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21 - Aperture Priority and depth of field

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When I'm out and the light is good I always walk around in Aperture Priority so I can control the depth of field. With a wide angled lens, aperture priority is almost a no brainer, but when hand holding long telephotos you have to keep an eye on the shutter speeds your camera is selecting. The rule of thumb for a decent shutter speed to minimise the risk of motion blur is 1.5x focal length. With a 200mm lens, 1.5 x the focal length is 300, so the slowest shutter speed you should consider is 1/300th of a second. If the light is good, select your preferred aperture and take a test shot. If the camera selects a shutter speed faster than 1/300th of a second, you can shoot away in aperture priority and not have to worry about blurry pictures. If you have image stabilisation, that's even better. If the shutter speed is slower than 1/300th of second, which on a bad light day is likely, you might have to go manual and crank up the ISO for sharp images.If you're using a wide angled lens, things are much simpler. I use the Fuji 16-55mm, so at the long end 1.5 x 55mm is just over 1/80th of a second. At 16mm, 1.5 x focal length is 24, so 1/24th of a second would do me. If I set my aperture to f5.6 and the shutter speed is 1/500th to 1/800th of a second or more, I can shoot away in aperture priority and simply forget about camera settings as I know every single photo will be sharp regardless of which aperture I choose. This leaves me free to control depth of field, and I trust my camera to control shutter speeds and ISO. My Fuji cameras perform brilliantly in this regards, they never let me down.

All the photos in this tutorial were taken in aperture priority using spot metering with the Fuji X-T1 and the Fuji 16-55mm. I like spot metering, because I can move the camera around until I find the exposure I want, then half press the shutter button to get a focus and exposure lock, and then move the camera for composition before taking the photo.

A shallow depth of field, achieved by opening your aperture to its widest, referred to as its fastest setting, which with my Fuji 16-55mm is f/2.8, allows me to control the bokeh, which is the lovely creamy out of focus background you can achieve with fast glass. This photo was shot wide open to throw the background completely out of focus. Being able to create gorgeous bokeh like this is why you spend lots of money on expensive glass.


On the other hand, if you're shooting a landscape, you don't want a shallow depth of field, you want everything in focus. In this next photo of a boat chugging up the River Brora towards the harbour, everything is in focus from the foreground to the horizon. Being in aperture priority allows me to control this depth of field. Most photographers I know, and most professional photographers I've talked to, walk around in aperture priority if the light is good so they can control depth of field.


In the first photo above, only the wee guy on the swing is in focus. This was achieved by opening the aperture as wide as the camera would allow, in this case f/2.8. I also moved in close to the subject to throw more of the background out of focus. This is known as a shallow depth of field. Closing your aperture, say to f/8 would bring more of the foreground and the background into focus, and with wide angled lenses would probably bring everything into focus, which is ideal for landscapes.

In this next photo, I wanted all the foreground in focus as the gorgeous soft winter light was creating extremely pleasing shadows running through the photo from right to left, giving it an unusual feeling. The wave that is about to break also adds power to the image, so I wanted that sort of in focus a little bit as well. I certainly didn't want it creamed out because its power is important. The horizon isn't an issue as you can only just make it out behind the wave, and the clouds looked soft naturally, so I chose an aperture of f/7 at 16mm to get what I wanted in focus.


There is nothing in this photo of the beach that was an accident. I stood there for ages just looking, took half a dozen test shots and checked each one in camera until I knew exactly what I wanted. That wave that's about to break extends across the whole photo. That was not an accident, that's what I wanted, and I kept taking photos until I got that. The curved shell in the foreground is the only shelI in the photo and it's placed exactly where I wanted it placed, leading your eye into the photo towards the sea. I also tried the camera at a few different heights above the sand to find the perspective I thought would best suit the feel of the image. The tilting rear screen is fabulous for that as I can hold the camera down near the ground and see what I'm doing. There was no post processing done to the image other than a slight colour and contrast adjustment to give the clouds a little more texture to balance the composition.

I also studied this next photo for some time and took test shots. The shell curving towards the centre balanced by the seaweed on the right curving the opposite way was intended. I also liked the two yellow shells in the middle foreground. However, the big stone this end of the shell ruins the photo as it unbalances the composition. Were I to take this shot again, I would remove that stone. The composition would also benefit by having the large shell and the seaweed both on a vertical third by moving the camera to the right. The image was desaturated slightly, but I brushed out the desaturation on the big shell using a layer mask to bring back all of its colour. This helps to focus and hold your eye. I don't particularly like the yellow shell top left, as it draws your eye away from where I want your eye to be, which is on the shell. I could photoshop it out I suppose, but this isn't a keeper, and it serves well to illustrate flaws. You never take perfect photos every time, it's all trial and error, but the more you practice, the better your eye becomes.


As we are on the subject of Photoshop, we might as well handle it here. Photoshop is a tool, and sometimes it can be extremely handy. Take this photo of a crab shell for example. The stones poking out of the image along its edges ruin the photo as they take your attention away from the subject and push your eyes out of the image altogether. Our job as photographers is to catch eyes and hold them in our images.


Photoshopping those offending stones out of the photo completely changes the image. Try it and see. Stare at the photo above and you will find your eyes keep going to the stones poking out of the right edge, the top, and sometimes even the bottom edge. Your eyes can't seem to focus on the crab, they want to look at those stupid stones. Stare at the photo below and your eyes stay on the crab's shell. This isn't an optical illusion, it's the power of composition. It is our job as photographers to compose images that hold a person's eye and Photoshop is a powerful tool that can help us to do that.


This photo also has a similar serious flaw - the stone poking out the bottom of the image. The stupid thing pulls your eye away from the subject. The photo does not work with that stone there.


The more I looked at this image, the more I really didn't want to drag it to the recycle bin and dump it. I felt the image was too good to throw away, so I took it into Photoshop and was able to crop the stone out. Cropping also moved the shell down onto the lower horizontal third and centred it, greatly improving the composition. Now your attention remains fixed on the shell and the creamy surf bubbling around it. Photoshop is an extremely versatile, powerful and useful photographic tool. You don't need the full Photoshop to work on photos. I use Photoshop Elements 15.


Now yes, it's better to compose your images when you take them so you don't need to remove stuff, but sometimes you just can't see flaws until you open the files on your computer and see them on the big screen. Besides, there are always birds as black specks in skies, sheep as white specks in fields and other flaws that need to be removed, so learn to use the basic tools in Photoshop to improve your photos.

In this last photo I wanted all attention on the sand encrusted dead root of the seaweed stalk.To do that I opened the aperture and moved in close to completely cream out the background. I had such a shallow depth of field that the back of the rock is also creamed out, and it's only inches away. However, the depth of field is not so shallow that parts of the seaweed roots are out of focus. To achieve this I used an aperture of f/6.4. This might not seem quite wide enough for the aperture considering I could open it to f2.8, but as I was extremely close to the subject I had to select an aperture that ensured all of the roots were in focus. I particularly like the vivid green living seaweed which the dead seaweed is served on. Yes, I picked the dead seaweed up off the beach and arranged it on the rock for effect. Curves and spirals are a dream to work with, and the curves in the image are not accidental.

Depth of field is perhaps the most powerful photographic tool we have for composing photos, so it is well worth learning how to use.


Now to real life. This first photo is a landscape and everything is in focus. The second photo of the bee was taken with the aperture opened right up. The depth of field is so shallow that the bee itself melts into the bokeh and only the flower is in focus. Have fun with depth of field!



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