Canon EF 25 User Manual download pdf (Page 4)

Technique Extension tubes

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For my water droplet photos I use an

EF 100mm Macro lens with an EF 25 II

extension tube and manual focus to get the

biggest, clearest droplet possible. I always

use a tripod and work with natural light.

I shoot my water drop shots indoors as

it’s usually somewhat breezy where I live,

but I have good light from large windows.

I set up the ﬂower with the background

positioned between 6 to 12 inches behind

it, depending on the desired result.

I place the water droplet on the petal

with a syringe and adjust the background

so that I can see it in the drop. It can be

a little time consuming, even frustrating,

to get a drop to a nice shape and make

it stay in place. The droplet has to be

positioned to get an unobscured view of

the background.

Sometimes I use printed matter such

as gift wrap or greeting cards to produce

the refracted image in the water droplet.

Designs with bright clear colours give the

clearest refractions. The image will be

inversed in the water drop. I position the

background sheet upside down so that

the design shows the right way up in the

refraction. I also like to use ﬂowers – again

the brightest coloured ﬂowers make the

clearest images.

Rodel Manabat Case studies

I have always been fascinated by macro

subjects, especially insects. I used to own

an EF 100mm f2.8 Macro lens, but it was

rather frustrating not being able to take the

shots I had in mind. So I sold my macro lens

and changed my set up to a more compact

solution. I now use an EF 12 II extension tube

with an EF 24-70mm f2.8L lens. It is easier,

quick to change and a great combination with

a fast aperture lens. It is a bit heavier than

the 100mm f2.8 Macro lens, but it serves a

dual purpose – a general walk around lens

and a good macro option (by attaching the

extension tube).

I like taking close-up and macro shots of

plants, leaves, ﬂowers, petals, butterﬂies,

water droplets and insects – anything with

symmetry, lines and interesting texture.

Most of the time I use my EF 12 II tube with

my EF 24-70mm f2.8L. I normally shoot at the

70mm focal length. Using the rule of thumb

for calculating magniﬁcation (magniﬁcation

= extension/focal length), at 70mm the

magniﬁcation is 12mm/70mm = 0.17x.

I set the focusing to manual or automatic

depending on the subject. If the subject is

moving (such as insect, ﬂower, plant, droplets

on leaves) then it is better to focus manually.

If your subject is ﬁxed you can mount your

camera on a tripod, set autofocus and use

a shutter release cable to minimize camera

shake. I prefer to use a wider aperture (f2.8 to

f4) to draw attention to only a portion of the

subject. I use selective focusing from the 9

autofocus points of my camera. If there is too

much movement in the subject AI focusing is

of great advantage.

Flash is important. I used to ignore

using the camera’s built-in ﬂash, but after

colleagues showed me the advantage of using

ﬂash it has now become part of my set-up. I

also use a Speedlite 580EX II with a Stofen

OmniBounce diffuser.

Third party

EOS-ﬁt extension

tubes are made by

other companies and

are less expensive

than those from

Canon. However, the

build quality can be

inferior and we have

not come across any

that are compatible

with EF-S lenses.

Canon extension

tubes maintain full

electrical contact

between the camera

body and lens, so

that you can stop

down the aperture

and, if you want to,

use autofocus. It

is possible to buy

extension tubes for

under £10, but the

catch is that they

have no electrical

contacts. You cannot

stop down your

lens and use a small

aperture as EF lenses

do not have manual

aperture rings. This

means that you will

be limited to using

your lens at its widest

aperture, unable to

increase the depth-

of-ﬁeld.

Tube pros and cons

The big advantage of extension tubes is that

they can be used with nearly any lens. They

can also be used in combination with close-

up lenses (covered in the July–September

2010 issue), or with a macro lens, for even

greater magniﬁcations.

Light loss

There is one major disadvantage – adding

an extension tube reduces the amount of

light reaching the ﬁlm or digital sensor.

This means that you need to increase the

exposure by increasing the ISO, using a

slower shutter speed or setting a wider

aperture. Light loss can be as much as two

stops at higher magniﬁcations – although

you always have the option of using off-

camera Speedlites so that you can use low

ISOs and small apertures. Both Lee Beel

and Rodel Mandabat, whose photos appear

in this article, use Speedlite ﬂashes with

diffuses ﬁtted to them for this reason.

Of course, much of the time you might

not be aware of this light loss. Unless you

are using the manual shooting mode, the

camera’s through-the-lens metering system

will automatically adjust the exposure values

to give correct exposure. However, it will

reduce your creative options for smaller

apertures or faster shutter speeds.

Focus shift

Another disadvantage occurs when you

use extension tubes with zoom lenses. If

you change the focal length of the lens, the

focusing distance changes as well, and you

need to refocus. You can get around this by

selecting the focal length you want to use

ﬁrst (normally the longest) before focusing.

You don’t have this problem if you are

using a prime (ﬁxed focal length) lens.

Telephoto lenses

Extension tubes work best with lenses that

have a focal length of between 35mm and

150mm. Below 35mm, you may need to

get so close to your subject to focus that it

becomes impractical. With longer telephoto

lenses, the increase in magniﬁcation is so

slight that using extension tubes may not

be useful. Canon’s 250D or 500D close-up

lenses will get you much closer.

Image quality

While Canon’s double element close-up

lenses, the 250D and 500D, are high quality

close-up lenses that have a minimal effect

on image quality, less expensive close-up

lenses can degrade image quality quite

badly. Extension tubes contain no glass and

so have little impact on image quality.

Above The

effectiveness of

adding extension

tubes depends on

two factors – the

focal length of

the lens and the

minimum focusing

distance. The shorter

the lens, and the

closer its minimum

focal distance, the

greater the level of

magniﬁcation will be

gained from adding

an extension tube.

May-lin Joe

The photos on this

page were taken using

an EF 24-70mm lens set

to 70mm and ﬁtted with

an EF12 II extension

tube. The depth-of-

ﬁeld is very narrow

but Rodel has used

this limitation to great

creative effect.

Above EOS 40D, EF

24-70mm f2.8L lens

with EF 12 II Extension

tube, ISO 100, f2.8, 1/40

second.

Right EOS 40D, EF 24-

70mm f2.8L lens with

EF 12 II Extension tube,

ISO 400, f2.8, 1/200

second.

Both Rodel and

May-lin can be

found online at

Flickr. You can

view their galleries

at www.ﬂickr.

com/photos/

rodjbman71 and

www.ﬂickr.com/

photos/mayj

respectively.

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