Photographing R/C Models

Mike Shellim

Last updated 10 January 2010

Airworld Fox (Ivinghoe Beacon)

In this article I will describe some key points in photographing model aircraft, including camera choice and shooting technique. All of the techniques described have been developed over many years of shooting models for the photo gallery.

Choice of camera

Taking photos of a model is easy enough when it's still. However the task becomes a whole lot more difficult when the model is in the air because of a number of factors. The model

Under these circumstances, a digital SLR is a better tool than a P&S (point and shoot) camera. The advantages of dSLR's are:

A P&S camera will still be capable of reasonable results if operated within its limitations. In particular it will work best in a narrower range of light conditions, and freezing action may be more difficult.

Megapixels - fact and fiction

Cameras tend to be priced according to the number of pixels recorded by the sensor. In theory the more megapixels, the greater the detail which can be reproduced.

Things are not so simple however, because there are various factors which limit the amount of usable resolution. Let's deal first with printed output.

A typical inkjet printer deposits 300 dots of ink along each inch of the page. Plugging in the figures for a 12 inch x 8 inch print, you need a camera with at least 9 megapixels to reproduce all the detail that the printer is capable of providing.

That is the theory. In practice, there are other limiting factors. Above a certain viewing distance, an average pair of eyes will not be able to resolve all the detail in a 300 dpi print. At 150 dpi, a 12x8 print at 150 dpi requires just 2.25 megapixels. If you looked with a high power loupe at two 12x8 prints, one produced by a 9MP camera, and one produced by a 6MP or even 4MP camera, you may notice less detail but in normal viewing conditions, there will be little or no difference.

For images intended to be viewed on a computer monitor, there is even less benefit in higher MP sensors - a 1280 x 960 monitor requires less than 1.5 MP. This is certainly worth bearing in mind if don't intend to print your images much.

What happens to all the 'wasted' pixels recorded by your sensor? They simply get averaged out in the process of 'downsizing' the image to fit the output. This downsizing can take place in a number of ways: in your display software (e.g. Windows Image and Fax viewer), in the printer driver, or under your own control in your image editor (e.g. Photoshop).

The upshot is that for images up to A4 or 12x8, 6 or 10 megapixels is entirely sufficient. If you print at A3 and above or if you do a lot of cropping, then 12 or 14 megapixels become worthwhile. However if you're really serious about high quality A3 output, there are many further issues to do with workflow, post processing, and colour management which means you probably shouldn't be reading this article.

So what to buy?

If your budget is limited, entry level dSLR's are so good these days that there's no need to go for the more expensive models. Also there are some good 6 and 10MP digital SLR cameras available second hand at very reasonable prices.

My own camera is a Pentax K100D Super with a 6 megapixel sensor. It's a small, light and relatively cheap dSLR which fits easily into the backpack with the transmitter and other flying gear.

Composition Tips

Many potentially good pictures are spoilt through poor composition and/or attention to detail. Just moving the camera a foot or two can make the difference between a pilot impaled by a fencepost, and a pleasing composition.

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

Capturing detail

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 (some post processing may also be necessary). 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 brightness in the image. The horizontal axis represents brightness levels from pure black at the LH end to pure white at the RH end, with the intermediate shades of grey in the middle. The number of pixels at each brightness level is represented by the height of the histogram.

Most importantly, the histogram tells you if there are areas of over- or under-exposure. These will be indicated by spikes at either end, representing pixels which are solid black or solid white. Overexposure is particularly to be avoided, and most cameras have a 'blinking hightlights' in addition to the histogram. Overexposed areas will flash rapidly between black and white.

No amount of tweaking with a photo editing package can ever reveal any colour or texture in the solid whites or blacks. A correctly exposed shot is simply one where the histogram has a gentle roll off at each end.

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. (Actually it does roll off, but very sharply).

CORRECT EXPOSURE - the histogram shows a gentle roll-off at each end, so the final image will show detail across the whole tonal range

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.

High contrast scenes

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 with bright, directly lit objects accompanied by deep shadows.

To obtain detail in both the highlights and shadows is by definition impossible under these circumstances. Usually, the best compromise is to sacrifice shadow detail by underexposing. This will generate a spike on the left of the histogram, while allowing the highlights to roll off gently. This is OK because human eyes are are less sensitive to shadow detail than highlight.

Sometimes however, shadow detail is crucial to the shot, e.g. if taking a photo of a R/C installation. In this case, it may be better to 'blow' the highlights which are not part of the main subject. This where the judgement and experience of the photographer comes into play.

Another method which I'll mention just briefly is a technique call High Dynamic Range (HDR) photography. 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, thus compressing the very wide tonal range. For obvious reasons, this isn't practical a practical method for moving objects, so we won't look at it further. (Don't confuse proper HDR with the horrid 'HDR-effect' filters provided in some cameras.).

Histogram operation

With older dSLR's, you can only view the histogram after the image has been captured. However with point and shoot cameras and dSLR cameras with 'live view', the histogram can be used to check the scene before capture, so the photographer can alter the exposure settings before capturing the scene.

If you're not familiar with the operation of the histogram, do take a look at your camera's manual.

Lighting the Scene

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

The best light for outdoor photography is generally when it's slightly overcast. On a sunny day, it's best when the range of brightness is within the sensor's capabilities, which is generally morning and late afternoon.

The worst lighting is invariably midday sun, because of the combination of deep shadows and bright highlights. 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! Yes, really.

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 a shot of just bright white clouds will come out darker. A sheet of dark grey or black paper, will come out mid-grey. The camera, being dumb, doesn't know that the cloud should really be brighter, or that the black sheet of paper should be darker.

Consequently, you the photographer will have to intervene and adjust the exposure yourself!

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. The metering has rendered the sky as a mid-tone, leaving the plane almost in shadow.

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 grey... 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 you'll end up with the opposite problem - 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 together. The histogram tells you if the image is overexposed, the highlight warning tells you where.

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, it works well where the model almost fills the frame. However because the exposure is locked, and because the model is moving, this method is only practical if the sky is evenly bright. If the light varies across the sky, then the previous 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!). A detailed treatment of constrast management is outside the scope of this article, instead I strongly recommend the excellent tuturials at Cambridge in Colour (see link at end).

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 above ISO 200 may show unacceptable noise.

Post processing: RAW format, JPEG's and editing

I find it very rare that an image does not benefit from some post processing. In fact some post processing is usually essential to produce a really good image, irrespective of how expensive the camera is.

The three main tasks are:

No need to go to the expense of Photoshop though, Google's Picasa is an excellent image editor and organiser which also happens to be free. See links below.

For ultimate quality, photographers set their camera to RAW (if it's available). The resulting files are large, and contain the raw sensor data. Conversion to JPEG is done at leisure in an image editor. It's worth noting that Google's Picasa also supports RAW for many cameras.

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