Photography: How to Use the Diaphragm Aperture & Work Depth of Field

Photography & Light Regulation

Now a days, cameras are very complex devices with multiple functions and appliances that enable us to play and develop interesting effects, altering or capturing reality in unimaginable ways. Nevertheless, the first step in photography will always be to learn the basic principles of light regulation, and the mechanisms with which the photographer can modulate light to create the image he wants to compose.

There are 3 basic mechanisms within any given digital camera that serve the purpose of light regulation: the shutter, the diaphragm and the sensor sensitivity or ISO. This article is about the diaphragm: what it is, how it works and what can we as photographers achieve by working with and prioritizing it.


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What is the Diaphragm of a Camera?

The diaphragm is a photographic device located in the lens of the camera, which regulates the aperture of the lens, thus regulating the amount of light that enters the camera. It is a disc, within the lens, that can open or close to different diameter values.

The more open the diaphragm is, the larger the diameter and the larger the amount of light that will enter the camera.

The smaller the diaphragm aperture is, the smaller the amount of light that will get to the image sensor.


Photo Example 1: Sunny Day, Diaphragm F8

The diaphragm aperture at F8 (relatively closed) regulates the light to a lesser degree, giving the image good detail and contrast. If the diaphragm would have been more open, the photo would have become very bright and flat because of too much light
The diaphragm aperture at F8 (relatively closed) regulates the light to a lesser degree, giving the image good detail and contrast. If the diaphragm would have been more open, the photo would have become very bright and flat because of too much light | Source

Diaphragm Aperture and Focus Scale Diagram

How to use the diaphragm to regulate light, achieve "depth of field" and work with color saturation or "chromatic depth".
How to use the diaphragm to regulate light, achieve "depth of field" and work with color saturation or "chromatic depth". | Source

How to Use the Diaphragm

Generally speaking, the idea is to counterbalance the atmospheric conditions we are working with. This means that when we have a lot of light, in sunny days for example, we use the camera’s mechanisms -in this case the diaphragm- to reduce the amount of light reaching the camera’s sensor (otherwise the photo would turn out too bright and colors as well as detail would be lost). In other words, if we want to take a picture in a bright sunny day, we would have to work with a small lens aperture or closed diaphragm.

The diaphragm aperture is measured in a “Focus” (F) scale that goes from F2 to F22, with F2 being the maximum aperture of the diaphragm, and F22 being the minimum aperture or the closest the diaphragm can be.

Remember it works kind of backwards: the larger the F number, the smaller the aperture, reducing the amount of light coming into the picture. The smaller the F number, the larger the diaphragm aperture and the bigger the amount of light we will be working with.


Photography Tip:

From a general point of view, a correctly exposed digital picture is a file that shows a full range of tones, from deep shadows to bright highlights, with detail across the entire image. You should see some detail in the dark shadow areas while at the same time retaining detail in the brighter highlight areas.


Photo Example 2: Diaphragm F5.6, Human Eye Perception

This photograph was taken below the shadow of those trees, where the light diminishes, and we need to work with open diaphragm values. With an F number of 5.6, the photograph has the same depth of field as the human eye perceives. The focus point is
This photograph was taken below the shadow of those trees, where the light diminishes, and we need to work with open diaphragm values. With an F number of 5.6, the photograph has the same depth of field as the human eye perceives. The focus point is | Source

The Diaphragm and Its Photographic Effects

When prioritizing the diaphragm as a light regulator, besides determining the exposure or amount of light entering the image sensor, there are two additional effects we can create and work with: “Depth of Field” vs “Blur”, and “Chromatic Depth”.


What is Depth of Field?

The easiest way to explain the depth of field in photography is to tie it to the general sharpness of an image. When every item of a photograph, located at different focus distances, is sharp and focused, it is said to have a very high depth of field. If a photograph has some parts very sharp and others out of focus or blurry, it is said to have a low depth of field.

Having clarified this, the depth of field is defined as the "distance between the nearest and the farthest object in an image, which are considered to be well focused".



Photo Example 3: Closed Diaphragm, High Depth of Field

This photograph is an example of high depth of field, which means a very closed diaphragm, little light coming through the lens, and high F numbers (F18). Even though it is a black & white photo, colors are solidified by the closed diaphragm and that
This photograph is an example of high depth of field, which means a very closed diaphragm, little light coming through the lens, and high F numbers (F18). Even though it is a black & white photo, colors are solidified by the closed diaphragm and that | Source

Photo Example 4: Open Diaphragm, Low Depth of Field, Blurry Effect

In this photograph, I worked with the widest diaphragm the condition of light allowed me, which was F3.6 (maximum aperture of the diaphragm in this particular case). The F3.6 diaphragm allows a great deal of light to come into the camera but has a ve
In this photograph, I worked with the widest diaphragm the condition of light allowed me, which was F3.6 (maximum aperture of the diaphragm in this particular case). The F3.6 diaphragm allows a great deal of light to come into the camera but has a ve | Source

How does the Depth of Field relate to the Diaphragm and F Number?

