MalVeauX wrote in post #18743801
You don't have to spend a mint to get a good filter.
It's best to get a larger filter than will fit all your lenses and simply use step down rings to get them to the size to thread onto your smaller lenses. For example, get a 77mm threaded ND filter, and then use step down rings to go from 77mm to 72mm or 77mm to 67mm or 77mm to 58mm and so on. They're inexpensive little metal rings. Then you use the one filter for all lenses no problem.
I just wish you could actually get reasonable cost ND filters in the larger sizes. Most of the ND filters in the sweet spot of price/performance only go up to 77mm in diameter. I could really do with both a one and a two stop ND filter for one of my lenses. I can find only one brand of screw in filter for sale in the UK, or EU for that matter, that comes in the required size. Interestingly they are made here in the UK and cost £250 each! Now I know there is more to it than just surface area, but to go from a 77mm diameter filter to the 95mm filter needed for my Sigma 150-600 C is only a 52% increase in surface area. Sigma make a well priced protective filter, and even a well priced CPL with the same strength features of the protective filter for the large diameter lenses, but no ND options. The Sport version is even worse at 105mm diameter for the filter.
I know it is unusual to need an ND filter for a lens with such a long focal length, but modern DSLR bodies are rather limited with ISO on the whole. If you need shutter speeds under even 1/200s on bright sunny days and want ƒ/numbers below ƒ/11, with minimum base ISOs of 100 you will need to be using one, two or even three stops of ND filter. Sometimes I need to get my shutter speeds to only 1/20s. Really hard to do with anything approaching a sensible aperture value, ideally I would be shooting at ƒ/8 since I won't need ƒ/11 for DoF. Given the native high ISO values that modern bodies can do, I would love instead to see a camera with two stops lower on the other end of the native ISO range at the expense of the current highest values. I never thought I would say it, but thanks to the cheapness of digital storage making shooting at slow shutter speeds viable, with low keeper rates, I kind of really miss having Kodachrome 25 around.