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Transcript for Extended Depth of Field Video

Narration by Ron Bigelow

Photoshop CS4 Used in this Tutorial

Hello, and welcome to the Ron Bigelow Photography Extended Depth of Field video. Depth of field is a very important issue in photography. In many cases, we want a very large depth of field. For instance, this is often the case in landscape photography.

However, This immediately causes technical problems. The usual solution is to stop the lens down to its smallest aperture. This maximizes the DOF, but the small aperture also significantly degrades the quality of the image due to diffraction.

Wouldn’t it be nice if we could get an extended DOF without any lose of image quality? Well, with a little bit of planning, we can in many cases. The trick here is that we take several shots of the subject with each shot focused at a different distance. That way, every point in the scene is in sharp focus in at least one of the images.

You might think that it would be difficult putting all those images together, carefully aligning the images, figuring out which image is sharpest for each point in the scene, and creating a final image. Actually, this is a very simple workflow. Photoshop will do almost all of the hard work.

Now, we are going to carry out this workflow with a series of images of this doll fire truck. You have probably noticed that we are in Bridge rather than Photoshop. This is because this process is easier if we start in Bridge.

You might have also noticed that this image has a very limited DOF. The front of the truck is in focus; everything else is not. That’s because, as you can see, we have multiple images of this fire truck. As we move through the images, you can see that each image has a different focus point.

Now, these images are raw files, so we need to do some editing in Camera Raw before we start working on the DOF. So, let’s open just the first image in Camera Raw by double clicking the thumbnail.

Let’s add a bit of contrast. I think that we should also add some saturation. We now click Done. This will assign these edits to the image, but it will close the image rather than open it in Photoshop. Let’s move back to Bridge by pressing Control+Alt+o on a PC or Command+Option+o on a Mac.

We have assigned edits to the first image, but we also need to assign those same edits to the rest of the images. To do this, we select those images and choose Edit/Develop Settings/Previous Conversion. Now, all of the images will have the same editing applied when we open them in Photoshop.

Next, we need to open all of the images in Photoshop, but we need to open all of the images as layers in the same file. This is easily achieved by selecting all of the images and choosing Tools/Photoshop/Load Files into Photoshop Layers. It is going to take Photoshop some time to convert these raw files and load them as layers, so let’s fast forward to the point where the conversions are done.

We are now in Photoshop, and the images are set up as layers in this file. Next, we need to make sure that all of the images are perfectly aligned. I shot these images with the camera on a tripod, so we might be tempted to think that the images are already aligned. However, I had to touch the camera between each shot in order to manually focus the camera. So, maybe the images are not perfectly aligned. Lucky for us, Photoshop can align the images for us. All we have to do is select all the layers by pressing Control+Alt+a on a PC or Command+Option+a on a Mac and choose Edit/Auto-Align Layers. Let’s use the Auto option and click Okay. Photoshop will now take some time to align the images, so we will do another fast forward.

We are now ready to blend the images. In this step, Photoshop will analyze the layers to determine which layer is sharpest at each point in the image and will create masks for each layer based on the analysis. We leave the layers selected and choose Edit/Auto-Blend Layers. We want to choose Stack Images. I also suggest that you uncheck Seamless Tones and Colors. Yes, I know that it sounds like a really good thing to check. However, if you check this box, Photoshop will try to match the colors of the layers on an area by area basis determined by the masks that get created. In other words, areas that are not masked out get affected but the other areas are not affected. This may create localized color shifts that may cause color problems for us later. So, we will leave the box unchecked. Photoshop will again take a little time to work through all of the calculations, so let’s do one last fast forward.

Notice that we have a bit of white along some of the edges that is a result of aligning the images. Consequently, the next step is to crop the image. See, I knew there must be a reason why I had the Crop tool active all this time. So, let’s fit the image on the screen by pressing Control+0 on a PC or Command+0 on a Mac. Then, we draw a rectangle and hit the Enter key.

Let us check out our work. Pressing Control+Alt+0 on a PC or Command+Option+0 on a Mac will bring us up to the 100% view. Using the Navigator, we can check out various parts of the image. Actually, that looks pretty impressive.

Notice that I said, “Pretty impressive”. I did not say it was perfect. In fact, there will usually be a small amount of cleanup work that needs to be done. The best way to clean up any problems is to identify the layer with the sharpest detail in the problem area. Then paint white on the mask of this layer in the problem area. Let’s do an example. First, let’s use the Navigator again. This time, we need to move to the lower right of the image.

If we look at the front of the image, we see some areas on the plastic tag that are not sharp. I happen to know, from some earlier experimentation, that the sharpest detail in this area is on the top layer. So, we click on the mask of the top layer, make sure that the foreground color is white, select the brush, and paint white on the mask in the affected area.

If you need to do any work on layers lower in the stack, you may find that just painting white on the layer with the sharpest detail does not completely resolve the problem. In this case, you will need to also paint black in the problem area on the masks of all of the higher layers. One other point that I would like to make is that I find it easiest to determine which layer has the sharpest detail for a problem area by first disabling all of the layer masks. Then, I can just click layers off and on until I find the sharpest layer.

Before we wrap thing up, I would like to mention that, while this image did require some clean-up work on the front of the fire truck, the rest of the image required very little work. So, overall, there really wasn’t a lot of clean-up.

Well, that completes this workflow. However, before I sign off, I would like to take this opportunity to let you know that you can download the transcript for this video, view several other photography videos, and access over 100 photography articles on my website.