Cross Screen Filters

You’re probably familiar with diffraction spikes around bright lights in photos, and they can be quite attractive. There are times when you shoot with your lens aperture wide-open, only to discover that those spikes disappear. How can you shoot wide-open and still get those spikes?

I have a couple of clear filters from Hoya called “Cross Screen” and “Star Six” that create spikes around lights, even when shooting wide-open. The “Cross Screen” filter makes 4-point spokes and the “Star Six”, like its namesake, creates 6-point spokes. I have also seen filters that create 8-point and even 12-point spikes. Several companies make filters like these.

6-point light spikes

Hoya Cross Screen and Star Six filters

An example of a pretty pricy camera that always makes diffraction spikes is the James Webb telescope, although it’s definitely not a mirrorless camera. This telescope produces 6-point diffraction spikes around the bright stars, along with 2 much dimmer spikes (from its secondary mirror support beams). These spikes are due to its 6-sided mirrors. In camera lenses, the spikes are always twice the number of aperture blades in the lens. When the lens is wide-open, the blades aren’t blocking any light and the spikes go away.

The Hoya filters have small straight-line etches in them to create the spikes. These spikes are always present, and get thinner with aperture changes. The exposure doesn’t change when using these filters, because the glass is completely clear and neutral.

Hoya ‘Cross Screen’ filter, 50mm lens f/1.8 and f/16

Note how the light spikes have a rainbow-like effect. Also note how you also get additional miniature diffraction spikes around the lights when the lens is stopped down.

Hoya ‘Star Six’ filter, 50mm lens f/1.8 and f/16

50mm lens f/1.8 and f/22, no filter. Gets 14 spikes from 7-blade aperture.

If your subject has lots of bright lights in it, the picture can get quite busy when using these filters. Unfortunately, you can’t rotate these filters, so you can’t easily control the direction of the light spikes. When I want directional control, I stack the cross-screen filter on top of a polarizing filter to allow rotating to any spike direction I want. It’s not an ideal solution, but it works.

Cross Screen stacked onto polarizer to rotate spike direction

‘Star Six’ stacked onto polarizer

Hoya does make a ‘Variocross’ filter with two indepently-rotating elements to adjust the spike direction pairs to obtain non-90-degree crosses.

Hoya ‘Star Six’ filter, 50mm lens f/1.8

The effect with a just a few distant bright objects can be quite nice. (The brightest object is Saturn).

‘Star Six’ filter

The effect can be a bit heavy up close.

Summary

These ‘star’ filters are like candy. The effect can be quite nice, but you shouldn’t make a steady diet out of them. If your nightscapes feel like they need just a bit more pizazz, you might give filters like these a try.