In this tutorial, I am going to explain how to take light trails photos and process them in Affinity photo to achieve a powerful image with a reasonable amount of light trails.
These kinds of photos are usually taken at night or dusk, in any case with low natural light. A tripod is necessary to have, moreover it is recommended to keep the ISO as lower as possible to reduce the amount of noise in the picture.
To get the light trails made by the car the exposure time can vary from few seconds to minutes, it depends from the car speed and the number passing through the scene. The low ISO is extending the shutter opening time already, the diaphragm is settled base on the field of view targeted. Going to small aperture, it increases the exposure time.
In this kind of photo, it is not necessary to protect the highlight when shooting for the car light; this is giving additional room to play with the exposure. There are dedicated photos properly exposed for the surrounding area and they are blended together with other later on. In the other side a long opening shutter time, can affect the detail, burn the highlight not only for the light but for other elements too.
My process is usually to take few photos focusing only on the light trails and after adjust the exposure to preserve the surrounding elements. At the end of the photo shoot there are up to 10 photos for the same subject. To simplify the post process I recommend the use of a tripod to assure a proper alignment of the photos and avoid camera shake in case of long exposure.
The post process I am going to describe below is a nondestructive process, all files are kept in different layers and the merging process is done through groups and layers, so it is always possible to go back later on and make further adjustments.
To import the photos in Affinity in the menu File select the function “new stack”. All photos exposed for the light and surrounding area need to be selected together. Select the feature “Automatically Align Images” to auto align all photos.
When imported the photos are aligned but in a single group, in this situation is not possible to post process the photos separately.
The first step is to ungroup the photos and to make them available in separate layers.
An easy way to bring the light trails from different layers together is simple and straightforward. Select all layers to be merged together, do not included the underexposed photos here, and blend them as “lighten”. This is taking only the highlight from each photo and shows them together. If the highlight looks too heavy, in particular the front light of the car, the amount of light selected can be manage through a mask on each layer.
First, deselect the layers one by one to see the effect of each of them. When this is done, you have a clear understanding about the impact of each single layer to the final photo. Base on the outcome, there are two possible decision, remove completely the layer or partially reduce the light trails. In the first case just make the layer invisible. In the second case add a mask to the layer, make the mask white so everything is visible and with a black brush paint out the area not required. If the effect is too strong, it can be reduced by moving the °opacity° slider from 1005 to a lower value.
After the process is done for all layers, the light trails should look fine, group those layers together to avoid additional modification to them by mistake.
It is now time to process the surrounding areas with the underexposed photos. Select the layers where the surrounding area is properly exposed. Base on the subject there are different way to blend the light trails with the other subjects in the photo. The first step is always to create a mask and make visible only the desired area from each of those layers.
When this is done, it is important to check if the different layers are blending together with a smooth light transition and there are not sharp changes in the light or artifact such as aloes around the edges or an unnatural color / light variation. Case by case there are different actions to improve the final result, reduce the layer opacity, clone the area with a clone brush tool, use a mask to remove undesired effects, use a gradient filter and so on.
When the final light trails effect is achieved and the light results properly balance in the photo, it is time to move forward with a standard post process flow for the photo. This is not part of this blog post and I could propose it as a separate topic. In fact I do not have a single standard process in the light room, it varies from photo to photo base on subject and what I am looking forward to achieve as a final result.