2020 Premium 6MT
Thanks Peaty! So if the Sport version is considerably brighter than the stock, the Pro or Max may get the attention of a police officer or two - not something I really want.For my Impreza I went with the sport version SS3's, they are way better than the OEM. Part of the reason was the cost too. While these aren't cheap, the others are super pricey. I have the Impreza sport so instead of fog lights it had DRL's in that spot so I had to rewire. My understanding is the Crosstrek it's just plug and play.
The fitment of the assembly should be the same for the most part:
Diode Dynamic Fog Light Install 2019 Impreza Sport
I've always been interested in how the eyes work (my biology background) and looked for the science behind selection of yellow for fog. In the process of trying to justify my use / like of yellow for fog lights based on science, rather than what I see on sites that sell fog lights. I could not find any. Did find one good paper with some interesting info. that suggested there may be a slight but non statistical advantage but for the life of me I can't find where I saved it. I found some others.
If anyone has good reference info that is more current than what I have, now that LED lamps are more prevalent, I would be very interested in seeing it.
Here are some clips of articles I've saved from science forums.
Most of the things I see today are not so much that yellow penetrates fog but the colour is easier on the eyes for the driver and on coming traffic. Not so much the yellow, but being away from the blue end of the spectrum, which is why white is okay too, if they are white with no blue.
There is no good reason why fog lights are yellow. Here is an excellent explanation provided by Professor Craig Bohren of Penn State University:
"First I'll give you the wrong explanation, which you can find here and there. It goes something like this. As everyone knows, scattering (by anything!) is always greater at the short wavelength end of the visible spectrum than at the longwave length end. Lord Rayleigh showed this, didn't he? Thus to obtain the greatest penetration of light through fog, you should use the longest wavelength possible. Red is obviously unsuitable because it is used for stop lights. So you compromise and use yellow instead. This explanation is flawed for more than one reason.
Fog droplets are, on average, smaller than cloud droplets, but they still are huge compared with the wavelengths of visible light. Thus scattering of such light by fog is essentially wavelength independent. Unfortunately, many people learn (without caveats) Rayleigh's scattering law and then assume that it applies to everything. They did not learn that this law is limited to scatterers small compared with the wavelength and at wavelengths far from strong absorption.
The second flaw is that in order to get yellow light in the first place you need a filter. Note that yellow fog lights were in use when the only available headlights were incandescent lamps. If you place a filter over a white headlight, you get less transmitted light, and there goes your increased penetration down the drain. There are two possible explanations for yellow fog lights. One is that the first designers of such lights were mislead because they did not understand the limitations of Rayleigh's scattering law and did not know the size distribution of fog droplets. The other explanation is that someone deemed it desirable to make fog lights yellow as a way of signalling to other drivers that visibility is poor and thus caution is in order.
the reasoning behind the selection of yellow as a fog light color had nothing to do with physics. I've heard two reasons cited as the rationale behind the use of yellow fog lamps: (1) yellow lamps suffer less backscatter into the eyes of the car's driver than blue or green, allowing them to see better in the fog; (2) yellow lamps are more readily seen by an oncoming driver, so that a car with fog lights on will be seen more readily than white lights would be. The first point is true for light scattered off very tiny aerosol particles in fog -- blue light is scattered out of the path from the sun to the viewer of a sunset, leaving white light minus blue to reach the observer... so he/ she sees yellow/red -- but is pretty irrelevant for the kind of yellow lights used for fog lamps. Those lamps were generally made by putting yellow filters over a hot tungsten filament incandescent lamp, so that a lot of light is lost in trying to make the yellow light -- reducing the brightness available for the driver to see, which is not such a good idea. Using a halogen gas fill increases the brightness of the bulb, but the same general principle of reduced brightness still holds. Additionally, the size of water drops in fog is generally not appropriate for producing the kind of scattering I mentioned above -- if so, headlights would appear very red to oncoming traffic, which they don't. The second point, that the yellow color is more visible to oncoming traffic is also true, but irrelevant as well. The point of fog lights is to allow the car's driver to see better, not to be seen better -- if you wanted to be seen better, a flashing strobe would be more effective, but you don't see much of those in the fog light business. Most likely, the real reason that people have used fog lamps that are yellow is that they look so cool.
This article is provided as a public service by the Geophysical Institute, University of Alaska Fairbanks, in cooperation with the UAF research community. Larry Gedney is a seismologist at the Institute. I was asked the other day why fog lights were yellow. When I couldn't come up with an answer, I started asking around and discovered, to my surprise, that apparently nobody else could either. Skiers, shooters and other outdoor types have long known that yellow goggles or glasses enhance outdoor vision. This is because the yellow lenses filter out the blue part of the spectrum and increase the contrast of a scene. But does the same thing hold the other way around? With the goggles, we are filtering reflected light entering our eyes, but is it possible to illuminate something with yellow light and achieve similar results? The answer, apparently, is no (which is likely to raise strong objections from people who have been using yellow fog lights for years). For expert advice, I contacted the Cold Regions Research and Engineering Laboratory (CRREL) on Fort Wainwright. Captain John Craig of that group then arranged to have a computer search made on the subject of light penetration in fog and mist from CRREL's headquarters in Hanover, New Hampshire. As a result, I obtained a list of over 200 references and abstracts of articles published by researchers all over the world. Not a single one asserted that yellow light has superior penetrating qualities, but several specifically stated that it did not. To quote from one Russian article, for example: "Investigations and practices of automobile traffic do not confirm any substantial advantages of yellow light over white light. The advantages ascribed to it may take place only in very thin fog or may be subjectively received by some drivers owing to their individual peculiarities of vision. Therefore, it does not make any sense to switch over headlights to yellow light, although the use of yellow light in special fog lights does not raise any objections." End of quote. The phrasing is quaint, but the meaning is clear. I had long thought that the yellow sodium-vapor street lamps that are becoming common were used specifically because they cut through fog better. I found out that there actually is a specific reason for their use, but that it is because they operate on only about half the power of conventional lamps. So, unless you just happen to like yellow, save your money and forget about so-called "fog-lights." They don't exist.
Did you get the amber backlight? What exactly does this do and do you think there is any value in it?