|
|
|
|
Sunlight
Getting good photos on a sunny days seems simple. You just take the camera, point it, and shoot. Lots of light makes for high shutter speeds with good depth of field, and the colors are brilliant. While there are times when that is true, a sunny day can also be the most difficult condition in which to get a good picture, depending on where the sun is in relation to you and the object you're photographing. On a sunny day, there's that big old light source up in the sky. Although far away, it is very directional and bright.
On a cloudy day, the clouds bounce the light around, so there is a relatively even, diffuse quality to the light--although not a lot of it reflects from your object, it seems to wrap around everything. But on a sunny day, when the light rays hit a tree, building, or whatever, they don't go through, thus creating a shadow. If you can position yourself with the sun at your back and the train in front of you, with nothing in between to cast a shadow, you have the classic sunny-day setup. This produces great shots that show all the details of your subject. You can typically use the camera's metered reading with no trouble. (B&O 4022, Walkerton IN)
Now, the problem with this "front light" setup is that it hardly ever exists in the real world--or least it seems that way when you're scouting for photos. Trains run on fixed routes and you can't always move around freely (and even when you can move around, there are times when you shouldn't--always stay on public property unless you have permission). This isn't a problem that only exists with trains. Fire apparatus is parked at a scene so it can work, which is not necessarily a perfect photo and light angle combination. Buildings are not going to move just to accommodate the light angle, either. So sometimes when you're out taking photos, you'll find that the sun is off to one side--logically enough, this is known as sidelight. This kind of lighting can produce a dramatic shadow.
It isn't so great for a roster shot, but for an action photo, it can add a feeling of depth. The problem with exposure is that you're trying to include some sunlight and some shadow, and neither film nor digital can generally include the details along all of that range. You'll need to decide what to emphasize. A reading from the meter will probably give you a nicely-exposed front end with deep shadows along the side (this is the option illustrated). Increasing the exposure 1/2 to one stop will lighten the shadow without turning the front end into a glare spot, although it may result in an odd-looking color. Using the "backlight" or +1-1/2 setting will give more shadow detail, but a lighter-colored front will be washed out, as will the ground details. (Conrail 6502 at Rolling Prairie IN)
As the sun rises in the sky, which occurs as solar noon approaches (if you observe Daylight Savings Time, or live near a time zone boundary, solar noon is not the same as chronological noon), the sidelight angle varies. The angle of the sun also varies with the season. As you approach the summer solstice (June 22 in the Northern Hemisphere), the sun is higher in the sky (just how high depends on where you are, it's directly overhead at the Tropic of Cancer). It then begins to move lower, reaching the lowest point on the winter solstice, when it is directly overhead at the Tropic of Capricorn (December 22 in the Northern Hemisphere). Thus a photo taken in a morning near the summer solstice and in a southern area (Dallas Engine 5; July 5, 2001) will exhibit less backlight than at other times. The sun is high enough here that while it throws a shadow, there is no problem getting good light for the details of the pump panel. The reverse is, of course, true as the winter solstice approaches: the lighting angle will become shorter, and you'll have far more trouble.
A common problem with photos is overlooking where shadows fall. It takes some experience to develop an ability to see this, but once you have developed it, you can use it to great advantage. The great photographer Ansel Adams often wrote of previsualization. His explanation of what is often called the "zone system" has left many photographers completely bewildered (although later explanations by others have helped relieve some of the distress). But whether you work it out fully or not (and some will notice that the guidelines given in these pages are based on his writings), there is no substitute for thinking ahead to get good pictures. On the left is Canadian National 3151, at Hamilton, Ontario in June 1975. It's late in the afternoon, and the photographer was paying more attention to those red Alcos than the tree a few feet away that threw its shadow over the first locomotive.
On the other hand, after a few years, he had a better developed sense of these matters. A request to get a photo of Dallas Engine 35 in March 2002 produced a challenge. The sun was low in the sky, and the firehouse (which, of course, would be difficult to move) faces north. The solution was to use the shadows created by the building, and put the whole engine in shadow. The presence of busy road just beyond the short apron required an angle that was closer to side-on. The rear of the engine is a bit darker than the rest, as it is more deeply shadowed, but a close-up meter reading kept details there, while not washing out the white on the cab. The sky is washed out, of course, and the flag is lighter than normal. In a spot like this, it's important to pay attention to shadows so you don't end up with a half shadow, half sunlit picture.
The hardest situation to judge is when you're shooting into the sun, known as backlighting. All that light coming into the meter will overwhelm it. As the meter attempts to decrease the exposure so the big, bright sun will be exposed properly, everything else will go dark, and the result will be a silhouette. Even worse, from most people's point of view, you won't even get a nice sunset--the camera is trying to make it look like mid-day. You can adjust the exposure to get a good sunset (by measuring your exposure from the reflected light on the ground, and using manual control or exposure memory), but an object in between you and the sun will still be dark. 
If that's the effect you want (and it can be dramatic), great. But if it's not, you need to use that "backlight" button or an exposure compensation setting of +1-1/2 to +2 to see anything of the paint job. If you do this, you'll lose most of the sky color. It will probably also give your photofinisher fits. If you've added exposure and still get a silhouette, that's the printer's fault, and you should ask for a remake (exposure can be adjusted in printing, but that doesn't mean that every lab operator knows how to do it). Some scanners also won't pick up on this--you'll need to override the exposure manually. Another way to deal with backlight is to use fill flash or a reflector. That's generally a little difficult with large objects, but it's quite practical for portraits. (Conrail 6069, December 1990, South Bend IN).
Another problem more common with sidelight and backlight is lens flare. Flare occurs when stray light starts bouncing around inside your lens. It's more common with zoom or short wide-angle lenses and is more of a problem the closer you get to head-on backlight. Flare can appear as colored spots (typically purplish) in the picture or as areas of low sharpness. Closely related to this problem is glare, where light bouncing off a reflective surface creates a washed-out highlight (and may cause flare of its own). There is no complete cure for flare. A lens shade, sort of like a visor for your lens, can help (make sure you get one that is matched to the lens). If you don't have one, using your hand as a visor can sometimes do the trick. A slight change of your angle can have the most effect in reducing flare. You might also decide that flare gives an artistic touch, especially combined with the deep shadows that are likely. (Amtrak 381 at Niles MI, date unknown).
