HDR Tutorial
High Dynamic Range (HDR) Tutorial
Hi guys, My name is Mike and I enjoy long walks on the beach (with my camera) and puppies. I also want to share with you my workflow with HDR images in depth.
Have you ever wondered why, when you take a picture of the sunset on your camera, that the foreground is so dark and the sky still looks a bit dull? How about a great foreground, but the sky is all white? What about when shooting indoors and the windows are all white? This is because the sensor on your camera can only pick up a certain luminance (light) range. It's like how when you step outside in full sun you can see everything just about perfectly, but you can also step out into starlight and see pretty well too (if you've eaten your carrots.) The amount of light you see on a moonless night is 1/1,000,000,000 of the light you see at noon. Yet, we can see both fairly well. Your typical outdoor scene consists of about 14-18 stops of dynamic range. (luminance/dynamic range is just the range of luminance values from light to dark, if everything is pretty bright or dark there is low dynamic range, if there are dark shadows and bright highlights, it has high dynamic range.) Your eye, without adjusting for light/dark scenes, can see about 17 stops. If you measure the range of light overall your eye can see, it is about 30(!) stops. Unfortunately, most point and shoot cameras can only discern about 10-12 stops of dynamic range. Modern DSLRs are between 11-14. My beloved 5DMKII has about 12, and much to my dismay his arch rival the Nikon D3X has almost 14. One point to Nikon.
So what to do? Contrast looks good in images, so maybe you don't need to do anything. It's ok if you have some shadow detail clipped or highlights blown out. Plenty of awesome pictures are highly clipped or blownout. But sometimes you want those awesome colors to pop in the sky, and see your foreground subject at sunset. this takes us to....
High Dynamic Range Imaging
High Dynamic Range (HDR) is a technique to use when you have dynamic range in a scene that is much greater than what your sensor can handle. I wouldn't recommend using it on scenes where the dynamic range is lower, as this comes off as gimmicky. This is just my personal opinion. If you want to use HDR on everything, Godspeed to you. HDR involves taking multiple exposures and then using software to merge them in your computer to create an image with more dynamic range than a single image. There are other ways, like single RAW HDR and exposure fusions that we will get into later. But first, let's sink our teeth into your normal, run of the mill HDR image.
There are a few things you will need to do HDR.
- Digital Camera with Manual or Aperture Priority modes
- (preferably with Auto Exposure Bracketing [AEB] also)
- Sturdy Tripod (highly recommended, but not absolutely essential. You will see why later)
- Shutter Release (optional)
- Photoshop
- Photomatix Pro
- Imaginomic Noiseware (optional)
- iTunes (also optional)
Once you have these pieces of equipment, we can start taking pictures. Find a scene with very bright highlights and dark shadows. This can be a sunset, sunrise, dark indoor room with bright windows, vehicles, whatever you want. I'd prefer you did not use it on people without then using photoshop to mask them back into the picture with a source image (we will go over this later) Not only do they move too much, but they look ridiculous in HDR un-edited. It gives them black speckles all over and weird details that are not at all flattering. Set up your tripod with camera attached In a good spot with a pretty view. Or, if your camera can fire upwards of 3 frames a second, you can put it in AEB and just hold it still in hi-speed fire mode. I do this a lot when I need to stay mobile and don't have time to set up a tripod.(or I'm feeling lazy.) Navigate to your menu on your LCD display. Somewhere in there, there will be "AEB". This tells your camera to take 3 or more pictures at different exposures. I usually use 0, +2, and -2 EVs. This works most of the time. For the rest of this tutorial I will assume we are taking 3 photos. Now put your camera in Av mode, so that to change the exposure the camera only has to change shutter speeds. This is so you do not make your DOF shallower or wider between pictures, as it will change the way the image looks obviously. You can also use manual mode and forgo the AEB, just change shutter speeds to give you the images you want. This is what I normally do. Finally, set your ISO to the lowest acceptable level as HDR creates a lot of noise and grain, and you do not want to add to it. Put your camera into high speed shutter mode if you own a remote shutter, or self timer if you do not. This will keep your camera perfectly still between images. Make sure you are in RAW and shoot the pictures until you have 3 taken.
These are the technical instructions on how to take them. Now let me get a little into theory. When you go to shoot an HDR, survey the scene and ask yourself a few questions. Are there moving things in my scene? Are there people in it? How great is the range between light and dark? How fast are the clouds moving? How windy is it? These are all things to consider. Let me say again, I don't like the way people look in HDR, so If there are people, I mask them in from a source file. Moving objects aren't always a problem, but they can be. Fast moving clouds will appear three times in your final image because if you don't shoot fast enough they will move between each exposure. Same goes for branches, trees, and grass on a windy day. I like to do HDR with a wide angle lens so you minimize movement in the details, you will barely be able to see it. Water will obviously look different in your image, No camera can shoot fast enough to freeze waves, especially at sunset with low noise. To combat these problems, I have a rule when I shoot HDR now. For each distinct part of the image, I like to have a separate exposure. So take your 3 images 2 stops apart, and if that doesn't cut it, take some more quickly. Let's say you have a scene with water, fast moving clouds and a piece of driftwood. Take 3 exposures 2 stops apart by metering on the point the foreground meets the horizon (where I always start, This way it averages the bright sky and darker foreground for my first image [0 EV] image.) Then, for your next series, go into manual mode and expose so that the brightest part is kind of dark, then take a shot one stop lower, and repeat until the darkest area of the image is kind of bright. This way you have all the information you need when you go to process. Don't go overboard, you probably won't need 10 exposures.
Now that you have the images, go home and grab some tea while your images upload to your computer. (I don't do this, but everyone seems to say this whenever you read a tutorial. I make myself a stiff cocktail, usually) Use whatever Library management tool you use, be it Lightroom, Bridge, Windows Explorer, whatever to select the pictures. I use Bridge. "Mike, why don't you use Lightroom?" Well, I have used it, and found it unnecessary for my workflow. I have a great system of storing photos on my computer and I do a lot of multimedia things so I need to use Bridge to get it all together, that's the only reason, I think Lightroom is great. I also make all changes in photoshop and camera raw, so lightroom is redundant. I use a PC too, so sorry if anyone is used to macs and the menus are different. Open up Photomatix Pro and just drop the 3 images from your library into the program.
Now is a good time to talk about the other program I have open, iTunes. I like to keep it chill sometimes when I'm editing, sometimes I like to amp it up. The only constant is you need a soundtrack to work to. I like Hans Zimmer myself while editing, but anything could work. I've run experiments before to see if it made a difference with my images. It didn't, becuase my photographs are always really good
At this point it is time to go on to the next page and learn about Photomatix Pro.