Manual HDR Bracketing Explained  - featured - 01

Manual HDR Bracketing Explained

Manual HDR Bracketing - Example: HDR created from 11 exposures in steps of 1EV (1). The brightest (2) and the darkest exposure (3) are too far apart for a standard Auto Exposure Bracketing series found in most cameras today.

HDR created from 11 exposures in steps of 1EV (1). The brightest (2) and the darkest exposure (3) are too far apart for a standard Auto Exposure Bracketing series found in most cameras today.

Have you ever been in a situation where you wanted to make a HDR image but the Auto Exposure Bracketing of your camera just did not cut it? It did not cover the entire dynamic range of the scene and you ended up with blown-out highlights and blocked-up shadows anyway? This is when you need manual HDR bracketing. But what’s the right technique for bracketing manually?

In this tutorial, I am going to show you a simple technique for freeing yourself from the limitations of your camera’s AEB function by using Manual Exposure Bracketing (MEB). We will go through the camera setup and a simple procedure for shooting the images without having to do any math. With a bit of practice, you can even use this technique when you’re shooting hand-held HDR.

Introduction

Typical AEB function (Nikon D7000): 3 shots with +-2 EV.

Typical AEB function (Nikon D7000): 3 shots with +-2 EV.

Almost every DSLR camera you can buy today has a function called Auto Exposure Bracketing (AEB). AEB comes in handy if you want to produce an HDR image since it can be set up to produce a series of photos with different exposures with a single click of the shutter release button. This is simple and quick, and it does not require doing any math while you’re out shooting. This is why most HDR photographers today use this function almost exclusively.

The problem, however, is that most camera manufacturers only equip their high-end models with AEB functions that can produce enough exposures (5, 7, 9 or 11) to cover all possible situations. Most entry-level and mid-range DSLR cameras can produce up to 3 shots with up to +-2EV steps (-2EV, 0EV, +2EV). This is enough for many situations, but not for all.

To overcome this limitation and to be able to cover all possible shooting situations with arbitrary dynamic ranges, owners of the latter type of camera need to revert to Manual Exposure Bracketing (MEB). However, setting up your camera to produce an MEB series and executing it reliably without making mistakes can be a daunting task.

We will go through the steps you need to take to set up your camera, to measure the exposure correctly (including a safety cushion to compensate for an incorrect measurement by your camera), and to actually take all the exposures you need.

Assumptions and Requirements

To keep the explanations simple, I will assume a few things:

  1. The scene is static: Obviously, producing the exposures for your HDR images manually requires more time than using the AEB function. In particular, the time that passes between the individual exposures of your series will be longer, and this implies that any movement in the scene will have a larger negative effect on your images. Blur and ghosting may be the result. Thus, the scene should be relatively static (e.g. no people, cars or fast-moving clouds) in order to be able to use a MEB technique.
  2. You are using a tripod: I will assume that you are shooting from a tripod. If you shoot hand-held, you need to make sure that the shutter speeds are within the range that you are able to hand-hold without introducing blur in the photos. This makes things a bit more complicated.
  3. Your camera has a shutter speed wheel: I assume that you have a DSLR camera that has a wheel to dial in the shutter speed directly. If your camera is operated differently, you need to consult your manual.
  4. You know the basics: I also assume that you know the basics of exposure (the relation between shutter speed, aperture and ISO sensitivity). This is quite fundamental stuff that you should know when you put your camera into manual mode.

Overview

A MEB series is produced by measuring the exposure (shutter speed) required for the darkest and the brightest parts of the scene. These define the two extreme exposures of your series. When you’re actually shooting the photos, you will start at one extreme and work your way to the other extreme stop by stop: When you’ve shot one exposure, you change the shutter speed by one stop and take the next shot until you have reached that other extreme end of the series.

For measuring the exposures, you need to use the single-point focus mode and the spot metering mode of your camera. This will allow you to select a specific region of the scene and measure the shutter speed required for exposing that region properly.

Since exposure metering is never 100% exact, we will add one stop on either end of the series (that’s two additional exposures) to make sure that we capture all the details in the shadows and in the highlights.

The Setup

The first thing you need to do before you start setting up your camera is to choose your final composition. Explore your subject and choose the right angle, distance and framing. This will be the basis for measuring the exposures for your MEB series. If you change your composition in the middle of the shoot, you will have to measure the exposures and set up your camera again.

If you are shooting from a tripod, put your camera on the tripod, compose the shot and tighten all screws. Make sure your tripod has a stable stand before you proceed.

