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Thread: How to make bike light beamshots

  1. #1

    Default How to make bike light beamshots

    Hello!

    I see many beamshots, which could be made far better, even on manufacturer's sites. And in the search I find mainly general (and old) recommendations. So I decided to put some more non-trivial aspects that I personally whould like to see (yes, I doubt many will read it before shooting, everyone will do it's own way anyway..). Somewhat special to *bike* ligths.

    A repeat of what everyone repeated (e.g., here): use manual camera settings and a tripod, experiment a bit, as there are no universally correct settings.

    =====

    Now less trivial (numbered - to separate one from another, not some steps to follow).

    1. Scene (ideally) should be an open, dry asphalt parking lot (yes, difficult to find because must be no cars, no people, and unlit).

    Put markers, like pairs, separated by (e.g.) 2m, at (e.g.) 2.5m, 5m, 10m, 15m, 20m, etc. Away - some kind of vertical stand, 2m high - to estimate how light is distributed vertically, will it blind. (yes, boring to measure and put many markers)

    If impossible, describe your scene's dimensions and lengths.

    2. Position the camera so that it captures the near field also (best if asphalt can be seen below the front wheel), as well as the (full) far vertical stand. If necessary (large focal length), move the camera away back - to compose the whole scene. Putting the camera at the place where bicyclist's eyes would be, will greatly narrow down visible angles, and is not necessary anyway.

    This is actually a point to look at - when viewing other shots. Most headligts are either bad, or not so good - at the near field, and manufacturers don't normally want to pinpoint this.

    3. Edits. Besides white balance and exposure - try to not edit. Don't crop the images, as it changes visually focal length (geometrical perspective).

    4. Publish accompanying info: light position (height), camera settings, make/model, camera position relative to the headlight, and headlight power consumption (also LED if known). Edits.

    There are many free image-hosting sites these days, as well as general-purpose ones (Google Drive, Microsoft's, etc). Link to your full-sized original shots.

    =====

    Optional. If difficult - forget it (or try harder?).

    1. (this one I'd actually wish to move above) Make several shots, with several exposures, like 3-4, separated by 2-3EV steps. At home decide what series would best describe the reality, adjust exposure (better in raw) if necessary.

    Photos (and monitors) are totally unfaithful at conveying darks (this also was written million times), so, mainly 2 ways for you to pass over the reality: Either compose several such shots into a single - this is difficult, only done by photo-professionals. Or, easier, what I (repeating many others) suggest, just leave the series as is, for interested people to peruse and imagine the scene as it really was.

    Example how one could use the series: from some past common experience we know that 1/4 of brightness is very much seenable - thanks to eye adaptation. Take beamshot +2EV. If you see same illuminance somewhere, as on the +0EV shot, you know that at that point, on the +0EV shot, it's perfectly seenable, with brightness - as from our common past experience - even though it appears to be (almost) black (on the +0EV shot).

    Publish the series - 3-4 shots, separated by some EV steps (2-3 - as you feel appropriate).

    2. White balance - better set in advance in the camera, close to what the headlight is. Or adjust later if needed (better in raw). The color cast (IMHO) doesn't really matter.

    3. If it's not very dark, make a shot with light off, to make sure dark is dark enough.

    4. Equivalent aperture and sensitivity - very optional. Most people are familiar with "equivalent focal length" - which is real focal length, multiplied by the "crop factor" (= ratio 36mm/size of your sensor). Similarly can be introduced for aperture and sensitivity. Briefly, at const shutter and fixed exposure, you can move along a line "low sensitivity, open aperture -- high sensitivity, closed aperture". That gives you a new freedom - in depth of view vs. noises. Familiarize yourself with this, and publish equivalents of the parameters (apert., sensit., focal length). Such "standardized" (wrt an old film, or modern full-frame SLRs) parameters will be (a bit) easier and clearer for comparison.

    =====

    My example:
    http://cantorbl.sourceforge.net/c_en-beamshots.html

    Neophyte, but bravely improving the quality of beamshots, all over the world, since July 3 2014

    (I'm really not a photo-professional or something, and welcoming comments)
    Last edited by abvgdee; 10-01-2014 at 09:13 AM. Reason: edited my example beamshot page to link to SourceFroge

  2. #2

    Default Re: How to make bike light beamshots

    Addition: for whom the above.

    Sure, I was aware of some "standard, universal iso, aperture, shutter" recommendations. It is for people who view tons of shots, and want fast visual comparison, mainly of brightness, and are not very fastidious about beam pattern. I didn't write for them.

    I wrote for those, who value beam pattern first (over its brightness).

    I don't mind re-adjusting exposure when comparing two shots - because there are only few interesting to me manufacturers (and I don't see it necessary anyway). But if there's no vertical something, or no near field, or unclear dimensions, beamshot is either lost, or of little use for me.

    So if you have one of those fine german master-pieces (B&M, Schmidt, BŁchel, Supernova), or you modded something interesting - please take the time to prepare everything physically (think through it), even though it's much more tempting to find and set some "standard camera settings".

    And thanks for not scolding at me.. this is weird..

  3. #3
    *Flashaholic* Str8stroke's Avatar
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    Default Re: How to make bike light beamshots

    Well, I am not sure what your goal is here. But, I think I get it. You are saying that the manufactures pictures could be better and you are giving suggestions and would like us to chime in?? Just seeing if I understand you. If not feel free to scold me!

  4. #4

    Default Re: How to make bike light beamshots

    Right, there's no clear goal.

    My intention was to make this post findable thru search, and hopefully, have others to consider these enhancements, and implement them for their shots. So, contribute to improving beamshots (if it can be called a goal).

    I certainly don't expect manufacturers to start changing their beamshots - only because people supported me here

    I didn't (and still don't) see how anything I wrote can hinder understanding of the beam (or hinder more than enhance). So this was intended as a safe check-list to keep in mind. But if you see it different - post your concerns!

  5. #5
    Flashaholic* Steve K's Avatar
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    Default Re: How to make bike light beamshots

    thanks for putting together a summary! For hobbyists, this is probably the best method available. Folks like Peter White have done a good job of this, allowing customers to get a good idea how to compare the lights he sells.

    If the world was perfect, manufacturers would be publishing proper graphs of their light's performance. I know that the German standards have specific requirements that the manufacturers have to meet, so the manufacturers should at least publish their performance relative to these standards.

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