Tuesday, 9 October 2012

Aperture/ISO/Shutter Speed Tutorial

Aperture/ISO/Shutter Speed

When altering the aperture on the camera settings, you are indicating how wide the lens iris opens, allowing you to control the amount of light that gets in. Aperture is measured in f-stop numbers (i.e f/2 or f/22 as you can see in the below diagram). The smaller the lens opening, the higher the f-stop and the higher the f-stop the less light, therefore more of the image will be in focus and vice versa.

When we alter the aperture we also must consider whether we should change the ISO or shutter speed to ensure the image is at its best quality. The shutter speed again dictates how much light can get into the camera, we may want to up the shutter speed, if we are using a low f-stop number to balance the exposure of the image.

We may also want to alter the ISO number, this determines the sensitivity of the image sensor (in traditional film photography, this was the sensitivity of the film) to light. So when shooting in low light but without the use of a flash, we could use a higher ISO number. '100' being considered the 'normal' ISO number, this low ISO number will give your images a crisp professional looking finish. The affect of upping the ISO number is that we get grain or 'noise' in images. (e.g. see example image below)

Experiment With Aperture

To try out the aperture/ISO/Shutter speed settings on our cameras, we experimented with them on one of our location shoots. The clip below, is one of the pieces shot with varied camera tech settings. As you can see, here, there is a shallow depth of field meaning we used a high f/stop number on the aperture setting, this allows less light into the camera, so we had to up the ISO so that the light sensitivity is increased, though this isn't too high otherwise the image would have suffered a grainy appearance. The shutter speed here would be relatively slow, as the camera remains still there is less risk of blurring and allows more light into the camera compensating for the small aperture.

The composition of this particular piece is fairly good, we maintain the rule of thirds as the subject remains central throughout the shot and his eye level is about at the cross over point of the grid that can be put onto the LCD camera screen to help position shots within the frame. 

Jack blackandwhite from Sammie Masters-Hopkins on Vimeo.

After shooting I chose to to edit this footage, changing it to high contrast black and white, making it reflective of the majority of the nouvelle vague films. The link to the New Wave for these particular pieces of footage are expanded in the previous post.

MVI 0487 from Sammie Masters-Hopkins on Vimeo.

Experiment With ISO

ISO from Sammie Masters-Hopkins on Vimeo.

This piece of footage was shot in a dark room with very little light for the camera to sense, therefore I upped the ISO number to increase the light sensitivity. The ISO was set to its highest for this particular piece, at 12800, with 100 being the lowest you can see how high the ISO needed to be in order to maximise the little amount of light I had to work with. This high setting is what causes the grain or noise in the image (you can see how it compares to the example image towards the start of this post). Although in this case the grain was an intended effect to add atmosphere to the image, this isn't always the case, in most instances the lower ISO number you can use the better as you will achieve a much more crisps finish to your final image.
Due to the high ISO, I had to alter the the other settings accordingly. I used a relatively slow shutter speed at 1/50 and an f/4 aperture setting, both of these again allow a good amount of light into the camera where little is available.
This is a piece of footage that was shot in order to show the effects of the ISO setting and therefore does not reflect the criteria outlined in the brief. It does bear some similarities to the New Wave, i.e. low budget and non-professional actor, however, the similarities are somewhat limited and would not be included in a final edit of the footage.

Experiment With Shutter Speed

When filming the tracking shots from the inside of a moving car, the first attempt (as you can see below) came out very blurred. This is an example of how shutter speed works. The blurred piece of footage had a shutter sped that was too slow for the nature of the footage that was being taken. Due to the fairly quick movement of the car, the camera was not able to capture the images fast enough. In this particular piece of footage the shutter speed was set at 1/50. After realising that this was too slow for this type of shit, the settings were altered and the shot was tested again.

This piece of footage (below) is again an example of filming from within a moving car. This time with the shutter speed at a much quicker setting, 1/500, meaning that the frame capture rate per second was much higher. Making the image much less blurred as the camera was able to capture more images within the same amount of time.

The pieces of footage, reflect the New Wave due to the low budget that is used. Not only this, but it is a direct technique of the new wave directors to make the most of filming upon or within something that is already creating movement. Godard does this multiple time in Breathless, two of which we have experimented. The first is in a previous post and was the camera upon an escalator (please click here to see it) and the second are these pieces of footage. By using a car to generate movement for the camera, we were experimenting with technique directly from Godard, this kind of creativity with camera movement was part of the reseaon the new wave directors became so well known and considered 'innovative'. By working with and trying out there techniques we are able to adapt them and come up with similar techniques of our own and still maintain the link that out original brief states we should do.

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