FOCUS STACKING
Taking Depth-of-Field To The Extreme
With the developments in what a digital camera in conjunction with the computer can produce, it has taken the craft of photography far beyond what was possible with film. Or at least what is possible by anyone other than a highly skilled photo retouching artisan.

Just as the techniques of HDR Photography have greatly increased the range of tones and colors in a image, the process of Focus Stacking increases the range of what's in focus (depth-of-field) astronomically. Also note that none of the example images had any in-camera sharpening added or any sharpening applied in Photoshop.

Keep in mind that both in-camera sharpening and any added by software is not actually optical sharpness but a matter of increasing edge contrast in pixels. In fact if you sharpen and image and then view it at about 300%, you will see what happens. While you think you are making it sharper, you actually are degrading the image at the same time. But it does give the appearance of a sharper image when viewed at small sizes and on computer screens.

I have read over articles and viewed videos on the process of Focus Stacking, although I never really tried it. But, like all of the projects in The Photography Experience, my curiosity led me to explore.

Personally I like the effects of shallow depth-of-field (DOF) in my works. The softness and distortions of shapes and colors help lead the viewers eyes to the main subject that would be in sharp focus. This attribute of the image lets the viewers subconscious sort of fabricate the image of what'so not in focus in their mind.

In this first example image shown, I have achieved basically what I wanted to by having soft out of focus background with sharp in focus subjects. This image, and actually all of the ones in this stack were captured with a 60mm Macro lens at ISO 400 for 1/30 of a second at f/22. The second image in this pop up window is after combining 6 images at the very same exposure and aperture with the only change being the center of focus.

The resulting image yields a sharpness range that was not possible in one shot, with not only the foremost front canister being sharp, but also the furthest back box of Ektachrome being quite sharp in comparison to the first image of the series.

As you can see in the larger examples of this scene shown here that at no point was the range of focus good enough to capture all six subjects at the same level of sharpness.

Also showing that the Hyper-focal Distance (defined as the focus distance which places the furthest edge of a depth of field at infinity) rule doesn't work in applications involving a macro subject or a macro subject with a background you also want in focus.

To achieve that, you will need to employ Focus Stacking to cover such a broad range of DOF. This is especially necessary when shooting with a macro lens since the arrangement of lens elements when focusing just inches away from the subject will limit the DOF quite severely. You can see here from the examples that the range of focus when in macro mode, will only be about 3 inches from front to back and even less when you move in closer to the subject.

You can see that even the slightest change of focus towards the back results in the ridges in the lid of the film cannister in the front to go soft and loose that tack sharp detail they have when it is the point of focus. Also the Ektachrome box in the back is never really sharp until I focused primarily on it.

For product photography this technique can make your good images become mind-blowing fantastic with the products being tack sharp while rendering the background as muted colors and shapes. And with scenes as in this example, you end up with extraordinarily sharp images that will have people wondering what kind of lens you used.

As a hobby/passion for me, I photograph 1/64 scale die-cast such as Hot Wheels & Matchbox cars for my OneSixtyFourth FaceBook page. Although I won't be doing Focus Stacking on all the images I post due to some of the factors involved, such as the use of a tripod and the additional processing time it will add to getting images posted. For me it's just something I like doing, but the set up needs to be simple and possible on a spur of the moment instance.

But yet, the DOF results are so dramatically different, I may tend to shoot that way every now and then. As you can see from the examples shown in this image set that it may be what I choose to do when I really want maximum DOF.

You can easily see where trying to use a Hyper-focal Distance technique to incorporate infinity and the foremost areas to be in focus, is not possible in macro situations when using a prime macro lens. Even when stopping down from f/22 to f/32, the DOF is not increased enough to make the entire scene tack sharp.

Most of the obvious examples of Focus Stacking you may come across will typically be a small object in the foreground very close to the camera and a scene behind it. There again most of those works will be with a macro lens or a lens that has some close focus capability.

When shooting with a more "normal" focal length, you may be hard pressed at times to tell if it was captured and processed with Focus Stacking because the DOF is already going to be most of the entire scene. The technique mostly pays off with mixing the close-up object with the background scene and have them both tack sharp.

The Image Capture Process
Focus Stacking is actually a simple process once you have the images to work with. And even capturing the images is not a difficult task. The basic capture process requires a tripod or some type of stable base to set the camera on so it will not move. I also used a wireless remote to fire the shutter to also avoid any possible camera movement. You could also use the self timer, or even fire the shutter as you normally do. Just be sure that the camera doesn't move between shots.

