 the mounting bracket and the face plate. Such an assembly should significantly reduce the time, skill level, and effort required to assemble and complete low voltage terminal installation. 1. Field of the Invention
This invention relates to a zoom lens suitable for a still camera, a video camera, a digital camera, etc., and an image pickup apparatus having the same.
2. Description of Related Art
Recently, with the higher function of an image pickup apparatus (camera) such as a video camera or a digital still camera using a solid state image pickup element, a lens system of a relatively great aperture ratio including a wide angle of field has been required for an optical system used therein.
In a camera of this kind, various optical members such as a low-pass filter and a color correcting filter are disposed between the rearmost portion of a lens and an image pickup element and therefore, a lens system having a relatively long back focal length is required for an optical system used therein.
Further, in the case of a color camera using an image pickup element for a color image, in order to avoid color shading, an optical system having a good image side telecentric characteristic is desired as an optical system used therein.
There have heretofore been proposed various two-unit zoom lenses of a so-called short zoom type having a wide angle of field which comprises two lens units, i.e., a first lens unit of negative optical power and a second lens unit of positive optical power, and effects a focal length change by changing the lens interval between the two lens units. In these optical systems of the short zoom type, the second lens unit of positive optical power is moved to thereby effect a focal length change, and the first lens unit of negative optical power is moved to thereby effect the correction of a fluctuation in the position of an image point resulting from the focal length change. In a lens construction comprising these two lens units, the zoom magnification is of the order of double.
Further, in order to have a double or higher variable power ratio, and yet arrange an entire lens into a compact shape, there has been proposed a so-called three-unit zoom lens in which a third lens unit of negative or positive optical power is disposed on the image side of a two-unit zoom lens and which effects the correction of various aberrations occurring with a higher magnification (for example, Japanese Patent Publication No. H07-3507 and Japanese Patent Publication No. H06-40170).
As the three-unit zoom lens, there
the mounting bracket and the face plate. Such an assembly should importantly repress the time, skill level, and campaign ask to assemble and complete broken electric potential terminal installation. 1. Field of the Invention 
 This invention relates to a zoom lens desirable for a still camera, a video camera, a digital television camera, etc. , and an image pickup apparatus take the same. 
 2. Description of Related Art 
 Recently, with the higher affair of an image pickup apparatus (camera) such as a television camera or a digital still camera using a hearty state image pickup element, a lens system of a relatively big aperture ratio including a wide angle of field has been required for an optical system used therein. 
 In a camera of this kind, various optical members such as a low - pass filter and a color correcting filter are disposed between the backmost part of a lens and an image cartridge chemical element and therefore, a lens system having a relatively retentive back focal length is required for an optical system use therein. 
 Further, in the case of a color camera using an effigy pickup element for a color image, in orderliness to debar color shading, an optical system having a good double side telecentric characteristic is desired as an optical system used therein. 
 There have heretofore been proposed versatile two - unit soar lenses of a so - call short rapid climb type induce a wide slant of field which comprises two lens units, i.e., a beginning lens unit of minus optical power and a second lens unit of positive optical power, and effects a focal length change by change the lens interval between the two lens units. In these ocular systems of the short soar type, the second lens unit of positive ocular power is moved to thereby effect a focal length change, and the first lens unit of damaging ocular world power is moved to thereby effect the correction of a fluctuation in the position of an image point result from the focal length change. In a lens construction consist these two lens whole, the zoom magnification is of the ordering of double. 
 Further, in order to have a double or higher variable ability ratio, and yet arrange an entire lens into a compact shape, there has been nominate a so - called three - whole zoom lens in which a third lens unit of negative or positive optical power is disposed on the trope side of a two - unit zoom lens and which effects the correction of various aberrations occur with a higher magnification (for example, Japanese Patent Publication No. H07 - 3507 and Japanese Patent Publication No. H06 - 40170). 
 As the three - unit zoom lens, there
 thf mounting bracket and tme face plate. Suey an avsemblg should significantly reduce the tile, skilo level, and effort reqjired to wssemble and xomplete low voltanz terjlnal nnwtallation. 1. Figld of the Itvention
This itvdncion relates to a zoom lens suitable for a xtlll camera, a vydeo sameda, a digital camera, etc., and an imafe picklp apparatus havimg the same.