Preparing your Camera

You are going to produce the exposures in manual mode (manual exposure and manual focus). While you actually shoot, the only thing that you need to change is the shutter speed. Everything else needs to be set up properly before you start shooting:

  1. Put your camera into A mode (aperture priority mode). You will do the actual shoot in M mode, but the A mode allows you to easily measure the right shutter speeds for your scene.
  2. Choose the right aperture. This depends on the lighting of the scene and on the depth of field you are trying to accomplish.
  3. Choose the lowest possible ISO sensitivity to avoid noise in your photos.
  4. Put your camera into single-point focus mode. This lets you manually select the point that your camera should use to focus and to measure the exposure.
  5. Set your focus. You can use the autofocus to get your main subject in focus. Switch the AF off once that’s done. Otherwise, your camera may decide to change the focus in the middle of the MEB series which would require you to start from scratch.
  6. Put your camera into spot metering mode. In this mode, only a small region around the active focus point is used to measure the exposure. The rest of the frame is ignored.
Setup example (Nikon D7000): Use A mode (1) to measure the exposures. Set your metering system to spot metering with your metering button (2). The symbol in the display (3) will only show the dot in the middle. Set the aperture (4).

Setup example (Nikon D7000): Use A mode (1) to measure the exposures. Set your metering system to spot metering with your metering button (2). The symbol in the display (3) will only show the dot in the middle. Set the aperture (4).

Manual HDR bracketing: Use the focus controls (1) to set your camera from Matrix Metering (2) to Spot Metering (3).

Use the focus controls (1) to set your camera from Matrix Metering (2) to Spot Metering (3).

Measuring the Exposures

Now you’re ready for measuring the shutter speeds you need. Your camera is in A mode with the aperture set correctly. All you have to do now is to position the active focus point on the darkest and on the brightest spots in your scene and read the shutter speeds your camera suggests. You can do this by taking your camera from the tripod again and by pointing it at the scene such that the active focus point is exactly on the darkest and brightest point respectively:

  1. Measure the shutter speed for the longest exposure (darkest area). Look through the view finder (or on your screen if you are using Live View) and move the focus point to the darkest area of the scene. Memorize the shutter speed indicated by the camera. We will call this value L (for low). Depending on the amount of light available in the scene, L may be several seconds long. The longest possible exposure for a typical DSLR camera is 30 seconds. Beyond that mark, you would have to use Bulb Mode and time your exposures manually, which should be avoided here. Since you need to add an additional stop at the low end as a safety cushion, L should be 15s at most. If L is greater than 15s, you need to increase the ISO sensitivity accordingly. In our example, L is 1.3 seconds.
  2. Measure the shutter speed for the shortest exposure (brightest area). Move the focus point to the brightest area of the scene. Memorize the shutter speed indicated by the camera. We will call this value H (for high). In the example, H is 1/200 seconds.
Manual HDR bracketing - Metering the Scene: Point your camera at the scene such that your active focus point is on the darkest part (1) and on the brightest part (2) of the scene, and memorize the shutter speeds measured by your camera. For the example, H is 1/200s (1) and L is 1.3s (2).

Point your camera at the scene such that your active focus point is on the darkest part (1) and on the brightest part (2) of the scene, and memorize the shutter speeds measured by your camera. For the example, H is 1/200s (1) and L is 1.3s (2).

L and H are the two ends of the dynamic range that we were looking for in this particular scene. Now, you can put your camera on your tripod again and create the exposure series between L and H accordingly.

Taking the Shots

During the actual shooting itself, you will produce an exposure series in which there is one stop (1EV) between each pair of consecutive shots. The series starts at L + 1EV (half the shutter speed you measured for the darkest area), and it ends at H – 1EV (twice the shutter speed you measured for the brightest area – 1/400s in the example). In our example, L + 1EV is 2.5s and H – 1EV is 1/400s.

This sounds complicated. But actually, it is not. You don’t need to do any math here since all modern cameras are built in a way such that you can increase the exposure by increments of 1/3 of a stop. This means that 3 clicks of the shutter speed wheel on your camera are a full stop. All you need to do is to go through the series of shots and click that wheel three times after each shot:

  1. Set-up
    1. Camera mode: Put your camera into M mode, and make sure your aperture is set correctly (to the value you have chosen for the scene).
    2. Shutter speed: Set your shutter speed to L + 1EV. Set it to L and then decrease the shutter speed by 3 clicks.
  2. Loop through the shots
    1. Shoot: Take a shot.
    2. Increase: Increase the shutter speed by 1 stop (three clicks of the wheel).
    3. Repeat: If your last shot was taken at or above the shutter speed H, take one final shot and you’re done. Otherwise, repeat from step i (Shoot).