  • The closer the diaphragm aperture is, the higher the depth of field we will attain.
  • The higher the F number, the higher the depth of field.

If we want to create an image where everything is correctly focused, including background, foreground, things at a close distance and things far away, we have to work with a closed diaphragm, which means F numbers from 6 onwards.

On the contrary, if we want to isolate a specific object in our photograph or create sharp & blurry contrast, we would have to work with an open diaphragm and low F numbers. In this case, we will achieve a sharp main focus and a blurry surrounding.

At F6 we start noticing the sharpness irregularities in the photograph, with some parts a bit out of focus; the lower the F number goes, the difference will be more and more obvious and the unfocused segments will become much more blurry.


Photography Tip:

If you want to create big focused/blurry contrast, work with two given objects that are relatively close to one another, this is when the effect becomes more obvious.

You´ll find more examples of this photographic effect and other useful tips to improve your technique, your photographs and your compositions in the following article: Nature Photography & Photography Tips.


Camera Used for these Photographs

Olympus PEN E-PL1 12.3MP Live MOS Micro Four Thirds Mirrorless Digital Camera with 14-42mm f/3.5-5.6 Zuiko Digital Zoom Lens (Black)
Olympus PEN E-PL1 12.3MP Live MOS Micro Four Thirds Mirrorless Digital Camera with 14-42mm f/3.5-5.6 Zuiko Digital Zoom Lens (Black)

All of the above photographs were taken with this Olympus Camera, which is a very compact SRL reflex professional camera, with a very good optic and a very practical, light design. Excellent for photographers that aren’t 100% dedicated to photography but never the less need high quality, professional photographs and can’t afford very high priced equipment; very good value for a very reasonable price.

 

Photo Example 5: How to Use the Diaphragm to Achieve Chromatic Depth

This photograph was taken with a moderate diaphragm aperture of F8, which falls into the range of chromatic depth (F7-F12) and is the reason why the colors in it are saturated and aglow (see focus scale diagram).
This photograph was taken with a moderate diaphragm aperture of F8, which falls into the range of chromatic depth (F7-F12) and is the reason why the colors in it are saturated and aglow (see focus scale diagram). | Source

What is Chromatic Depth

When working with F values from 7 to 12, which means relatively closed diaphragm, there is another effect that comes into play, called “chromatic depth” (see diagram above).

Chromatic depth means that colors in the photograph will be saturated and become more intense, radiant, bright.

In other words, red will become RED, green will be GREEN, orange will be ORANGE! And so forth.

This color saturation is obviously more relevant to color photography but can also be noticed in black and white photography, where the different scales of grey will become more solid.

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Comments / Questions on Photography Tips, How to Use the Diaphragm and Work With Depth of Field 25 comments

RTalloni profile image

RTalloni 5 years ago from the short journey

Interesting. I'll be coming back to review this--thanks!

Voted up and bookmarked.


Claudia Tello profile image

Claudia Tello 5 years ago from Mexico Author

Hi RTalloni, I am glad you find these information useful, thanks for reading, as well as for your nice comments and input.


whizcreed profile image

whizcreed 4 years ago from India

An interesting article thanks for sharing.. I really liked the pictures take by you.


Claudia Tello profile image

Claudia Tello 4 years ago from Mexico Author

Thanks! I am very flattered. I hope this article helps you make a better use of the diaphragm and experiment with depth of field and chromatic depth or color saturation. Thanks again for your kind comments.


eddiecarrara profile image

eddiecarrara 4 years ago from New Hampshire

Hello Claudia, I have always seen the F scale when taking pictures in auto focus, but never took the time to learn about it. Thank you for sharing this information in such an easy to read and digestible hub. You have given me some great tips and I can't wait to try them out. I have a few photos that have a focused specimen and a blurred background, but I never knew how to do it, it was more trial and error. I'm off to read more of your photo tips. Voted up and awesome!!!


Claudia Tello profile image

Claudia Tello 4 years ago from Mexico Author

Hi Eddie, I see you are a natural photographer working with depth of field without even knowing!!! Now that you have the diaphragm principles to make blurry effects and work with depth of field you will do wonders! Thanks for your interest, enthusiasm and input, hope you have fun applying all of this photography tips to future shots.


lisa42 profile image

lisa42 4 years ago from Sacramento

I knew aperture affected depth of field, but I didn't realize it also affected chromatic depth. Definitely good to know. Thanks!


Claudia Tello profile image

Claudia Tello 4 years ago from Mexico Author

Hi lisa42, thanks for your feedback, I am glad to be of service and to know you learned a new photography tip. Happy photo shootings!


sgbrown profile image

sgbrown 4 years ago from Southern Oklahoma

Very good information here. I really like the way in which you explained things, very easy to understand. Voted up and useful. Thanks for SHARING! :)


jainismus profile image

jainismus 4 years ago from Pune, India

Claudia,

Your this Hub is very useful for those who want to use manual functions in a camera. Thanks.


