Flash photography basics: every common question answered

jmeyer | Photography Tips | 05/02/2013 16:00pm

0 Comments

1234Next »

TTL? Rear Curtain Sync? Guide Number? All the flash photography basics you need to know are right here, as we answer all the common questions to all the common problems photographers have about using flash, as well as share some of our best flash photography tips.

Image by Rolfo Rolf Brenner

Sometimes my SLR’s flash pops up and sometimes it doesn’t. Why?
When you’re in fully automatic ‘green square’ mode, the small flash built into the majority of DSLRs will activate automatically when light levels are low.

However, in the advanced P, A, S, M modes you can pop the flash up manually whenever you like by pressing the button marked with a flash symbol.

This is useful for adding a little extra illumination, such as a brightening up an outdoor portrait. Bear in mind that you’ll have to stick with a shutter speed that isn’t faster than the maximum flash sync speed.

Maximum flash sync speed?
Despite the light from a flash being emitted very rapidly, you can’t freely choose the fastest shutter speeds your camera offers when you’re using a flash.

This is due to the way in which the two shutter ‘curtains’ inside a typical SLR work. These open and close to allow the imaging sensor to be exposed to light.

When you press the shutter-release button, the mirror flips out of the way and the first curtain opens to allow light to hit the sensor. This is followed by the second curtain, which closes across the sensor to end the exposure.

At very fast shutter speeds, the second curtain starts closing before the first curtain has finished opening – so the image is recorded through a rapidly moving gap rather than all in one go.

Because the burst of light from a flash is so brief, it would only be recorded on the narrow part of the sensor that’s clear of the curtains when the flash fires, and the exposure would be uneven across the picture.

The flash sync speed is the fastest shutter speed at which the shutter is fully open, ensuring that the exposure is even across the frame.

Historically, this has been 1/60 sec, but many current DSLRs take advantage of the fact that flash duration is extremely short and offer high sync speeds of 1/250 or 1/500 sec.

I’ve heard that I should use the built-in flash as a last resort. Is this true?
Yes and no. The trouble is that the small size of the flash unit and its position on the camera means that the light it produces is direct and harsh.

Other limitations include the risk of red-eye, due to the close proximity of the flash to the lens, and the fact that you need to be fairly close to the subject, as the Guide Number of a pop-up flash is comparatively low.

What’s the Guide Number?
The Guide Number (GN) is a measure of the maximum power of a built-in flash unit or a flashgun – the bigger the number, the more powerful it is.

The Guide Number = distance x f/stop at ISO100. We know – it all seems to be getting complicated again! Knowing the Guide Number is useful if you’re shooting with manual flash, because it helps you calculate the aperture you need to set, or the distance the flash needs to be from the subject in order to get a good exposure.

However, these days, exposure can be taken care of automatically by TTL flash metering.

TTL flash metering? Things really are getting complicated…
TTL – or Through the Lens – flash metering actually makes things easy! The latest ‘intelligent’ versions, such as iTTL on Nikon and E-TTL on Canon, fire one or more brief flash bursts or ‘pre flashes’ are fired before the main flash.

The camera registers the amount of light returning through the lens (hence the name), and then works out the right amount of light to pump out for the main flash exposure.

However, just like normal exposure metering it can be fooled by dark, light or reflective backgrounds, 
and you may need to adjust the flash exposure to compensate.

How do I alter the TTL flash exposure?
The camera will automatically control the flash exposure for consistent results in TTL mode, no matter what aperture or ISO or shutter speed (as long as it’s slower than the flash sync speed) you choose.

That is, as long as the flash has enough power to reach the subject. If you’re too far away, your flash-lit subject will appear too dark, and you’ll need to move the flash closer, choose a wider aperture and/or increase the ISO setting.

If you want to fine-tune the flash exposure, the easiest way is to use flash Exposure Compensation (FEC). Look for the button marked with a zig-zag flash symbol and ‘+/-’. See the previous page for alternative ways to control the brightness of your flash.

Controlling flash exposure

Three quick and easy ways to ensure perfect results by adjusting the exposures of your flash pictures

1 Flash Exposure Compensation
This allows you to adjust the output from the flash, making the subject 
lit by flash either brighter (positive compensation) or darker (negative compensation). Flash Exposure Compensation can be applied on the camera, or on a dedicated flashgun attached to the camera.