The 30 second video below illustrates the actual shooting loop.

Questions and Answers

  • Why should you use a 1-stop difference between shots? The first reason is that 1 stop is good for covering the entire dynamic range such that you have enough information in your photos to avoid halos and to get smooth transitions in the final image. The second reason is that it is easy to do 3 clicks of your shutter speed wheel without having to count. This eliminates at least one source of errors: getting the counting wrong.
  • What can I do if the scene has more movement? You can use 2 EV steps instead of 1 EV steps for scenes with more movement. This will give you fewer photos but it reduces the time it takes to produce the entire series. Thus, the effect of the movement will be less pronounced in the final image.
  • Why should you proceed from L to H and not vice versa? I simply chose this order since it is my personal preference. But there is no good reason why you shouldn’t do it the other way around if you prefer that.
  • What about the white balance? Don’t I need to set that manually too? Well, yes, you could set the WB manually before you start shooting. But unless you really need the colors to be 100% spot on and unless you have a grey card with you to set the WB correctly, this is a waste of time. I would advise you to shoot in RAW mode and set the WB for your RAW images in post-production. With RAW images you have full control over the WB without losing any quality.
  • Couldn’t I just set my camera to A mode and use the exposure compensation function to control the exposure? Yes, you could. But unless your camera is in manual mode, it may change its opinion about the right exposure in the middle of the shoot. This means that your base exposure (the one you are adding and subtracting stops to and from) may change slightly, giving you an exposure series with varying steps between the photos. This may or may not work depending on the software you use for creating your HDR image. Another important point is that instead of only moving a wheel on your camera, you will need to press the exposure compensation button and move a wheel. This is more inconvenient, takes longer and has a greater chance of moving the camera around during the exposure series.

Summary

Using Auto Exposure Bracketing (AEB) is sometimes not sufficient or simply not available in your camera. In those cases, you have to take your HDR exposure series manually, but doing so is a daunting task for many photographers. In this tutorial, I have described a manual HDR bracketing technique that helps you get the perfect exposure series for every conceivable scene. It is simple and reliable, and you don’t need any math that goes beyond counting to three.

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14 Comments on "Manual HDR Bracketing Explained"


Guest
Ratul
2 years 4 months ago

Klaus,

Very detailed technique. But I have a question, why do I need to go through this if I can look at the histograms and make sure I am not loosing any details in highlights and shadows ? In otherwords, I look at the histogram and see my highlights are not blown away (the histogram stays just before the right hand edge) and then look at the shadows side and see my curve is just off of the left side. Then I have a middle exposure or take extra 2-3 exposures to be safe. I have seen, those two exposures which are just off of the dge takes care when I run all the exposures through Photomatix.
Do you see anything wrong with this ? Thanks.

Guest
2 years 4 months ago

Hello Klaus…this is the technique I use for all my city night scenes. It works, is easy to implement and produces great images.
You are the first, however, to label this technique MEB (Manual Exposure Bracketing)…I call it simply exposure stacking (or blending). I use LR Enfuse to blend the exposures in post-process (although you could use Photomatix or HDR EFEX Pro, etc.) I usually take 5 or 7 exposures, rarely do I need 9 or more. Great article.

Frank V.

Guest
2 years 4 months ago

Very detailed post and thank you – this is definitely a post I will come back to when time allows.

For now I will continue to cheat and go with AEB courtesy of the MagicLantern firmware ‘addon’ for a large number of Canon based cameras. ML allows me to set the number of exposures from 2 to 11 (or auto), the stops and various other aspects. But I hadn’t realised going 1 stop as opposed to say a third apart reduces halo’s.

Guest
2 years 4 months ago

Great tutorial as usual. I think there is some flexibility here and every photographer will try to experiment with this set-up. I’ll definitely try anyway.

Guest
Peter Muks
2 years 4 months ago

Hallo Klaus
Wenn ich mit meiner EOS im A-Modus bin zeigt der mir im Himmel z.b. F10 an und am Boden F5.6, somit stimmen doch die Verschlußzeiten auch nicht mehr wenn ich verschiedene Blenden angezeigt bekomme. Weißt du da auch einen Rat?
Gruss
Peter