Using Manual Mode: Exposure Lesson #4

Using Manual Mode: Exposure Lesson #4

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This is the third in a series of four articles about exposure. You can read the first lesson, which explored the reasons for using program, aperture priority and shutter priority modes,  the second lesson, which explained why your camera’s meter gets exposure wrong, and the third lesson, which looked at your camera’s metering modes.

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In my last article, I explained that evaluative metering (also known as matrix or multi-segment metering) is the most advanced built-in metering system that camera manufacturers have yet to come up with.

However, despite its sophistication, evaluative metering mode can still get the exposure incorrect.

With the camera in any automatic exposure mode (such as program AE, aperture priority or shutter priority) and the metering mode set to evaluative metering you may see the exposure reading change in the viewfinder as you frame and reframe the subject, exploring different compositions. This is despite the ambient light levels staying the same.

In theory, if the ambient light levels are steady, the camera should return the same exposure reading no matter how you frame the subject, right? No – because the camera is measuring light reflected from the subject. If the balance of light and dark tones within the frame changes, so will the exposure reading given by the camera.

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The above photo shows a situation where this can happen. The model is dressed in white and posing against a dark background. With a scene like this the camera’s suggested exposure settings change as you frame the model in different ways.

Switching to manual mode prevents that from happening. The advantage of manual mode is that once you have determined the optimum exposure settings, you can set the ISO, aperture and shutter speed and keep them the same until the light changes (or you want to alter them for creative reasons).

Manual mode works best when the light levels are steady. If the light is constantly changing, for example if the sun is going in and out behind clouds, then you should use one of the automatic exposure modes.

There are the types of subject for which I prefer to use manual mode:

Portraits

When I take someone’s portrait I want to concentrate on composition and expression. It’s essential to communicate with the model and direct her to achieve this.

In order to simplify the process I prefer to set the camera to manual mode. This means that I don’t have to worry about exposure as I’m taking the photos.

I start by setting the camera to aperture priority and taking a test photo. I then look at the histogram to see how accurate the exposure was, adjust and take another test photo if necessary (if you’re unsure how to use the histogram to check exposure then read this article).

Once I’m happy with the settings, I switch to manual mode and lock in my chosen ISO, aperture and shutter speed. I only need to adjust exposure if the light levels change.

Portable flash

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Manual mode is also useful if I’m using off-camera flash to light the model. I set the exposure for the background (I like to underexpose it for dramatic effect) then adjust the power on my Speedlite to give the correct exposure at my chosen aperture. I use my Speedlite in manual so that it outputs the same amount of light each time I take a photo.

Landscape photography

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I also use manual mode when I’m taking landscape photos. Dusk is my favourite time for shooting landscapes and I often take a series of photos as the light fades.

I keep an eye on the histogram – it creeps to the left as it gets darker and I normally increase the shutter speed to compensate (or sometimes I open the aperture or raise the ISO, depending on the situation).

Long exposure photography

When the required exposure is longer than 30 seconds (the longest available shutter speed on most digital cameras) you need to switch to bulb mode. In bulb mode, the shutter stays open as long as you want it to (use a cable release or remote release to open and close the shutter without touching the camera). This is another form of manual mode.

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This photo was taken with an exposure of five minutes. Compare it to the previous photo, taken with a shutter speed of 30 seconds, to see the difference the long exposure makes to the texture of the sea.

Creative Exercise:

Using manual mode is an excellent way to learn about the relationship between ISO, aperture and shutter speed.

The purpose of this exercise is to slow down the shooting process and get you thinking about the relationship between these elements of the exposure triangle.

In manual mode, there will be an indication in your viewfinder as to whether the exposure settings you have selected are correct according to the camera’s built-in meter. Check your instruction manual to see how it works on your camera.

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The above diagrams show how it works on Canon EOS cameras. The arrow shows that the top display is correctly exposed, the middle display is overexposed by a stop, and that the bottom display is underexposed by a stop.

If you’ve read the previous articles in this series you will understand that the camera’s meter may not get the exposure right. For example, if you are taking a photo of a white flower, then you will want to overexpose the photo by around two stops to obtain the optimum exposure. Once you have decided on the settings to use, take a photo and look at the histogram to see how accurate the exposure was. You can then adjust if necessary and shoot again.

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Andrew S. Gibson is a writer, photographer, traveler and workshop leader. He's an experienced teacher who enjoys helping people learn about photography and Lightroom. Join his free Introducing Lightroom course or download his free Composition PhotoTips Cards!

