of the critical techniques to master is
exposure. The definition of Exposure is the amount of light that reaches the
film and therefore involves three factors, two of which are under the direct
control of the photographer:
(a) Amount of light reflected by the subject, (b) Amount of light transmitted by the lens and (c) the amount of time that light is allowed to reach the film. The two factors (b) & (c) are directly controlled by the photographer by use of the aperture (b) and the shutter speed (c). If you use a flash gun then factor (a) can also be controlled to some extent by the photographer as well.
So let's see how this is put in practice.....
One option for the Aviation photographer is the 'old sunny 16 rule' This is a rule that's seen me just fine over the years. This rule states that (On a clear sunny day) the correct exposure should be the speed of the film set as the nearest shutter speed (i.e. 64 ASA Film = 1/60th) and the aperture set to F16 (See table for other combinations). To do this your gonna have to come out of program mode and into manual mode.
Now I hear you saying, 'That's fine in Nevada where it's very bright but what about in England where the sun isn't so bright?' Well I usually use the next slower shutter speed or higher F-stop, i.e. K25 Film, F5.6 and 1/160th instead of 1/200th.
Sunny 16 will give you a remarkably accurate exposure on a sunny day. With a little practice you will be able to adjust for cloudy, rainy, and evening conditions on the fly. Give it a try!
You can also see how accurate your meter is by comparing what it says to what the Sunny 16 Rule tells you to do. If there is a big discrepancy, have your meter adjusted.
Sunny 16 Rule (1/3rd Stops)
|F Stop||K25 Shutter speed||K64 Shutter Speed|
Locking the Exposure
Before we discuss ways to lock the exposure, we need to find out what to take a light reading off. What we need is a good average tone, being lit by the same light as the subject. One way is to meter of a photographic grey card (These can be purchased at most specialist camera stores) Another way (and probably much more applicable) is to point the camera at the horizon and meter from approximately 2/3 ground, 1/3 Sky. If you do this right, you'll probably find the meter readings are pretty close to the 'sunny 16' table above (if of course it's a clear sunny day).
Now this is fine if the subject aircraft is an average tone, i.e. a grey or maybe sand/brown camouflaged aircraft (and as we all know, living in the year 2000, most modern military aircraft are exactly this colour!) But if the subject is a lot brighter or darker than our average tone, then we need to adjust our meter reading slightly. What in effect were doing is to slightly overexpose the darker aircraft and underexpose the lighter one's. So say were shooting our friend the European One A-10 again then we need to meter off something a bit darker, maybe 3/4 ground, 1/4 sky or using the 'grey card' to get an average exposure, and then adjust either the aperture or shutter speed. Which brings us nicely to how we lock the exposure...
One way is to do this is, switching the camera to manual and adjust either the aperture or shutter speed, whilst metering of our chosen average tone. Another way is by using a feature of most cameras, the exposure lock button. So let's go back to our earlier example...
Most exposure metering systems work on the premise that every scene or picture contains an even amount of tones, so for example if you was to photograph a wall painted white, it's more than likely in the resulting photo the wall would appear grey. The same situation applies to a black painted wall, the camera's metering system would attempt to render the wall a mid grey colour. Now if the wall was painted a Mid Grey (Yeah..Lots of work for Painters & Decorators going about!) the resulting photo would turn out correct.
What's happening here is the camera's exposure meter is assuming wrongly (Have you ever tried to argue with a light meter) that the white wall is mid grey but it's just very bright and visa versa with the black wall, it's still mid grey but someone's turned out the lights!
Bottom Line. The Camera's exposure meter ALWAYS assumes the scene/subject/picture is a mid-grey/average tone. The other thing to keep in mind is that's there's no such thing as a correct exposure (unless your photographing a grey aircraft against a grey sky) it will always be a compromise between overexposing and underexposing.
For a final example, let's look a typical aviation photo opportunity....
Typical summers day, blue sky with clouds, unbroken sunshine. Subject is a European One scheme A-10 on approach. The A-10 fills probably about a quarter or third of the screen, blue sky/cloud's the other three-quarters/two-thirds. Now the light meter looks at this scene decides that it's too bright (That's the sky acting like the white wall) and adjusts the camera/lens (i.e. Increases the shutter speed or shuts down the aperture depending on what mode your cameras in) What the resulting photo looks like is this, quite well exposed sky, maybe the clouds are a touch dark but an underexposed A-10.
Now I know what your gonna say...but the A-10 was dark like maybe that black wall, shouldn't the metering system have made it come out like grey or what? Well no.. as stated above the meter is averaging the overall scene and there's more sky than aircraft. If you had zoomed in close (with that new 100-400 5.6 lens you just got), with no sky in the shot, then you would get the black wall scenario, but that doesn't solve the problem either, as the meter would attempt to turn the A-10 Mid grey (Which would be fine if it was a Ghost grey scheme A-10 but not our dark European one scheme)
We'll come back to this example later after we see how we can solve this problem.
Partial or Spot Metering
Partial or spot metering enables you to keep the camera pointed at the subject and eliminates the 'metering of average tone/recompose shot method' I'll quickly explain what Partial and spot means..
Partial metering mode normally uses a medium size circle in the centre of the viewing screen for its exposure reading, rather than the whole viewing area as normal.
Spot metering mode uses an even smaller circle (or 'spot'!) for it's exposure reading. Also on most cameras with these modes, the reading is locked when you depress the shutter button 'half way'
I personally think that Partial mode is the more useful one of these, as the exposure area would normally cover a good percentage of the subject but also include some sky, which gives us our nice average tone were after. Spot on the other hand, because of the very small exposure area, will only be metering off the subject and (unless it's a mid tone) if it's either a very dark or light tone will confuse the meter into over/underexposing the subject.
Well that takes care of the exposures on bright sunny days, now what about British/European summertime...No sun, cloudy, raining etc. (American's can stop reading and go get themselves a beer whilst I cover this!!).
I'm tempted to say if it's overcast don't bother getting the camera out! especially if your shooting to trade and/or sell your slides (Everyone wants clear sunny slides! If your reading this and are happy to receive overcast badly lit slides, please get in touch because I've got plenty of shit...sorry I mean arty and atmospheric slides available!!) but we all shoot in bad light. The reasons for this are probably among these:
Its a very rare/special/unusual aircraft
I'll just take a couple of shots just in case the light gets worse
10 minutes after reason above, Ummm it's got brighter, I'll just take a couple more ( It's not got brighter, but were getting desperate!)
I've travelled a long way and/or paid lots of money, I'm going to take photo's if it kills me!!
And in every case, you'll get the slides back and think "WHAT THE F#*K DID I SHOOT THAT FOR!!!!"
Sorry I'm drifting of the point...shit what was it again? ah yeah what exposure should I use in overcast conditions? Well you could try adding 1 F stop to what ever your light meter says, for example Meter says 1/125th at 5.6, you use 1/125th at 4.0. or you could add 2 stops or spot meter from the aircraft and add 1/2 stop or..... Yeah you've guessed, Exposing film in conditions other than very bright sunlight comes under the heading of...(Drum roll, please) EXPERIENCE!!!!
The next time it's overcast or cloudy or raining or anything except perfect over your shoulder sunlight, go out and shoot something (No Please not the weather forecaster!!!, I mean shoot as in expose film using camera!!) take a shot using your light meter, then add a stop/take a pic, then add another stop/take a pic etc. etc. Make a note of what you've done and then compare the shots and see which one you prefer.
that's all I've got to say on the subject, except my vote goes to the first
choice and that is...
If it's overcast DON'T GET YOUR CAMERA OUT!!!!!