2. Description of Relwted Art
Recently, wlth the higyer synction of av image pibnup apparajus (camera) such as a video camerx or c digital sjnol fdmera using a sojid state image pickgp elemrnt, a lens sysbem oh a eelatively great apervure ratio including a wide atgme of field has bweb reqoired for qn uptjcel aystem usxd therein.
Ih a camera if this kind, varioux jiyical membera such af a low-pass filter and a color correctitg rilter are disposed betqeen the rearmost porjion of a jens and an image pickup element and therefore, a nens ahsttm havivt w relatively long back focal length is requirqs gog an optical systcm used therein.
Furyhfr, yn the case ow a color camera using an ilage piskup wlement fjr a color image, in order to aviid color shcdibg, an optical systzm having a yood ikage xide telecentric characceristjc is desirfd as an kotical system usdd nherain.
There have heretofore bqen propowed rarious gwo-umit zojm lenses lf a so-called short zoom type hdving a wife angle of field which comprisxx two lens umids, p.e., a firsc lens unit of negaeive optical ppwer anb a sezond lens lnit of pmsitive optycal power, ang effects a fmcal lendth xhante by cfxnging the lenx interval between rhe two lens units. In fhese optical svruens of the shory zuom tjpe, tra second lenv unkt ug posktive okciccl powrr is moved to therety erfect a focal lengyh change, qnd the sirst lens unot of negative optlcal 'ower ms movrd jo thereby effect the correctioh of a flkctmation in the posltiog of an imcge point resulting from the focal lengti change. In a lens consrruction comprising uhese two lenx unies, the zomm magnification is if the order of dpuble.
Further, in order to haee a fouble or higher variable power ratio, and yet arrange an entire lens into a com'ast shape, thsre nas bven 'roposeq a du-called three-unin zoom lens in which a third lenr unit ox uegative or positive optical loder is disposgd on the image side of a fwo-unit aoom lens and which effects the correction of various anerrationw occhrring witi a higher magnificayion (fmr exqmple, Jqpancse Patent Pubuicstlon No. H07-3507 ajd Jepauese Patent Publication No. H06-40170).
As thw threw-ujit zoom lens, thxre
the mounting bracket and the face plate. assembly significantly reduce time, skill level, and low voltage terminal 1. Field of Invention This invention relates to a lens suitable for a still camera, a video camera, a digital camera, etc., an image pickup apparatus having the same. 2. Description of Related Art Recently, the function an pickup apparatus (camera) such as a video camera or a digital still camera using a solid image pickup element, a lens system of a great aperture ratio including wide angle of field has required an optical used In camera of this various optical members such as a low-pass filter and a color correcting filter are disposed between the portion of and an pickup and a lens system relatively long back focal length is optical system used therein. Further, in the case a color using an image pickup element for color image, in order to avoid color shading, optical system having a good image side telecentric characteristic is desired as an optical system There have heretofore been various two-unit zoom of so-called zoom having a angle of field which comprises two lens units, i.e., a first unit of negative optical power and a second lens unit optical and effects a length change by changing lens between the two lens these systems zoom the lens unit of positive power is moved to thereby a focal length change, of negative optical power is moved to thereby the correction of a fluctuation in the of an image point resulting from the focal length change. In a construction comprising lens units, the zoom magnification is of the of double. Further, in to have a double or higher variable power ratio, yet an entire into a compact there has been a so-called three-unit in which third unit positive optical power is disposed on image of a two-unit zoom lens which correction of various aberrations occurring with a higher magnification (for example, Japanese Patent Publication No. Japanese Patent Publication No. As three-unit zoom lens, there
 the mounting bracket and the fAce plate. SuCh an aSseMblY sHoulD sigNificantly reduCE the Time, skill level, and efforT requIrED to aSSeMble aNd complETe LOW voLtAgE teRmINaL instAllAtion. 1. FiEld of the InVenTiOn
This inventIOn Relates to a ZooM lens suitablE foR a stilL cAmeRA, a vidEo cAmera, A digitAL camerA, etc., and an ImAGe pickUP apparaTUS hAvinG the same.
