Difference Between Subject Isolation & Subject Separation

I wanted to share about a topic which a newbie was asking me last week, he asked what is the difference Isolation and seperation, and photographers often used it inter-changeably.

These are my thoughts below:

Subject Isolation is more straight forward as the term suggests ‘isolation’, it is achieved through the use of depth of field. In photography terms, there are a few reasons why you would want to isolate a subject.

To give it a distinction to the background (and foreground if any)
It is also the best way to draw your viewers’ eyes to where you want them to view
To keep the intended focus and the imagery clear of distractions

The most often used technique would be the layman term ‘Background Blur’ or ‘Bokeh’ in a more technical way. Using a wide aperture, it would create a nicely blurred background/foreground. The most common aperture setting would be anything from f2 or wider. In this sense, the main tool in achieving this has got to do with your lens. In addition, there is also one more usage of lenses which could create similar result - that is to have a long lens! About 105mm or longer lens would gives a similar effect even though they can be at aperture of f4 upwards. This method uses depth of field to create the isolation, but the compression is going to be obvious (Means that the background would appear a lot closer to the subject.

(For those interested, this is a good article with visuals/animation explaining it https://mastinlabs.com/blogs/photoism/the-truth-about-lens-compression )

The main purpose of subject isolation is to create a visually appealing image where the subject stands out prominently against a soft, blurred background, often used in portrait, macro, and wildlife photography. Hope I have explained subject isolation in an easier-to-bite way on the above.

In summary, the distance between the subject and background/foreground do play a big role in subject isolation as well.

Here are two shots showing subject isolation through the use of various lenses and aperture settings. The first was shot using a 35mm at f2.0 where I wanted to isolate the subject yet I wanted to show the viewers a bit of the environment while the second was shot using an 85mm at f1.4 giving a blur which the viewers cannot really make up exactly what the background was.

Next, Subject Separation involves various methods to separate the subject from everything else. It involves lighting, composition and sometimes including depth of field. Subject Separation is a much more wider term, and it encompasses an umbrella of methods underneath. The main subject is distinguished from its surroundings not just by blur but also by contrast in lighting, color or even the position of the subject within the frame. Many of these methods can be done using photoshop and similar software in post-production as well.

To ensure clarity and distinction between the subject and its environment, enhancing the overall composition and narrative of the photograph. This technique is often used in environmental portraits, street photography, and landscape photography.

In summary, I would try my best to explain the key differences between the two. A subject isolation is often a portrait where a person’s face is distinctly focused against an often completely blurred background. Subject isolation primarily relies on depth of field to blur the background or foreground and it creates a clear distinction between the subject and what is behind/in front. It is mostly used to emphasize the subject’s presence and isolate it from distraction.

While for subject separation, you can imagine with me a street scene where a person is in focused but stands out slightly against background where you can still see the background of activities such as other passersby, streetlamps, rails, etc. - Subject separation emphasizes clarity and distinction through various visual cues such as lighting and composition. It is akin to creating visual hierarchy and context within the frame.

Here is an example of subject separation using photoshop. (Can you pick out the subtle but useful difference?)

[Left: Composition subject seperation including her 'victory sign' / Right: Addition of color/darkening of background and brightening of subject to enhance subject separation]

Hope it helps.

Cheers,

Jay.C