| Questions about HSM |
- Are
HSM lenses available for Minolta and Pentax Mount Lenses?
- What
is the difference between built-in HSM lens and DC-motor
lens?
- Auto
Focus of HSM Lens for some Nikon Cameras does not work.
|
| How to use |
- What
is the meaning of W and T symbols on the depth of field
scale?
- Minimum
Close-up Distance (working distance) from the front
of Macro Lens.
- How
should I use the Macro Switch of 28-80/3.5-5.6 Mini
Zoom Macro, 70-300/4-5.6 and Apo Macro Super and 70-300/4-5.6
DL Macro Super?
- What
is the difference between 50/2.8 EX macro and 105/2.8EX
Macro with Life Size Magnification?
- Sigma
has many Macro Lenses, so what kind of differences exist
among these lenses?
|
| Miscellaneous |
- I
would like to purchase a new camera of another brand,
in this case is it possible to change the mount of my
previous lenses?
- If
you compare the angle of view of the 14mm f/3.5 ultra
wide-angle and 15mm f2.8 fish-eye lenses, which lens
has wider angle of view.
|
| The
meaning of some abbreviation |
|
|
What
is APO ? |
|
An
Apochromat lens, which keeps color aberration to
a minimum, using Special Low Dispersion glass is
called an APO series lens at Sigma. As the refractive
index of glass depends on the wavelength of the
light, color aberration occurs when different colors
form images at different points. This problem often
occurs with telephoto lenses. In the case of normal
optical glass it can only be corrected for two primary
spectral colors by combination of low dispersion
convex and high dispersion concave lenses. Sigma
Apo lenses use SLD (Special Low Dispersion) or new
ELD (Extraordinary Low Dispersion) glass to offer
superior sharpness, high contrast and color correction
by minimizing the chromatic aberration.
|
|
What
does EX Lens mean ? |
|
The
Excellent features of these Sigma lenses such as
new optical and mechanical design concept, superior
performance, perfect handling, ultra compact design,
durability etc., are symbolized by the EX mark.
@These professional type lenses are distinguished
by their the distinctive EX finish and EX logo on
the lens barrel.
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|
What
is DG? |
|
These
are large-aperture lenses with wide angles and short
minimum focusing distances. With an abundance of
peripheral illumination, they are ideal lenses for
Digital SLR Cameras.
|
|
What
does DC stand for? |
|
These
are special lenses designed so that the image circle
matches the smaller size of most digital SLR cameras.
Their specialized design gives these lenses the
ideal properties for digital cameras, including
compact and lightweight construction.
|
|
What
is HSM? |
|
HSM
stands for "Hyper Sonic Motor". The HSM motor is
driven by ultrasonic waves and it makes auto focusing,
precise, silent and high-speed. Sigma's HSM version
lenses are available only for AF Sigma, Canon and
Nikon AF cameras.
|
|
| Questions
about HSM |
|
|
What
is the difference between built-in HSM lens and
DC-motor lens? |
|
With
conventional auto-focusing, auto-focus is driven
by electromagnetic force of a DC-motor, gear and
shaft mechanism. However, Ultrasonic Oscillation
Energy operates the HSM lens and creates high-torque
drive. Since this motor has no reduction gears,
it has much quicker response to start and stop compared
to DC- motor lenses. HSM system has virtually silent
auto focus function, very quick responsive auto
focus function and "full-time" manual focus, wherein
AF can be overridden without disengaging the AF
mode altogether.
|
|
Auto
Focus of HSM Lens for some Nikon Cameras does not
work. |
|
The
AF control system for some Nikon Cameras does not
work with HSM lenses. Sigma's HSM lenses have full
compatibility with F5, F4 series, F100, F90/N90,
F90X/N90S, F80/N80 F70/N70, u/F65/N65,Pronea 600
and Pronea S. With other Nikon cameras, Sigma's
HSM version lenses can be only used in manual focusing
mode.
|
|
| How
to use |
|
|
What
is the meaning of W and T symbols on the depth of
field scale? |
|
W
indicates wide focal length and T indicates telephoto.
For example on a 28-80mm zoom lensW is equal to
28mm and T is corresponding to 80mm.
