Irix 15 mm f/2.4 User manual

Extended User Manual
Irix 15 mm f/2.4

Extended User Manual – Irix 15 mm f/2.4
Thank you for choosing an Irix lens. You hold in
your hand the fruit of the dedication and experien-
ce of the combined forces of engineers and photo-
graphers.
Using the nest available materials, state-of-the
-art technologies and cooperation, our team has
created an excellent tool for both professional and
amateur photographers.
The Irix 15 mm f/2.4 is an ultra-wide-angle, rectilinear, manual
focus lens, designed for full-frame DSLR cameras. It is also com-
patible with many crop-sensor models.

Extended User Manual – Irix 15 mm f/2.4
[3 ]
TABLE OF CONTENTS
FRONT LENS CAP 4
FRONT FILTER THREAD 5
LENS HOOD 6
FILTER WINDOW 7
FOCUS SCALE CALIBRATION 8
FOCUS RING LOCK 9
FOCUS RING 10
DEPTH OF FIELD SCALE 11
HYPERFOCAL SCALE 15
REAR GELATIN FILTER SLOT 17
HOW TO ATTACH THE LENS TO THE CAMERA 18
REAR LENS CAP 19
APERTURE CONTROL 20
HARD LENS CASE 21
MAINTENANCE 22
SAFETY PRECUTIONS 23
TECHNICAL SPECIFICATION 24
TEMPLATE FOR CUTTING GELATINE FILTERS 25

Extended User Manual – Irix 15 mm f/2.4
[4 ]
FRONT LENS CAP
The front lens cap protects the front lens element
from possible contamination and impact damage.
The cap should always be attached when the lens
is not in use.
To attach or remove the front cap, hold the lens
body rmly in one hand and grasp the cap with
your thumb and nger by the recesses in the front
of the cap. Squeeze gently toward the center of the
cap to release the latches.
Additional lens caps may be purchased through
the Irix Online Store www.irixlens.com.

Extended User Manual – Irix 15 mm f/2.4
[5 ]
Your Irix lens can accept 95 mm screw-in lters via
the front threads. Due to the wide angle of view,
the use of “slim” lters is advisable to prevent
vignetting. Filters with a low prole of 5.3 mm or
less are recommended. Stacking multiple lters
may also cause vignetting.
Irix Edge lters are highly recommended, as they
are engineered to be fully compatible with the lens
design.
To attach a threaded lter, align the threads care-
fully and rotate it clockwise while facing the front
of the lens. The lter should turn smoothly and
with very little eort. If it appears to be crooked or
binds, reverse the rotation to remove and realign
the lter.
Excess pressure or misaligned threads may permanently dama-
ge the lens and lter.
Before tightening the lter, ensure that it does not come into
contact with the front element of the lens Contact between the
surfaces may cause permanent damage to both.
FRONT FILTER THREAD

Extended User Manual – Irix 15 mm f/2.4
[6 ]
LENS HOOD
The removable and reversible lens hood helps
prevent unwanted sidelight from the sun or other
sources from entering the lens. It also helps pro-
tect the lens from accidental impact damage. We
recommend having your lens hood attached at all
times.
There is no need to remove the lens cap when re-
moving or attaching the lens hood.
To remove the lens hood from its storage (rever-
sed) position, rotate it counterclockwise (when
facing the lens) until it releases (approximately 1/8
turn).
To attach the hood for use, align the white line on
the hood with the corresponding line on the end of
the lens. Slip the hood gently over the mount and
rotate it clockwise until it clicks rmly into place.
The alignment mark should now align directly with
the line on the angled portion of the lens barrel.
To reverse-mount the lens hood prior to storing the lens in its
transport case, use the same procedure with the lens hood
facing the opposite direction.

Extended User Manual – Irix 15 mm f/2.4
[7 ]
FILTER WINDOW
The lter window in the lens hood provides access
to the edge of lters that rotate, such as circular
polarizers, graduated lters and variable ND l-
ters. This feature allows you to adjust those lters
without removing the lens hood.
To open the lter window, push the raised portion of the blind
toward the front of the lens hood, sliding the blind until it clicks
into place. To prevent unwanted side light from striking the
lens, close the blind when the window is not in use.

