I have a Sigma 35-70mm filter or Cap can I use...... Please be aware there are many versions of Camera Lenses made by maufacturers. For exsample Nikon have made over 7 different verisons of 35-70mm lenses. The correct way to ask is to give the seller as much information about your lens as possible. I have a Nikon 35-70mm F3.3~4.5. If you wrote this I would say Ah its 52mm. Why because if you asked for a 35-70mm filter size, I could of said to you its either 52mm, 55mm, 62mm or 58mm. Not excactly much of help to you is it. Also if you have a Canon the version of camera body you have is paramount. So if you have a ef mount canon SLR give them the information as well. Though the fastest way to find out is usually a quick search by google "CAMERA BRAND" and "MODEL" + Specification + Review eg Nikon 35-70mm f3.5-4.5 specification review