Photographing R/C Models

Mike Shellim
Last updated 8 July 2008

Airworld Fox (Ivinghoe Beacon)

Most modellers like to take pictures of their creations, if only to keep a record in case the unmentionable happens, but also to capture some of the atmosphere on the flying field.

This article describes describes some of the photographic techniques employed in my photo gallery.

Choice of camera

Taking photos of aircraft is easy enough when they are on the ground and any point and shoot camera will do the job admirably. However it's more difficult when they're in the air because:

Because of these issues, digital SLR's are more suitable for our purposes than to point-and-shoot ("P&S") cameras. The specific advantages of dSLR's are:

If you already have a P&S camera, fear not - it should be capable of good results too, if operated within its limitations. In particular it will provide best results in a narrower range of light conditions, and freezing action may be more difficult.

Megapixels - fact and fiction

These days, cameras are often priced according to the number of pixels recorded by the sensor, measured in megapixels (MP). In theory the more megapixels, the higher the resolution (i.e. detail) which can be reproduced.

Things are not so simple however, because up to a certain print size, the limitation is printer technology, not your camera's megapixe count.

Printers are the real limitation

Currently, most good quality printers, including commercial outfits, print using 300 dots of colour along every inch of the page. The number of megapixels in an image to make a sharp print at 300 dpi is approximate (width x height) / 11, where width and height are the dimensions of the print in inches.

Plug in the figures for a 12x8 inch print, and you get a sensor of around 9 megapixels. However as print sizes increase, viewing distances also tend to increase - people tend to view A3 images from a greater distance than a 6x4 enprint. So paradoxcially perhaps, at larger print sizes, even a 150 dpi printer will produce sharp looking images.

So, do you really need 15 megapixels?

The upshot is that six megapixels is usually adequate for images up to A4 or 12x8. Only when you print A3 and above, will the benefits of a higher megapixel camera be noticeable.

For images intended to be viewed on a computer monitor (as opposed to printing), there is no advantage at all in higher MP sensors - a 1280 x 960 monitor requires less than 1.5 MP.

However, a high MP camera will allow you to crop your images a little more before degradation occurs.

So what to buy?

If you're looking for a new dSLR, the entry level these days is around 10-12 MP, and for the majority of weekend shooters, there's absolutely nothing to be gained from spending extra on even more megapixels.

If your budget is limited, there are some excellent 6MP digital SLR cameras on eBay thanks to their owners 'upgrading'. Smaller sensors offer some practical advantages too: smaller file sizes (useful if you shoot in RAW), better performance in low light, and usually a smaller camera.

My own camera is a Pentax K100D Super. This has 6 megapixels, yet even 12 x 8 prints are sufficiently sharp. It's a small and relatively light and cheap dSLR which fits easily into the backpack with the transmitter and other flying gear.

Composition Tips

Many potentially good pictures are spoilt through lack of decent composition. Just moving the camera a foot or two can make the difference between a pilot impaled by a fencepost, and a pleasing composition. Or a model which looks awkward in the air, and one that's really flying.

Rule #1 Fill the frame. Use a telephoto or else move closer to the subject. If this isn't enough then crop the photo afterwards.

Filling the frame

Rule #2 Isolate the subject by choosing a complementary background, or select a wide aperture (low F number) to blur the background. .

Rule #3 Lead the eye. The eye tends to follow converging lines, and is also attracted to bright areas. Bear this in mind when you frame the shot.

Rule #4 Avoid distracting highlights near the edges of the frame. When framing a shot, try and get into the habit of looking all around the frame for distractions, especially areas of brightness round the edges.

Rule #5 Use the "Rule of Thirds". The rule of thirds is a useful rule for landscape shots. Some cameras even show the thirds grid in the viewfinder.

In this shot taken after the 2007 Welsh Open, the horizon splits the image 1/3 water and 2/3 sky.

Rule #6 Leave space to move into. When photographing flying models, leave more space in front of the model than behind. This will produce a more dynamic image.

Leave space for the model to fly into

Use your camera's histogram!

Detail is what brings a picture alive. Detail means being able to see the fluffiness in a bright cumulous cloud, or the panel lines on the dark underside of a wing.

In order to capture detail throughout the image, correct exposure is vital. So what do we mean by correct exposure? Essentially it means that the range of tones in the captured image should all lie within the dynamic range of the sensor. Or put it another way, there should be little or no solid blacks or solid whites in the captured image.

