Essential Filters: Further Thoughts
Over the past few weeks' PhotoTips on essential filters, several people have asked me questions that I thought it appropriate to respond to here while the topic is fresh on everyone's mind (you have been reading these tips regularly, haven't you?)
Quality versus cost
As you have probably discovered if you've shopped for filters at all, seemingly similar filters can vary widely in cost. However, if you look more closely, different brands have different manufacturing methods and use different materials. Filters made of glass tend to cost more but are much more durable than plastic, resin or other materials. Plastic scratches easily and filters have way too many exposed surfaces to recommend anything other than glass. Even in terms of glass filters there are differences. B+W brags about cutting their filters from solid cores of Schott glass. That never has impressed me all that much. What I do care about is consistency and purity of production. Neutral density filters should not add a color cast but many do. B+W offers that as well, as does Singh-Ray. If you need to work within a budget, the best mid-price filters I have found are from Tiffen. By all means avoid Cokin resin filters; at around $10 apiece they are cheap, but you get what you pay for.
What size to get
Although sometimes I wish they did, not all lenses have the same diameter, and thus filter size requirements vary. When I first bought good lenses way back when, I bought all 62mm-threaded ones so my filters would all fit (back then I had a lot more filters before I learned there really is no substitute for reality). Over the years, I added some with 52mm and other thread sizes and now I mainly have 77mm-threaded lenses. Progress, perhaps, but how do you buy filters for them all? Within reason, of course, the answer is step-up rings. I still maintain polarizers, warming filters and straight ND filters in both 62mm and 77mm sizes, but use step-up rings for other odd sizes. For graduated filters, the standard is the Cokin "P" size that is 84mm wide, so these will fit all the lenses in my arsenal. Be careful not to limit your upgrade options when you buy filters. Good filters can cost money so you don't want to have to replace them all that often.
How to carry filters
Rectangular graduated filters such as those from Singh-Ray already come in usable vinyl cases. Even lowly Cokin filters come in plastic cases that are compact and sturdy enough to carry in the field if you so desire. Screw-on filters, on the other hand, always come in these ridiculous over-sized cases that would take up way too much space in your bag. Another option would be one of the many filter wallets that are available. These too seem to take up too much space for me since they never really come in the right size to fit the filters you have. Instead, go out and get a set of filter stack-caps so you can screw all of your filters of the same size together with a cap screwed on each end. The resulting stack is compact and convenient. Cost? Around fifteen bucks.