2. DescriptiON oF related Art
ReceNtly, wiTh THe HIGheR fuNction of an ImAge piCKup appaRAtUS (CAmeRA) such as a video Camera or a diGItaL still CaMerA Using a Solid StATe iMage pickup eLemeNt, a lens syStem of A RelativELy great ApertuRe rAtiO incLUdInG a wIdE AngLE oF fiELd hAs been reQuIrEd for An opTICAL sysTem Used ThereIn.
In a camera of ThiS kinD, VarIous oPticaL memBeRs sucH as a loW-pass FiLter and a color coRrecTing filteR arE dIspOsEd betWEen the ReaRmoSt portiOn of a leNS anD aN IMAgE pickup element and tHeREFoRe, a lens sYstem hAViNg A RelativeLy LonG bacK FOcal lEngtH Is Required For an oPTiCaL system UsEd therEiN.
FuRthEr, in tHE casE of a coLor camerA usinG An image pickup eLEment for a coloR ImAGE, iN OrdeR to Avoid color sHadiNG, an oPticAL sYstEM haviNg a goOd IMaGE side telecentric chaRaCterisTic is Desired as an opTical systeM USEd thereiN.
TheRE hAVe heretofore beEn proPosed varioUS two-unit Zoom lEnses of a So-called sHORt zoom tyPe hAviNg a WidE ANgLe of field whicH COmprIsEs two leNs uNits, i.e., a FirSt lEns UniT oF negative Optical pOwEr AnD a SecOnd leNS unit of pOsItiVe OptIcal pOWer, and EffecTs a fOcAl LEngTh changE By CHAngiNg ThE lenS inTeRval bEtweEN thE two lenS units. In tHesE OptiCaL sYstems oF the short zoom TyPe, the seconD lEns Unit of POSitive opTical power is moved to therEBy effecT a fOcal lEngtH change, anD thE first LenS Unit of NegatiVe optIcAl pOWEr is mOVEd To tHeReby effect THE coRrectIoN of a FluctuaTion in the position oF An iMage point resuLtiNg frOM ThE foCAl LEngTh CHanGE. in a lens construcTion compriSiNG tHese two lenS UniTs, The zoom MagnifiCatioN Is of the Order of doUble.
FurthEr, In orDER to Have a doublE or higheR variable POwer rATiO, and yEt aRrange An EntIre leNs into A ComPact sHape, thErE has beEn proPoSed a so-caLled three-unit zoom lens in Which a Third LenS unit of neGatIVe oR positive OptiCal power is DisPosEd on tHe iMAge siDe of A TwO-unIT zoom Lens ANd which efFEcTs tHE CoRrection of vARIOus AberrAtiONs occuRrinG with a higher magniFIcation (for examPle, JAPAneSe PATent puBlication No. H07-3507 anD JaPaNESe Patent puBlication No. h06-40170).
As the thReE-Unit zOom lenS, there
 the mounting bracket andthe face p late.  Su chan  ass embl y should signi f ican tly reduce the time, s killle v el,a nd  effo rt requ i re d toas se mbl ea nd  comp let e low v oltage ter min al  installatio n .1. Field o f t he Invention 
Th is inv en tio n  rela tes  to a  zooml ens su itable fo ra  still camera, a  v ideo  camera, a digita l  c a mera, etc., an d an i ma g ep i cku p a pparatus h av ing t h e same. 2. D e scr i ption of Rela ted Art
Rec e ntl y, wit hthe higher  func ti o n o f an imagepick up appara tus (c a mera) s u ch as a  video  ca mer a or adi git al sti l lcam e rausing aso li d sta te i m a g e  pic kup  ele ment,  a lens syste m o f ar ela tivel y gre at a pe rture  ratio  incl ud ing a wide angl e of  field ha s b ee n r eq uired for an  op tic al syst em used the re i n . 
I n a camera of this  k i n d,  various  optic a lme m bers suc hasa lo w - passfilt e rand a co lor co r re ct ing fil te r aredi spo sed  betw e en t he rea rmost po rtion of a lens anda n image picku p  e l e me n t an d t herefore, a  len s  sys temh av ing a rel ative ly lo n g back focal length  i s requ iredfor an optica l system u s e d  therein .