Depth of field region can be determined by combination
of depth of field scale and distance scale. The
depth of field scale is printed on depth of field
scales on the right and left sides of the center
index line. These figures show the depth of field
for each aperture setting. The range between numbers
of the same f-number is the depth of field. For
instance, choose the aperture, f22 and rotate the
zoom control to the wide position until it stops
and focus the lens on a subject. The distance from
the camera to the subject will be shown on the distance
scale by the center index line. Therefore, the region
between the right and left sides of the center index,
which will be in the range of the same f-number
at the chosen aperture, will be in-focus. The same
process also can be applied for tele-position. Set
the focal length to tele-position, choose the aperture,
f22. You would see the range on the distance scale,
which corresponds to the depth of field.
|
|
Minimum
Close-up Distance (working distance) from the front
of Macro Lens. |
|
This
is the distance from the front lens element to the
subject to obtain maximum close-up magnification.
|
|
How
should I use the Macro Switch of 28-80/3.5-5.6 Mini
Zoom Macro, 70-300/4-5.6 and Apo Macro Super and
70-300/4-5.6 DL Macro Super? |
|
First,
set the zoom control to its maximum telephoto position.
Then, slide the Macro Switch to the "Macro" position.
Now the focus ring can turn from infinity to macro
range. (The macro switch cannot be changed to the
"Macro" position if the zoom ring is set to other
than the maximum telephoto setting.)F While the
Macro Switch is set to the "Macro" position, the
zoom ring is locked in the maximum telephoto setting
and zooming is not possible. To avoid damage to
the lens, please do not force the zoom ring to turn.
To return the normal mode, please then turn the
focusing ring out of the macro range. Then slide
the Macro Switch to the "Normal" position. If the
focus ring is in the macro range, the switch will
not move.
|
|
What
is the difference between 50/2.8 EX macro and 105/2.8EX
Macro with Life Size Magnification? |
|
The
image of the subject, which is taken by both lenses,
will have same magnification, however the size of
backgrounds will be different. The picture, which
is taken by 50mm/f2.8 EX Macro Lens, will have wider
background if compared with the 105/f2.8 Macro Lens.
Further, lens to subject distance will be different
for making life size pictures with both lenses.
The subject to lens distance for 50mm/f2.8 is 40.5mm/1.7in.,
however this distance is 120mm/4.7in., for 105/2.8EX
lens.
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|
| Lens
Accessories |
|
|
Is
it possible to attach filters, which are produced
by other makers to the filter holder of Sigma Lenses? |
|
The
filter size of 300/2.8EX, 500/4.5EX and 800/5.6EX
lenses have 46mm filter size and there is no problem
if you attach the filters of the other brands. However,
if the thickness of the filter is over 5mm then
you cannot attach this filter to its holder. In
the case of PL filters you can only use the exclusive
filters (if you use the PL filters of other brands
you cannot get the PL results). The filter diameter
of 600/8-mirror lens is 30.5mm and it is impossible
to attach a filter if its thickness is greater than
3.5mm.
|
|
APO
TELE CONVERTER Can the Apo Extender 1.4x and 2x
be used with all lenses? |
|
Click Here
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What
is the magnification of 28-200/3.5-5.6 DL Aspherical
Hyper Zoom Macro with close up attachment? |
|
The
magnification will be 1:2.7 and minimum object distance
will be 0.39m/15.4in., at 0.5m/1.5ft. distance scale
setting and 200mm focal length setting.
|
|
| Miscellaneous |
|
|
I
would like to purchase a new camera of another brand,
in this case is it possible to change the mount
of my previous lenses? |
|
Sigma
produces lenses with exclusive fixed mount systems;
therefore it is not possible to change the mount
of your previous mount system lenses.
|
|
If
you compare the angle of view of the 14mm f/3.5
ultra wide-angle and 15mm f2.8 fish-eye lenses,
which lens has wider angle of view. |
|
14mm
f/3.5 has an angle of view of 114.2¡, however
15mm/2.8 EX diagonal fish-eye has an angle of view
of 180¡ (in the diagonal direction). Therefore,
15mm lens has a wider angle of view.
14mm f/3.5 has 104.3¡ horizontal and 81.2¡
vertical angle of view. On the other hand, 15mm
f2.8 Diagonal Fish-eye has 141.4¡ horizontal
and 90.8¡ vertical angle of view.
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