Street Photography Magazine

In contrast, most close-up lenses made for
attachment to the filter thread on a lens have
single-element designs and cannot be
corrected using additional elements.
Some high-end close-up lenses (or
‘achromats’, as they are sometimes called) are
constructed using twin-element achromatic
designs and are appropriately corrected.
Some achromats are designed for use with a
specific lens and offer appropriately high
image quality with relatively few chromatic
aberrations. Twin-element achromats are,
however, larger, heavier and more expensive
than their single-element counterparts. As far
as we are aware, there are no three-element
apochromatic close-up lenses.
Many of the telephoto and wide-angle
accessory lenses available for compact cameras
represent a serious change in the design of the
camera’s optical system and often produce
obvious chromatic aberrations as a result.
High-end accessory teleconverters like the Nikon
TC-E3ED use low-dispersion glass and are a lot
more expensive than the competition as a result.
Introduced in 2004, the Nikon TC-E3PF
telephoto converter is based on a Phase
Fresnel lens that works much like the Canon
DO lenses described above. In spite of its small
size and light weight, this innovative
technology didn’t gain a foothold in the
market and, along with the other planned PF
lenses, has now been discontinued.

Chromatic Aberrations | Lenses

Chromatic aberrations are caused by the

refraction of light in optical lenses, so the

fewer lenses an optical system contains,

the less likely it is to produce irritating

fringing effects. Mirror telephoto (or

‘catadioptric’) lenses contain very few

elements and those they do contain don’t

refract the light entering the lens to a

great degree. As a result, these lenses

have a reputation for producing little or

no chromatic aberration. On the negative

side, mirror lenses produce donut-shaped

bokeh, which is generally considered

unattractive.

There are still a number of third-party

manufacturers – mainly in Asia and eastern

Europe – producing this type of lens.

These include Vivitar, Rokinon, Bower,

Phoenix, Opteka, Walimex, Danubia,

Maksutov and Samyang. Most of the

lenses we have seen look extraordinarily

similar to the models offered by Maksutov

and Samyang, and we are fairly sure that

many are simply rebranded lenses made

by one or other of the two.

Mirror telephotos are cheap, lightweight

and compact. The disadvantages of this

type of design are their relatively small,

non-adjustable apertures and their

vulnerability to capturing stray light.

In general, conventional lenses with glass

elements produce better-quality images,

relegating mirror lenses to the level of a

hobbyist’s tool in most everyday

photographic situations.

Mirror Telephoto Lenses

Mirror telephoto lenses are light and

compact in comparison to the

conventional competition. The Rubinar

500mm f/5.6 lens shown here weighs

just 1.6 kg (3.5 lb) and is 23.5 cm

(9¼ inches) long.

Image: Wikipedia/Armin Kuebelbeck

Achromatic lens Apochromatic lens

The structure of an apochromatic lens is

more complex and therefore more expensive

than that of an achromatic lens

Apochromatic correction is, theoretically, capable of completely
eliminating secondary spectrum and requires the use of at least
three elements made of three different optical materials