There are many techniques one has to know when taking landscape shots, and today I will try to explain focus blending :)
What is Focus blending
Focus blending, or also know as focus stacking, is a technique where you take multiple photos, all focused on a different distance and part of the scene, and put them together in one photo, where everything is in focus. This approach is very popular in Macro photography, where you just can’t get everything into focus in one shot, but is also very useful in landscape photos, where often you want to incorporate a foreground subject, that is just to close to the camera.
Here are two examples where I blended exposures with different focus.
How to take photos with different focus
For focus blending exposures, I really suggest going with full manual. Manual mode and also manual focusing. First of all you need to have the same exposure for all the shots. So setting it up for one, and than just keeping it the same is the simplest way to archive this. Secondly, you want to be 100% sure where the camera is focused, and this is just not possible with autofocus.
The number of needed exposure at different focus, depends on what you are taking photos off. It all depends where the blending transition will be. If it is in the sky, water or any other continuous transition, you will be OK with just two exposures that you can then blend manually. If the transition is much harsher, as the difference between the foreground and the background is bigger, you will need more exposures, and blend them automatically.
To take the shots, just start by focusing either on the background or the foreground, take the shots in full manual mode, and then without changing anything else, refocus on the the next part of the scene. If you are taking more than two shots, do the refocusing just by rotating the focus wheel a little towards infinity, or near focus (based on where you started) and repeat until you have the whole range.
If you want to be exactly precise or are doing macro shots, the best way to go is having a special remote, that can do this for you. For instance the Promote remote can take photos for focus stacking automatically, you set it up for how many shots you want. There are also different software, that can control your camera from a pc or a phone (check out the Helicos Focus), and if you have the Magic lantern firmware, you can do it directly in the camera.
Manual Focus blending
When combining only two exposures, doing it manually is mostly the way to go. Especially when the area of focus is quite different. You will quickly notice, that if someting is in the foreground, and out of focus, it is bigger, than if it is in focus. So blending it just in is not always that simple.
You can see this in this example photo I took in Dubai from Burj Khalifa. The corners of the glass wall, are much thiner when in focus. The only way I was able to manually blend them together was by the use of the sky, as that is same in both photos. On the bottom one, I had to leave a 1-2pixel wide gap, as that was an area for which I had no photo where it was in focus.
To manually blend, just load both images into Photoshop into separate layers. Hide the top one with a black layer mask, take a white soft brush, and start painting on the mask, where you want to reveal the top layer. In this example, it was the top and bottom part.
You can see here also a failed attempt to combine them in Helicon Focus, which didn’t work for the lack of exposures.
Automatic Focus blending
When trying to combine more than two exposures, this becomes a very hard task when doing it manually. But that’s what automated software is for. You of course need more exposures, as you will need a more gradual transition for them to work correctly. If you use bigger steps between exposures, there will be areas that are out of focus on every shot, and the software has nothing to use there.
Let’s look at this example series (please look at them only as an example, as I don’t have a macro lens, and this is not usually what I do :)). This series was taken with the help of the Magic lantern firmware.
One can either just use Photoshop or a specialized software. In Photoshop, you have to load all the images into separate layers, select the layers and then choose Edit->Auto-Blend layers. From there choose Stack images to get what you need. The option for Seamless tones and colors can help you get a better result, but it also can have a opposite effect, so I suggest experimenting and trying both.
For a specializes software, this is Helicon Focus. It does exactly what Photoshop does, just the algorithm is different. From my experiments, the results were better, but it depends quite a lot on the photo. Same as in Photoshop, it’s were easy to work with it, just load all the exposures you want to use, and choose a render method, that it.
In both options, after combining, you still have the possibility to mask out parts of any exposure, to get an even better result. And most of the times, this will be required.
That’s all for this article, and as always, feel free to ask if you have any questions.