Interesting choice of black and white for a cactus. Being experienced with cactus, I think you have done good job capturing this one. That main thing with them are the spines. It is hard to sharpen them just right to avoid the "jaggies". You do have have some here. Judicious use of the smudge tool or selecting out the offending spines before sharpening will reduce the "jaggy" effect.
I think this would have worked better in landscape orientation. The thorns of the cactus (on the left) direct my eyes to the left, only to run into an abrupt crop.
black and white is cool here... good DOF nice crop.. I like this one a lot.. those stickers really stand out.. my top pick this week. I cant stop looking at the spikes lol
A very sharp photograph... I like the DoF in this, where the spikes on the cactus are the sharpest portion of the photo. B/W does seem to add to this shot.
Well done with b/w and DOF. Good job cropping, too. One thing confuses me and that's the upper right corner. Why is that group of "spines" blurry and the ones below not blurry? 7