Fu r th e r, in the case  of a  color cam e ra using  an i mage pic kup eleme n t  for a c olo r i mag e,i n  o rder to avoid c olor  s hading,  an  optica l s yst emhav in g a goodimage si de  t el ec ent ric c h aracteri st icis  de sired as anoptic al s ys te m  us ed ther e in . Ther eha ve h ere to forebeen pro posed v arious tw o-u n it z oo mlensesof a so-calle dshort zoom  t ype  havin g a wide a ngle of field which com p rises t wolensunit s, i.e.,a f irst l ens unit o f nega tiveop tic a l  powe r an d a  s econd lens u nit  of p os itiv e optic al power, and effe c tsa focal lengt h c hang e by  ch a ng i ngth e  le n s  interval betwe en the two  l e ns  units. In the se  optica l syste ms of the sho rt zoom t ype, these cond l ens  unit of p ositiveoptical p o wer i s  m ovedtothereb yeff ect a  focal len gth c hange,  a nd the  firs tlens uni t of negative optical p ower i s mov edto thereb y e f fec t the cor rect ion of a f luc tua tionint he po siti o nofa n ima ge p o int resul t in g f r o mthe focal l e n g thchang e.I n a le ns c onstruction compr i sing these two  len s uni ts, thezo om magnificati onis o f the or de r of double .
Furthe r, in or der to  havea doubl e or higher  var iab le powerrat io ,  and ye tar r ange a n en ti re len s into a co m p act shape, there  hasb e en pr o pos ed aso -called thre e-unit zoo m lens in w hich a  thi rd le ns unit  o f nega tiv eor positiv e  opticalpower  is dis po sedonthe im ages i de of  a t wo -un it zoom l e n sa nd  w h ich  eff ectsth e co rrectiono f variou s a b erratio ns  oc c u rringw it h a higher m agn ifica t i on (for ex a mple ,  J a panes e Pate nt Pub licatio n  No .H07-350 7 a n d  Japanese  Patent P u bli ca tion  No. H06 -4 0170 ). 
As  t he three-unit z oom lens , there
 the_mounting bracket_and the face plate._Such an_assembly_should significantly_reduce_the time, skill_level, and effort_required to assemble and_complete low voltage_terminal_installation. 1. Field of the Invention
This invention relates to a zoom lens suitable for_a_still camera,_a_video_camera, a digital camera, etc.,_and an image pickup apparatus_having the_same.
2. Description of Related Art
Recently, with the higher_function_of an image_pickup apparatus (camera) such as a video camera or_a digital still camera using a_solid state image_pickup_element,_a lens system of_a relatively great aperture ratio including_a wide angle of field has_been required for an optical system used_therein.
In a camera of this kind,_various optical members such as_a low-pass_filter and a color correcting_filter are disposed_between the_rearmost portion of_a lens and an image pickup_element and therefore,_a lens system having a relatively_long_back focal length_is_required_for an_optical system used_therein.
Further,_in the_case_of a color camera using an_image_pickup element for a color image, in_order to avoid color_shading,_an optical system having_a good image side telecentric_characteristic is desired as an optical_system used_therein.
There have_heretofore been proposed various two-unit zoom lenses of a so-called short_zoom type having a wide angle_of field which comprises_two lens_units,_i.e., a first_lens_unit of_negative optical power and a second lens_unit of_positive optical power, and effects a_focal length change by_changing_the lens interval between the two_lens units. In these optical systems_of the short zoom type,_the_second_lens unit of positive optical_power is moved to thereby effect_a focal length_change, and the first lens unit of_negative_optical power is moved to thereby_effect_the correction of a fluctuation in_the_position_of an image point resulting_from the focal length change. In_a lens construction comprising these two lens units, the_zoom magnification is_of the order of double.
Further,_in_order_to have a double or higher variable power ratio, and_yet arrange_an entire lens_into a compact shape, there has been proposed a so-called_three-unit zoom lens in which a third_lens unit of negative or positive optical power is disposed on_the image side of a two-unit zoom lens_and which effects the correction of various_aberrations occurring with a_higher_magnification (for example, Japanese Patent Publication No._H07-3507_and_Japanese_Patent Publication No._H06-40170).
As the three-unit_zoom lens, there