Lens Compatibility with Digital SLR Cameras
CAN 35MM SLR LENSES BE USED ON DIGITAL CAMERAS?
In most cases, the answer is yes. If you have a lens for a fairly recent 35mm SLR camera, it can be used on a
new digital SLR from the same maker. (See the information below under the various camera brands for specific
details about using existing lenses on new cameras.) If the 35mm camera lens produces good, sharp, contrasty
images on film, it will produce good digital photos, too. One big difference is the angle of view. The imaging sen-
sor in most digital cameras is smaller than 35mm film, measuring about 23 x 16mm. Therefore, wide-angle lens-
es for 35mm camera are not as wide when used on a digital camera, but telephoto lenses are stronger. With
35mm cameras, a 50mm lens is the “normal” focal length that gives you about the same view as the human
eye. Below 50mm, the view gets wider, above 50mm it becomes telephoto and draws the subject in closer. For
digital cameras, this “normal” focal length is about 32mm, so an old 50mm lens from your 35mm camera will be
a short telephoto (equal to 80mm) when used on a digital. An 18-200mm zoom lens for a digital camera has
about the same wide coverage and telephoto magnifying power as a 28-300mm lens on a 35mm camera. To
convert the equivalent view of a 35mm lens when used on a digital camera, multiply by 1.6X.
A few high-end digital cameras, such as the Canon EOS 1Ds and EOS 5D have full-frame sensors. Since these
sensors match the 24mm x 36mm size of 35mm film, there is no conversion factor when they are used with
35mm lenses.
LENS CONVERSION FOR VARIOUS CAMERA FORMATS
Extreme Wide Wide Angle
97 degrees AOV 75 degrees AOV 46 degrees AOV 27 degrees AOV 12 degrees AOV
Normal
Short Tele Moderate Tele
Digital SLR
(1.6X factor)
12mm
19mm
18mm
28mm
50mm
32mm
50mm
80mm
56mm
90mm
128mm
200mm
35mm Film
6x6cm Film
40mm
(88 deg.)
150mm
(30 deg.)
350mm
(13 deg.)
AOV = angle of view
6x6cm = 2-1/4 x 2-1/4" format on 120 film
DIGITAL-ONLY LENSES
Since the future of SLR photography is digital and since most digital cameras have sensors that are smaller
than 35mm film, manufacturers are making digital-only lenses. The primary difference is the reduced area of
coverage provided by digital-only lenses. These lenses have the same mounting style as 35mm format lenses
and they can be mounted on 35mm camera bodies (except Canon EF-S lenses), but they will not cover the full
image size. This causes vignetting around the edges of the 35mm image, especially at the widest end of the
lens zoom range.
Perhaps the most backward-compatible camera brand, a new Pentax digital SLR camera will accept a lens
made for one of the first Pentax K bayonet-mount 35mm cameras back in the mid-1970s. If the lens has auto
aperture control (Pentax KA) and autofocus (Pentax KAF) capability, those features will couple to the D-SLRs
controls. A Pentax digital SLR will even accept old Pentax screw-mount lenses made for cameras in the 1960s
and early ‘70s, provided a Pentax Lens Mount Adapter B is used.
Pentax is now collaborating with Samsung on digital SLR design, so present (and most likely, future) Samsung
digital SLR cameras use the same lens mounting system as Pentax.
OLYMPUS
Unlike the other 35mm camera brands, Olympus was never successful with their 35mm autofocus SLR system
so they didn’t have a legacy lens system to use with digital SLR cameras. Thus they created a new lens system
open to other camera makers as well, called the Four Thirds system, after the 4:3 aspect ratio of the sensors
used by Olympus D-SLRs. The size of sensors used in Olympus D-SLR cameras measure 17.3 x 13mm, much
larger than commonly used in “point & shoot” style cameras, but smaller than the approximately 23 x 16mm
sensors used by other D-SLR makers. One significant difference is Olympus focal lengths are one-half the
equivalent of 35mm format lenses (a 2X factor) for the same field of coverage. So a new 25mm lens is equal in
view to a 50mm lens on a 35mm camera, a 14mm wide-angle is equivalent to a 28mm film camera lens, etc.
These lenses are designed specifically for digital SLR cameras.
Olympus made an earlier manual-focus 35mm camera system called the OM system. While Olympus makes a
lens mount adapter to attach OM lenses onto their D-SLR cameras, there is a significant loss of features.
INDEPENDENT LENS MAKERS
Lenses made by independent lens makers usually have the same compatibility characteristics as camera-brand-
ed lenses. For instance, a Tamron lens made for a Canon EOS film camera will work on a Canon digital camera
in the same manner as a Canon brand lens. Independent lens makers have often kept mechanical aperture
rings on Nikon and Pentax-mount lenses long after those two camera makers have dropped them from all but
select series of lenses.
TAMRON
Tamron’s latest generation of lenses is called the Di-II series. These digital-only lenses cover digital sensors,
without the covering power needed for film. Tamron also has Di lenses that will cover film and digital formats
and they have been optimized in their design and multi-coatings to perform better on digital cameras than earlier
lenses made only with film photography requirements in mind.
SIGMA
Sigma makes several lines of lenses, with DC format lenses their digital-only line. Sigma’s DG lenses are opti-
mized for better performance with digital cameras, but will work fine with 35mm cameras and will cover the full
image size.
TOKINA
Pro DX lenses from Tokina are digital-only and won’t cover full size sensors or 35mm film. Some Tokina lenses
are designated ProD and will work fine for both film and digital cameras and have the improved multi-coatings
for excellent digital performance.
Courtesy of Porter’s Camera Store
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