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Camera Settings for shooting Aerial Photography - Part I
First published 17 January 2016
This article concentrates on shooting images from a moving platform e.g. a drone, kite or a mast. However steady your platform appears to be, there will always be movement and just setting the camera to auto will not work. The article is aimed at those new to aerial photography and also those that still use their cameras on Auto mode. Nothing wrong with that, if I have to grab my camera for a quick shot, full auto is the fastest solution. However, if you have the time available, some effort will produce better results.
I do not profess to be an expert photographer and I'm always learning. if you have any tips or suggestions (or corrections....), do let me know in the comments box, below. However, this is what I have worked out during my flights. It's not a very long article and it assumes no knowledge beyond how to turn a camera on and take a simple shot.
It goes without saying that you are using a camera that is capable of having different modes set. If not, move on, nothing to see here. Just set it to Sports Mode and click away.
Topics to be covered
- The basics of taking a correctly exposed shot (Part I)
- The Magic Settings (an introduction to what settings affect exposure) (Part I)
- JPEG or RAW? (Part I)
- Adjusting the exposure value (ev) (Part II)
- Using High Dynamic Range (HDR) (Part II)
The basics (sort of)
When you press the shutter to take a photograph the camera opens a window (the aperture) to let a certain amount of light fall onto a light-sensitive area of an electronic circuit. This area is made up of a grid of detectors that each measure the amount of light and its colour. The circuit and camera automatically save this information along with the detectors' positions on a bit of memory on your memory card. This information can be read by a computer and the picture can be reproduced on a screen or onto print material.
Light might look like it's a constant stream, but it is in fact made up of individual packets of light (photons). The more photons, the brighter the light.
How many photons fall onto each detector depends on the brightness of the light coming in from the source in the first place, the size of the aperture letting in the photons and the length of time that the camera opens the aperture for (shutter speed). Each detector then converts these photons of light into electrons that can be counted. More photons = more electrons = a higher count so a brighter point of light is recorded.
Bear with me, I'm getting to the point....
The Magic settings
When you put your camera on to a fully automatic mode it will monitor these detectors and try to ensure that the right amount of light comes in. Too little and everything will look black (underexposed picture). To much and everything will be white (overexposed picture). It will adjust one of three parameters to try and achieve this balance. The three parameters are
- Aperture size. The bigger the hole, the more light is let in.
- Shutter speed, or how long the aperture is opened for. The longer that it is open, the more light that can get it.
- ISO rating. What this does is to adjust the amount of light needed to come in to get an average reading. We'll tackle this later but for now, a higher ISO number means that you don't need so much light to make a picture.
So, in Auto mode, it will sense the light coming in and (for instance) if there is not enough, it will open the aperture more or slow the speed down to get more light in. It tries and keeps the values to reasonable levels. If the speed is too slow, anything moving might get blurred. If the aperture is too wide, then not everything will be as in focus as it could be. However, you can see that it is a balancing act and what it thinks is best might not always be best for you.
As well as fully auto mode, modern cameras also have different user settings - e.g. 'sports', 'landscape', 'close-up'. If you use these modes, your camera is still automatically adjusting the parameters, but you are telling it to favour one setting over another. For example, in sports mode, it will keep the shutter speed a bit faster than Auto (at the expense of the aperture) to reduce the amount of blurring of anything moving. Note that the camera still has the final say.
The next step up from the user settings are the A S and P modes. This is where it starts to get interesting.
'A' mode allows you to set the Aperture size and the camera will adjust the
speed to keep the exposure in balance.
'S' mode allows you to set the speed and the camera will adjust the Aperture size to keep the exposure in balance.
'P' mode allows you to adjust both of these on a sliding scale using a rotating dial. The camera will automatically keep the exposure in balance. As you turn the dial one way, the shutter speed gets faster and the aperture enlarges to compensate. And vice versa.
Finally there is the 'M' mode
'M' mode allows you to adjust both of the settings independently, but it will not keep the exposure in balance. It is down to you to make sure the exposure is what you want. Note that the cameras have a built-in exposure meter and readout on the screen so you can see whether your picture is going to be over, under or correctly exposed.
|Nikon D5100 Dial Settings||Panasonic GH4 dial settings|
So, what should we use for aerial photography? Well you can probably guess that I'm not a fan of the Auto or semi-auto modes. You just cannot control anything and you are at the whim of the camera. It might choose a relatively slow shutter speed, in which case you run a high risk of blurred images, for instance.
Similarly, unless you have remote control of your camera settings, 'M' (Manual) mode is no good. Whatever you set on the ground will have no bearing on the exposure needed in the air.
'P' mode gives you a bit more flexibility by being able to adjust other parameters such as ISO and Bracketing (if available) but this is more useful when you have the camera in your hand (or on a tripod) since you probably can't play with the settings once it is in the air.
This leaves 'A' (Aperture priority) and 'S' (Shutter priority) modes. When I first started, the camera was a Panasonic Lumix LX3, which was a fairly simple compact camera. Limited options and, worse, the camera gimbal had minimal damping and zero levelling, so whenever the drone leant in any direction, so did the camera. The only way to minimise the shake was to set the aperture as wide as possible on 'A' mode so that the camera maximised the speed. This works reasonably well provided that you keep an eye on everything.
To cut to the chase, I permanently use 'S' mode nowadays. That way, I can control the shutter speed and keep it at a suitably high value. Then, by adjusting the Aperture and the ISO, I can get the exposure into an acceptable range. With my old camera mount, I aimed for a shutter speed of 1/1000s, but my current mount is much better behaved and 1/500 give me either a bit more depth of field or a lower ISO number, so less grain. I know of some operators that work on 1/250s. I wouldn't recommend anything slower than that as, however stable it seems, it is still not a tripod up there.
JPEG or RAW?
For the beginner, this means the format that is used to store the image on the memory card. In short, images take up memory on the card, so the smaller the size of the image, the more images that can be stored on a card. JPEG is a way of compressing an image so that it takes up less storage space. It finds areas of the image that are the same colour and uses formulae to represent this using less memory. It comes at a price, however, as some of the original detail of the image is lost and cannot be recovered. If the images is edited and resaved as a JPEG, then a bit more information will be lost.
Often this does not matter. For snapshots and low resolution images, this is absolutely fine. However, if you are working at the high end of the market and are editing the images to any extent, you really need to be starting with the RAW image, which holds a lot more information about the image. Once editing is complete, then you can convert it to a JPEG for the end user. The main downsides of using RAW are:-
- A much larger file size, so fewer images can be stored.
- Not all image viewers will actually display RAW images (Web Browsers will not, for example)
- A larger file means that it takes longer to save the image to the memory card so it takes longer between shots (although in practice, cameras have memory buffers and can save the images there before writing to the card and carry on taking pictures. Eventually the buffer will fill up and the repeat rate for taking shots will then slow).
So, what's the answer? Here's what I do. Firstly I always ask the Client what they want. If they are not sure, I'll explain the options, but the chances are that if they don't know then JPEG will be fine.
I shoot in JPEG when I am practising or I have agreed with the Client that they want JPEG. Estate Agents (Realtors) for example will usually only want JPEG as they are not doing much with the images and won't have the software to process RAW.
I shoot in RAW when dealing with a Client that will be manipulating the image afterwards (e.g. for Computer Generated Images - CGI).
I occasionally shoot in JPEG AND RAW when we need a quick and dirty way of viewing the images on location before manuipulation later. However, this slows the camera down and takes up additional storage - especially when shooting HDR (See later article) as that will mean 6 images are saved for each shutter press!