Instagram issue

[Natos89]

Hello

When i use the instagram app to take photos, the photo is bigger than what show on the screen. Let's say i wanted to take a photo of a white square over a black background. I put only the white square on the app's camera screen so that no black background show in the frame, yet when i take the photo not only shows the square but also a bit of the background around.

Is there a way to take a photo only of what's showing in the app's camera screen or it always ends up with a little bit more?

Thanks