>>3633481>Use /gear/ for gear related stupid questions.You're looking for macro lenses. You can also get pretty good results with your 75-300 and extension tubes. Extension tube decrese neares focusing distance of a lens, they are also cheap, even auto focus ones, so they're usually first step to macro for many people.
>>3633373Go even lower. If you're shooting flowers, have flower at least in half of the image, only exception to this is that you've a beautiful background to complement it. Use weak fill flash, or various reflectors when flower is in shadows. I lean to reflectors for this, since I can better direct them. Get background separation. Long focal lengths or large apertures help in this.