Cameras and beamshots: Which roads to use, markers, how beamshots do not show what you see in reality

This page explains the reason for using certain camera settings, positionins, which roads to use, and what problems there are in interpreting beamshots, because beamshots do not show what you see in reality.

As with light output measurements (in lumen or lux), with beamshots you should also keep in mind: Beamshots are NOT a review. Beamshots like measurements of light output are only a small supporting part of a review. This is because with beamshots you cannot convey what you actually see while riding. The actual experiences, and comparative experiences in particular, of headlamps and taillamps, are far more important. I already wrote about this when I started my website in 2008, but when I started to seriously expand the lighting section of my reviews (since summer 2010) and started reviewing a lot more lights, the importance of this issue got even more clear.

1 Roads to use

To come

2 Markers

To come

3 Camera: Field of view, perspective etc.

The camera will show a view starting on the ground at specific distance and ont he road surface going to infinity when aiming at the horizon or the roadsurface distance it was aimed it at the center when aiming it at a certain spot on the road.

Example: Samsung EX1 which has a wide angle lens, mounted on 1.65 mm height (centre of lens) and aimed at 50 m, the field of view starts at about 3.12m distance from the camera on the road.

More to be added.

4 Interpretation of beamshots

4.1 Perspective over accentuation of the near field

The further away the smaller the surface area a piece of road takes up on screen. This is the problem of perspective over accentuation which became clear to me when examining the E3-pro-StVZO beamshots which seem to show that the E3-pro-StVZO is much brighter than the Philips SLD and Edelux, but in reality this is not the case.

The way to counter this, is the following method that I thought of after that experience: Take a piece of paper, cover up 2 beamshots you want to compare, and move the paper down a little bit, examine, etc. This way you will not be influenced by the brightness of the large area in the bottom of the pictures, and you can compare very well how much better or a worse a specific headlamp is at those distances.

More to be added.

4.2 Adjustment of the eye to the brightest spots on the road

A further problem in examining beamshots is that the eye will adjust to the brightest areas lit up by a beam. This is why most headlamps with a symmetric beam (no cut-off) seem very bright but will not have very long throw in reality because the areas at long distance that look nicely lit up on a photo, are not well visible when riding because the eyes adjust to the large brightness of the road close to you. This is the reason why though the Betty 2011 at 1850 lumen looks better in beamshots than the Philips LBL (270 lumen), when examining how they light up the road (though not by much), but in reality I found that it was hardly better.

Whenever you see beamshots of headlamps where the nearfield is washed out and the rest of the picture is well visible, you will in reality not have that good a view. These sort of illuminations look good on beamshots but are in fact rubbish. There is no real way to counter this except look at the near field, and compare the brightness of that to the brightness at long range. If the brightness difference on the picture is very large, it means you will NOT see things in the distance as well as on that picture.

More to be added.

5 Correcting/adjusting beamshots for these problems?

I've been experimenting with this using my own computer programs that take a beamshot, take camera information (height, aim, field of view), and change illumination based on the 2 problems. It is difficult. I will give more information and test results after more testing and examining. My aim is to make beamshots such that they give the best possible idea of how you would experience a lamp in real life.

Last modified: Tue Dec 18 09:07:22 CET 2012