Indoor Flash Photography – Aperture

During last week’s post of No Fear Flash, I stressed the importance of digging in and learning flash photography for your indoor sessions. This week, I’m digging into the our first component of the exposure triangle, aperture, and discussing how flash affects it. When learning indoor flash photography, it is vital that you have a foundational understanding of how each camera setting affects your overall exposure. If you take a test shot and don’t like the results, this knowledge will guide the problem solving process. This post will help dissect the relationship between aperture and flash.

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Aperture in Natural Light Photography

When shooting manually, aperture is a member of the exposure triangle, affecting the bright brightness of your photo. Aperture also dictates the depth of field in a photograph, meaning how much of your photograph is in focus. A wide aperture (i.e. f1.8 or f2.0) physically opens up the hole in your lens, allowing in more light in for a brighter exposure. That wide aperture also results in a narrower depth of field, meaning less of your image will be in focus. If you think of your photograph as a block of cheese, a wider aperture results in a thinner slice. A narrow aperture (i.e. f8 or f16) physically closes the hole in your lens, making the overall exposure darker. A narrow aperture results in a wider depth of field, meaning more of your image will be in focus. If you go back to that block of cheese, a narrow aperture results in a thicker slice.

As a portrait, photographer, when adjusting my exposure, aperture is the the setting I address first. I prefer for my subject to stand out from the background. Therefore, I use a wide aperture (i.e. usually f1.8-f2.8) to surround my subject with bokeh (a blurred background).

Aperture in Indoor Flash Photography

When adding flash to your photograph, aperture plays a key role. With indoor flash photography, aperture tends to affect the overall brightness of the subject. A wide aperture (i.e. f1.8-f2/8) generally is going to allow more of the light into your lens, resulting in a brighter subject. A narrow aperture (i.e. f8 or f16) will generally allow less light into your lens, resulting in a darker subject. After taking a text shot, if your subject is too bright in comparison to the background, try making your aperture narrower.

My resounding theme for this blog series is: “Practice makes proficient!” So I have some homework for you. Get out your flash, put it in your hot shoe, put your flash in manual mode and play with your aperture. (Here’s a link to the flash I use: Yes, I realize that we’ve not even addressed power settings or modifying the light. I actually usually avoid on-camera flash. You probably aren’t going to love these photos and they aren’t going to win you any awards. That’s not the point of this exercise! We are purely trying to understand the role aperture plays in indoor flash photography. Try dialing in these settings: Shutter speed 1/200, ISO 200, flash power 1/4-1/32. You may have to adust your flash setting up and down depending on the ambient light in the room. Once you are getting close to a correct exposure, leave it alone and only adjust your aperture. (These settings are not my generally recommendation. They are purely for this learning exercise.) Now take pictures of an object, altering nothing but your aperture each time, observing the results.

Note: If you don’t know how to put your flash in manual mode, look up some tutorials for your flash model on youtube. “TTL” stands for “Through The Lens” and is basically the “auto” mode of flash.

Natural Light RAW: f2.8, ISO 200, Shutter 1/200
Flash: 1/4; f2.8, IS0 200, 1/200
Flash Power: 1/4, f4.0, ISO 200, Shutter 1/200
Flash: 1/4, f5.6, ISO 200, Shutter 1/200

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