When Canon sell you a new printer they supply a Canon PG-510 black and a Canon CL-511 colour cartridge. Well these cartridges only hold 9mls black & 9mls colour ink in them which is written in really really small writing on the back of the cartridge boxes. For higher yield cartridges what you really need is the Canon PG-512 black which holds 15mls of ink and for the colour you should be using the Canon CL-513 cartridge which holds 13mls of ink. There is a company that I have also found (advantage online) which stock the Canon originals and a British premium compatible 512/513 maximum yield version which holds 20mls of ink in each cartridge and work just the same. Canon make there money out of selling you a very good printer (MX340) but then sell you cartridges that have hardly any ink in them (PG510 & CL511). Don't fall into the Canon ink con trap!!