ADVANCEDPROJECTS
118 OCTOBER2020|COMPUTERSHOPPER|ISSUE392
aperture ring moves once it’s attached to the
HQ Camera. Youtherefore need to lock the
focus screw,unscrew the aperture screw,turn
the aperture ring as fartoClose as possible,
lock the aperture screw,unscrewthe focus
screw,twist the focusringuntil the image on
your screen is sharp,and then tighten the
focus screw.The 16mm Telephotolens has
separaterings forfocus and aperture,so
there’s no swapping between elements.
Notethat as you close the aperture,you’re
not only increasing the depth of field but also
reducing brightness, so you’ll need to balance
those considerations, or increase the lighting
if you want maximum depth of field.
All the same switches and controls apply
when using the HQ Camera as the Pi Camera
V2. The only change is the optical hardware,
not raspistill and raspivid commands.
NETWORK CONTROL
Youcan do all of this remotely,which
might be useful foraCCTVsetup or wildlife
camera (either indoors or with proper
weatherproofing). First, you’ll need to
enable SSH connections through the same
menu in which we enabled the camera
connection (Raspberry menu, Preferences,
Raspberry Pi Configuration, Interfaces tab).
Then find the Pi’s IP address by entering
ifconfigin the Pi’s Terminal window and
checking the wlan0 entry.
On your Windows PC, you can
connect via SSH by launchingPowerShell
(search the Start menu) and entering
sshpi@<IP-ADDRESS>and then entering
the Pi’s password. Then you can issue
commands as if you were using the
Terminal window on the Pi.
Fetching images from the Pi over your
network is also relatively easy.You could
install Samba and set up ashared folder,as
we showed you inAdvanced Projectslast
month, or use the Apache software to
createaquick and easy FTP file server.For
Glossary
GiventherelativecostoftheHQCameraanditslensestothePithey’reattachedto,it’sperhaps
notsurprisingthatthere’salotofphotographyjargontodealwith.Here’sahandyreference
APERTUREThe opening through which
light enters the lens unit; the larger the
opening, the more light can enter (per
given time period, see exposure) and
the larger the ‘f number’(f/1.4rather
than f/16, forexample).
BACK-FOCUSRINGAn adjustable
ring that allows you to focus the
HQ Camera when using fixed-focus
lenses.
BARREL DISTORTIONThe effect of
straight line in an image seeming to
curve.Thisiscausedbythe curvature
of alens.
DEPTHOFFIELD(DOF)The amount of
foreground and background in focus.
Creative use of depth of field is usually
achieved by adjusting the aperture –a
larger aperture will result in ashallow
depth of field, forexample.
EXPOSUREThe amount of time over which
the sensor records the light received.
FNUMBER(ALSO‘FSTOP’)The measure
of aperture size,expressed as afraction.
So f/4 gives alarger aperture than f/16
in the same waythat^1 / 4 is alarger
number than^1 / 16.
FIELDOFVIEW(FOV)Theangle of
sight from the lens unit opening. This will
be tighter with longer telephotolenses,
possibly near-90owith astandard or
wide-angle lens, and exceeding 90owith
afisheye lens.
FISHEYE(LENS)Alens unit capable of
a100-180ofield of view (byusing a
concave lens).
FOCAL LENGTHThe distance between
the focusing lens and sensor when the
subject is in focus.
FOCUSAdjust this to move the lens in the
lens unit forward or back to make your
image ‘sharp’(not blurry) instead of
physically moving the camera. See also
depth of field.
TELEPHOTO(LENS)Alens unit that
houses multiple lenses such that physical
focal length is shorter than the optical
focal length (so a500mm telephotolens
need not be 500mm long, forinstance).
This allows close-up images of subjects
while maintaining alarge physical distance
with amore compact camera setup.Not to
be confused with zoom.
WIDEANGLE(LENS)Alens unit capable of
awide field of view, usually ageneral-purpose
lens (not to be confused with afisheye lens).
ZOOMThe ability to adjust the level of
magnification within alens unit (byaltering
the focal length). See also telephoto.
⬆Toachieveclearfocus,locktheaperturethumbscrew,openthefocusthumbscrewandrotatethefocusringtowardtheNearmarkerforfourorfivefullrevolutions
Before After
