Yuav siv rab phom twg? Thawj qhov uas yuav tsum tau ua kom meej yog qhov koj npaj siab yuav txhim kho qhov ntsuas ntawm. Cov phom sib txawv muaj qhov sib txawv rau kev txhim kho cov khoom siv sib txawv, cov mos txwv siv yog sib txawv, cov recoil tsim txawv, thiab cov cuab yeej pom kev uas tuaj yeem ntsia tau rau nws txawv. Piv txwv li, lub peev xwm siv rau ntawm rab phom thiab lub peev xwm ntawm rab yaj phom (yog, lub peev xwm kuj tuaj yeem ntsia tau rau ntawm rab yaj phom) tsis tuaj yeem zoo ib yam hauv qhov taw qhia ntawm qhov muag deb, vim tias rab yaj phom tsis zoo ib yam thaum tua. Zoo li rab phom, koj tuaj yeem lo koj lub ntsej muag rau lub pob tw tab sis khaws ib qho kev ncua deb ntawm tib neeg lub qhov muag, yog li koj yuav tsum muaj qhov muag ntev. Ib yam li ntawd, qhov kev siv ntawm rab phom scout (tseem hu ua rab phom scout) feem ntau yog ntsia rau hauv pem hauv ntej, yog li nws yuav tsum muaj qhov muag ntev dua. Ntev qhov muag nyem (LER) scopes feem ntau tsis muaj siab magnification.
Qhov deb ntawm lub qhov muag ntawm rab yaj phom (sab laug sab) thiab cov phom sij scout (sab saum toj sab xis) yog qhov loj dua li ntawm rab phom loj (hauv qab). Lub qhov muag nyem (qhov muag nyem) txhais tau hais tias nws tuaj yeem siv yam tsis muaj vignetting. Qhov kev ncua deb zoo tshaj plaws (nruab nrab ntawm tib neeg lub qhov muag thiab lub qhov muag) uas muab rau tib neeg lub qhov muag nrog qhov loj tshaj plaws ntawm kev pom yog qhov kev ncua deb tshaj plaws rau tib neeg lub qhov muag kom pom kev yooj yim. Yog tias qhov kev ncua deb ntau dua lossis tsawg dua qhov kev pom qhov deb, vignetting yuav raug tsim tawm thiab kev soj ntsuam zoo yuav cuam tshuam tsis zoo. Yog vim li cas rau vignetting yog tias tib neeg cov menyuam kawm ntawv tsuas yog tso cai txwv lub teeb nkag mus rau qhov muag. Yog hais tias lub teeb los ntawm lub hom phiaj yog ib nrab thaiv los ntawm iris, tsis tsuas yog cov duab ib feem ntawm cov duab ntxoov ntxoo dub yuav projected ntawm lub retina, nws kuj yuav distorted cuam tshuam nrog cov duab teeb uas tau nkag mus rau hauv cov menyuam kawm ntawv. Ntawm qhov muag deb, qhov ua tau ntawm vignetting yog qhov tsawg tshaj plaws. Ntxiv nrog rau qhov muag pom kev deb, cov tub ntxhais kawm tawm kuj tseem yog qhov tseem ceeb ntawm qhov muag pom qhov tsis zoo uas feem ntau saib tsis pom thiab feem ntau tsis meej pem nrog qhov muag sib nrug. Txoj kab uas hla ntawm cov menyuam kawm ntawv tawm yog txoj kab uas hla thiab qhov dav ntawm lub aperture (tawm cov menyuam kawm ntawv) uas tau npaj los ntawm lub qhov muag ntawm qhov muag deb, uas yog qhov ntev ntawm tus nqi perpendicular mus rau qhov muag deb. Nyob rau hauv cov ntaub ntawv ntawm lub teeb txaus (xws li lub teeb thiab Hitachi lub broad daylight), txoj kab uas hla ntawm tib neeg cov menyuam kawm ntawv feem ntau yog hais txog 2 hli. Ntev npaum li txoj kab uas hla ntawm lub aperture tsim los ntawm lub qhov muag ntawm lub qhov muag deb yog ntau tshaj 2 hli, nws muaj peev xwm yeej lav tias txawm tias tib neeg lub qhov muag Vibration yuav tsis tsim vignetting; tab sis yog tias qhov ci ntsa iab ntawm lub teeb poob (nyob rau hauv cov teeb pom kev tsawg), tib neeg cov tub ntxhais kawm yuav dilate. Yog hais tias txoj kab uas hla ntawm lub eyepiece aperture yog me dua lub dilated tub kawm ntawv txoj kab uas hla, vignetting kuj yuav tshwm sim nyob rau hauv lub qhov muag nyob deb li cas. Yog li ntawd, thaum yuav ib tug Scope, sim txiav txim siab xaiv ib tug me ntsis loj tawm cov tub kawm ntawv txoj kab uas hla.
