CinePacks Split Diopters

• Diopter by CinePacks

A split field diopter is literally a diopter cut in half, which allows a lens to focus both near and far on different sides of the frame - or, the “field”. More exotic variants may have different splits to the field like a central cut out.

But if you want to see things both near and far, why not simply deepen your focus? The problem with that is, now you see everything. You aren’t *directed* anymore. Plus that costs a lot of light!

What the split diopter does is maintain that narrow plane of focus, preserving the out of focus areas, and prompting our brain to draw its attention to a particular area. But when there’s two of those areas, our attention, like the lens itself, is split, and that feels a bit strange.

You might notice the blurring seam that occurs with the split diopter - a consequence of having literally half a piece of glass in front of your lens. And like all technical accidents and imperfections, filmmakers both hide it and use it.

Keeping this seam in provides this dreamlike quality, like in Blowout, as utilised by a champion of the split field diopter: Brian de Palma. If you want something more discrete like the effect of the two areas of focus, it can be seamlessly hidden, like in Jaws where the seam is masked by conveniently placed pipe work.

Aside from the psychological implications, it’s just a very different aesthetic, that can help stamp a unique impression into a film.

Split-field diopters have not been tools for indie and low-budget filmmakers. They usually come in four and a half inch frames or larger, which require a lot of support gear.

This set of split diopters from Cine Packs are brilliant in many ways. First of all the finger support helps you quickly position the filter to find the placement you need, and if you’re doing a quick shot, that’s enough.

Besides that, you can lock them in position using the quarter inch hole on the handle, for longer shots, or moving shots, or just to free up your hands. One of the biggest advantage of this format is the split doesn’t have to be placed on the very center of the frame!

This is a really special effect and it would be a pain to re-create in post. Bokeh becomes super pronounced on the out-of-focus areas, and you can create a very unique look.

On the technical side, Cine Packs offers splits in +1, +2 and +3 strength.

The last thing to remember is that the convex side of the diopter must be pointing out, towards your subject! If you orient it backwards, it might still look “okay”, but I assure you performance will take a hit.