One of the things that bugs me (and others, from what I've read) is the inability of the lens makers to standardize on filter sizes. For my little m43 kit, I need 37mm (Oly 45/1.8), 46mm (PL 25/1.4, Oly 17/1.8), 52mm (Oly 9-18/4.0-5.6) and 58mm (Pan 12-35/2.8, 35-100/2.8 and Oly 40-150/4.0-5.6). Again, like others, I bought a set of step-up rings and standardized on 58mm filters. After loosing my umpteenth lens cap, I started wishing that all the lenses took the same cap size as well so I could just order a few extra and use them for whatever. In addition, while out shooting I tend to drop the caps in my bag and not replace them on the lenses until the end of the day. So I have to sort out the sizes; not a big deal, but seemingly unnecessary. Finally, taking the step-up rings off of one lens to use a filter on a different lens is yet another pain from this inconsistency. So I had the idea to put a xx-58mm step-up ring on each lens and leave it there. I then bought a bunch of 58mm caps. Now all of my lenses share front and rear caps and filters. They all fit in the same sized slot in my bag. The only downsides are that lens-specific hoods are an issue, and the stack is a bit taller because of the adapters. The offset to the last is that the adapters no longer take any space in my filter bag. The filter bag now just carries three 58s: a CP, and 6- and 10-stop NDs. Left to right: 35-100/2.8, 12-35/2.8, 17/1.8 back-to-back with 9-18, 25/1.4. Any thoughts, comments or even better ideas?