20 6 July 2019I http://www.amateurphotographer.co.ukI subscribe 0330 333 1113
DOES A NEW LENSNEED TO BECALIBRATED?Technique AF MISTAKESManufacturingtolerancescanresultin a DSLR’sAFsensoranda lens
notbeingperfectlymatched,whichmeansthatyoursubjectisn’tas
sharpasyoumightexpect.Thankfully,high-endcamerashavea lens
calibration or AF Microadjustment feature that allows you to correct this
problem.ThefollowingstepsshowhowtheAFMicroadjustmentfeature
worksusinga CanonEOS5DMarkIVanda calibrationtargetcreated
froma freetemplatedownloaded from the internet at http://www.squit.co.uk/
photo/fi les/FocusChart.pdf.4 FindAFMicroadjustment
Fromthemenu,selectAFMicroadjustmentin
theAFoptions.PressSetandscrolldownto
‘Adjustbylens’beforepressing the Info button
to access the options.
7 Setfocusadjustment
Usethemaindialtosetthefocusadjustment;
usea positivenumbertocorrectfrontfocusing
anda negativeoneforbackfocusing. Press
Set followed by the Menu button.
2 Usethewidestaperture
Setthewidestapertureandputthecentre
AFpointoverthechartfocusmarkerbefore
focusingandtakinga shot.Refocusagain and
repeat until you have fi ve images.1 Setupyourtarget
Assembleyourcalibrationtargetandmount
yourcameraona tripodat least25xthefocal
lengthof thelensaway. Next, select mirror
lock-up mode.
5 Checklensserialnumber
PresstheInfobuttonagaintocheckthelens
serialnumber.If necessary,usetheSetbutton
andmaindialtoenter the correct number,
then select ‘OK’.8 Refinethecalibration
Shootthetargetagainandexaminethe
imagestoassesstheimpactof theadjustment.
If necessary(it probablywillbe)repeatthe
adjustment process to refi ne the calibration.3 Reviewtheimages
Opentheimagesonyourcomputerand
examinethemat 100%onscreentosee
whetherthecamerais focusingthelensin
front of or behind the intended target.6 Adjustfocuspoint
Youcanadjustthefocuspointof theshortest
andlongestfocallengths.Usethescrolldialto
selectthefocallengththat you want to adjust,
and then press Set.9 Repeatforotherlenses
If you’recalibratinga zoomlens,repeatthe
adjustmentprocessforthelongestfocal
lengthonceyou’vegotthefocusing right
for the shortest focal length.