it swallows too much light

I am an absolute beginner in terms of photography. Since I find macro shots very interesting, I chose as an alternative to this macro extension tubes. Very positive I think that must be installed this macro rings stable. Also the automatic focus works perfectly and easier to frame immensely. However, my paintings have been very dark and thus needed a high ISO value. Thus, the photos came over very noisy and looked totally unattractive. That really annoyed me. Sometimes you had to raise a lot of patience even when anfokussieren. As Annex I to a photo drangehangen. As you can see, the image noise very well. I have the macro extension tubes tested for 1 week and sent back. For me, unfortunately, not an alternative