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Step into the world of 35mm photography with the Photography Discussion Roundtable, heard every Monday evening at 7:00 PM ET on BrandMeister DMR Talkgroup 31266 — the MichiganOne Nets channel. This engaging net is your chance to explore the art and science of photography, ask questions, and sharpen your skills in a welcoming, knowledge-rich environment.

Hosted by James N8TMP, Bob KB8DQQ, and Rick AD8KN, each brings a wealth of experience to the mic. Bob and James are seasoned wedding photographers, while Rick adds deep technical insight and practical know-how. Together, they guide discussions on camera features, techniques, terminology, and everything from aperture to artistic vision.

Whether you’re just starting out or looking to refine your craft, tune in and join the conversation. Your next great shot starts here.

Aperture in photography is the adjustable opening inside the lens that controls how much light reaches the sensor and how much of the scene appears in focus. It is expressed in f-numbers (like f/2.8, f/8, f/16), and changing aperture affects both exposure and depth of field.

Core definition

• Aperture is the opening in the lens through which light passes into the camera.
• It is one of the three exposure “triangle” settings, along with shutter speed and ISO.
• The size of this opening is given as an f-number or f-stop (for example f/1.4, f/4, f/11).

How f‑stops work

• The f-number is defined as focal length ÷ aperture diameter, so for a given lens, a smaller f-number means a physically wider opening.
• Small f-number (f/1.4, f/2, f/2.8) = large opening = more light; large f-number (f/11, f/16, f/22) = small opening = less light.
• Each full stop change (for example f/2.8 to f/4 to f/5.6) roughly halves or doubles the amount of light reaching the sensor.

Aperture and exposure

• Opening the aperture (going from f/8 to f/4) brightens the image because more light reaches the sensor in the same time.
• Closing the aperture (going from f/4 to f/11) darkens the image because less light gets through, unless shutter speed or ISO are adjusted.
• In practice, photographers trade between aperture, shutter speed, and ISO to maintain the same overall exposure while changing creative look.

 Aperture and depth of field

• Depth of field is how much of the scene from front to back appears acceptably sharp in the photo.
• Wide apertures (small f-number like f/1.8 or f/2.8) produce shallow depth of field: the subject can be sharp while foreground and background blur.
• Narrow apertures (large f-number like f/11 or f/16) produce deep depth of field: more of the scene, from near to far, appears in focus.

Creative uses of aperture

• Portraits often use wide apertures to isolate a subject against a soft, blurred background and draw attention to eyes and face.
• Landscapes and architecture typically use mid to small apertures (around f/8–f/16) to keep foreground and distant elements sharp.
• In low light, opening the aperture allows handheld shooting at lower ISO or faster shutter speeds, reducing motion blur and noise.

Optical limits and diffraction

• Very small apertures cause diffraction, where light bends at the edges of the opening and slightly softens fine detail.
• On many full-frame cameras, diffraction starts to become visible around f/11–f/16, while smaller-sensor cameras may show it earlier at larger f-numbers.
• Lenses often have an “optimum” aperture (commonly in the f/5.6–f/8 range) where sharpness is highest before diffraction and aberrations become more noticeable.

Summary

Aperture is a lens opening that simultaneously controls light and depth of field, making it one of the most powerful creative tools in photography. Wide apertures give bright images and background blur; narrow apertures give darker images and greater front‑to‑back sharpness. Understanding how f-stops relate to exposure, depth of field, and diffraction lets photographers choose settings intentionally rather than relying on the camera’s automation.

5‑question multiple choice quiz

1. Which option best describes aperture in a camera lens?
   A. The time the shutter stays open
   B. The sensitivity of the sensor to light
   C. The adjustable opening that controls how much light enters the lens
   D. The distance between the camera and subject
2. Compared to f/11, an aperture of f/2.8:
   A. Lets in less light and has greater depth of field
   B. Lets in more light and has shallower depth of field
   C. Lets in less light and has shallower depth of field
   D. Lets in the same light but changes only color
3. Which aperture is most likely to give a very blurry background in a portrait?
   A. f/2
   B. f/8
   C. f/16
   D. f/22
4. A landscape photographer wants everything from foreground rocks to distant mountains sharp. Which setting is most appropriate (all else equal)?
   A. f/1.4
   B. f/2.8
   C. f/8–f/16
   D. f/22–f/32 with no diffraction
5. What is one potential downside of using extremely small apertures like f/22?
   A. The camera cannot autofocus
   B. Diffraction can soften fine detail
   C. The lens zoom range is reduced
   D. The ISO automatically doubles

Here are the answers and brief explanations for each question.

1. C– The adjustable opening that controls how much light enters the lens. Aperture is the physical opening in the lens diaphragm that controls light reaching the sensor.
2. B– Lets in more light and has shallower depth of field. A lower f-number like f/2.8 means a wider opening, more light, and a thinner zone of sharp focus compared to f/11.
3. A– f/2. Wide apertures (small f-numbers) are used for strong background blur and subject isolation in portraits.
4. C– f/8–f/16. Landscape photographers typically choose mid to small apertures to maximize depth of field from foreground to background.
5. B– Diffraction can soften fine detail. Very small apertures such as f/22 increase depth of field but also increase diffraction, which reduces image sharpness.

Next week we’ll discuss: What is the Golden Triangle

Previous and upcoming Photography Discussion Roundtable topics:

https://thediabeticham.com/previous-and-upcoming-photography-discussion-roundtable-topics/