Originally Posted by
cyccommute
Burton said to do a reality check, so I did. I took pictures on the way home from my truck to show what the light from other cars is really like. Here's a truck across a 2 lane intersection that was roughly 30 feet away. He's in a left turn lane as am I and he is slightly up hill from me. It was a Ford pickup and my truck is a later model Chevy Tahoe which sits higher than current models.
So where's the reality. Your eyes use a logarithmic reference system and digital camera sensors use a linear one, so your eyes can register a much broader dynamic range than any digital camera or film. That's just a fact and it doesn't matter how much the camera cost. So you attempted to expose for the background and ended up overexposing all the highlights and want to pass that off as glare? You were there and you KNOW that photo isn't representative of what you were looking at. Those washed out traffic lights are a good visual reference point after the fact and if they're overexposed then so are the headlights. That's not glare you've captured - just blurred, overexposed photos.
Not a lot of cutoff there and this is still not full dark. The light is a least as glary as Burton's picture but from further away.
Maybe before you want to start making comparisons you should post your EXIF data. Your shots were all taken at high ISO values and with shutter times so long you couldn't even hold the camera steady. Mine weren't. Which means relative to anything I've posted your shots are so overexposed that making any sort of comparison is both pointless and misleading.
Here's a sedan across an intersection and, again slightly up hill.
In Canada at least it's illegal to operate driving lights and / or high beams within city limits or on lit autoroutes and that's clearly what that that second vehicle back in that photo is doing. And all that does is illustrate the OP's concern about glare caused by a beam with no cut-off as is found in many models of MagicShine and other bike lights. So the point of posting this deliberately overexposed, blurry photo was what exactly? Are you saying that because some people feel free to cause issues by using their automotive high-beams illegally it should be OK to do the same thing with a bicycle?
If you look at the lights they don't project as asymmetrical but as a round light source. The car was a late model Toyota. The car in the background's lights are even brighter and up close have more glare than the Toyota
His lights are much brighter than mine as the light you see on the snow comes from his lights and not mine. The car was a Subaru Outback.
Sorry, I'm not buying it. That nearest automobile is 40 to 50 ft away. Energy (light is a form of energy) is exponential in nature and to overpower YOUR headlights from that distance, HIS headlights would have to have been at least 4x as powerful as yours. Alternatively each of a set of four lights would have to have been at least twice as powerful as yours if you only had two. Its hard to tell because the photo is so overexposed and has so much blur from handshake that I can't even tell how many lights are actually on the car. But in any case no-one makes and markets any single lamp OEM replacements that fits either description. Moreover, the complete absence of any light, both in front of, and on the RHS of your car (where the low-beam cut-off directs light outwards and upwards to pick up street signs) makes it much easier for me to believe that you were simply parked with your lights off taking pictures.
There has been no radical change in the lighting of a Chevy Tahoe in the last twelve years that would make your lighting so inferior to even another vehicle equipped with aftermarket lights that it would force you to make some of the claims you're making.
Overall, and I've experienced this before, sharp cutoff lights look great when projected against a garage door. Head on, a substantial portion of the light isn't cut-off but is projected upward. That is by design because you want some illumination of overhead signage.
Nope - properly adjusted DOT approved low beams by design will NOT illuminate overhead road signage. And since overhead road signage is only found on autoroutes with highway lighting and where it's illegal to use a high-beam anyway - its a non-issue. However a DOT approved cut-off IS designed to extend a vertical wedge of light along the RHS of the road to illuminate the street level signage normally found on rural and urban streets. And the presence of that is conspicuously lacking beside YOUR vehicle in all your photos so you might want to either get your lights checked or simply turn them on.
OK So I've stated that the highlights (and therefore the headlights) in your photographs are overexposed. That's not 'just my opinion' it's a fact that is reproducible.
This photograph was taken at 1/60 sec, ISO1600 and f3.5.
Is it representative of what I was looking at overall? Naaawwwwww. The highlights are all overexposed and the shadow areas are still too dark because of the limited dynamic range of the camera sensor. 'Technology' sucks.
But like your photos it does burn out the traffic signals and it did overexpose the car headlights so much that it looks like it could be a glare issue. Except that it isn't. The highlights have simply been overexposed by a factor of 20. And I'm thinking that's still low compared to yours.
Glare is associated with bright light sources and can have a couple different effects. It normally produces a haze across part or all of the photo, reducing overall contrast and color saturation - even if that light source isn't actually visible in the photo. Alternatively, a bright light source within the image area will produce visible artifacts (lens flare) as well as reducing contrast and color saturation, either locally or in the overall photograph, depending on the size and intensity of the light source. I'm not seeing any of that - just exposure issues.
Without resorting to an HDR process and combining a series of photographs with different exposure values, it's impossible to even approximate what your eyes can capture in a high dynamic range situation and IMO this post doesn't warrant that kind of effort. Not for your benefit anyway. An acceptable exposure of the headlights was all I'm interested in- NOT the background areas - so I'm going to simply expose for the highlights.
So what to use as a reference point? No magic involved - there are signal lights and street lamps at the intersection so I'll just take an EV reading and work out what it would take to correctly expose them, and set the white balance for the headlights.
Subsequent shots of the street lights and signal lights confirm that those parts of the digital images are almost EXACTLY what I was looking at with my own eyes.
The numbers are very straight forward: 1/100 sec, ISO 400 and f5.6 Anyone can use them with any camera and expect similar results.
Using those exposure values, the only headlights that showed any issues at all with flare were in the second car back in this photo, that sported a set of illegal aftermarket HID lights with no beam cut-off. The color and throw was a dead giveaway.
And let’s be very clear. If the backgrounds are underexposed, that's incidental to the point of the discussion. This isn't about pretty pictures. It’s about capturing an accurate representation of the headlight illumination for the purpose of evaluating glare and THAT is EXACTLY representative of what I was looking at with my eyes.
NONE of my photos showed the extent of the kind of 'glare' issues produced in YOUR photos. Because its an exposure issue - not a 'glare' issue.
And one that can be reproduced even using low powered LED lights like Knog Frogs.
These things are really so dim any car driver could easily miss them from 10 feet away. Which is why they all NEED a flashing mode. Your eyes are particularly sensitive to change of any sort. Movement or light intensity.
But gee, simply by holding open the shutter and making a ridiculously extended exposure like you did, they can be made to look like real flamethrowers. At least in an photograph that, like the initial street shot, has been overexposed by a factor of 20x.
I just wouldn't want to try to pass that off as 'representative' myself. Even if I was trying to sell them.
And you seem have some paradoxical questions to boot. Exactly how do you expect anyone to accurately depict a 700 lumen light source on a monitor anyway? It's physically impossible since any monitor currently on the market has a screen with a maximum lumen output well below that.
As for your statements that such lights shouldn't be a problem if cyclists rode where they're supposed to - personally I ride where I HAVE TO and some routes and road conditions FORCE ME to drive within a few feet of oncoming traffic.
Which is exactly why I CAN'T use those particular lights anywhere except off-road and personally don't recommend their use in the city. And actually I'm not too happy about that because it forces me to use multiple lights.
But that's me. You can do whatever you want to yourself - just don't try to sell any of it to me. I don't consider your opinions objective in the least, and for someone trying to pass themselves off as some kind of scientist - that’s a major shortcoming.