How many times have you taken a picture and the focus isn't what you want? For instance, the subject is perfectly clear and wonderful, but so is everything around it, so there is no separation to make the subject stand out. Or, you have the most lovely soft focus and gorgeous bokeh, but your depth of field is so shallow that the image doesn't have enough crisp detail. Even when the balance of focus and depth of field to softness and bokeh is very nice, sometimes it would be nice if there could be a little more control.

Aperture Sets
Before I got my Canon 5D Mark II, my husband used our Canon 5D (Mark 1) and he'd always take sets of apertures for every subject he photographed. I didn't really understand why he did it. I had my trusty point and shoot Canon 30SX IS and keeping it at an aperture of 2.8 most of the time was fine. Why bother with all of those pictures?

Once I got my Mark II with my 100mm lens, I quickly understood why aperture sets are such a good idea: for any subject, it's impossible (for me anyway) to know exactly what aperture will give me the dof, focus and bokeh that I'm envisioning. True, I could examine every picture I take, and often I do check if I'm concerned about a certain detail, but this process takes me out of the moment and I would rather have a lot of pictures that I throw away than to stop what I'm doing to check every image. So, I take sets of 3-10 different apertures per subject, usually 3 stops apart, so that I'll have a range to look at. Depending on how dark the area is, I'll up my ISO when the shutter speed gets to 60 or less.

Focus Stacking without Rails or Tripod
I discovered a clever trick the other day which works quite well. I was looking through the images of a mushroom I took and found myself annoyed and frustrated because what I wanted was a crisp, clear mushroom in a nice, soft setting. But my assortment of apertures didn't have everything I wanted in one image. Suddenly it hit me...why don't I just cut out the crisp mushroom from one image and put it into the image with the soft background? This technique is called focus stacking, and it's usually done with fancy equipment and tripods, but I have my own method. Here's how I do it:

Here is the original image at an aperture of 8.0. As you can see, the background has too much focus and is very distracting.

First, select the crisp subject:
You will need photo editing software like Photoshop to do this. There are a number of ways to cut the subject out.

Using the Lasso tool:

1. I like to use the polygonal lasso but others like the magnetic tool to carefully select the subject. This usually takes a long time, but is sometimes faster if the background is really busy.
2. You can use the Lasso tool to roughly select the area around your subject and then use the Magic Wand tool to de-select the areas which aren't your subject, using the Lasso tool to de-select problem spots (or you can roughly select along the inside of the subject and add to the selection with the Magic Wand tool).
3. Once the subject is selected, I decrease my selection by a couple of pixels and then add a feather of about 2-4.
4. Copy and paste to a new layer and and save the file for future use if needed.
5. Keep that copy on your clipboard for the next step.

Here you can see my selected mushroom from the 8.0 aperture image.

Creating an easy mask with Topaz Lab's Demask:

1. I am not a pro with Photoshop masks (though masks are not terribly difficult, the following is much easier for me), but I do know how to use Topaz Lab's amazing DeMask software, which make it relatively easy and fast to create a super mask. (You can find a free 30-day trial here: Topaz Labs: Downloads)
2. When your mask is just right and you create it, there will be another layer with the mask on it. Save the file so you have it to go back to if needed.
3. Copy the layer to your clipboard for the next step.

In this image, you can see that I've used the Clone tool to carefully push in the edges of the mushroom all around. It's ok that it's messy looking because you'll be covering up the mushroom bits with the crisp mushroom!

Second, go to the image with the soft focus you want for the background and prepare the setting:
You'll need to remove some of the subject from the image becuase the blur will cause it to spread out and when you place your crisp subject on a layer above it, the blurry original will be visible around the edges.

1. Paste the crisp subject layer from the other file. This action will automatically create a new layer.
2. Using the Move tool, maneuver your subject so it's just over your soft version. You may need to use the Transform tool to rotate the subject slightly and/or shrink the subject to fit. Notice that the blurry version pushes out around the edges of your crisp version. We need to fix that.
3. Hide the layer with the crisp version. You will turn this layer on and off while doing the next step to check your work.
4. Using the Clone tool, carefully replace the blurred edges with soft background immediately next to the blur. The idea is to push the blurry areas inwards so that you won't see them when your crisp version is in place. Reading this part without seeing the two layers will be very confusing but clear when you see it!
5. Note: the area under the crisp subject will be totally messy but you won't see it, so don't worry about it! :)
6. Check to make sure all the blurry area is pushed in and that the area that's replaced is smooth. You may want to use the smudge tool and/or low opacities of the clone tool to create a nice, smooth gradient into the rest of the background. Back out to 100% to see how it looks and alter if needed.
7. Turn the crisp layer on and use the Erase tool if needed to clean up the edges.
8. Use the Blur tool or Erase tool at low opacities to soften the edges just a bit so they look more natural within the soft background.
9. Check to make sure your subject isn't too bright or dark in its new setting. Adjust levels if needed.