I also found in my Focus Stacking experiments that any moving objects, due to the wind blowing or other reasons, will not yield good results since Photoshop will try to find the common bits of the image to align them. If the wind is blowing something in the scene, it will just create a big blur in that area of the image.

As for the EV (Exposure values) I chose to shoot at f/22 but also conducted some test in this project shooting all the images at f/5.6. Overall the best results were from the scenes I shot at f/22, but if you just have to shoot at a bigger aperture due to certain lighting conditions, you will still get favorable results.

Make your first exposure with the camera focused as close as it can to get the subject closest to the camera in focus. You can use the viewfinder or live view to get this first image compose and the closest subject in focus, most likely in macro mode of the lens.

Then make as many exposures as you wish following the first one with the only change being that you rotate the focus ring slightly to move the center of focus further away from you. Continue doing this until you have reached the infinity range of the lens.

In the example images of this project, you will notice most of them are captures with the macro lens. This makes it easier for you to see the dramatic changes in focus and final results as compared to landscapes and wide area coverage scenes where you also can employ the Focus Stacking process.

As you can see from this series of example images (although I only show 4 of the 7 images used in this stack) the difference and gain in DOF is pretty amazing.

Stacking The Big Picture
Focus stacking is incredibly awesome process to use for macro photography, and it also has it's place in other areas too such as landscapes.

Just as in trying to capture macros images at a slow shutter speed with the wind blowing, the same problem happens in focus stacking with landscape images. Although you can shoot at a fast enough shutter speed to freeze the motion of things blowing in the wind, when you stack the images you will get a blurred image of the items that were moving.

Since Photoshop will try to align the images into one, it will have difficulty trying to align a portion of the image that is in different places through the multiple images to be used in the stack.

You can see the effects if you notice the taller wheat strands that extend above the horizon in the images in this series of samples. The slightly different location of the wheat strands during the various captures produced a slightly blurred area in the final image. But in this case it is quite acceptable, although in about 5 previous attempts at capturing a landscape for focus stacking, I had unsatisfactory results due to the wind blowing during the series of exposures to make the stack.

In the previous image examples I used a macro lens, but in this landscape example I used the 50mm Normal Lens. And just as with the macro lens, another problem you will encounter is the change in size of the subject of interest. As you move the focus ring from the closest point of focus through to the furthest back, you will get some distortion in the images closest to the lens. Then when putting them together in Photoshop there will be issues getting them aligned since in some images the subject will have sharp edges and in the images where the back area is in focus you will get softness in the front subjects.

You can spot a little of this distortion problem encountered if you look along the right edge of the No Trespassing sign in the final image. There is some roughness along the straight edge that is produced from the blending of the distorted last image and the sharp in focus first image.

You may not want to always use focus stacking in your landscapes, and most likely you won't be able to in a majority of situations. There are times when you want the lack of DOF to help isolate the subject, and sometimes having a scene with it 100% in focus may be the result you want.

The Image Stacking Process
Once you have the images (RAW or JPEG) downloaded to the computer, you can drag the entire series into Photoshop to open. Hopefully you shot them in RAW and will have a lot more editing changes available than if you shot JPEG's.

For my project, since I always shoot in RAW, obviously I will have a few steps extra to take. But... those extra steps have the ability to improve my base images greatly.

Once you drag the raw files into Photoshop, they will open in Adobe Camera Raw. You can see the series of steps in the process shown in this pop-up window. The open files will show up along the left side of the ACR window. The open file will be at the top and available to make any of the changes you wish to make.

Once you have made the adjustments you wish to make, then "Select All" from the menu drop down at the top (It is slightly different in various versions of the programs). Then, from the same drop down menu, select "Sync Settings" and then a new window will pop up with all the boxes checked except the bottom 3. Not sure why the selection "Local Adjustments" isn't already checked, but I have found you will want to select it also if you have made any adjustments. Click the "Ok" button then the final step in ACR is to click the "Open Image" selection.

I also found it best for simplicity, to have only the images for that series open, so that when you make the next step in Photoshop which is to select "File/Scripts/Load Files Into Stack".

In the following window that pops up, select "Load Open Files" and also select the "Attempt To Automatically Align Source Images" option. The result will be a Photoshop file with each of the images on a layer of its own.

The final step is to select all the layers, and then from the edit menu select "Auto Blend Layers". Then a window will pop up and as you can see from the screen shots in this set of examples, you need to also select "Stack Images" and "Seamless Tones and Colors".

