Hello, this is David Robinson and here I'm going to show you a couple of techniques
that you can use to take accurate bracketed exposures for HDR processing.
When you use these techniques, you'll know that you have perfectly covered
the lighting range in your scene.
This is especially important with interior real estate photographs
where there may be very wide differences in brightness.
There are 3 basic steps:
Set up the camera.
Which photos to take.
Taking the photos.
When you're taking bracketed shots for HDR, they should all
have the same ISO and Aperture.
Only the shutter speed should vary.
First set the camera to Manual mode
and then set both the ISO and Aperture.
The ISO setting determines how sensitive your camera is to light.
A higher ISO allows you to use a shorter shutter speed
but it can also introduce unwanted noise.
So, you should set the ISO as low as possible
to reduce the possibility of noise.
Avoid going higher than ISO 400.
At this point, you'll also need to select a suitable aperture.
This will vary, depending on the scene, but f/8 is a good balance
between depth of field and shutter speed.
Because you will be taking a number of shots
and some of these may have slow shutter speeds,
it's important to mount the camera on a good solid tripod.
Pressing the shutter button may cause the camera to move a little,
causing blur within the photos.
Using a remote shutter release solves that problem.
When you're taking a bracketed set for HDR, it's very important that
the darkest photo has all the details in the highlights
and that the brightest photo has the details in the shadows.
Between these two you then need to fill in the mid-tones with additional shots.
Since you have already chosen the ISO and the Aperture you'll be using for the bracketed set,
what you now have to find out is the longest,
and shortest shutter speeds.
The easiest way to do this uses Spot Metering mode on your camera.
Normally, when working out what exposure to use,
your camera looks at a large part of the scene
but in Spot Metering mode it looks at just a small area,
usually around the centre of the image.
Because you want the camera to work out the exposure to use with the aperture you've chosen,
switch to Aperture Priority mode.
The first reading is for the photo that requires the longest shutter speed.
Point the camera at the darkest area inside the room.
Read the exposure shown in the camera and make a note of it.
Now, you need to find the photo that requires the shortest shutter speed
so, point the camera at the brightest part of the room and make a note of it.
Just remember to avoid pointing your camera directly at overly-bright objects,
such as the Sun or any reflections.
There's another way to determine the longest and shortest shutter speeds
which is more precise but takes a little longer;
using the brightness histogram on your camera.
Most cameras have a setting that displays a histogram
of the brightness levels of photos that have been taken.
For this method, keep the camera in manual mode
and point it at the darkest area of the room.
Now take a test shot.
If you have a vertical line at the left side of the histogram,
then there are dark areas you haven't covered yet.
Change the shutter speed to something longer and try again.
When you have a histogram nicely balanced like this,
you've got a good shutter speed, so make a note of it.
Now do the same thing for the shortest exposure.
Point the camera at the brightest part, adjust the shutter speed till it looks well exposed,
then take another test shot.
This time you need to look out for a line on the right hand side of the graph.
If you see this, adjust the shutter speed so it becomes shorter
and try again until you have something that looks more like this ...
and make a note of the shutter speed used.
Now that you've made a note of the longest and shortest exposures,
take the photos, from the fastest shutter speed through to the slowest,
and with the right number of photos in between.
I'm going to show you two methods to do this:
The Semi-Automated method and the Full Manual method.
The Semi-Automated method uses the Auto Exposure Bracketing (AEB) function of your camera
and the HDR Exposure Calculator.
Most DSLR cameras are capable of taking a certain number of shots automatically,
with exposures bracketed around a central shutter speed.
And the calculator will tell you which shutter speeds to use
and how many automatically bracketed sets will be required.
Here's how the HDR calculator works:
Open the app, and using the readings you noted earlier,
in the first box, enter the value for the shadows
which is the shutter speed for the darkest part of the room,
the longest exposure.
And in the second box, the value for the highlights,
which is the shutter speed for the brightest parts of the scene,
the shortest exposure.
Below this, enter the AEB capabilities of your camera,
that is to say, the maximum number of exposure bracketed photos it can take.
And in the final box, enter the stop difference between them ...
the EV spacing that you want to use.
Now click 'Get Exposures' and the calculator will tell you the exact number of photos to take ...
the settings for the bracketed set and how many bracketed sets you'll need
using the AEB function on your camera.
So, once your camera is on a tripod, framed and focused, we can begin taking the photos.
Start by activating the AEB function on the camera ...
and make sure that the camera is in Manual mode.
Set the shutter speed to the first value given ...
select your bracketed of 5 photos ...
and without moving the camera, take the bracketed set
by pressing the remote shutter release.
Or, if you're not using one, by pressing the shutter button.
If your camera doesn't have an AEB function,
or you don't have access to the calculator,
then there's another method to get the photos you need.
Select Single-Shot mode on your camera, and in Manual mode,
dial in the fastest shutter speed.
Now, take a photo.
Then, decrease the shutter speed by one stop,
also known as 1 EV, and take the next photo.
Repeat the process until you've reached the point where you've taken a photo
with the slowest shutter speed.
Using this method means that you're constantly touching the camera,
so make sure that your tripod doesn't move and that all the joints are solid.
So, here are the important points to remember
when taking bracketed sets using the advanced technique:
Keep your ISO and Aperture unchanged between shots.
Use your camera's Spot Metering function or histogram to work out the shortest and longest shutter speeds.
Use the HDR Exposure Calculator to work out the photos you need.
You can also take your photos manually, one at a time.