‘M’ is for Manual Photography Week 3 – ISO and Depth of Field
PHOTO 1: Depth of field – Shot at F2.8mm Note the focus point doesn’t change in the following images. Wallpaper, book, phone, most of tulips and chair in foreground blurry. Click on photo to read all text
A big fabulous good morning to you as I am about to leave for Sydney.
This is the 3rd post in the series ‘M’ is for Manual photography and it is for those of you who want to get off automatic on your fab digital SLR and head on over to manual. You can catch the first two posts here Your Camera and F-Stops and Shutter Speeds .
So here we go on one of the most exciting things about photography and something all the girls love. Good old depth of field.
Depth of Field
The depth of field refers to the amount of distance in your photo that is in focus from your focal point (the point you choose to focus on). Yep with manual photography we get to decide what we want in focus and what we want blurry.
Now here is the brain bender for all of us! There is double whammy bonus that is associated with F-Stops. Not not only do F-Stops control the amount of light coming into your camera (which you saw in Week 2 they also control the depth of field).
Are you still with me?
So we learnt last week that F-Stops halve or double the amount of light coming into your camera as we change them but something else happens.. drum roll….
Yep, girls it’s called more blur or less blur and it is one of the most fabulous techniques in photography.
So let’s talk about the difference in depth of field of our F-Stops.
When you choose a point to focus on in your image known as focal point that is the point you want to be sharp. There is a ‘field’ of space that is in focus other than the focal point depending on the F-Stop you have chosen.
I did a little example for you starting with F2.8 changing to F5.6 then F8 then F22. The top shot (Photo 1) was shot at F2.8 and I focus on St Gennaro the little statue and you can see very little other than the stack of photos he is sitting on is in focus and maybe one of the tulips.
PHOTO 2: F5.6 same focal point on St Gennaro
In Photo 2 I didn’t change the focus point here I only changed the F-Stop and the shutter speed. Changing From F2.8 to F56 meant I gained a lot more depth of field. If you have a look at the line on the right it has lengthened from the first shot. The foreground is in focus (not the chair) and more of the tulip flowers are in focus.
PHOTO 3: F8 – Same focal point on St Gennaro
In Photo 3 I have kept the same focal point and changed the FStop to F8 and I am gaining more depth of field. You will see the line on the right stretches from in front of the chair right back to the tip of the book. The red phone is also starting to come into focus and the wallpaper is far less blurry than in Photo 1.
In Photo 4 I went from F8 to F22 and you can see everything is in focus from the white chair in the foreground to the crazy wallpaper including the book, the orchid and the phone. F22 is the big kahuna of FStops, you know you want everything in focus this is your starting point.
F2- Only the focal point is in focus and a couple of mm behind it and the rest of the photo and background is soft blur.
F2.8- Still a very shallow depth of field but a little more field than the F2
F4 – More depth of field but still considered a shallow depth of field
F5.6 – A middle of the road depth of field that you will still have blur in the background
F8 – Good when shooting more than one person who are on different planes
F16 – Almost all the image is in focus
F22 – The whole world is almost in focus from the point of focus to the infinity of the background..
Image via Fuji
Remember in the old days when you wanted to take some photos you would buy a roll of film. Often the person at the camera shop would ask you would you like a 100, 200 or 400 etc?
These numbers referred to ISO or sometimes ASA and they are the numbers that determine the sensitivity of the film. You would choose your film based on the ‘amount’ of light you were going to shoot in or the effect you wanted.
The higher you go in the ISO numbers the more sensitive the film or ISO becomes which basically means it’s like gaining stops of light. So if you went from a 400 ISO to an 800 ISO it’s like doubling the light that will enter your camera. The same concept as we saw with F-stops and Shutter speeds (say for example you were working at 1/125 second, F4, ISO 400 but you wanted to shoot at 1/125 second F5.6 to have more depth of field you could go up 800 ISO and that would give you an extra stop of light you need via the sensibility of the film/digital).
Now let’s talk about light for a second because that’s the basis of photography.
When is there lots of light and when is there less light?
Midday in the middle of summer is about the most natural light you can have.
When you go into the shade on a sunny day there is less light than standing the in full sun.
In summer in the morning or the evening the light is softer, less harsh or strong than at midday so technically there is less light.
In winter the light has different angles and is softer than in summer and for example on a Parisian’s winter day the light is very low .
Entering a building you are dramatically reducing the amount of light that your camera will see.
Twilight hour as the sun is going you are loosing light.
Night – very low light
So it is really important that you understand what kind of light you are shooting in as this will help you choose your ISO. If you were shooting hand held (not on a tripod) the following may help you select your ISO.
ISO Number – Light conditions
100 – Bright sunny day tonnes of light – Low grain/noise
200 – You have a little more flexibility with 200 than 100 like gaining a stop of light – low grain/noise
400 – Good for lower light conditions, cloudy, shady – Grain/noise
800 – Shooting hand held inside or as the light is fading around twilight
1600 – Photo journalists often used this ISO as if they wanted to shoot inside or outside they had a lot of flexibility
3200 – Shooting at night or in low light interiors hand held – Really Grainy
You will see from the list above that as you go up in ISO your images will have more grain or noise. Everything in photography is a trade-off.
Now the key with ISO is about what light you are shooting in. In the old days say I wanted to shoot in bright sunlight (ie tonnes of light) I would have chosen a 100 ISO film and that is exactly what I would choose now on my digital dial. Why? Because having a lot of light I don’t need to compensate by using more sensitivity with my ISO.
Now we are really lucky with digital because instead of having a roll of film in our camera that doesn’t suit the lighting conditions we can simply change the ISO setting on our camera by pressing the ISO button and rolling our dial.
I would suggest you do some tests of your own like I did in the above example with F-Stops to see what happens before your eyes and blow the images up on your screen. It’s magic.
Also press down your ISO button and see what happens. You should see the numbers moving along the bottom when looking through the viewfinder.
You’re almost there.. Next week exposure and once you have nailed that you are on your way.
Best of luck
“Balance of light is the problem, not the amount. Balance between shadows and highlights determines where the emphasis goes in the picture…make sure the major light in a picture falls at right angles to the camera.” Elliot Erwitt
Please share with your friends