Photoshop will process all the files, align them and mask out the unsharp areas and you end up with a multi-layer file with a final merged image on top.

You can click through the layers and see the mask applied to each one and if you choose, you could alter the mask on each and make another merged layer. The ability of Photoshop to align each of the layers absolutely is mind blowing.

As you can observe through the camera as you shoot your stacks, that the proportions and distortions change from one to the other, yet Photoshop aligns them to appear as if it was truly shot in one image.

Capture At The Sweet Spot or f/22
Does your choice of aperture make a difference?
In this series of images shown, the differences in shooting the files for the stack at f/8 (the aperture that produces the sharpest image, known as the sweet spot on most lens) and shooting the stack at f/22.

As you can see the difference in Depth-of-Filed between the first image of the stack captured at f/22 and the first image of the stack at f/8, is quite noticeable. And as in all the images from this project... No in-camera sharpening or sharpening in Photoshop has been applied to show you the truest results as far as sharpness and DOF are concerned.

In fact, I never have in-camera sharpening turned on and very rarely use a sharpening tool in Photoshop.

In the final result images shown in this series, you can see that for the most part they are quite similar except for the loss of depth at the very back of the images. You can see more details in the petals of the flowers in the f/22 stack. But if you had to shoot at a larger aperture like f/8 to create your stack, I would suggest making it a 15-20 image stack to allow for all areas of the scene to have been captured in focus in at least one of the captures.

Your percentage of favorable results will be much higher in macro applications, but when doing landscapes and trying to combine such a wide range of area, you will encounter distortions that will need addressed. Although Photoshop will do a great job putting all the images together, it does have it limitations.

No matter if you are shooting images for focus stacking with the macro lens or any other, you will need to be aware of the problems that arise due to the distortion from focusing on the very closest subject to the lens and then to the very furthest away.

Although you may not notice it in this small thumbnail or even in the 800 pixel wide sample in this series shown in the pop-up window. But the following image in this series is a close up portion of what will happen when you have a subject very close to the lens and also want the very distant background to be in focus.

I even tried a 16 layer image stack and the results were about identical to the 11 layer stack as shown in the examples. And a 2 layer stack of the first capture and the last capture were much worse.

Even if you can't get Photoshop to make a perfect stack for you, there is always the option of masking out areas by hand and combining the layers manually. I did attempt to try and produce a final example of this image for this project but soon realized it would take several hours to mask out the blurred barbed wire and then place the sharp barbed wire over top. Although it can be done, it would need to be a image you have the time it will take to produce it manually.

Parting Thoughts
As I wrap up his project on Focus Stacking, I have come away with some basic guidelines and essentials for a successful focus stacked image.

The choice of lens doesn't matter as much as the depth of the scene you wish to stack. If it's a macro scene or the entire area of depth you want to cover is not more than a few feet in depth, you will most likely be pleased with all your attempts in this range. If you wish to cover a large expanse of land in a landscape, you will need to be very selective in what type of subject you have in the closest proximity to the lens. You can see from the examples that a nice defined shape like the no trespassing sign will work fine, but intricate shapes like the barbed wire will distort too much in the multiple captures to blend as good as the well defined simple shapes will.

Obviously you will want to use a tripod or very stable surface to set the camera on. To keep your exposure values the same, I would suggest you capture in manual mode at the smallest f-stop using the self timer or preferably a wireless remote to fire the shutter as to reduce the possibility of camera movement between exposures. Using manual focus as well, being very careful rotating the focus ring between exposures to also prevent camera movement.

Capture at least a half dozen images for the stack, or preferably more for the best results. Although my computer had no problem churning through 20 images and blending them into one stacked file, I have seen macro examples of over 200 images used to make the stack, but your computer may not want to cooperate with that may files at once.

And foremost... Experiment, Experiment, Experiment. As it took about five different photo journeys to figure out what I needed to do to get landscape stacks to not only be sharp throughout, but also to not have blurred subjects due to wind or from being too close to the camera in relation to where the focus ring will need to rotate to capture a sharp background area.

When you have your set up ready to shoot, you can look through the viewfinder as you rotate the focus ring and see the degree of distortion you will have. You can literally see the subject grow in size and move in the scene slightly as you change the center of focus to the area behind the front subject.

Cover | About TPE | Previous Issues | Workshops | Gallery 5
Website Designed & Powered by Doctorsid Visual Media