can anyone help me,please. I have a Sigma lens APO DG 70-300 but don't know the fitting. |It won't fit a Nikon.There is a number 3023276 but no other indication.
Yup, that's a Pentax mount. There's a company that makes adapter rings, but I can't remember the name of it. Do a Google on Nikon to Pentax adapter rings.