The Other Night Vision Goggles

The Orion red goggles are a simple and effective way to build night vision when you are forced to be in an illuminated environment. Bring them along when you go out to a cabin in the country and you can stay indoors in warmth with the family while building up night vision, then pop outside, close the door, and take off the goggles, and be fully dark adapted. The only drawback, well, you are going around with red goggles on, and the family will see humor in it. On the other hand, they are also an interesting experiment in human neurophysiology, as my review will make clear.

Background

You have great night vision. No, really, it's true. It's better than a bear's. It is better than a camera. It's far better than using daytime vision with a flashlight. We just use it so rarely in the age of electric lights, we have forgotten about having it. And yet, the dark adapted human eye lies dormant, waiting to give us light amplification so powerful, the faint stars of the Milky Way can cast a visible shadow on the ground.

The world is now filled with electric lights, often for no other purpose than attracting attention. We hang lights on the outsides of buildings in the peculiar belief they make us secure (the only break-ins I have personal knowledge of have happened under lights). [Incidental note, I have found old 300 watt bulbs among my grandparent's things sent out by the power company at no charge in boxes saying "Light the night! Drive away burglars" dated around 1970 with cartoon cat burglars on the package. It would seem the real goal was to sell electricity, since the only proven correlations are more light=more crime.]

We have filled the modern world with insults to the delicate night vision of our eyes, which takes half an hour to fully engage, but can re-light adapt in seconds. The daylight vision we use comes from three types of cells in our eyes called cone cells. They come in three colors, two of which are able to see red, yellow, and green (with a weighting towards yellow-red for one, and yellow-green for the other) with a third clearly balanced towards blue. This means the color vision in our eyes is most sensitive in the yellow-green area, where the sun is brightest, and is sensitive to light from red to violet, a wavelength range from 700nm all the way to about half that wavelength at 380nm. These are the cells in the fovea, or highest resolution central region of the eye. Although the eye can see light at the extremes, its sensitivity drops off quickly so a red light must be far brighter to have the same apparent brightness to green (this is why green laser pointers seem so bright compared to red ones, though both operate in the same power range). These cells do have some night vision capability, which they reach in about 5 minutes- which is why if you stand in the back of a movie theater for only a couple of minutes, you gain enough dark adaptation to see your way to a seat.

Intermixed with the cone cells away from the center of the retina up onto the sides of the eye are rod cells, which are high sensitivity light sensors with a peak sensitivity in the blue-green area. Like the daytime eye, their sensitivity drops off towards red, though in absolute terms, their sensitivity is close to that of the daytime eye when dark adapted (more on this later). These cells are exposed as the iris opens up to respond to darkness, but they take time to reach dark adaptation. The rule of thumb is 30 minutes, though in my own experience I have noticed night vision continues to improve past that point. The idea with the Orion red goggles is to reduce the visible light getting to the eye so it will adapt for darkness.

In the last 20 years, the military has had a large shift away from red night lights because far-red, though only dimly visible to the eye, is very visible to electronic night vision devices. At the same time, extremely dim blue-green lights will work very effectively to make everything easily visible to a dark adapted person while being completely invisible to electronic night vision equipment. Obviously, any color of light could be seen by a dark adapted eye without destroying night vision as long as it wasn't bright, so seeing the yellow star Capella isn't going to wreck your night vision. But remember, much of the amateur astronomy community is still hooked on red as the only allowed night vision color, and some will react badly to seeing a hint of non-red light, so be careful who you use other parts of the spectrum around.

Description

The goggles show up in a white box with blue writing on it which looks like it is too small to contain a set of goggles. Upon opening, it turns out the box is, in fact, too small to contain the red goggles, and the sides arrive with a semi-permanent set from being squeezed into the box. As of yet, whenever I have tried these out in a brightly lit area, there is a bright reflection of outside light on the right side thanks to the deformed side of the goggles not wanting to conform to my face.

The silicone rubber portion is a pinkish looking red with inset black light-proof vents. The lens in the front is a flexible plastic in a very pure dark red. I am left wondering why they didn't use lightproof black silicone for the rubber section, since all that can be seen through it is red light, rather than any image in your peripheral vision, as in standard safety goggles.

The good news is the lens in the front is very clear red and optically flat, so there is no distortion and your eye can achieve a nice sharp focus. The lens is buttoned into the silicone rubber housing, so it can be removed if serious cleaning is needed.

Usage

Like in the old war movies, there is an old trick of using red filters on lights to preserve night vision, since the eye is not very sensitive to this color. And, of course, red light has a warm look people find attractive. The Orion Night vision goggles convert all visible light to far red, right before your eyes, so only you are in the all-red environment.

In practice, this makes the outside world look very dim, and you will find your well-lit living room is only dimly visible when using the red goggles. At the same time, displays on clocks and other devices with blue or green lights are invisible, as though they were switched off. The interesting thing is, after you have had them on for a while, red is no longer the only color you will see. As the rod cells in the eye adapt for dark, their absolute light sensitivity eventually makes them more sensitive to red light than the red cone cells. What this looks like is darker areas in your field of view will look green-gray. So, for example, if you are in a room with a carpeted floor and furniture, where the floor is in the light, it will look red with the texture of the carpet. Where the carpet is in shadow, it will still have the same texture visible, but the color will be green-gray (to say the least, this looks bizarre). However, this is an easy way to test if you are dark adapted.

Anyone who has been fully dark adapted when they have seen car brake lights knows how painful red light can be, and how it can break down night vision. By using these red goggles, you are just tinting light, but looking at bright lights will still break down your dark adaptation. But, for the most part, I have found I can reach far greater dark adaptation with these in the city than I otherwise would. One of the difficulties in the city especially is the ease of ducking in and out of doors will keep degrading night visions, where if I were on a dedicated observing trip, things would be set up to stay dark adapted. In this mode, the red goggles work very well, and make going indoors possible without eliminating night vision. Given the other technique for this is to wear an eye patch to keep one eye in darkness, the goggles work fairly well to.

The good news is they do fit over eyeglasses fairly easily, but you need to pay attention to keep from pulling them off with the goggles. The goggles are definitely easier to make work with glasses than an eye patch.

Conclusion

The Orion Red-Tinted Astrogoggles are a simple way to build up and preserve night vision for astronomy. The packaging does distort their shape, and this degrades their usefulness by producing gaps in their fit. At the same time, the pale red color of the flexible mask part is more of a distraction than useful feature. They are simple, and useful, but they could do better on some of the details.