Fundamental Series

• ISO
• Aperture
• Shutter speed
• File formats
• Priority modes
• Light metering

A significant difference between traditional film photography and digital photography is what do we correctly expose for. In film we would expose for the shadow or the lowlights within the shot but for digital photography we do the complete opposite.  With digital processing we can often bring back the shadows or lowlights to an image, but recovering highlight detail is all but impossible.

Understanding the light meter:

Understanding metering is a fundamental knowledge and requirement to further your photography skills. Once you understand metering you are better armed to use this to adjust the actual metering needed.

First we need to know what the metering is trying to accomplish, all light meters try and establish a benchmark of 18% grey. It is in the bottom line that misinterpretation can take place and why you need to understand metering so you can bring that enormous human brain into the picture and make educated adjustments.

For example if we are shooting in snow, a typical meter will instruct you to underexpose a shot by anything up to three stops, in addition if we are in a low light situation we are often led down the path of overexposing. With the light meters want to achieve the 18% grey it cannot take into consideration what it is we are actually shooting.

On camera metering:

The average dSLR camera is equipped with four metering modes; some do have more in the upper professional range but let’s stick to the average dSLR.

Evaluative or Multi-pattern metering:

In most situations this is the best metering to use and should provide accurate results under normal shooting conditions. (Normal conditions – without extreme variants in light) Evaluative metering takes many readings from various segments of the frame; the amount of segments it analyses depends on the level of your dSLR.

Centre-weighted metering:

Like as the name suggests the centre weighted metering takes readings from the centre of the frame. When we are presented with shots that have a high contrast this can be a particularly useful metering mode.

Spot metering:

Working similar to the centre weighted metering; spot metering evaluates a very small segment of the frame, this can be used to evaluate light and dark parts of the frame and give you a little insight into the correct exposure.

Auto Exposure:

You will soon discover if you have not already my dislike for anything that begins with ‘Auto’ although auto expose can be reliable in the post perfect of conditions it is easily confused. Low light and extreme contrast furthermore back-lighting and reflections can all throw the auto-metering mode into disarray.

What’s your dynamic range?

All digital cameras have a dynamic range, discovering your cameras range will allow you to shoot with far more confidence.
Metering is to establish the best overall exposure for a given shot, but we have to explore and acknowledge that there might just be a better exposure for the given shot. This is often why we will bracket (more about bracketing at another time) if we know our cameras dynamic range we can explorer other exposures and often will discover what we thought was the right exposure turned out to be wrong.

Finding your cameras dynamic range:

Off to the newsagent a pick up a piece of grey card, you can often purchase 18% grey card from a good photography shop. Now take a shot of the grey card and continue taking shots changing the exposure each time by 1/3 EV when you have finished you will have a range from completely overexposed to completely underexposed. 

If you have done this correctly you should have a range from totally black to completely white. I would say this should be in the vicinity of 7 to 8 stops and for an average lets say you have 8 stops this means that 4 is right in the middle of your cameras range. Knowing your mid point gives you the confidence to of 3 stops each way and knowing the outcome.

Bracketing with auto-exposure:

Bracketing is a wonderful tool and with the knowledge of knowing your cameras dynamic range we can set up our bracketing accordingly. Consult your manual on how to set-up exposure bracketing on your dSLR. You will be able to set an each way bracket for example +1.5 and -.1.5 which gives you a stop and a half each way, of course this could be half a stop or even 2 stops, experiment with exposure bracketing.

Hand held light meters:

You will often find photographers that don’t use the on camera light meter especially ones who have been shooting traditional film photography for some time.  Hand held light meters do allow for far greater accuracy although do not take into account filters you may be using, and as such you have to allow for these when making your final decision.

Hand held meters are particularly handy allowing for accurate readings close to your subject furthermore if using a tripod there is no need to remove the camera. 

Hand held meters allow for difficult lighting situations, also allowing for reflected light readings and incident light readings. Although not a necessity the hand held light meter can be a valuable asset to your photographic equipment.

Photo credits
Intro photo by Stuckincustoms the featured image is a HDR photo we will be covering HDR photography shortly