Scrub up to the digital age and the concept of filters has become somewhat more abstract. They aren't little glass discs any more. Sure, there are still a few glass discs around. Or we couldn't debate the utility of putting a protective filter over that expensive new lens.

And a circular polarizer or neutral density filter are still best put on a lens rather than emulated in software. But physical filters that mount on the front of your lens are just a part of the story these days. Fujifilm, which prides itself on still thinking film, got rid of the filter threads on some of its digicams in favor of basic in-camera filter effects (like a Yellow Wratten #8) that you can apply as you shoot in monochrome mode. But you don't need a special camera (or even filter threads) to apply a filter to your images.

Tiffen Filters FREE SHIPPING. Tiffen is a leading manufacturer of imaging accessories for the consumer/professional imaging. Dfx digital effects software.

When your image migrates to your tablet or computer, it can take even larger leaps of the imagination when it comes to filters. Some of them are actually special effects. Which, after all, is what made Instagram a household name. The wealth of options -- and the control over them -- are what's so great about filters in the digital age. Face it, on a film camera, using filters was entirely theoretical. That Wratten #8 was going to darken the sky and lighten foliage, yes.

But you had no say in how much. You took what you got. With a digital yellow filter, you can see exactly what happens and fade it back to something you like.

Or dump it in favor of something more appropriate. Internet Explorer 8 For Windows 7 Ultimate 64 Bit. You don't even have to know what direction to take it.

In fact, you don't even have to click on another option because the array of options often includes a thumbnail of the effect to help you decide. Talk about living in interesting times. Tiffen knows the difference between a filter and a special effect. Fortunately, both are on the guest list for the party that's Photo fx Ultra, which runs rather nicely on a iPad with iOS 4.3 or later. The app retails for $4.99 through the Apple App Store. Photo fx Ultra is part of a suite of filter applications from Tiffen. The company also offers Dfx, a desktop application with a bit more meat on its bones, which we also plan to review.

You can actually email Photo fx Ultra settings for import into Dfx. Tiffen also provides a filter set for the iPhone called Photo fx. Now in its fifth version, Photo fx Ultra provides eight categories of 77 filters with 934 presets (all with thumbnail previews of your actual image). Tiffen describes the set as simulations of Aikido 3d 2.0 Full. 'Tiffen glass filters, specialized lenses, optical lab processes, film grain, exacting color correction, natural light and photographic effects plus a clever paint system with a variety of brushes.'