2 Flash Exposure Lock
Some cameras (like Canon’s 7D) have an FEL (Flash Exposure Lock) or FV (Flash Value Lock) button. Ensure the main subject is in the middle of the picture, then press the Flash Lock button. The flash will fire without an exposure being made, but the exposure setting will now be locked in. Simply reframe and take the picture.

3 Flash Exposure Bracketing
If timing isn’t crucial, try taking a series of exposures at a range of Flash Exposure Compensation settings to improve the chances of getting the perfect ratio of flash to ambient light. Advanced flashguns and cameras offer Automatic Flash Exposure Bracketing.

How to get flash in sync

Slow Sync is useful when shooting in low light, allowing a long exposure to be combined with a brief burst of flash. Rear Curtain Sync allows you to fire the flash at the end of an exposure, rather than at the start.

Normal flash
Automatic camera modes default to a flash sync speed of 1/60 sec, which is too short to allow much ambient light in at night.

Slow Sync flash
By using slow-sync flash, a longer exposure can be used to allow ambient light to register on the sensor as well. Use a tripod too.

Front Curtain Sync
In a long exposure, subject movement recorded after the flash fires will appear as a trail in front – they’ll seem to be travelling backwards!

Rear Curtain Sync
The results look more natural, but it’s harder to predict where the subject will be when the flash fires at the end of the exposure.

Flash photography cheat sheet – what you need from a flashgun

Now that we’ve broken down some of the misconceptions about flash photography, let’s take a look at what you need from a dedicated flashgun.

In our flash photography cheat sheet below we’ve illustrated some of the most useful features for photographers and what you can do with them.

Simply click on the infographic to view the larger version of this cheat sheet, or drag and drop to your desktop.

How to photograph a reflection in an eye

jmeyer | Photography Tips | Portraits | 07/11/2014 00:01am

0 Comments

Discover how to photograph a reflection in an eye ball with this simple step-by-step tutorial!

This is a quick and easy photo project that only takes minutes to shoot, but produces amazing results. If you’ve ever taken macro shots of eyes before you’ll know how much fun it is, but you can take things a step further by including a reflection of a local landmark.

Not only will this result in a more visually striking image, but if you choose a landmark that’s got some personal significance to your subject, you’ll end up with something that is also much more personal and intimate, not to mention more interesting.

The trick is to choose a landmark with a very distinctive shape, and ideally to set it against a brighter sky, as this will make for clearer, more recognisable reflections.

If the sky is blue, so much the better. Here we chose to capture a reflection of Beckford’s Towernear Bath.

SEE MORE: How to focus a portrait – get pin-sharp eyes in 3 easy steps

How to set up your camera to photograph a reflection in an eye

01 Get up close
A macro lens is essential for this project. We used Nikon’s 105mm f/2.8 Micro, which gives one-to-one magnification. This means we could focus close enough to fill the frame with an object the size of our camera’s sensor, which is roughly the size of someone’s eye!

 SEE MORE: Fashion and beauty portrait photos: 3 tips for instant success

02 Set your aperture
Next, set your camera to aperture-priority mode and decide on an aperture; something like f/13 should do the trick. Just ensure this gives you a shutter speed fast enough to shoot handheld – if it doesn’t, raise the ISO to 200 or 400 to enable a faster shutter speed.

Autofocus point options: what subjects should each be used with?

jmeyer | Photography Tips | 17/11/2013 00:01am

0 Comments

Your DSLR offers a variety of autofocus points, which can be used in different ways. But which focus points should you use, and when?

Our quick cheat sheet below explains your different focus point options and when they are most opportune.

We used a Nikon camera for the purposes of this tutorial, but the same principle applies for other brands even though other cameras will have AF systems with a different number of AF points.

SEE MORE: How to take control of autofocus to get the shots you want

Click the infographic to see the larger version, or drag and drop to your desktop to save.

Auto Area AF: best for snapshots
In Auto Area AF mode, you’re leaving it to the camera to decide what to focus on. It will check all its focus points and choose either the object nearest to the camera or, on later Nikons, any faces the camera detects in the scene. This mode is a good fallback for novices, but the camera will sometimes focus on the wrong thing.

Single-point AF (51 points): best for precision
In single-point AF mode, you pick the focus point yourself. This gives the most control, provided you’ve got time to select the correct point (or you could use the ‘focus lock’ method, see overleaf). Single-point AF is ideal for relatively static shots where you’ve got a little more time to get set up.

Single-point AF (11 points): best for everyday
If you have a camera with a large number of AF points, you have a sophisticated autofocus system at your disposal, but it can take too long to select between them. On Nikons with 39-point or 51-point AF systems, you can restrict the number of AF points to 11 for quick manual focus point selection.

