Friday, 20 January 2012

Exercise - Focus at different apertures

Subject: CDJ decks and mixer (again)

I decided to use the same subject as the previous exercise as it demonstrates the learning points quite well and it is still raining outside, so indoors is where it's at tonight.  I used the AF to focus on the centre of the jog wheel again, then switched to manual focus so it would stay locked for all the images.

From left to right:  f1.8, f8, f22
The variation between the 3 images is fairly obvious - I have placed a red box around the area I would say is in sharp focus.  With f1.8 set, the area of sharp focus is very slim.  At f8 it is much larger, and on first glance the area of focus appears to be larger than what I have highlighted.  When I looked in more detail though I saw it was not sufficiently sharp to be said to be considered as part of the depth of field.  In the third image at f22 the limit of sharpness extends almost throughout the image.  However, the top 1/5 of the image is again not perfectly sharp - this could be in part due to the lens's inherent lack of sharpness towards the edges of the image.  The rest of the image is lovely and crisp but my favourite has to be the first image at f1.8 because the colours and shapes of the lights in the out of focus areas balance the image nicely.  

I have also made a note to give the decks a good dusting.

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