crash course 4: exposure and focus

How I expose an image and where I focus in it is just as important for me as its composition.  It can completely change the look and dynamic of any scene and is vital in conveying mood or a sense of how I’m feeling at the time the image was taken.

I shoot all my images in "raw" picture format as this ensures I record all the information my camera's sensor "sees".  Shooting jpegs means the camera processes the file and discards some of the information originally recorded.  Shooting "raw" allows far more leeway in editing images at a later stage too.

There are five elements to consider when exposing for ambient light or how you want to artistically convey your image:

- aperture

- shutter speed

- ISO
- white balance

- metering mode.

I shoot the vast majority of my landscape images in “Aperture Priority” mode.  This means I choose the aperture I want and allow the camera to decide on shutter speed depending on the metering mode I’ve chosen.

Also, regardless of the length of the exposure, 99% of my images are shot using a tripod.

Aperture:

Larger apertures (say f2.8) along with the type of lens and distance from any foreground will result in a shallower depth of field, isolating the in-focus part of the image from the rest of it.  This is particularly useful where you want to attract the viewer’s eye to a particular part of an image.

Here, I wanted to isolate the lighter, golden leaves from their darker, verdant background so shot the image at f4.  This has the effect of slightly and ever so subtly blurring the background and focusing the eye on the main subject, the leaves.

Larger apertures also mean the camera lets in more light, giving faster shutter speeds.  As I wanted to make sure the leaves above were sharp despite a breeze blowing through the woods, the larger aperture helped facilitate this.

Normally though, I want to get as much of my image as possible in sharp focus.  To achieve this, I usually shoot at smaller apertures of f8 to f11 on my X-T3, and f14 to f16 on my GFX50R.  This usually results in a far greater depth of field.

The above image was shot at f11 on my X-T3 and 10-24mm lens at 10mm, ensuring that the entire image is sharply in focus.

I avoid really small apertures (f14 and f18 upwards on my X-T3 and GFX50R respectively).  Using these can result in diffraction: an effect causing loss of sharpness and is best avoided.

Shutter Speed:

Shooting in aperture priority means that my camera chooses a shutter speed to accurately expose the scene it sees.  However, this may not always convey what I want to artistically achieve in the image.  Quite often I want to employ a slower shutter speed to show a sense of motion in an image particularly in moving water or fast-moving clouds.

To do this I switch to full manual mode.  If the slower shutter speed results in the image being over exposed, I might lower ISO to below the camera’s “native” limit or employ a filter.  More of that next time though.

I got very lucky with this scene, as it was dead calm at ground level, but the high-level clouds were being blown along at a tremendous rate.  Slowing my shutter speed meant I could convey that movement and the juxtaposition between the ground and the sky.

ISO:

This largely relates to old film speeds which were measured in ASA.  Films with higher ASA values were more light sensitive, making them ideal for use in low-light environments or for getting faster shutter speeds.

The same is true of ISO.  Higher ISO values mean the camera’s sensor is more sensitive to light.

However, as it’s rare for me to shoot landscapes in low-light situations and without a tripod, or to want to artistically add grain or noise to an image, I tend to leave ISO fixed at my camera’s lowest native setting (100 on my GFX50R and 160 on my X-T3).

In general I never touch these settings as I want to retain as much detail and image fidelity as possible, and increasing or “bumping” ISO can introduce unwanted noise into an image, removing detail and contrast in the process.

Therefore, I will only increase this to achieve a faster shutter speed as a last resort.  An example is in the image of the beech leaves above.  As it was quite windy and I wanted the subject (the leaves) to be as sharp as possible, I increased the ISO to 800 affording me a faster shutter speed.

White Balance:

Getting the white balance correct is important if you want your images to look true to life and resemble the scene you’re shooting.

Imagine shooting a wedding and getting the white balance wrong.  The bride’s white dress would look grey, or blue, or yellow even.

For my landscape shooting, I set the white balance in my camera to a colour temperature of 5600 kelvin.  This gives a great starting point as it will cover the majority of conditions you shoot in from cloudy to sunny, and make editing later a breeze (as long as you’ve shot in raw!).

Cameras do a great job with auto white balance too.  I don’t use that though as it can result in a variance of looks within a series of images as the light changes.  This is particularly important when shooting a series of images to stitch together as a panorama (or when shooting video), where changes in look would be very difficult to overcome and result in a very strange looking image or movie.

Metering Mode:

My camera has a number of metering modes which help to expose a scene accurately or get creative.

I tend to leave it on evaluative metering most of the time, meaning the camera meters the entire scene and applies an exposure to get the most dynamic range possible.

Here the camera has metered this very difficult scene well, with no extreme highlights or shadows.

It might sometimes be necessary to manually adjust the camera’s exposure – by introducing exposure compensation.  A classic example is in a snowy scene, where the bright snow will force the camera to under expose the image, making the snow look grey.  By dialling in 2 stops or so of positive exposure compensation though, this can be overcome.

Sometimes though I may want to isolate say a bright area of a scene, and to do this I’ll switch to spot metering.  This means the camera takes a meter reading and exposes from the point at which I’ve focussed the camera.

For this image of some bright, white wild garlic I metered on the brightest part of the scene, resulting in a faster shutter speed and throwing the green background into almost total darkness.

Putting all the above into practice will make sure you get the picture you want.

Focus and focal point:

Shooting a “normal” landscape image with a wide-angle lens and aperture of around f11, focusing pretty much anywhere in the scene will result in most of it being in sharp focus.

But to attain peak sharpness I find that focusing either a third of the way into my scene (the hyper-focal point) or at a point close to infinity achieves this.

Sometimes though, where I have a scene with a prominent foreground element leading into a vast scene, no matter where I focus will give enable 100% sharpness.  To overcome this problem, I will usually shoot two images – one focused on the foreground element and the other on the background and combine them in Photoshop.

To get all of this image in sharp focus, I shot one image focused on the closest rock, and another further back on the lighthouse.

When using telephoto lenses though, more care needs to be placed on accurately focusing on the scene, as by nature they offer less depth of field.

The beauty of digital landscape photography though, is that as long as you are not rushing to capture great light you can shoot different exposures at different focal points until you achieve your desired result.  Just shoot, practice and learn from your mistakes!


Long Exposures:

A lot of my images employ a long exposure - opening the camera's shutter for an extended period of time to convey movement or drama into a scene, or when shooting in low light situations.

If you want to shoot sharp long exposures (and admit it, you do!), there are some steps you need to take to ensure pin-sharp images.

- use a sturdy tripod
- make sure everything on it is tightened down so neither it or the camera can move
- use the thinnest lower legs last as they are the least stable, and avoid extending the centre column if you can
- place one tripod leg in line with your lens
- in really windy conditions, get down as low as you can
- on soft ground, place a CD under each tripod foot to spread the load and stop the tripod from sinking
- if your camera or lens has some sort of stabilisation system switch it to OFF
- use a remote shutter release or the camera's built in self timer to trigger the shutter
- do not touch the camera or tripod during the exposure time
- if you're on soft ground (e.g. wet sand) place something like a CD under each tripod foot to spread its load more evenly
- if you're using a DSLR, use something to cover the viewfinder to stop light leaking into your exposure
- again, with a DSLR, shoot in Live View or, if it has it, "mirror up" mode.

Long exposure photography heavily relies on the planning and scouting phase.  I want to arrive in plenty of time with prior knowledge of where I want to shoot from so I'm not rushing around.  Sometimes, with a very long exposure, I might only get one chance to get the shot I want - so planning is crucial.