HDSLR cameras are taking off in a big way as cheap video rigs with quality interchangeable glass – but the more you get into SLR filmmaking, the more obstacles you find yourself working around. One of those obstacles is that you can't stick your eye to a viewfinder – you have to watch an LCD screen. And in harsh sunlight or wide aperture conditions, that makes it very difficult to get a tight focus on the action. And that's exactly why Zacuto's Z-Finder EVF was built; it's an alternative plug-in LCD screen for your DSLR that can be mounted on a frame or held separate to the camera. It's got higher resolution than your camera's screen, it's got a rubber eyepiece to block out ambient light, and a bunch of other pro video-friendly features that help move your DSLR closer to a proper video camera form factor.

Canon's 5D MkII, 7D, 60D, T2i … Nikon's 3Ds, D700, D7000 … these cameras were never made to be pro video systems, they're pro stills cameras that happen to shoot excellent video. They've been nothing short of revolutionary for the filmmakers of this generation – but there's a lot of stuff they just can't do without help.

When you're shooting close-up video where action is moving all over the place, it's nigh on impossible to keep a DSLR still if you're hand holding it. This is not a problem with a traditional big ol' video camera, which sits on your shoulder with an eyepiece you can stick your eye into.

The eyepiece is another thing; you can't use the camera's viewfinder when you're shooting video, because on a DSLR you have to lift the mirror up and fully expose the sensor in order to go to video mode – so the viewfinder is blocked off.

Instead, you use the LCD screen in the back of the camera – which is fine for static shots, but I defy you to get good focus on a moving object using a wide aperture lens while looking at that tiny screen. It's really hard.

For a serious DLSR filmmaker, the camera itself is only a tiny part of the setup. People are building huge frame rigs to hold all the bits and pieces they need to compensate for a DSLR's shortcomings, while still enjoying their advantages. Matte boxes, shoulder mounts, HDMI monitors, boom and wireless microphones, focus pullers… DSLR-specific video accessories are springing up all over the place.

And one that will make a lot of lives easier is Zacuto's Z-Finder EVF – a standalone LCD screen and eyepiece for DSLRs that can be mounted more or less anywhere on your camera rig.

It's not just the eyepiece and flexibility of the EVF that makes it such a step up from the standard screen: it's also significantly higher resolution. On the back of your Canon 7D or 7D camera, you're only getting a 640x360 pixel look at your shot, when you're shooting in 16:9 widescreen. The Z-finder EVF bumps this up to 800x480, a 56% jump in resolution.

Those extra pixels (and the fact that they're significantly smaller than the standard screen's pixels) will be all the more noticeable through the eyepiece, which magnifies the whole thing up to 2.5 times. You can really notice the blocky pixellation on a stock screen under this sort of magnification (such as with a regular Z-finder) – early reports would suggest that this is much less apparent with the EVF.

Another two key features are the EVF's focus and exposure assist settings. Focus assist enhances edge sharpening on your image to make it much easier to tell what's in and out of focus - a key challenge for filmmakers since most DSLRs don't offer full-time video autofocus yet, and wide aperture lenses can have a razor-thin depth of field that's very sensitive on focus.

The exposure assist will be another huge help – it's a 2-level set of zebra stripes that can be set to separate exposure levels. Most people will probably use the standard setup – one set to 100% white to show areas on the screen that are overexposed beyond the ability to recover detail, and the other set to 55 IRE, showing areas on the screen that are perfectly exposed for skin tone.

Other features include monochrome mode, zoom-in ability, image flipping for oddball Z-finder positioning, saturation controls, anamorphic mode, adjustable frame lines for shooting in different aspect ratios, image scaling, brightness and contrast adjustments, audio metering and assignable function buttons. As this is a first release for Zacuto, you'll also be able to upgrade your firmware as new options become available.

Physically, the Z-Finder EVF is quite small. It uses the same batteries as the 5DMKII or 7D (a full charge should last half a day) and it takes its input from the HDMI port on your DSLR. It has an HDMI out port as well, in case you're outputting to another monitor down the line.

Price wise, there's a few options, ranging from the EVF alone at US$675 to the pro setup at US$1000, which includes an anti-fog 2.5x magnifying eyepiece with diopter, mounted on a flip-up plate to the body of the monitor.

The Z-Finder EVF is a limited release right now – if you want to get hold of one, contact a Zacuto dealership. Each dealership will get an allowance of these to sell, but it's unlikely to be a large allowance in the short term.

Oh, and while they're going to be extremely useful for DSLR users, they're compatible with any camera that's got an HDMI output – so they'll be handy for anyone who needs to decouple the viewing screen from the camera. Nifty gadgets!

View gallery - 7 images