Unfortunately the camera's metering has its limitations, and even with the best cameras, you can't guarantee a perfect exposure every time. Which is where the histogram is your friend.

Enter the Histogram

Virtually All cameras offer a histogram facility. The histogram shows the distribution of tones as a graph with 256 brightness levels along the X-axis, and the number of pixels at each brightness level on the Y-axix. Most importantly, this allows you to identify areas of over- or under-exposure.

When assessing a histogram, look for tell-tail spikes at each end. These indicate areas of solid black or solid white in the image, and these areas will be lacking in detail. No amount of tweaking with a photo editing package can ever reveal any colour or texture at these extremes. (The only exception to this rule is with metallic reflections ("specular highlights") which can be allowed to go solid white.) A correctly exposed shot will produce a histogram with a gentle roll off at each end.

The way you view a histogram depends on the type of camera. With most dSLR's, you view the histogram post-capture. With point and shoot cameras, and newer dSLR cameras with Live View, the histogram can also be viewed before capture, giving the photographer a chance to tweak the exposure before taking the picture. If you're not familiar with the operation of the histogram, do take a look at your camera's manual.

Here are some screenshots of the histogram on my camera:

OVEREXPOSED - Where's the fluff in those cumulous clouds? Blown out! That's why there's a spike at the RH end.

UNDEREXPOSED. There's fluff in the clouds, but oh dear, the dark bits are total black! Note the spike at the LH end.

CORRECT EXPOSURE - the histogram shows a gentle roll-off at each end, and there's detail throughout the image.

Exposure compensation

If the histogram indicates under- or over-exposure, then use the exposure compensation feature to increase or decrease the exposure relative to the camera's automatic metering, and re-take the scene.

HDR

Sometimes there is so much contrast within the scene that it's impossible to avoid a spike at either end of the histogram. Or to put it another way, the dynamic range of the scene is greater than that of the sensor. Typically this can happen on a very bright day.

There are two ways to deal with this. The first is to sacrifice shadow detail by underexposing. This will show as a spike on the left of the histogram, while allowing the highlights to roll off gently. This is acceptable because human eyes are are less sensitive to shadow detail than highlight.

The second method is to use a technique call High Dynamic Range (HDR). In HDR, multiple images of the identical scene are recorded, each with a different exposure. The different frames are combined into a single 'HDR' image. Since this isn't practical when photographing models so we won't look at it further but it's worth mentioning.

Lighting the Scene

Light is of course a vital - and varying - factor. A small change in the light can have a profound affect on the range of tones in the scene.

The best light for digital photography is morning and late afternoon, or when it's overcast. The difference between the lightest and darkest tones are much more likely to be within the sensor's capabilities.

The worst lighting is invariably midday sun, because of the combination of deep shadows and bright highlights can exceed the dynamic range of the sensor. If the light is bad, then put the camera away until the light improves.

With this in mind, let's move on to some specific techniques.

Exposure systems are stoopid! Well, almost.

Your camera's metering system is pretty simple in the way that it treats an evenly lit scene: it tries to make all tones a neutral grey. So if you take a bright sky on its own, then the shot will come out a muddy grey. And if you take a dark sheet of paper, again, it'll come out gray. The camera, being dumb, doesn't know that a cloudy sky should really be brighter, or that a black sheet of paper should come out darker.

Consequently, you the photographer may have to intervene to get the results you want. Let's see how.

Shooting a model against the sky

The classic problem is the "model-against-sky" shot . This photo of Andy Blackburn's Mig shows the issue - there's very little detail in the model, because the meter is being overly influenced by the much larger expanse of bright sky. It's made the sky gray, and the plane even darker.

There are various techniques to deal with this. The first, and the one I use, is simply to add +1.5 or +2 EV exposure compensation via the dedicated button on my camera. The camera will say to itself "there's lots of bright sky. Usually I'd make it gray... but the user has asked me to brighten it". The extra brightness will not only make the sky more realistic, but also show some extra detail under the wing.

Be careful not to dial too much compensation though, otherwise part or all of the sky will end up pure white and all detail in the clouds will be lost. Most cameras have a highlight warning feature which indicates which parts of the image are 'blown'. Use the highlight warning, and the histogram, to help judge the correct exposure!