Extended User Manual – Irix 15 mm f/2.4
[ 8 ]
FOCUS SCALE CALIBRATION You Irix lens has been engineered to exacting stan-
dards. The focus scale is factory calibrated and
should be accurate. In some cases, however, you
may nd that the innity mark on your lens does
not correspond to the optimum focus setting for
distant objects. While the focus ring will rotate past
the innity setting to allow you to compensate for
this, it may be more convenient to re-calibrate the
innity setting on your lens. You can make this ad-
justment yourself or contact the Irix support team
for help.
To calibrate the focus ring:
1. Remove the calibration window cover by unscrewing the T6
Torx screw and sliding the cover outward.
2. Set the focusing ring at the innity position and rotate the
focus lock ring to the locked position. The internal calibration
ring and at head locking screw should be visible.
3. Using a at head screwdriver, loosen the screw on the cali-
bration ring. Be careful not to allow the screws to fall into the
lens housing. A screwdriver with a magnetic tip is recommen-
ded.
4. Using your camera’s Live View and LCD zoom, rotate the cali-
bration ring to focus carefully on a distant subject (farther away
than 50m/164ft).
5. Lock the calibration ring by re-tightening the screw and re-
place the calibration window cover.

Extended User Manual – Irix 15 mm f/2.4
[9 ]
FOCUS RING LOCK
The focus ring lock allows you to x the focusing
ring in a selected position. This innovative feature
helps prevent accidental movement, resulting in
focus shift.
You may want to use the focus lock during long
exposures, time-lapse imaging, or whenever re-
petitive shots are called for. You can also use it to
avoid changing the focus setting while mounting
or removing the lens or to retain the focus setting
when storing it in a bag, case or backpack.
Landscape photographers, street photographers
and journalists can utilize the focus lock to keep
the lens at the innity setting or hyperfocal distan-
ce for a given aperture.
To use the focus lock, focus the lens, then rotate
the locking ring in the direction of the “lock” arrow
until you meet resistance. Don’t over-tighten. To
unlock, rotate the ring in the opposite direction
until “unlock” aligns with the top of the lens.
CAUTION: Forcefully rotating the focus ring with the lock enga-
ged may cause permanent damage to your lens.

Extended User Manual – Irix 15 mm f/2.4
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FOCUS RING
The focusing ring moves the internal focusing
elements of the lens to achieve the desired focal
point. You can focus visually while looking at your
subject in the viewnder or LCD screen or by using
the distance, depth of eld or hyperfocal scales on
the lens barrel.
Your Irix lens allows you to set the focus at innity without the
need to look at the scale. While rotating the focus ring, innity is
indicated by a click and a denitive stop in the rotation.

Extended User Manual – Irix 15 mm f/2.4
[11 ]
DEPTH OF FIELD SCALE
The depth of eld scale provides a visual reference
for the range of maximum sharpness in your pho-
tos at a given aperture and focus setting. It allows
you to determine the plane of focus, within which
objects in your image will be at their sharpest.
Using the scale correctly takes practice. The following examples
will demonstrate how to use it for creative control of depth of
eld (DoF).
DoF control is achieved with the lens aperture, so you will need
to set your camera to Aperture Priority or Manual mode.

Extended User Manual – Irix 15 mm f/2.4
[12 ]
DEPTH OF FIELD SCALE
ExAMPLE NO 1
In this example, the lens is focused on the eighth
key from the font of the image. The lens aperture
is at its maximum setting of 2.4.
You can see in the image that only the neighboring
keys are in sharp focus at this aperture setting.
The term for this eect is “shallow depth of eld”.
As this demonstrates, it would be virtually impos-
sible to provide legible marks on the DoF scale for
this aperture setting. DoF scales are only useful for
a smaller aperture setting (higher f/number).
In the case of your Irix 15 mm lens, the lowest
number represents f/8.

Extended User Manual – Irix 15 mm f/2.4
[13 ]
DEPTH OF FIELD SCALE
ExAMPLE NO 2
In this image, the focus setting remains the same
as the rst example, while the aperture setting is
changed to f/8.
Consulting the DoF scale, we can now use the two
numerals “8” on the scale to determine the distan-
ces where sharpness will drop. Simply look for the
distances in feet or meters that align with the “8”s
on the scale to determine the closest (left “8”) and
farthest (right “8”) points that will be in focus.
You can verify the change in depth of eld in the image. Notice
that the number of keys in focus has increased.

