Originally posted by diaseis So does it implies that I cannot use it at all ? I'd like to take macro pictures with my camera but I don't have the budget to buy a new lense.
Sure you do, perhaps just not a new new lens. If you can afford tubes you can squeak something to use on them until you can get something better. All you need is a little prime lens, like one of the older 50mm. For the first several years I shot macro I was using a set of tubes like you have with a Pentax A 50mm f./2, which was a kit lens on some old film cameras. It cost about $20 for the lens, and you should have no trouble finding one around that price. It's not the sharpest 50mm lens out there, and you'll get better quality if you can spend ~$100 on a Pentax F 50mm f./1.7, but it will allow you to learn to shoot macro in the meantime, and then when you have an opportunity for a better lens sometime in the future, you'll see the quality jump in your work. You'll already know what you're doing so you'll be able to fully leverage the new lens.
Be sure to get a prime that has an aperture ring. Keep the aperture ring set to the aperture you want to use while using the tubes. A lens lacking an aperture ring will only shoot wide open on tubes, which isn't useful.
I understand your disappointment, but you don't want to use extension tubes with zoom lenses, anyway. Some zoom lenses won't work at all with tubes. Due to the design of their optics, when you add extension the focal point can be reduced to being inside the front element of the lens, making focusing on a subject impossible. Zoom lenses with extension will also show more distortion, as a rule, because they're not designed to have the same resolving power as a decent prime. Extension exaggerates any flaws present in the optics of a lens.
This thread helped me get started a decade ago, and it's still entirely relevant. It's a good read. Don't get discouraged. You have so much good stuff ahead of you if you pursue this.
Edit to add: My Pentax A 50mm f./2 is pretty beat up, the coatings are a bit messy, but if it's of use to you and you're willing to cover the shipping I'll send it to you at no additional cost. I'm located in Canada. And edited again to correct a misremembered point.