Aviation Photo Technical Presentation

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Aviation Photo Technical

A presentation to the Stansted branch of Air-Britain by
Nick Challoner

The notes below are my thoughts. If yours differ, that is perfectly ok! There’s usually more than one way to do it when it comes to photography. But hopefully the thoughts
below will be of use, and if nothing else prompt you to experiment with your photography (something that costs nothing other than time with digital photography).

Histogram

• Extremely useful
• Graphical representation of the tones (lightness) in the shot
• Immediately accessible after each shot is taken
• Avoid chopping
• Use exposure compensation

The histogram is a chart of the tones (lightness) in a shot, from black on the left side to white (right side). If the graph is chopped off at the left hand edge it means
the shot is underexposed. If the graph is chopped off at the right hand edge it means the shot is overexposed. Both situations should be avoided. This can often be done by
setting exposure compensation. It could also indicate that the camera settings cannot deal with the light conditions (e.g. trying to shoot in a dimly lit environment with
a high shutter speed and a low ISO setting), so those settings should be modified.

This image is correctly exposed. Notice how the chart is positioned within the chart area. It may be a model, but it is Stansted related!

This image is underexposed. Notice how the chart is positioned to the left with some values chopped off.

This image is overexposed. Notice how the chart is positioned to the right with some values chopped off.

ISO

• Equivalent to film speeds (used to be called ASA!)
• Same as volume control on an audio amplifier
• Audio hiss = image noise
• Use lowest ISO possible (usually 100)
• Be prepared to increase on cloudy days when shooting flying at high shutter speeds (200 or 400)

In digital cameras, ISO is effectively the amount of amplification applied to the electrical signals generated by the digital sensor.
This is beneficial in low light and/or when using high shutter speeds.
However, in the same way audio amplifiers produce hiss as the volume is increased, digital images suffer from noise (similar to film grain) when the ISO is increased.
Therefore it’s usually best to use a low ISO. 100 or thereabouts is often the lowest.

Focussing

• Depth of field
  • How much of the image in front of and behind the focus point appears to be in focus
  • Smaller aperture = more depth of field
• Lens sweet spot
  • Best lens performance
  • Typically f8 to f11

A smaller aperture (e.g. f22) will result in most of a scene being in focus (both objects close to the camera and those far away). This is often useful for landscape shots,
or shots where both the main object and the background are required to be in focus.
A larger aperture (e.g. f4) will result in objects only at the focussing distance being in focus. This is often used in portrait shots to draw attention to the subject (because
everything else is blurred).
In aircraft photography, the most important thing is usually to ensure the entire aircraft is in focus. However, different parts of the aircraft can be at significantly
different distances from the camera. Therefore a large aperture will often result in part of an aircraft being out of focus (not by much perhaps, but slightly blurry). Therefore
an aperture of f8 to f11 often yields good results.

Lenses have a sweet spot where they perform at their best (producing the sharpest shots etc). This is usually between f8 and f11.

Focussing – Static

• Don’t use multi-point – will lock on to closest point (e.g. wingtip) rather than the fuselage
  • Select a suitable focus point
  • Use the centre focus point and focus lock. This May also lock exposure – not usually a problem but it can be over-ridden (check histogram!)

When multi-point focussing is in use, the camera will typically focus on the closest object it can find. This is because the closest object is often the one being photographed
(e.g. portrait of a person).
This often isn’t the case for aircraft, e.g. the wingtip will often be much closer than the fuselage when photographing an aircraft side-on, but the fuselage is more important.
One option is to manually set the focus point to use for each shot. That works well, but can be a fiddly. The alternative is to just use the centre focussing point and focus lock.
Point the centre focussing point where the focus is to be set (e.g. somewhere on the fuselage), partially depress the shutter button, keep the shutter partially depressed and
recompose the shot, then take the photo. Keeping the shutter button partially depressed locks the focus, so it doesn’t change when the shot is recomposed.
This may also lock the exposure, which isn’t usually a problem. Checking the histogram after taking the shot will indicate whether or not the exposure is acceptable. If not acceptable,
use exposure compensation, or use the dedicated focus lock button if the camera has one.

Focussing – Flying

• Use a single focus point – faster
• Usually the centre point – better performance
• Switch to multi-point for formations
• Use tracking/predictive AF mode (Canon: AI Servo, Nikon: AF-C)

If multiple focus points are in use, the camera has to try and focus each one, then decide which one is focussed on the closest object. This takes time; not much, but with a fast
moving aircraft it could mean the difference between getting a good shot and not getting one at all. If just a single focus point is in use, the camera has to do much less work
and is therefore faster to focus. Usually the centre focus point is the logical choice. Because of this, the centre focus point is often made more sensitive than the others, making
it even faster and more accurate. Switch to multi-point for formations because often the centre focussing point will not be over one of the aircraft.

Many cameras have tracking/predictive autofocus, which is very useful for photographing flying aircraft. The tracking system enables the camera to continually refocus on an aircraft
as it is flying along. There is a slight delay between pressing the shutter button and the camera taking the photo. This is in the order of 0.1 of a second, which isn’t really
noticeable, but could mean a fast moving aircraft going out of focus. The predictive system allows the camera to use data it has gathered on how the subject is moving to decided
where it will be when the shot is taken, and focus accordingly.

Exposure Settings – Static

• Aperture priority (Av)
• Use f11 for good depth of field and lens sweet spot
• Use f16 or f22 if shooting along the length of an aircraft
• Use image stabilisation if available
• Ensure shutter speed doesn’t drop too low (reciprocal rule)
• Consider using shutter priority (Tv) and a slow shutter speed to capture propeller discs

The aperture setting is the most important setting when photographing static aircraft, so set aperture priority mode (Av). In general, use f11 because of the lens sweet spot and to ensure
all parts of the aircraft are in focus. If shooting along the length of an aircraft, use a smaller aperture because there will be a big difference in distance between the closest
and farthest parts of the aircraft, therefore a large depth of field is required.

