Understanding and application of ISO value of beginners' sensitivity

Lead: In fact, this article is not only about ISO sensitivity, but also about a phenomenon, why the sensitivity of digital cameras is getting higher and higher, and even a small consumer DC can set ISO to 12800. What's going on here? Let's have a better understanding of ISO through this article.

ISO sensitivity definition

Sensitivity, also known as ISO value, is a measure of the sensitivity of negative film to light, which is determined by the measurement of sensitivity and several values, and has recently been standardized by the International Organization for Standardization. For the negative with low sensitivity, it takes a long exposure time to achieve the same imaging effect as the negative with high sensitivity, so it is usually called slow negative. Highly sensitive negatives are therefore called fast negatives. Whether it is digital or negative photography, in order to reduce the exposure time, the relative use of higher sensitivity usually leads to the decline of image quality (due to thicker negative particles or higher image noise or other factors). Basically, the higher the sensitivity, the worse the photo quality.

ISO sensitivity (hereinafter referred to as ISO) is a measure of the sensitivity of a negative to light. At present, its commonly used units of measurement are ISO 100, 200, 400, 800 and so on. , which is the result of multiplying each time by a multiple of 2. At present, most common digital cameras can be set from ISO 100-3200 or even 6400.

The camera advertisement can see the ISO application scope of this camera. As shown in the above picture, Canon PowerShot G 16 claims that ISO 12800 can be used, which emphasizes the photographic ability of this camera.

Find out the camera settings and you will find a pattern marked with ISO value. As shown above, the camera panel of Canon EOS 650D is marked with ISO 400.

Sensitivity is the degree of sensitivity to light. At the same aperture value and shutter speed, the higher the sensitivity, the brighter the photo will be. As shown in the above figure, with the ISO increasing from 100 to 12800, the photos will gradually become brighter, and the components in the photos can be distinguished more and more.

Sensitivity application

Sensitivity can effectively improve the brightness of photos. When the photo is too dark and not bright enough, increasing the sensitivity can effectively solve this problem.

Arc de Triomphe in Paris, France: F3.5, 1/30 seconds, ISO 1600.

When we shoot at night, we often feel that the picture is too dark. As shown above, the author shot the night scene at the Arc de Triomphe in Paris. The aperture was set to the maximum value of F3.5, and there was no tripod. In order to stabilize the shutter, the shutter speed was set to 1/30 seconds, and the picture was not bright enough at ISO 1600.

Arc de Triomphe in Paris, France: F3.5, 1/30 seconds, ISO 3200.

When I increased the sensitivity from ISO 1600 to ISO 3200, we obviously felt that the photos were brighter and better looking, without changing the other two variables.

Without changing the other two variables, if you want to improve the brightness of a photo, you can only improve the sensitivity. In this kind of night shooting with people and scenery, improving the sensitivity, such as upgrading ISO 1600 to ISO 3200, can also effectively improve the brightness of the photos.

When going abroad to play, there is often no tripod at hand. If you often feel that the photos are not bright enough, it means that the exposure is not enough. Under limited circumstances, we can only take clear and bright photos by improving the sensitivity.

Eiffel Tower, Paris, France: F4, 1/30 seconds, ISO 3200.

Venice, Italy is a romantic city. The dim street lamps at night add a lot of enthusiasm in silence to St. Kyle Square. Under the hardware limitation of the camera, the maximum aperture of the lens is only limited to F4.0 In order to stabilize the shutter, we used the shutter speed of 1/40 seconds, tried several photos taken with different ISO values, and finally chose ISO 4000 for shooting.

San Kyle Square in Venice: ISO 4000, 1/40s.

Vatican City in Rome, St. Peter's Cathedral: F5, 1/40/40s, ISO 1600.

In the indoor situation, even if it looks very bright to the naked eye, it may need higher sensitivity to cooperate. If any lens uses the maximum aperture, the picture quality will not be the best, but slightly reducing the aperture can improve the picture quality, so I adopted F5.0, hoping that the shutter speed 1/40 seconds would be stable, and finally adopted ISO 1600 to make the picture brighter and more magnificent.

It costs about 5 euros to climb to the top of the tower and get a panoramic view of Rome at night. How charming. Thank God for giving me such good weather and opportunities. I also reduced the aperture to get more detailed image quality. I used a shutter speed of 1/30 seconds to stabilize the photo. Finally, I tried several photos with different ISO values, and finally I chose ISO 1600 for shooting.

Vatican City, Rome, St. Peter's Cathedral: F5, 1/30 seconds, ISO 1600.

Edinburgh, England is the most romantic city in Britain, and it is worth visiting again. It was the atmosphere of Christmas at that time, and the whole city was full of festive atmosphere. At this time, I took out my camera and photographed this beautiful night scene. Because it was too dark, I adjusted the aperture to the maximum value of F3.5, leaned against the railing, and reluctantly adopted a slow shutter of 1/6 seconds (it is still possible to cooperate with the lens to prevent hand shock). Finally, I adopted ISO 3200 and took a satisfactory photo.

Edinburgh, UK: ISO 3200 3.5 seconds, 1/6 seconds.

London, England: ISO 6400 0/25 seconds.

When I came to London, it was actually very hard to take pictures of Big Ben and Parliament Building, because there were no railings to lean on, and the shutter speed of 1/25 seconds was barely enough. At the same time, the maximum aperture was F3.5, and the sensitivity must be ISO 6400 to take pictures that were in line with the scene feeling at that time. Of course, you don't have to be as high as ISO 6400, just try to lower the shutter speed to 65433.

conclusion

We simply explained the definition of camera sensitivity ISO and the use of ISO in taking pictures. Finally, we will show you how the camera sensitivity ISO can help us in different beautiful scenery in several different countries. I believe you can also clearly understand the usage of ISO here. Sensitivity is so easy to use, why not set it higher to make every photo brighter? There is no such thing as having the best of both worlds. The higher the sensitivity, the brighter the photo will be, but the side effect is the destruction of image quality, which is a factor we must measure.

The improvement of ISO sensitivity can really improve the overall brightness of photos, but the side effect is that the picture becomes very obvious and rough, which is the key point that you must consider when taking photos to measure sensitivity.

Let's discuss another example. The brightness of the left picture and the right picture are almost the same, but the shooting method is completely different. Both pictures were taken in M mode. The left picture is equipped with a tripod, with ISO only 50 beats, shutter for 45 seconds, aperture F 14, right half ISO 6400, aperture F3.5, shutter 1/25 seconds.

When we enlarge the photo by 100%, we will know how much damage ISO has done to the photo quality. Of course, the above picture is an extreme comparison.

One idea that is very certain here is that if you want pure, exquisite and moving night photos, you must use a tripod with low ISO to shoot them. If you don't use a tripod, only by increasing the sensitivity can you get enough exposure and the photos will be bright enough. I believe that seeing this conclusion, combined with the example in the above picture, you will understand that a delicate night scene photo still needs to be taken with a tripod. Sensitivity has many advantages, but it also has many effects on image quality. However, whether to take out the tripod for that exquisite photo is up to you.

This lecture on photography is over. I believe you have a basic understanding of the understanding and application of sensitivity ISO.