Claudia Tello profile image

Claudia Tello 4 years ago from Mexico Author

Hi sgbrown, I am glad you dropped by. Thanks again for your interest and input; I really hope you can enhance your photographic experiences with the photography tips within this hub. I love to work with the focus scale to create different photographic effects and that’s why I wrote this hub on how to use the diaphragm. I feel flattered by the fact you felt it worthy of sharing, thanks :)


Claudia Tello profile image

Claudia Tello 4 years ago from Mexico Author

Hi jainismus, glad to see you here! I think that the focus scale of the diaphragm is quite easy to use and can be exploited to create beautiful effects like color saturation or chromatic depth, as well as blurry effects and depth of field. One just needs to start getting creative with them!

Thanks for your feedback, it is much appreciated.


Magicdust Staff profile image

Magicdust Staff 4 years ago from Sydney, Australia

Great hub, very useful info made understandable to newbies :)


Claudia Tello profile image

Claudia Tello 4 years ago from Mexico Author

Hi Magicdust Staff,

I am glad you find this photo tips useful. Photography is quite simple, the important part of it is to practice, and when you know more about photography, you tend to feel more like using the camera to the fullest.

Thanks for the feedback!


TrahnTheMan profile image

TrahnTheMan 4 years ago from Asia, Oceania & between

Thanks Claudia, very helpful and comprehensive hub! Voted up!


Claudia Tello profile image

Claudia Tello 4 years ago from Mexico Author

Hi TrahnTheMan, I am pleased you found this hub on how to use the diaphragm helpful. I try to explain my photography tips as clear as I can to make evident how easy it is to create effects as "depth of field" and "chromatic depth" when one understands the diaphragm of a camera and works with the focus scale.

Thanks for your input! I really appreciate it :D


TrahnTheMan profile image

TrahnTheMan 4 years ago from Asia, Oceania & between

Sure thing Claudia! I should also say that your hub title caught my attention- I mean this with the utmost respect but I've never heard the term "diaphragm" be used to describe a camera iris/aperture, so that intrigued me. Chromatic depth is also an interesting concept given the possibilities in post production (in programs like Photoshop). Look forward to more articles! PS Your diagrams are SUPER helpful and clear too!


Claudia Tello profile image

Claudia Tello 4 years ago from Mexico Author

Hey TrahnTheMen!

The diaphragm is the structure that regulates the aperture of the lens and thus the amount of light passing through the lens. Most modern cameras today use a type of adjustable diaphragm called “iris diaphragm”, from there the term iris, which is also used to refer to the diaphragm. I guess we always learn something new and through this written conversation we make our hubs richer. So thanks for your input.

Even though one can retouch and modify digital photographs in many ways (photoshop and the likes are a fantastic and an excellent tool for certain kind of photography), I like to use all the tools available in my camera and get my photos as closely possible to my desired end result. Playing with my camera is much more fun for me than playing with my computer, each and all of us have the right to chose what we want and go for it; the important thing is to know the possibilities available.

Thanks again for your very interesting input and comments.


TrahnTheMan profile image

TrahnTheMan 4 years ago from Asia, Oceania & between

Thanks Claudia :-) Once I started shooting in RAW it really changed my perception of 'in-camera' processing compared to 'post-camera' (that is, in computer) processing. Elements like focus, framing, shutter speed, exposure are all fixed, but there is much more latitude in exposure afterward (where to fix the highlights and blacks) and white balance when shooting RAW. I guess I can geek-out a bit so I enjoy the process of both taking pictures and working on them afterwards! Happy shooting C.


Claudia Tello profile image

Claudia Tello 4 years ago from Mexico Author

Fantastic! I see you are really passionate about photography and we have that in common :) Photography is so full of possibilities and that´s what makes it so exciting. You should write some photography hubs as well and expand on that good knowledge of yours!

Thanks again for your interesting input. Happy shootings :)!


TrahnTheMan profile image

TrahnTheMan 4 years ago from Asia, Oceania & between

Gracias Claudia! That's very kind, and inspiring! Tu tambien!


LetitiaFT profile image

LetitiaFT 4 years ago from Paris via California

I'd never heard of chromatic depth. I'm going to study this one more in detail. This would work for photos in every field, from nature, as you've suggested in your great article on nature photography, to food photography as well. A real keeper. Voted up and awesome, as with so many of your hubs!


Claudia Tello profile image

Claudia Tello 4 years ago from Mexico Author

Letitia,

You are absolutely right, every kind of photography can be enhanced by working with the diaphragm to create chromatic depth. One would imagine your food photography couldn´t get any better, but they say there is always room for improvement.

The fun part of photography is that there are so many different effects one can accomplish that it is possible to keep on learning and experimenting with the camera.

Thanks for all your comments and input, I am very flattered :D


keyvan 3 years ago

I want know a bout diaphragm effect on depth of field


Claudia Tello profile image

Claudia Tello 3 years ago from Mexico Author

keyvan: hi, I've explained how to use the diaphragm to create depth of field in this article, I hope you find it useful.

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