A variation of this technique is to point the camera at the brightest area of the sky, then add around +1.5 EV exposure compensation, and then lock the exposure (using the Exposure Lock facility on your dSLR). Then refocus on the model and shoot. By adding +1.5 EV, we push the camera into recording more light from the sky, just as in the last example. However, because the exposure is locked before capture with this method, this method is only practical if the light conditions are constant across the sky, and in time. If the light varies then the first method is better.

The third method is a bit of a copout but is the most reliable - just wait for a nice blue sky and shoot with the light casting directly on the model. The sky will form a less contrasty background. This photo (right) shows the same model taken later that day.

Before we leave the subject, a quick word about post processing. To retain detail in both the sky and the subject, try playing with the contrast adjustment in your photo editing package. Contrast is basically the separation of adjacent tones, the more contrast in a particular tonal range the more detail you can see in those tones. Often, reducing the mid-tone contrast will provide better results. Why? Because reducing mid-tone contrast paradoxically increases the shadow and highlight contrast (something the magazines don't often tell you!).

Lighting for people

Shots of people are often best taken in overcast light, in shade, or early or late in the day when the sunlight is more gentle.

In the shot on Mark Southall (left), the slanting evening sun has caught the folds in Mark's clothing. Note how the gentle light has allowed some detail to be retained in the shadows.

 

Lighting for objects

When photographing R/C equipment, it's doubly important to render shadow detail. No need for expensive flash setups, just shoot outdoors in cloudy/overcast light.

The shot of a Multiplex Evo RF module (left) shows the result. Notice the detail in the shadows.

 

P, Av, Tv... what mode to use?

All dSLR's come with at least three basic shooting modes: P (program), Tv(shutter priority), Av(aperture priority), and M (manual). In addition many dSLR's have special scene modes like Landscape, Portrait, Action etc.

For general shots my camera stays on P so the camera decides on a shutter speed/aperture combination. It's good for those quick grab shots.

For shooting models in flight, I use either Av or Tv mode, forcing a fast shutter speed. I also the focus mode to 'continuous' so focus follows the model.

For portraits I use Av mode and a large aperture (small F-number) to isolate the subject by blurring the background.

 

Polarising Filter

Polarising filters are very useful for deepening the blue in a sky. The only downside is that they soak up about 1 - 2 EV of light. You therefore have to slow the shutter speed, or choose a wider aperture. This makes them less suitable for flying shots. However they are a great way to add some bite to skies in static scenes.

The shot on the right of Frank Hulton's 'Falcon' was taken using a Hoya circular polarising filter (cost ~£15).

Nowadays a similar effect can be achieved in some editing packages - the tool is usually called 'vibrance' (a more refined version of 'saturation' adjustment, because it affects some colours more than others).

More Shooting Technique

Shots of models in flight have more impact if the pilot is included in the shot. To achieve this requires effective communication between pilot and photographer and preplanning.

The first job is to choose a suitable location for the shot, normally one or other side of the slope - depending on the light.

Here, Andy Ellison (standing on the left) is flying his Mach 1. What it doesn't show is the rather loud communication going on as I tried to get both the model and Andy in the frame. Andy had to fly several passes before we got the shot.

Reducing Blur

To help reduce the effects of camera shake, or when following a fast moving model, consider increasing the ISO setting to 400 or 800. Increasing the ISO setting effectively increases the sensor's sensitivity, thus allowing a shorter shutter speed to be used.

Each doubling of ISO allows the shutter speed to be halved, so a shutter speed of 1/60th at ISO 200 becomes a much faster 1/250th at ISO 800. This can make the difference between a blurred and an acceptable shot.

There's no such thing as a free lunch of course, and the price is increased image noise. Normally for a dSLR, ISO 800 is a reasonable limit. With a point and shoot camera, anything about ISO 400 may show unacceptable noise.

Photo editing

These days, I shoot all my images in RAW and convert them to JPEG on my PC. However it's perfectly possible to get good results using JPEGs straight out of the camera.

Either way, most images benefit from some tweaking of contrast, saturation etc. No need to go to the expense of Photoshop though, Google's Picasa is a superb image editor and organiser which also happens to be free. See links below.

Finally

I hope this has stimulated you to take a camera to the slope and start shooting. I promise it will add some extra fun to your flying sessions!

Links