These types of eye contact give different results to your photos. Maybe we've been very often and commonplace for all of us. But there's no harm in discussing it to make us more aware.
1. Direct eye contact
Usually in direct eye contact, the subject looks at the camera and realizes they are being photographed. Indirectly, there is a connection made between the person being photographed and the person looking at the photo through the expression that the person shows. It can be happy, angry, sad, disappointed.
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2. Eye contact between subjects
This type of eye contact usually depicts the relationship between the subject being photographed and is not related to the person viewing the photo. You can use this type of eye contact to describe a condition and emotion, such as romance, or anger. This type of eye contact is not only between 2 people but can also be like a person with their pet, or a person who is arranging a bouquet of flowers with a good mood.
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3. No eye contact
This is known as a candid photo where the subject is not looking at the camera and the photo seems to have been taken surreptitiously. The result is like there is something unknown that caught the subject's attention. But you can also incorporate into the frame elements that explain where the subject's attention is.