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ISO

Does ISO Affect Sharpness? (Yes, But…)

Posted on Author photosmekaaPosted in FAQs, Photography

Any good photography is founded on three main pillars:

  • Aperture
  • Shutter speed
  • ISO

These three significantly affect the outcome of a photo. This article will focus on how the ISO affects the resulting images.  

So, does ISO affect sharpness? The answer is Yes, the ISO does affect the sharpness of a photo. Generally, the ISO setting works to either increase or decrease the brightness level of a photograph.

But besides that, it also influences the dynamic range and noise/ grain levels. With the lowest ISO setting (base), the images will contain the highest dynamic range and the least noise, making post-processing more flexible. 

This post seeks to educate you on all you need to know about the ISO factor in photography and what different ISOs would mean to a picture.

Moreover, we explain how you can effectively use this factor to get the best results. 

What is ISO, and How Does It Affect Sharpness?

What is ISO?

ISO in full is the International Organization for Standardization. However, the camera ISO is not directly related to the organization that creates the various product and technology standards.

Initially, the term ISO defined the film sensitivity, but with time, manufacturers of digital cameras adopted the term to refer to maintaining the same brightness levels as films. 

In basic terms, ISO can be described as the camera setting that darkens or brightens a photo. An increase in the ISO number progressively increases the brightness of your photos. Therefore, ISO plays a significant role if you intend to take pictures in a darker environment so you can easily capture images, as well as enjoy more flexibility when it comes to shutter speed and aperture settings. 

However, an increase in ISO number comes with some consequences. It compromises on quality in that the resulting photo will contain a lot of noise, also referred to as grain, and will not be very usable. Thus, brightening your photos by increasing the ISO number might not be the best idea. 

You can only increase the ISO number if it is impossible to brighten the photo using the aperture or shutter speed. For instance, if you set a longer shutter speed, the subject will turn out to be blurry. 

What are the Common ISO values

Each camera is designed with a varying range of ISO values, sometimes referred to as ISO speeds, that you can set. The standard sets include; 

  • ISO 100 (low ISO)
  • ISO 200 
  • ISO 400 
  • ISO 800 
  • ISO 1600 
  • ISO 3200 
  • ISO 6400 (high ISO) 

Doubling the ISO value translates to doubling the brightness level of the photo. Therefore, a photo taken in ISO 400 will be twice brighter than one taken in ISO 200, which in turn will be twice brighter than the ISO 100 photo. 

What is base ISO?

ISO

The base ISO refers to the lowest possible native ISO number on your camera. This setting is crucial since it determines the image quality and allows you to deliver a photo with as minimal noise as possible. 

Some of the older DSLR models and some modern camera models like the Fuji X-T2 are designed with a base ISO of 200, while most modern digital cameras start at ISO 100. 

For optimum results, try maintaining the base ISO as this guarantees the highest quality of your images. However, that can be impossible when you are working in environments with low lighting.

Low versus high ISO noise visibility 

As earlier explained, ISO affects the noise visibility of photos. When comparing two images taken at ISO 200 and ISO 3200, respectively, you will be able to tell the difference. 

The ISO 3200 image displays much more noise than the one taken at ISO 200. Therefore, you should avoid using the higher ISO speeds as much as possible unless the conditions force you to. 

What Camera ISO Should You Use?

Many photographers tend to understand ISO basics but do not know which ISO value to apply when in the field. Practically, there is a reason why cameras come equipped with numerous ISO settings. Different situations will require different ISOs. Below are the common scenarios you are likely to encounter. 

When to use low ISO

As explained above, always try to stick to the lowest ISO as much as you can. In most cameras, it is ISO 100 or ISO 200. If you are shooting in an environment with sufficient light, maintain the low ISO while minimizing the noise appearance as much as you can. In dark or dim environments, it is possible to use the base ISO. 

For instance, if the camera has been mounted on a tripod or sitting still on a table, using the low ISO is possible, and the photo can be brightened by using a long shutter speed since the camera is not likely to shake. However, you need to remember that if you are using the long shutter speed, if anything moving is captured, it will resemble a ghost. 

When to use high ISO

Inasmuch as a low ISO value is highly recommended, plenty of situations will call for using the high ISO. In some cases, it is only possible to take a good photo with a high ISO value. 

The common culprit is the motion blur, where you are forced to choose between a harp photo at a high ISO value or a blurry photo taken at a low ISO. Therefore, when there is no other possible way to capture a sharp and bright photo or inadequate lighting, you can increase the ISO value. 

Moreover, when you are shooting indoors without a flash for handheld photos, you are advised to set the ISO at a higher number so you can capture the moment and not introduce any blur. A high ISO can also be applied when shooting an ultra-fast action such as birds in flight. 

Most camera models come with an Auto ISO setting that works best in low lighting conditions. The good thing about this setting is that you can input the highest ISO you are willing to use to ensure the camera does not go beyond that limit. 

For example, to limit the noise level in a photo, you can set your maximum ISO value to something like ISO 1600 or ISO 3200. The only trade-off will be that the camera will need longer shutter speeds if you are using these ISO limits, and this introduces more motion blur.

How to Change ISO

ISO Speed

We explain how to change the ISO for beginners in photography. Changing the ISO speeds varies with the camera you are using, but the common ways are explained below. 

Firstly, you need to set a mode that allows you to change the ISO yourself. For example, get out of the Auto mode and enter aperture priority, shutter priority, program, or manual. Most preferable are the manual and aperture priority modes. 

For the entry-level DSLRs and mirrorless cameras, you may be required to open a menu and locate the ISO section. You can select the ISO value you want to work with or set it to auto from there. 

Higher-end cameras may come with a dedicated ISO button fitted on the camera. The button should be pressed while simultaneously spinning one of the wheels to change the ISO value. If you cannot locate the ISO button, your camera may possibly allow you to program one.

Other camera models are fitted with wheels marked with various ISO values. These are the easiest to work with.

If you are still unsure, you can refer to the camera manual. But it would be best if you kept in mind that changing the ISO setting is an essential skill that you will be using quite often, especially when working in low lighting conditions without a flash or a tripod. 

How to Maximize Image Quality and Minimize Noise 

A common misconception that most photographers tend to adopt is that to get high-quality images at all times, the ISO value has to be set at the base ISO throughout. When you are in a dark environment, you will have no other choice other than using a higher ISO value. But we have explained the situations that may require a different ISO setting. 

The base ISO should only be used when the amount of lighting allows.

Forcing a base ISO in dark environments will result in a dark photo. In the same vein, you will be using a fast shutter speed to capture the action, which is the same as shooting in a dark environment since you limit the time taken for the camera sensor to capture light.

Thus, a high ISO might be the only option you have for some action and sports photography. 

To maximize the image quality, here are the steps you can follow:

  • Start by setting an aperture that provides a desired depth of the field, then set the lowest ISO value with the shutter speed to any setting that provides adequate exposure. 
  • If the subject appears blurry, you can progressively increase the ISO value and use faster shutter speeds until the blur disappears. 
  • If the ISO setting reaches too high, you have the option to select a wider aperture. Open the aperture until the ISO level is more manageable. Sometimes this could mean sacrificing some depth of the field. 
  • That way, you are guaranteed to capture the highest quality images every time. You will be able to find the perfect balance between depth of the field, motion blur, and noise. 

Conclusion

The ISO value affects the sharpness of any photo. It is therefore vital to know how to adjust it appropriately for the best results. 

The above article touches on all you need to know about the ISO concept in photography. 

With that, you will know what to apply depending on the environment you are shooting in.