01 What is the Jelly Effect The Jelly Effect is a type of image distortion in photography caused by the working mode of the image sensor, more specifically, the **rolling shutter. This phenomenon commonly occurs when shooting fast-moving objects. It typically manifests as distortion, skewing, or wobbling of the subject in the frame, resembling the elastic deformation of jelly, hence its name. For example, as shown in the following image:

As we can see, when filming a helicopter, the rapidly rotating propellers at the top of the aircraft show obvious distortion, while other objects with relatively lower motion speeds remain largely unchanged. Generally speaking, the appearance of the jelly effect is related to the relative motion of the subject being photographed. For horizontal movement, it usually appears as the subject tilting or stretching (for example, vertical utility poles appearing slanted in the frame). For vertical movement, it appears as the object being compressed or elongated (for example, a rapidly ascending or descending elevator appearing flatter). For rotating objects (such as propellers, fan blades, etc.), it results in bending, breaking, or a "smearing" effect, as shown in the image above. It should be noted that we are referring to relative motion here, not just the motion of the object itself. For instance, this image was taken from a fast-moving car, capturing roadside fences. Although the fences themselves are stationary, the high-speed movement of the camera inside the car still creates relative motion, resulting in the jelly effect.

02 Shutter Speed and Jelly Effect The jelly effect is caused by the working principle of the rolling shutter. Next, we will explain rolling shutter, global shutter, and how the jelly effect occurs. The difference between these two shutters lies in their exposure methods. Since this article focuses on the jelly effect, we will not go into technical depth but provide a simple explanation. a Rolling Shutter and Jelly Effect When shooting with a rolling shutter, the entire frame is not captured instantaneously. Instead, the sensor scans the image **line by line**. In this process, one row of pixels is read at a time, while other unread rows continue to be exposed and only form an image when read. Because the rows are not read simultaneously, there is a time delay between each line when capturing fast‑moving objects. This time difference results in the jelly effect. b Global Shutter Now let’s talk about the global shutter. As the name suggests, unlike the line‑by‑line scanning of a rolling shutter, a global shutter exposes all pixels at exactly the same time. Since all pixels capture the image simultaneously, there is no time lag as in a rolling shutter, so the jelly effect is naturally avoided. 03 Sensors and Shutters In the previous explanation of the two shutter types, I did not mention actual sensor types. We will now elaborate based on real‑world sensor categories. a CMOS First, let’s look at CMOS sensors. As mentioned in previous articles, CMOS sensors are relatively low‑cost. Most mainstream CMOS sensors use a **rolling shutter** exposure method, which is why the jelly effect is common on most CMOS devices. Global shutter CMOS sensors do exist, but they are still relatively expensive at present. However, with technological development, their cost will gradually decrease, and such sensors will become more widely available in the market. b CCD CCD sensors mostly adopt the **global shutter** by design, determined by their internal structure. 04 How to Reduce the Jelly Effect Finally, let’s cover methods to reduce the impact of the jelly effect. a Fundamental Solution: Change Equipment The most thorough solution is to upgrade your equipment. Using a camera with a global shutter sensor (whether CMOS or CCD) can completely eliminate the jelly effect. b Reduce Impact: Increase Shutter Speed If you do not want to replace your device, you can reduce the effect by using a faster shutter speed. As explained earlier, the rolling shutter scans line by line, and the jelly effect comes from the time difference between rows. By shortening the exposure time per row, the time lag is reduced, thus weakening the jelly effect. However, a higher shutter speed means shorter exposure time. To avoid underexposure, you need to use a wider aperture or higher ISO, which may result in a shallower depth of field and increased noise. c Use Mechanical Shutter Using a mechanical shutter can also reduce the jelly effect to a certain extent. However, the shutter speed of a mechanical shutter is limited by its physical structure, and not all cameras support mechanical shutter shooting. 05 Summary To sum up: The jelly effect causes image distortion, often seen in high‑speed photography. It is caused by the rolling shutter, which scans line by line and creates timing offsets. A global shutter solves this problem by exposing all pixels at once, avoiding distortion. Most CCDs use global shutters, while mainstream CMOS uses rolling shutters. If you keep your current device, shorten the exposure time to minimize the effect.