. Also, the extra tools may have some appeal. Just beware that PhotoPills can still be frustrating to use at times.

Another Option
I recently tried a new app called LightTrac by Rivolu Pte Ltd. It is available for both iOS and Android for $4.99. My first impressions are it's essentially a lite version of TPE. It is user friendly and a few bucks cheaper. This might appeal to someone wanting something with no frills and is easy to use. Otherwise, I didn't see any reason why it would replace TPE for me, which is more versatile and nearly as easy to use. 

CameraAngle by Geometry ($0.99, iPhone only)

[Update. After upgrading to iOS 8.0.2, this app no longer works on my iPhone 5. The camera image fails to display. This may be unique only to my phone, but I don't care anyway because I found an ever better app: Theodolite by Hunter Research and Technology, iOS only at $3.99. There may be a similar (but not the same) android app called Theodolite Droid at Google Play. What makes Theodolite a better app is you can use the camera image crosshairs to sight a compass heading. This provides the same function as a sighting mirror on a conventional compass. This is useful when you want to, for example, align the exact position of the sunrise in your composition. I will post a review of Theodolite after I've field tested it.] 

In the above lighthouse example, I knew in advance that I wanted the moon to be about 10-degrees in elevation. Often, the only way you can precisely position the moon or sun within a composition is to be there. But, you still need a way to measure elevation and so you need an inclinometer. There are many inclinometer apps, but sighting an angle with them is rather cumbersome. CameraAngle solves this by using your phone’s camera. Simply line the crosshairs where you want the moon (or sun) to be and read the angle. In the screen shot below, you see approximately where I wanted the moon to be relative to the lighthouse. (Note that it shows the angle as negative for reasons I can’t explain.)

Pocket Light Meter by Nuwaste Studios (free or $0.99 to remove ads, iPhone only)

I can imagine many DSLR users asking why would I ever need a light meter? Well, generally you don’t, but it can useful in certain situations. In my ebook on HDR, I talk about using a light meter to help determine the dynamic range of a scene so you can set the appropriate bracketing range. I have a spot meter that is the perfect tool for that task, but to be honest most times I determine bracketing based on experience and a little trial-and-error. Still, with a light meter conveniently in your hip pocket (or wherever you keep your phone) you may find it useful to quickly size up a scene’s dynamic range. Though Light Meter is not a spot meter, it’s close enough to be useful.

Now I can imagine another question: why not just use the DSLR’s internal light meter (assuming you have a spot mode). The problem is you want to know the range in stops. Cameras normally indicate exposure by shutter speed and f-stop. Trying to figure the stop difference between two exposures takes a little math. Instead, you want to read exposure in EVs (Exposure Value). That way it’s easy to mentally subtract the two numbers in your head to determine the dynamic range in stops. That’s exactly what Light Meter can do for you.

In the screenshots below, you see two readings of a daylight scene in a local park.  The stop difference between the sunlit and shadow areas is: 14.21 – 10.08 = 4.13 stops. You can tap the red rectangle anywhere within the screen or simply repoint the phone to measure the desired area. But there is a drawback: the dynamic range is actually more than 4 stops and probably closer to 5 stops. The problem is the large measuring area. This makes it difficult (if not impossible) to pinpoint either the highlight or darkest shadow without being thrown off by surrounding light. This is why the 1-degree spot meter is more adept at this job. The silver lining, though, is this drawback may work to your advantage.

The reason is the true dynamic range of a scene isn’t necessarily the bracketing range you need. As I explain in my HDR ebook, you need only pull back the highlights and shadows about one-third from their histogram ends. Any light meter, instead, wants to place them roughly in the middle, which is too far. So for the above example, though 5-stops may be the true dynamic range, a 4-stop bracketing range may be more appropriate (i.e., set your camera’s auto bracketing to ± 2 stops). So it’s possible that most times merely subtracting the two readings is close enough for government work. Still results can vary, so you may need to empirically determine a correction factor that works for you. Remember that precision accuracy isn’t necessary. You just need to get close enough so, at most, you need only tweak the bracketing range a little after previewing the histograms.

As for the general accuracy of Light Meter, first off, displaying EV to two decimal points is totally ludicrous and a complete false sense of accuracy. Nevertheless, I compared Light Meter to my Minolta spot meter and most times the readings correlated reasonably well. Actually in one case, while my spot meter was thrown off by the color of a reflective surface, Light Meter nailed it. I’m guessing Light Meter may use the color information to correct for any non-midtone-like colors. However, Light Meter could get quirky at times. The red rectangle is not a precise metering area and sometimes seemed to exhibit a hysteresis-like variability in its readings relative to its red boarder. But that’s needless quibbling since, as I said before, all you need is a reasonable approximation of the dynamic range. Plus Light Meter costs less than a buck while a good spot meter is over $500!