In simple terms, the aperture is a hole which can be opened or closed to control the amount of light reaching the camera sensor. The wider the hole, the more light is let in (helping compensate for darker conditions, for example). Remember, the smaller the f/number, the wider the aperture.
Every lens performs better at some f/numbers than others. Generally, you will see the image resolution & contrast deteriorate at the end of the f/number spectrum. To determine the optimum aperture for the lens you own, find a piece of paper with fine printed type (eg. the financial pages or a Bible). Set up your camera to photograph the page straight on & frame it to fill the viewfinder. Now set the camera to AV mode & take pictures working your way through the apertures. Load the images onto your computer & view them at high magnification. You should see a gain in resolution & contrast as you close the aperture down from maximum & then a drop as you approach the smallest apertures.
On the lens I have which came with the camera (a Canon EF-S18-55mm) f/13 appeared to give the best results.
I recently purchased the November 2014 edition of “Digital SLR Magazine” which contains an article on “Seasonal Inspiration”. One of the suggestions in this piece was a still-life photo (you know the usual couple of pumpkins, old bottle with some autumnal flowers stuck in it, all arranged in an artful fashion etc.) with a textured layer added to give it that painted-on-canvas appearance. So one overcast morning I thought I’d have a try at recreating a similar scene for myself.
The magazine explained the final photo was an HDR image comprising of three photos taken at different exposures (one stop apart). The aperture was f/18 using a Canon EF 50mm f/1.8 II lens & seeing as I have this lens I was fairly confident of my chances. However, when I came to create the HDR image in Photoshop Elements I could see the three images were not perfectly lined up. The method I had used was to take the photos in AV mode & to maunually dial up or down the exposure between shots. All this touching the camera (despite it being on a tripod & my efforts to be extremely careful!) had obviously altered what was in the frame slightly. I have since learnt that my Canon EOS 600D has a feature called AEB (Auto Exposure Bracketing) which does this for you. Under the Menu, select “Expo. comp./AEB” & use the dial to set the AEB amount (eg. one stop, two stops etc.) Then press “set” to set it. If you then set the shooting mode to “continuous shooting” the camera will take three bracketed photos continuously.
Despite this setback, I decided to proceed with the canvas texture stage anyway, as practice for when I came to try this again. So I added a canvas layer & adjusted the opacity as required. I then stumbled upon the “Effects” button & after trying a few of the “Artistic” settings, settled on the one shown below.
In the end then, despite not replicating the style of image I initially set out to, I was quite happy with the result & I’d learnt a couple of things along the way.
With Halloween approaching I thought I’d have a go at creating a zombie picture using Photoshop Elements. It’s pretty straight forward & utilises “layers” to combine the following two photographs
Firstly, open the picture of the woman. I duplicated this photo & desaturated it (CTRL+SHIFT+U). Set this duplicate layer to ‘soft light’ in order to increase the contrast & give it more consistancy. Next, drag the concrete photo onto the main workspace area (we’re using this as texture) which will create another layer. Set the blend mode of the texture layer to ‘colour burn’ & reduce the opacity to give the required effect. Now use the brush tool to remove the texture from the places you don’t want it (eg. the model’s hood, the background etc.) Because the texture is all over the model’s face I thought it looked a little flat. Plus, with her face now not as clear as the sharply in focus hood, I thought the picture looked a little fake (too Photoshopped if you like). So I used the ‘eraser’ tool to carefully remove parts of the texture inbetween the cracks. I also removed this layer from her eyes & lips.
Finally, I added a ‘brightness/contrast’ layer. I took the brightness down to create a darker, more mysterious feel to the photo & increased the contrast slightly. The result is shown below.
(Created using Photoshop Elements 12)
The ability to have some parts of a picture in focus while others parts are blurred was probably one of my main reasons for buying an SLR camera. One way to determine how much of a picture is sharp (known as ‘depth of field’) is by altering the aperture.
The narrower the aperture (large f/number eg. f/22), the greater the depth of field (ie. most of the shot in focus).
The wider the aperture (smaller f/number eg. f/4), equals a shallow depth of field.
Two other factors effect depth of field. Firstly, focal length. As you zoom into a subject, the amount of depth of field reduces. Think of how wide-angles lenses (used for landscapes) keep everything in focus while telephoto ones (sports events, close-up wildlife) tend to blur the background.
Secondly, the distance between you to your subject. The closer your lens is focused, the less depth of field you’ll capture.
So to summarize, if you want to maximise the amount of depth of field, use a wide focal length, narrow aperture & don’t focus on anything too close to the camera.
Having recently purchased my first DSLR camera I’ve been exploring the almost endless possibilities this fun, new piece of equipment provides. It’s definitely become a very creative, engaging hobby. However, due to the general constraints of family life (or, me not committing to photographing everyday you could say!) after a few months of trying various hints & tips from magazine articles, photography websites, You Tube etc. I found I was forgetting some of the earlier stuff I’d learnt. I was then left trying to remember which source I’d used to do obtain the information required.
So I’ve decided to start a blog, mainly for my own benefit, to use as a source of reference where I can jot down any useful pieces of information gained & have then all in one place.
As I mentioned, I’m an absolute beginner at this so a lot of the posts may be too simplistic for all you hardened photographers out there. But if by following my journey you gleam something you previously didn’t know or, you just want to have a laugh at my elementary mistakes, then I hope you come back to read more.