Extended User Manual – Irix 15 mm f/2.4
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DEPTH OF FIELD SCALE
Przykład 3
Next, the aperture setting is decreased to f/16,
without changing the focus setting. This smaller
aperture will increase the DoF.
You can see the increased plane of focus in the
image. Consulting the DoF scale at “16” will show
a corresponding change in the indicated distances.
The DoF scale can be used in this manner to esti-
mate the plane of focus in your images at aperture
settings of f/8 and smaller.
The DoF scale on your lens indicates the results with a full-fra-
me camera. Using your lens with a camera with a smaller sen-
sor will noticeably aect the depth of eld and the accuracy of
the scale. Practice will help you determine and compensate for
the dierence.

Extended User Manual – Irix 15 mm f/2.4
[15 ]
HYPERFOCAL SCALE
In landscape, travel and similar types of photo-
graphy, it’s often benecial to maximize the depth
of eld in your images. This is best accomplished
by setting your focus at the closest point of sharp
focus for the chosen aperture setting. That point
is known as the hyperfocal distance. Even when
using the DoF scale, this distance can be dicult to
determine in the actual scene.

Extended User Manual – Irix 15 mm f/2.4
[16 ]
HYPERFOCAL SCALE Your Irix lens includes an innovative feature that
allows you to quickly focus your lens at the hyper-
focal distance for apertures of f/8 to f/16. The hy-
perfocal scale is located above the distance scale
on the lens barrel.
After selecting your aperture setting with your
camera in aperture Priority or Manual mode, sim-
ply align the corresponding f/number on the hy-
perfocal sale with the center of focus indicator (the
center mark on the DoF scale). Your focus is now
set to the hyperfocal distance and there’s no need
to focus visually!
The landscape image to the left was taken using
the hyperfocal scale at f/16. Notice the overall
sharpness in the image.
Notes:
1. When using the hyperfocal scale for several consecutive pho-
tos, consider using the focus ring lock.
2. The hyperfocal scale is calibrated for use with a full frame
camera. Using a camera with a smaller sensor will cause a shi-
ft in DoF and a corresponding shift in the hyperfocal distance.
With practice, you can learn to determine and compensate for
the dierence.

Extended User Manual – Irix 15 mm f/2.4
[17 ]
Your Irix lens is equipped with a 30 mm x 30 mm
slot behind the rear element to accommodate ge-
latin lters. A template for pre-cutting lters is inc-
luded on the last page of this document.
Using gelatin lters allows you to add rear lters in
conjunction with front-mounted threaded lters,
while avoiding the vignetting that can be cause by
stacking multiple front lters. For instance, a color
correction lter can be added while using a circular
polarizing lter or ND lter.
Exercise caution when inserting lters to avoid touching the
rear lens element and electrical contacts on the mount.
Filter dimensions that do not match the template in this manual
should not be used.
REAR GELATIN FILTER SLOT

Extended User Manual – Irix 15 mm f/2.4
[ 18 ]
HOW TO ATTACH THE LENS
TO THE CAMERA
Exact mounting methods vary from camera to
camera. Consult the user’s manual for your came-
ra for instructions on mounting your Irix lens. The
dot on the case bevel closest to the camera indica-
tes the alignment mark for mounting.
Exercise caution when attaching and detaching your lens. Do
not force the lens. Be sure to press the lock release on the
camera body when detaching the lens. Consult your camera
manual for the exact location of the release. Failure to follow
these steps may cause permanent damage to your lens and/
or camera.

Extended User Manual – Irix 15 mm f/2.4
[19 ]
REAR LENS CAP
The rear lens cap protects the mount and rear ele-
ments when the lens is detached from the camera.
It should be attached immediately when the lens
is removed.
Your Irix lens comes with a spare rear cap, which
you can nd inside the lens box. Additional lens
caps can be purchased from www.irixlens.com if
needed.
To avoid damage, never place the rear of the lens on any surfa-
ce with the rear lens cap removed.

Extended User Manual – Irix 15 mm f/2.4
[20 ]
APERTURE CONTROL
Your Irix lens is equipped to function with your
camera’s electronic aperture controls. It also com-
municates the aperture information to the came-
ra’s software for display and EXIF data.
This feature allows you to fully utilize the creative
aspects of lens aperture in conjunction with your
camera’s metering system and autoexposure set-
tings.
There are a few important points to know about
your lens and its aperture settings:
1. Using an aperture setting higher than f/16 may
cause some lack of sharpness do to an optical phe-
nomenon known as diraction. This is not a defect,
but a natural occurrence in all optics.
2. When selecting the maximum aperture of f/2.4,
some camera models will display f/2.5. This is a so-
ftware issue with some systems. The actual aper-
ture size will be f/2.4.