Some Older Comments

  • Janet M June 21, 2012 12:05 am

    I think the most important thing is knowing what settings are right for you, personally, in each individual situation. Learning how to use manual mode, and using it frequently, is the only way you'll be able to feel confident when using it. I use manual most of the time because I enjoy it, no snobbery involved. I like to meter on a few different areas in the frame and choose the correct settings (not practical for fast action shots like wildlife though). It's fun to experiment and as you practice you'll see better results. Knowing when not to use manual mode is important too. I don't think we should judge other people's choices but be happy with our own.

  • Bill M June 17, 2012 03:16 am

    I think learning to read a histogram and using that experience and knowledge to alter exposure is quite valuable in producing a good image. The great thing about photography are the choices we can make in producing quality shots. Not sure it matters how we get there.

  • Mark June 16, 2012 11:16 am

    @Alexx -- M is not the way to go if you shoot wildlife action shots!!! There is no way that you can respond fast enough to changing light metering as an eagle flies from the sky in the background to trees in the background to a shot with the river in the background -- all in under 5 seconds!!!! I am lucky to get a burst of shots as I am panning to follow his path!!!

  • Marco June 16, 2012 11:15 am

    @Alexx -- M is not the way to go if you shoot wildlife action shots!!! There is no way that you can respond fast enough to changing light metering as an eagle flies from the sky in the background to trees in the background to a shot with the river in the background -- all in under 5 seconds!!!! I am lucky to get a burst of shots as I am panning to follow his path!!!

  • Marco June 16, 2012 11:10 am

    @Mridula - Please explain further how anything you said had to do with setting the camera manually in "Manual" mode. Flash off is not a mode controlling the exposure. In Manual Mode, you set the aperture, shutter speed and ISO manually thus not allowing the meter in the camera to dictate the exposure of the image. You either do this by using a hand held light meter or by guessing at the correct exposure and adjusting by steps until you get what you want. And for all who BRAG about using Manual Mode only -- You don't shoot wildlife in their natural element as I do!!!! No time for manual mode when an eagle is attacking for food!!!!

  • Les June 16, 2012 12:39 am

    You state "it creeps to the left as it gets darker and I normally INCREASE the shutter speed to compensate (or sometimes I open the aperture or raise the ISO, depending on the situation)."

    Shouldn't that be "DECREASE" (or lower) the shutter speed? You need to get more light onto your sensor, something that you will achieve with opening the aperture (but this affects the DoF) or raising the ISO.

  • TJ June 15, 2012 05:51 am

    I'm sorry, but I can't for the life of me understand the snobbery of those who brag about only, mostly or even ever for that matter, using manual mode for general photography. I would be surprised beyond belief if the average amateur who reads this gets better pictures by glancing at a histogram than by relying on an advanced multi-segment metering system for proper exposure. I would be further surprised if 2 of 10 of those same amateurs even know how to read a histogram.

    I use manual mode with a flash meter when I use studio lights, but I see no advantage to using manual with a speedlight, and then guessing at what is proper exposure, over using TTL metering. Anyone trying to convince me that they can get better exposure by looking at a histogram than the computer in the camera can do by averaging multiple readings and weighting them for subject placement has a lot of convincing to do.

  • Edmund June 15, 2012 01:35 am

    "I keep an eye on the histogram – it creeps to the left as it gets darker and I normally increase the shutter speed to compensate" I think you meant decrease - no?

  • Scottc June 11, 2012 09:43 am

    I'm sure you meant to say "decrease" shutter speed on landscapes as it gets darker.

    Nice article, thanks.

    http://www.flickr.com/photos/lendog64/5577283782/

  • Alexx June 11, 2012 01:48 am

    I always shoot in manual mode with raw and manual focus.

    M is the way to go!

  • Steve June 11, 2012 01:29 am

    Night work is a classic where manual mode is a definite need:

    http://wildlifeencounters.photoshelter.com/gallery-image/Scenes-of-France/G0000BzQXTlspD3c/I0000YDrI97zkQdM

  • Mridula June 11, 2012 01:00 am

    I entirely agree about knowing my camera and using the manual mode but recently I was trekking up to Everest Base Camp and the altitude messed up my head so much that most of my pictures were in flash off mode!

    http://blogs.gonomad.com/traveltalesfromindia/2012/06/everest-base-camp-trek-day-11-namche-bazaar-to-lukla.html