The reciprocal rule states that a lens can be hand-held with the shutter speed set to at least 1 divided by the focal length of the lens. Any slower and there is a good chance
that the shot will be blurred due to camera shake.
For example, a 50mm lens should be used with a shutter speed of at least 1/50th of a second, and a 200mm lens should be used with a shutter speed
of at least 1/200th of a second. Image stabilisation can help reduce these speeds, otherwise either increase the ISO and/or open the aperture a little.

If propeller powered aircraft (or rotorcraft) are running, switch to shutter priority mode (Tv) and set a slow shutter speed to ensure the blades/rotors are blurred. A very slow
shutter speed can result in a complete propeller or rotor disc being captured. Here are some examples:

G-EEEK, Extra EA200, Great Oakley, 11 October 2008.
ISO 100, 1/60th second set in shutter priority mode, f16 (selected by the camera), 17-85mm lens set to 50mm. Note complete propeller disc.

66-0215, Lockheed MC-130P Hercules, 67 SOS/352 SOG, RAF Northolt, 13 June 2010
ISO 100, 1/30th second set in shutter priority mode, f32 (selected by the camera), 17-85mm lens set to 59mm. Note complete propeller discs.

66-0215, Lockheed MC-130P Hercules, 67 SOS/352 SOG, RAF Northolt, 13 June 2010
ISO 100, 1/125th second set in shutter priority mode, f14 (selected by the camera), 17-85mm lens set to 61mm. Note nicely blurred propeller blades, but not complete discs due to the higher shutter speed than the shot above.

Exposure Settings – Flying

• Shutter priority (Tv)
• Minimum of 1/500th for jets (1/1000th better)
• Try and keep aperture around f8
• Be prepared to increase ISO in poor light
• 1/250th for props and helicopters
• Image stabilisation if panning mode available

A fast shutter speed is required to capture a sharp image. 1/1000th is best if the light/ISO allow it. Try to keep the aperture around f8 for the sweet spot.
Use 1/250th or slower to blur propeller blades and rotors.
Only use image stabilisation if it has a panning mode (often called mode 2 on Canon lenses). Not really of use when using fast shutter speeds, but can be useful when using
slower shutter speeds for props and rotorcraft.

Exposure Metering – Static

• Use “intelligent metering” (Canon: Evaluative, Nikon: Matrix)
• Check histogram after each shot!
• Consider exposure bracketing – but lots of work later

Intelligent metering often works well, but checking the histogram will reveal any errors, which can then be corrected using exposure compensation or by using a different metering
mode. Exposure bracketing can be very useful, but it can be a chore to check a days’ shooting when there are three times as many shots as there would otherwise be!

Exposure Metering – Flying

• Much more tricky!
• Intelligent metering can be hit and miss
• Try centre-weighted average with exposure compensation
  • +1/3 against blue sky
  • +1 against cloudy sky
• Regularly check the histogram to ensure good exposures and adjust as necessary
• Shoot test shots at regular intervals (e.g. light aircraft arriving at an airshow, or RYR 737s at Stansted!)
• Set back to normal for ground shots (e.g. when a display aircraft lands)

Of all the items in this discussion, this is probably the one that is best to experiment with. This is because there is so much variation in lighting when photographing flying
aircraft, and in how cameras decide to expose such scenarios. I have consistently found the above settings to work well.

Cockpit/Flight Deck

• Expose for the ground/sky outside
  • Use spot metering on grass (or other mid-tone area) then transfer settings to manual
• Use flash to “fill-in” the aircraft interior
  • Modern cameras very good at setting flash power automatically
• Vary shooting angle to avoid reflections from instruments
• Get permission from the captain before using flash!

The issue is there are two separate exposures to take account of: the relatively bright ground outside, and the relatively dark interior of the aircraft. Set the camera as
above to expose the ground correctly, and then let the camera set the flash to expose the interior correctly. Here is an example:

G-CCIJ, Piper PA28R-180 Cherokee Arrow, Andrewsfield, 5 June 2010.
ISO 100, 1/100th and f11 set in manual mode after spot metering the grass outside, 17-85mm lens set to 17mm.

Nightshoots

• Tripod
  • Obvious requirement; or is it?
• Remote release / camera timer
• Mirror lockup
• Protect from wind
• ISO 100 – best quality, but very long exposures
• More shots with a higher ISO
• Metering
  • Brighter than reality
  • Centre-weighted averaging with exposure compensation

A tripod is normally used because of the very long exposure times required in the dark. However, camera high ISO performance is now so good (hardly any noise) that it is possible
to hand hold using a high ISO. A remote release switch is best because pressing the camera’s shutter button introduces camera shake. The camera’s timer can be used instead because
the delay allows the vibrations from pressing the shutter button to subside before the shot is taken. Mirror lockup can be used to reduce the risk of camera shake from the mirror
moving up before the shot is taken (but not essential and best avoided by beginners to nightshoots due to the faff involved).
With ISO 100, exposure times can be in the order of 30 seconds. This could result in missing shots, so a higher ISO can be
used to speed things up. Make use of the histogram to ensure good exposure and compensate as necessary. Some examples, all with good rotor and prop blur due to the long exposure times:

XZ345/M, Westland Gazelle AH1, Army Air Corps, RAF Northolt, 18 October 2012.
ISO 100, 20 seconds, f8, tripod with remote release.

XX484/CU566 Scottish Aviation Jetstream T2, 750 Squadron, Royal Navy, RAF Northolt, 30 September 2010.
ISO 400, 2 seconds, f11, tripod with remote release.