Hi I am new here but I am having a technical nightmare. I am trying to buy a filter at 77mm (what is this called where the mm number is on the lens cap)? to fit on a 67mm lens. I don't know if I need a step up or step down ring for this filter - 77mm to 67mm Also I am looking at 2 other filters of 49mm and 58mm but I don't have any lenses that say that size on them so what am I looking for? My kit lens is a zoom lens even though I have a cropped frame camera - Canon EOS 7D Mk2 Can you help me? I have been doing photography a while but I still need help on some things. Thanks Kaylee
Those are all common filter sizes. The diameter of the lens will give to the filter size, you can look this up for each lens you own easily online. http://www.eflens.com/lens_articles/ef_lenses_by_filter_size.html You did not mention which zoom you have, but the advice will not matter which exact lens you have. You can look at the lenses you have and the sizes, as well as any lenses you plan to have. And purchase accordingly depending on the filters you want. For example most of my primes take 58mm and my L zooms take 77mm so I have a circular polarize in both sizes for convenience. I have a 100mm macro which takes a 67mm and a cheap step up ring to fit a 77mm filter on the 67mm lens thread. I do not advise a step down ring, mounting a smaller filter on a larger lens thread for example 52mm filter on 58mm lens thread, that will in most cases introduce noticeable vignetting to the image.
there are also some variable thread size filters that do away with step up rings you might want to take a look at too
