Focus Stacking is a cool technique with many uses. If you’ve not heard of Focus Stacking, this article will tell you what it is, why you should use it, compare it with other methods, and show you one way to do it.
What Is Focus Stacking And Why Bother?
I love shallow depth of field. If you’re new to photography, I bet you do, too. “Hmmm, this location is rubbish…I know! I’ll shoot everything at f1.4. Oh yeah, I’m good.” Hands up how many of you have done this? I have. Don’t get me wrong; there is a time and a place for using a shallow depth of field and there’s nothing wrong with using the technique. God knows I do it. But (and it’s a big BUT), if you only ever shoot wide open because you think your photos look better, or it’s “your style,” then I’m tempted to say that either you’re lazy or scared. Things can get a little tricky when you open that aperture and more of your scene comes into focus.
Alright, minor rant aside, Focus Stacking is a technique which allows us to blend the in-focus areas of our images to increase the perceived depth of field. We’re not actually increasing the depth of field of our lenses, but we are increasing the amount of in-focus objects in our image. Hence, increasing the perceived depth of field. Even if you increase your f-stop to its maximum, you still won’t be able to have everything in your photo in focus. By Focus Stacking, blending the in-focus areas, you can. How? Simple. We just rack the focus, shoot multiple images, and blend them together in post.
So, why should I bother? If you’re asking that question, then clearly you have no imagination and should just give up now (I’m joking, of course). Imagine you’re shooting a landscape image, there’s a beautiful foreground and background, but you can’t have both in focus. Using Focus Stacking, you can. If you’re photographing a product for a client, they WILL want every part of their carefully designed baby as sharp as possible.
The last two photos are a perfect example of focus stacking. The top image shows one in a series which was captured with the intention of focus stacking. It was shot at f/11, a pretty narrow aperture, and yet the top and bottom are still soft. For those that don’t know, your distance to subject plays a big role in how wide your depth of field will be; as does aperture and focal length – for more tips like that, make sure you take a look at Photography 101. It’s an essential resource for every amateur photographer, click here – Using Helicon Focus, I was able to focus stack the series and have everything, top to bottom, perfectly in focus. The next step will be some significant editing, but the focus stacking was an essential step.
Can’t I Just Use A High F-Stop To Increase My Depth Of Field?
Yes and no. Yes, you would be correct in saying that by increasing your F-stop (using a higher number), more will be in focus. But, you would be incorrect if you thought that by increasing your f-stop, everything would become sharp. Doesn’t work like that I’m afraid. Not only that, by increasing your aperture, a negative consequence begins to rear its ugly head. Diffraction.
As I mentioned before, distance to subject, focal length and aperture, all play a role in determining your depth of field. I won’t be covering these concepts in detail here. (If depth of field, aperture, focal length, distance to subject, etc. are a little confusing to you, then all is explained in Photography 101. It truly is the best resource for any amateur). With the example of the Vape Pen above, even if I were to increase my aperture to say f/22 (I believe that’s the maximum aperture for that lens), the whole pen still wouldn’t be in focus. The only way I could get the whole thing in focus, without focus stacking, would be to either, use a wider angle lens, or back up significantly and use a slightly wider lens (or use a Tilt-shift lens but I’ll get to that later). Either way, I wouldn’t be able to fill the entire frame with the subject and, therefore, would be losing detail.
Diffraction, You Horrible Thing You
I briefly mentioned diffraction before. It is yet another reason why increasing your aperture simply will not do. In the photo above, you can see the effects of diffraction. Open that image in a new window, zoom in, and examine it. If you look closely, you’ll see that even though it appears to be in focus, there isn’t actually anywhere which is tack sharp. The whole photo is slightly soft. That’s caused by diffraction and is a result of, in this instance, shooting at f/22. This video by Steve Perry provides a fantastic explanation of diffraction.
Can’t I Just Use A Tilt-Shift Lens?
Again, the answer is yes and no. If you’re shooting something relatively thin, you’ll probably be ok. Try to shoot an entire landscape or a large product which fills your whole frame however, you’ll have some trouble. A tilt-shift lens allows you to change the focus plane (i.e. rather than front to back, you could make it side to side). This can help immensely in certain situations, but it won’t allow you to get your entire frame in focus. Focus Stacking will still be necessary.
Tilt-shift lenses can actually be used for a lot more than simply changing the focus plane. Take a look at this video by the lovely people over at CreativeLive.
Focus Stacking Summary
Focus stacking is a wonderful technique which can open up a new realm of creative opportunities. And, in some cases, is absolutely essential. Now that you know that, you need to find out how to do it. I use program called Helicon Focus for my product photography, but you can also focus stack in Photoshop. Why do I use Helicon? I’ve found that for very close subjects, where your lens will breathe quite significantly, Photoshop doesn’t tend to do a great job. On the other hand, I know plenty of photographers who Focus Stack in Photoshop for landscapes. Check out this video from our very own Matthew Saville, which will show you exactly how to Focus Stack your landscape images in Photoshop.
As for Helicon, I plan to do a review of that program in the coming weeks. Keep an eye out.