I’vebeenlookingat buying
a new 200mmtelephotolens
but can’tfindanyinfoon
how muchlenscompressionit offers.
Why aren’tthesedetailsincludedin
th e onlinelistings?
BasilRawsthorne,London
Adamsays:A commonmisconception
li esattheheartof thisquestion– lens
compressionisn’tactuallya propertyof
yourlensatall,butrathera propertyof
whereyouarestandingin relationto your
subjectandthebackground.It’seasy
toseewhy thisgetsconfused.We usually
onlyseetheeffectsof thiscompression
when usinglonglenses.Whyis this?
Whenshootingwitha telephotolenswe
te ndto be standingfurtherawayfromour
subjectthanwe wouldwhenshooting
witha wide-anglelens.Thismeansthe
comparativedistancefromus to the
subject,andthesubjectto thebackground,
isdifferentin thetwoshots– we’re
lo okingatit froma differentperspective,
and that’swhatcausesthecompression.
Ifyoustandin thesamespotandtake
a photoon a telephotolensandthena
widelens,theywillhavethesamelevel
of‘lenscompression’betweensubject
and background.Moveyoursubject
cl oserto youforthewideshotandyou’ll
noticetheygetbiggerin theframe– the
backgrounddoesn’tmovein relation
toyouandso staysthesamesize.The
resultingimagemakesthebackground
lo okmuchfurtheraway.
Soto answeryourquestion,thelonger
the lensyouoptfor,thefurtheryou’llbe
ableto standbackfromyoursubjectand
get a greatercompression.Therewon’t,
however,be a differencebetweenthe
compressionyou’llgetwithlensesfrom
di fferentmanufacturers.
70 PRACTICALPHOTOGRAPHY
Thereareso many
di fferentfile typesthat
I’mconfusedas to
when I should use each one.
Why are there so many, and
what are they used for?
Jim Poole, Derby
Kirk says: There are quite a few
image file types, and each has a
di fferent application or benefit to
it s use. Here are the main types
to be aware of...
n RAW OR DNG
This isn’t so much
a file type as it is
all the data your
camera captured
when you pressed
theshutter. It’s best used to edit
from, but in its original format,
it’snot suitable for use.
n JPEG
A widely used file
type, it features
lossy compression
re sulting in much
smaller file sizes
withthe trade-off of loss in
quality. It’s great for displaying
images on websites or sending
via email. It has become an
industry standard.
n PSD
Photoshop’s
proprietary format,
PSD, is a lossless
file type that can
store layers and
editing data, allowing you to save
yo urwork mid-edit and come
back to finish or tweak it later.
Being lossless, the file sizes are
large and can be unwieldy to store
and use. PSDs are best used to
save any Photoshop edits you
have made to your images.
nTIFF
A lossless archival
format used for
storing high-quality
im ages, it features
a modest amount
oflossless compression resulting
in large file sizes. It’s Ideal for
storing high-res images.
What are the
different file
types used for?
SHOTAT 200mm SHOT AT 24mm
Above This time we kept our subject the same size in the frame by moving her closer to us
in the wide shot and did not crop in. The background looks much smaller in comparison.
Above Taken from the same standing position, you can see that when zoomed in on the
wide-angle shot it looks the same as the long lens version.
What is long lens
compression?
SHOT AT 200mm SHOT AT 24mm
WELCOMIA
A
