Good lighting requires the luxury of time and access. Photos like this are too often the result when you have neither. The other side of this engine was sunlit, but the land on that side is private property. The contrast here is too drastic to be repaired fully via digital editing.

Four sun-hours later, the sun began to shine on this side of CSX 756. The lighting isn't great, but it's better than in the prior photo. There's also the train meet, always worth a photo. Full disclosure: same engine, same location, same month but a different day.

You can't quickly change where the sun is in the sky, and you can't pick up and rotate a locomotive into a better pose, but sometimes you can shift your location. It might not yield the ideal shot, but this is a better photo of number 756 than the dark one at top. All train photography involves compromises.

If you seek drama and color, take your camera out on sunny days.

Sunlight scattered by clouds illuminates more evenly. It is better for revealing details in darker areas, such as the wheels and undercarriage. Cloudy days are better for documenting history and details that would be overcome by glare.

When there's not enough light for trains, consider how to make something out of the darkness. For example, rail commuters have deserted their parking area prior to a late-summer sunset.

Cameras with HDR (High Dynamic Range) features can automagically balance varying brightness, but overdone HDR often results in an artificial, overly-processed-looking image.

"Keep the sun at your back" is the general rule. Many railcars are painted black and require substantial illumination.

Many trains have a mixed consist, that is, a variety of railcars. You won't know in advance whether arriving cars are dark or light in color, so you'll have to depend on your camera's automatic exposure choices. Even so, light-painted cars can become over illuminated, as in this example. Shading varies a bit on the bright side of this car, which reveals it is not so overexposed that it can't be improved via digital darkening tools. A later lesson will tackle that.

With the subject in a shadow under a bridge and the sky overexposed, there's no real way to rebalance the light in this photo. The camera chose an exposure based on the center of the image, as configured, but that washed out the sky. All of the sky is full white (&HFFFFFF, RGB 255 255 255), which means if you darken it digitally, it will merely become a uniform gray that lacks detail and looks unnatural.

With film, a shot like this is wasted money. With digital, the cost of one more photo is near zero, so hit the shutter button and see what turns out.

You've probably seen photos in which the foreground is in focus but the background is not. How did they do that?

Depth of field refers to the range of distances from the camera in which objects are in sharp focus. A shallow (narrow) depth of field means that only objects within a small range of distance are in focus.

In this example, notice that the front of the train has sharp focus, but the farther into the distance you look, such as at the blue shelter, the softer the focus becomes. Note the distortion above the engine is due to its exhaust heat, so do not confuse it with depth of field.

Photographers will intentionally employ a shallow depth of field to draw attention to the objects in sharp focus and form bokeh (soft focus) around others.

Depth of field is largely determined by how widely the lens aperture is opened. Large openings create a shallow depth of field, as in this photo. Small openings cause a deep depth of field, causing more objects to be in sharp focus.

Depth of field is important for photos of moving trains. To avoid blur, you must employ a shorter duration exposure that lets in less light. To compensate for less light, an automatic camera will open the aperture wider, which leads to a shallow depth of field. If that's what you seek, excellent. If you want all objects to be in focus, you want lots of light, i.e. brighter days, and higher light sensitivity (ISO).

ISO in photography is something of a misnomer since it is a measure of light amplification that was co-opted from the name of the International Organization for Standardization. Photography ISO is a numeric value. The higher the number, the more the camera amplifies the incoming light. The values originated as a measure of film sensitivity to light but have been adopted by digital cameras.

Better digital cameras operating in an automatic mode will choose what they deem a suitable ISO for the lighting conditions. In dim light, they will choose a higher ISO, which means they will use amplification to create an image from less light.

Since light is a limited commodity, you might quite logically wonder why we don't just use a high ISO for everything. We don't because a tradeoff exists. The higher the ISO, the "faster" the film and the more randomness (noise) introduced into the image. The occurs for both film and digital because when the sensitivity is high, the ratio of noise (quantum uncertainty) increases relative to the signal (desired light from the subject). Noisier images look less sharp. What look like specks of dust on this high ISO film photo of a dimly-lit DC Metro car is noise.

An older, common abbreviation for a film's speed rating was ASA (American Standards Association). A film's ASA and ISO film speed numbers are identical. Film speed has increased with improvements over time, generally yielding better images from less light. Original, three-color Kodachrome had an ASA of 6 (or 10, sources vary) when introduced during 1935. That is very slow by modern standards and is why early color movies such as 1939's The Wizard of Oz required extensive lighting of their subjects. With good light, many modern digital cameras will choose an ISO of about 100.

Train station interiors are not as brightly lit as the outdoors, so to avoid blur, I forced the camera to use a higher ISO, specifically 800. The results are somewhat grainy, but the camera chose 0.03 seconds for the exposure, which was brief enough to prevent blur except on people moving quickly.

After the interior views of Union Station, I forgot to restore the lower ISO once outside. The camera compensated by using a short exposure of just 0.0005 seconds. The resulting photos are grainy and unsharp as if looking through fine snow. This example was cropped but not digitally resized. The higher the ISO, the more the camera amplifies the incoming light.

Some photo editors offer a denoise (de-noise) feature, but you'll get better results if you initially capture less noise by choosing a lower ISO when sufficient light exists.

To facilitate a comparison, this photo was also cropped but not digitally resized. It was shot a few minutes after the prior photo and after I'd lowered the ISO to 200. The camera chose an exposure of 0.002 seconds, four times longer than the prior photo. Note the improved clarity.

Cameras with larger light sensors can do better at high ISOs, as will be detailed later.

What's the best season for train photography?

Winter sun is weakest so light is at more of a premium than during other seasons. Consequently, winter can be your best opportunity for south-facing photos with less worry of an overexposed sky. It's also the time to photo subjects ordinarily obscured by foliage.

In this area during spring, the sun is high in the sky and not yet reduced by summer haze. That leads to high contrast and harsh glare on sunny days. If you leave a thermometer in the sun in this region, you'll find the highest temperatures of the year are recorded in May.

Summer is typically the season with the most foliage. The maximum hours of sunlight make for more photo ops than in other seasons. Note that haze is present in this photo due to the increased moisture capacity of warmer air.

Sunlight becomes softer by autumn and illuminates colors not found in other seasons. Autumn temperatures are usually more comfortable than those of summer and winter. Since it also lacks the glare of spring, autumn might be the optimal season for train photography.

Many photogs recommend the light an hour after sunrise and an hour before sunset.

Dawn and dusk photos can be worth trying for their unique light. Since autofocus can have trouble in low light, practice how to use manual focus during daytime in case you need it later.

Exterior lights can help with a dusk photo. Here, a freshly-painted Bollman Bridge is being adorned with holiday lights.

The lights of train stations make them a viable night subject. Typical camera flash units are not powerful enough to illuminate distant objects.

You'll want to use a tripod at night because unzoomed exposures longer than about 0.02 s (1/50 second) are subject to blur from camera movement. Zoomed views need shorter exposures than that because they are more susceptible to camera movement.

The pairs of red lights are B&O-style Color-Position Light signals. CSX swapped them out for other signals a few years after this photo.

Change for: more about night photography at this site

If you can find two owls in this trackside wood, you have the necessary skills to find good light for photos.

The next lesson compares the impact of cameras on rail photos.