coffeeguy415 wrote in post #7250768
Thank you for showing per example of how DOF works in such a close range. I now understand DOF in close range needs longer exposure
Almost. You need to understand the relationship between apertures and DOF and apertures and exposure time. A wide aperture of f/2.8 will have a narrow depth of field while a smaller aperture of f/16 will have a greater depth of field. For a greater Depth of field in close range you need a smaller aperture which results in a longer exposure time because the smaller aperture lets through less light than the wider aperture.
1. Do I buy some type of ring to reduce the focal length?
2. Which lens should I use to shoot close up flower shots?
Canon EF 85mm F/1.8
Tamron 28-75mm F/2.8 Macro
Tokina 12-24mm F/4
Can I use any of mine existing lens with a ring to take macro shots?
Your Tamron 28-75 as suggested above would be a good choice as it has a better close-focus range than the other lenses you have. Although it says "Macro" on the lens, it is not a "true" macro lens. Only prime lenses with the "Macro" designation are true macro lenses.
Here's a good link to help you work out depths of field: http://www.dofmaster.com/dofjs.html
Also look at the articles there for more info on the subject.