Exercise: Focus at different apertures

The purpose of this exercise is to see the depth of field available at different aperture settings – the smaller the aperture (the bigger the number) then the greater the Depth of Field, the range of the image which os sharp.

For the exercise the subject needed depth to give me something to clearly show the results, and as it was raining (again!) I chose the best thing I could think of, which would be easy to see the results on – hence my big sewing ruler!

Kit: Nikon D300 with 18-55mm lens, at 55mm focal length. ISO 400, aperture priority, allowing the shutter to look after itself, whilst I adjusted the aperture to suit the exercise.

The camera was monunted on a tripod to make sure all the images were from the same location, and I chose the 40 cm mark on the ruler as my focus point for all the images.

For the first image my aperture was set to the widest available – f5.6 and as the image shows, the DOF is extremely narrow – from the 39.5cm mark up to just over the 41cm mark.  This image also shows the unequal areas in focus in front of and behind the focus point – the area in focus to the front of the focus point (40cm) is less than the area in focus to the rear.

For the second image I adjusted the aperture to f16 which increased the DOF by about 1.5 cm to the front and rear of the focus point.

In this final image I closed the aperture down to f36 which increased the acceptable sharp areas to around 15 cm.

Having played around with Depth of Field, otherwise known as the Hyperfocal distance, in the past, this is the first time I’ve actually had a go at measuring it, so quite an interesting exercise, albeit the narrowness if over emphasised by it being a very close-up subject.

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Exercise: Focus with a set aperture.

My course begins with “The Art of Photography” and the course is designed for all levels of learners, include those with little photographic experience. The opening introductory section is to get you used to the basic functions of the camera, begining with the aperture, and the way that changes can effect your image.

For this exercise I had to take 2 – 3 images of a scene with depth, to play around with different focus points. As it decided to start chucking it down as I was prepping my kit, I had to create a scene indoors, so grabbed me some food jars from the cupboard!

Kit used:Nikon D3000, on a tripod set to 400 ISO, 1/5th Second due to the low light levels in my dining room, and an aperture of f5 to give me a really narrow depth of field – the distance between the nearest and farthest points of the image that are in focus.  The larger the aperture hole (the smaller the number) the smaller the depth of field is, so really useful to emphasis the point of focus.

My first shot I focussed on the nearest jar, the second one I changed my focus point to the lens in the middle, and the third I focussed on the jar at the back..

  

*note – photograph of a particular brand does not mean an endorsement! 🙂

** Unless it’s Nikon – I love Nikon!

As I was looking at the raindrops pouring down the patio doors I thought I’d repeat the exercise looking out into the garden, using subjects who were even further apart – the raindrops on the glass, the back of a garden chair, and the hedge at the back of the garden.

  

Interestingly, the further out of focus the raindrops are – the more they dissapear from view – really useful if shooting something through a window, or even a fence.

As I’m a sucker for a shallow depth of field, I like all of these images, but in particular the raindrops on the window, it’s a bit more abstract.