. ▁ ▁Re verse ▁zoom ▁ ▁An ▁unusual ▁aspect ▁of ▁the ▁f / 2 . 8 ▁M k ▁I ▁l ens ▁( and ▁the ▁ 2 8 – 7 0 mm ▁f / 2 . 8 L ) ▁is ▁that ▁its ▁bar rel ▁extends ▁as ▁it ▁zo oms ▁toward ▁its ▁short est ▁foc al ▁length . ▁When ▁used ▁with ▁the ▁supplied ▁l ens ▁h ood , ▁which ▁attach es ▁to ▁a ▁non - mov ing ▁part ▁of ▁the ▁l ens , ▁this ▁extension ▁results ▁in ▁a ▁properly ▁matched ▁sh ade ▁at ▁every ▁angle ▁of ▁view . ▁Most ▁zoom ▁l ens ▁h ood s ▁are ▁designed ▁for ▁only ▁the ▁wid est ▁angle ▁of ▁view , ▁offering ▁progress ively ▁in ade qu ate ▁sh ade ▁at ▁longer ▁foc al ▁lengths . ▁ ▁This ▁reverse ▁zoom ▁is ▁illustrated ▁with ▁the ▁following ▁two ▁pictures : ▁ ▁At ▁the ▁tele photo ▁end ▁( 7 0   mm ), ▁the ▁end ▁of ▁the ▁l ens ▁is ▁the ▁most ▁ret ract ed ▁providing ▁the ▁most ▁sh ade ▁protection ▁from ▁the ▁l ens ▁h ood . ▁At ▁the ▁wid est ▁end ▁( 2 4   mm ), ▁the ▁end ▁of ▁the ▁l ens ▁is ▁the ▁most ▁pro tr ud ing ▁providing ▁the ▁least ▁sh ade ▁protection ▁from ▁the ▁l ens ▁h ood . ▁ ▁The ▁f / 2 . 8 ▁M k ▁II ▁l ens , ▁however , ▁has ▁a ▁more ▁conventional ▁design , ▁with ▁the ▁bar rel ▁extending ▁as ▁the ▁foc al ▁length ▁increases . ▁The ▁l ens ▁h ood