Dynamic area AF (nine points): best for action
Dynamic area AF mode is designed to make the autofocus system more responsive and more reliable for moving subjects. You still select the focus point manually, but the surrounding AF points act as backups to keep the subject in focus if it moves briefly away from your chosen AF point.

Dynamic area AF (21 points): best for erratic action
You can include more AF points in Dynamic area AF mode. Nine points offers greatest accuracy if you can follow your subject in the viewfinder, but for subjects which move more erratically, the 21-point option may be more effective. Try out the options to see which best suits your subjects.

Dynamic area AF (51 points): best for subject tracking
You can use all the camera’s focus points in Dynamic area AF mode. Some models offer 3D tracking, which uses information from multiple AF points to predict your subject’s movement. This suits shots where you want to keep the camera framing the same while shooting a moving subject.

Waterfall pictures: how to find, set up and shoot moving water

jmeyer | Photography Tutorials | Tutorials | 08/10/2014 00:01am

0 Comments

12Next »

Capture stunning waterfall pictures with our step-by-step guide to exposure, motion blur and more…

If you’re into landscape photography – and let’s face it, most of us are – late autumn can sometimes be a pretty torrid time of year, partly because of the wet weather, but mostly because the light is just so unpredictable, and what light there is tends to be a bit cold and flat.

Happily, though, there is one landscape subject that’s perfectly suited to being captured in flat, even light, and that’s waterfalls.

Read on to find out why, and to discover the settings you need to capture stunning waterfall pictures and artful images of tumbling cascades…

SEE MORE: Water photography – how to take stunning pictures of water in any environment

How to shoot waterfall pictures

Step 01: Keep an eye on the weather
Weather is critical, but not for the reasons you might think. Direct sunlight is more of a hindrance than a help, because it casts dark shadows and creates blown highlights in the white water.

As well as being distracting, the contrast between these shadows and highlights makes it impossible to get a balanced exposure.

Rain is also a factor: too much water flowing over your fall will result in images with wide expanses of featureless white water.

What you’re looking for is gaps between the trails of falling water, as this helps to add texture and contrast.

SEE MORE: 6 ways to keep shooting when it rains

Step 02: Get set up
For successful waterfall shots, you’ll need to mount your camera on a sturdy tripod, and to use a remote release to fire the shutter – or your camera’s self-timer function if you don’t have one.

It’s also a good idea to set mirror lock-up right at the beginning of the shoot, to reduce the risk of unwanted vibrations from so-called mirror slap during the long exposures required for waterfall pictures.

Finally, if you’re shooting in daylight, even on cloudy day, you will probably need a filter to enable you to set slower shutter speeds (see Step 05).

SEE MORE: Dull day photography: what (and how) to shoot when the sun isn’t shining

Step 03: Set the exposure
Once you’ve composed your shot, it’s time to set the exposure. The best way to do this is to set your camera to Manual mode, and then dial in your lens’s smallest aperture (this will probably be f/22 or f/29).

Next, adjust the shutter speed so the exposure level indicator lines up with the ‘0’ on the exposure scale. On an overcast day, this will probably be in the region of 1/4 sec.

As you can see from our example image, this is slow enough to blur the water, but not slow enough to make it appear wispy.

SEE MORE: 10 common exposure problems all photographers face (and how to avoid them)

Step 04: Evaluate the exposure
To evaluate your initial exposure, check your camera’s histogram view. As you know that the very brightest areas of falling water are actually supposed to be white, with very little texture or detail,you can expose your shot so that your histogram is as far to the right as possible, without the highlights being clipped (i.e. bunched up at the right hand end).

If your histogram is too far to the left (i.e. under-exposed), simply decrease the shutter speed to let in more light; if it’s too far to the right (i.e. over-exposed), increase it to let in less light.

SEE MORE: Fall color: how to photograph autumn leaves and seasonal textures

Step 05: Slow everything down
If you’ve set your camera’s lowest ISO and your lens’s smallest aperture, the only way to reduce the shutter speed still further is to attach a filter.

A Circular Polariser will reduce the amount of light reaching the sensor by two ‘stops’, so for a correct exposure you’d need to increase the exposure time by two stops (so 1/4 > 1/2 > 1 sec).

To slow things down even more, you’ll need a Neutral Density filter – these come is different strengths, and for every stop of light that’s blocked, you need to double the exposure time.