There are many factors to consider for cloud photography. To achieve long exposures, we must take into account the amount of light hitting our sensor, which can sometimes be very high.
Depending on the speed of the clouds, the hour, the weather etc., we will have to close our diaphragm or use an ND filter in order to reduce the amount of light and prevent our photos from being overexposed.
In fact, I’ve created a list of factors to consider, explaining how they affect our moving cloud photos. It doesn’t matter what order they appear here, because sometimes we won’t need to use all of these factors.
Work with the right focal length
Personally for this type of photography, I prefer wide angles between 11 and 24 mm, which allows me to have wide viewing angles and to integrate almost all of the available sky.
On the contrary, the apparent movement of the clouds in the frame will slow down and move the background shot away from the foreground. Sometimes this technique is counterproductive if we do not take into account the explanations given in the photographs with the wide angle lenses.
Standard focal lengths as an alternative
However, it is possible to obtain good results using telephoto focal lengths or at least standard 50 mm focal lengths, because telephoto lenses have a compression effect of the planes, which allows them to assemble the different layers and to to obtain pretty luminous sillages.
In addition, we will obtain an increase in the apparent speed of the clouds because the distance between the planes will be less.
Choose quality lenses
We must be equipped with quality lenses, especially in the case that we use film lenses, since there are many lenses with large geometric aberrations that will be seen in photos of moving clouds. This will give us a lot more to correct in post-production.
For my part, my favorite film lens for this type of photos is the DZOFilm Pictor, because not only does it not geometrically distort our shot, but, unlike other lenses, it also allows me to use my filter holder with rectangular filters both rigid and graduated with which I manage to obtain the necessary exposure times so that the luminous trails of the clouds are highlighted when we need them.
Use filters
As we commented at the beginning of the article, when the light is too high, we have to increase the exposure time in order to capture movement. We will be forced to use a series of filters that will reduce the amount of light hitting our sensor.
Solid ND filters
These are the most used filters since they reduce the same amount of light over the entire frame.
If we associate a sky covered with moving clouds with any stream, we will obtain spectacular photos, with a silky effect.
In these photos, everything looks fluid and the objects in focus will only be those that are static in the frame, giving them greater presence. We can achieve effects of complete calm, desired in bucolic photographs trying to convey peace and tranquility.
Work with neutral filters
It is very important to take into account these ND filters because they are the most neutral and they will not add additional colors to our photos. This simplifies our task because if they left dominant colors, it would be complicated to remove them from our photos afterwards.
For my part, I have circular filters that attach directly to the film lenses, but for some time I started using square filters with a filter holder. I am satisfied with the results, especially for their versatility and the comfort when installing them after framing my photo. Fast and convenient at a great price.
The range of density is relatively wide and it is not necessary to have everything, but it is good to use a relatively low value and another higher, in order to be able to use them separately and together.
With some lenses, such as the DZO Film lens, we can use gelatin filters which offer sufficiently good quality. We must not rule out its use, especially for those on a tight budget, since the quality-price relationship is very interesting.
Graduated ND filters
If there is one type of filter ideal for capturing cloud movement, it is graduated ND filters where the density of the filter varies from maximum to minimum, normally corresponding with the center line of the filter.
They are usually rectangular in shape and allow us to adjust the density as it suits us, lowering them or raising them at the level of the filter holder.
It is necessary to take into account the degraded form of the filter which can be light, dark or even of two shades (darker in the center and lighter on the upper part).
With the graduated filter (GND) alone or combined with solid ND filters, it will be necessary to increase the exposure time of the photo without burning the sky.
For this, I use it when I want to take photos of moving clouds in the blue hour, where there is a high difference in exposure between the sky and the earth.
In this way, we do not overexpose the sky which has a perfect level of exposure, while obtaining a terrestrial foreground where the shadows are highlighted.
Be careful not to overexpose the image
If instead of GNB I use a standard ND, I won’t get the proper exposure at the bottom of the frame, which will be overexposed. In addition, as I commented above, the filter holder allows me to combine two filters, which gives me the possibility of increasing the exposure time with a solid ND filter, especially with the ND8 or 16.
Bring your tripod
When we talk about long exposure photography, it is inevitable to talk about the tripod. Having the camera on the tripod will allow us to have a photo where only the clouds will be moving.
But to have this result, we need to use a stable tripod that does not move when there is a lot of wind.
General tips
- Do not pull out the center column of your tripod
- Do not extend the lower sections of the tripod
- Hang the backpack on the base of the column (be careful with this advice because if the wind is strong, the tripod may fall)
Another factor to take into account is the type of head that we are going to use, since we must be able to frame in any position easily and maintain it throughout the shot.
Also keep in mind that filters and filter holders add weight to the ends of the lens.
The gift trick
I’m going to end this article with a trick that I discovered by chance and that can help us to take photos of moving clouds, even when we don’t have filters to increase exposure times.
The trick is very simple: it’s all about exposing to get adequate light with the longest exposure time. And make a high number of shots until we are satisfied with the movement of the clouds.
Then, during post-production, we will overlay these photos in the same way that we do circumpolar photos.
In this way, we will obtain a photo very similar to the one we would have obtained by adding the exposure times of all the shots.
We can use Photoshop or any other editing program. In order to avoid that we are left with hollows on the photos of moving clouds, it is recommended to use an intervalometer trigger in order to be able to program the shots. Thus, we don’t need to be focused on the shots, allowing us to enjoy the moment.
Conclusion
There are other factors, of less importance, but which we should also take into account when taking photos of moving clouds. For example, the level of noise resulting from the heating of the sensor during long exposures. But with modern cameras, it is now reduced which means that it is not such a decisive point.
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