Depth of Field
Tom
points out to the group that they must always be aware of the
background, otherwise there is the risk that it could intefere with the
main subject of the image. Highlights around a flower and a defocused
background produce great results, with all the distracting elements
removed so that nothing can detract from the subject.
photo by Heather Buckley
‘To
get this type of effect, you need a shallow depth of field,’ says Tom.
‘A shallow depth of field relies on a wide-lens aperture and that,
somewhat contrarily, means a small f-number, such as f/2. On the other
hand, for scene-setting pictures over a wide expanse of garden, you’ll
want a deep depth of field, which requires a small aperture and a large
f-number, such as f/16. Thinking of the f-numbers as fractions can help
you remember which way round this works – 1/2 (f/2) is obviously larger
(hence larger/wider aperture) than 1/16 (f/16, with its smaller
aperture).’
photo by Philip smith
While a wideangle lens can capture everything sharply
from front to back, the long end of a telephoto will naturally focus on
the subject and blur the background details.
Remember that with
close-up shots, depth of field can be extremely shallow and that only a
very small proportion of the subject might be in focus.
This can make
for interesting, almost abstract, effects, but if you want to include
more of the subject you’ll need to go for a smaller aperture, such as
f/8.
‘It also pays to check your floral subject very carefully to ensure it’s fit for such close attention,’ says Tom.
‘Disregard flowers with rough edges and be prepared to do a bit of “gardening”, such as removing dead foliage.’
