Beamshot standard ?

I think it would be a good idea if every indoor beam shot from now is taken in the same way, thus giving the viewer the ability to judge the beam.

All these random distance beam shots are actually useless if trying to understand the beam as even 12 inches difference makes a huge difference to the beam shot.

maybe the standard indoor beam shot could be taken:

4 feet from the wall to the front of the flashlight, with a standard tape measure held open across the beam. to give clear indication as to the width of the hotspot and spill qualities/size.

with currently accepted photography variables and a little effort i could make the beam shot of an incan m*g solitaire identical to a P7 m*g.

just my latest 0.2cents :tired:

I'd prefer SI-approved units.

edit: You'd also have to adress the white balance problem. Just setting the WB to a common preset wouldn't work either, those presets aren't standardised.

im only thinking about the physical shape / form of the hotspot and spill.

tint is another matter.

I would like to know why long exposures are used for the photography. Why not use an iso of 800, 1,600 or 3,200 with a 1/60 second time? My Nikon can go to an iso of 25,000. Iso and exposure times should be standardized.

aehaas

The noise would not be too nice...

You need to get the details of the beam, and it isn't easy.

I like to underexpose mine a little so that they are more "realistic".

The only way a standard can be done is if you only look at one persons shots, there are far to many variables...

Long exposure is favored over cranking up the ISO because of digital noise, which lowers image quality by obscuring detail, looks nasty, and also reduces the dynamic range. A good dynamic range is important when doing beamshots for accurate representation of what the beam would actually look like, as well as avoiding blown highlights, which can interfere with brightness comparisons between lights.

I would suggest standardizing exposure values, so that photographers are free to use whatever TV/AV/ISO combination they prefer. Of course, you then run into the problem of different cameras having different tonal responses; on top of that, some camera models tend to under- or over-expose consistently, so you would have to compensate for this if you owned such a camera.

beam profile not photo exposure.

Okay, so what about a standard focal length as well? Focal length would have a big impact on the appearance of the beam. Standardizing it as 35mm equivalents would be necessary but tricky, as point and shoots my not provide that info, and even if they did zeroing in on the right fl might be tough.

it doesnt have to be difficult

4 feet from the wall to the front of the flashlight, with a standard tape measure held open across the beam. to give clear indication as to the width of the hotspot and spill qualities/size.



anyone can do that ^

and if everyone did, it would make KNOWING what any flashlight beam was actually like.

is the hotspot from 4 feet: 8 inches wide? 4 inches? 12 inches?

is the spill tight or wide? etc etc from 4 feet.

then you go take your favorite light and set it up 4 feet from a wall, and compare your beam to the one in the beam shot.

then if you buy the iight, when it arrives you have a very good idea of beam shape is compared to the light you already own.







quick and dirty (point and shoot camera) both from 4 feet, the difference in beam profile is obvious.

The way I do mine is one head-on against the wall and another profiled from the side, with the ISO set to 50, the flash off (obviously), the EV turned down to -2, and the white balance set to Neutral Fluorescent. (I know Daylight is the "standard", but my camera seems to be more accurate if I use Neutral Fluorescent instead.) This results in pretty consistent pictures that aren't burned-out in the center of the beam, and the exposure usually auto-adjusts to ~.5sec to compensate for the bright-light ISO and the reduced voltage going to the image sensor. (That's what the EV setting is for.) Obviously this necessitates a stable surface to put the camera on, but it's a small price to pay for clear images.

As far as the hotspot size, I think that's largely irrelevant; what more important (to me, at least) is the ratio of hotspot size to spill size, and that is readily-apparent without a measuring device.

fyrstormer said:

As far as the hotspot size, I think that's largely irrelevant

Click to expand...

orly?

http://www.urbandictionary.com/define.php?term=orly

ya rly.

I think our "professional" reviewers have it down pretty good and are consistent with their beamshots. No complaints there. For the rest of us amateurs a few standards sounds like a plan.

Good idea waddup.

Geoff

There have been many attempts to standardize beamshot's over the years, ever since I was just a lurker here.

The problem is always the variables, hundreds of them. Your proposed simplified method is a good idea in that it's simple but it's probably not something that many are going to what to adopt, no matter how simple or structured the plan is. For some people shinning up a stairwell is easiest, for others down all hallway and for others a basement, and for still yet others, a white wall. Personally, I don't have a lot of open white wall space in my house and it's not the way I prefer to examine beam characteristics.

All the variations in camera sensors, lenses, and camera set-up can be so vastly different that it's probably not going to be worth the effort to "unify." Your plan would regularly show the dimensions of a beam hot spot and that's all. Well, no disrespect to you but I don't prefer to know hot spot dimensions at four feet. I just don't see myself spending the time examining another's beamshots and thinking, "hey, I wonder if my AAA light is wider or more narrow than his AAA light" then go about setting up my camera and tape measure to compare. Instead, I'll just wait for someone to post a direct comparison or do it myself if I have the two lights at hand. That's all I'm after anyway, a relative comparison, taken by the same camera, with the same settings and the same time.

Typically what happens here, as you know, is that people take the beamshots that they prefer, enjoy, or what's practical within their given time or convenience. For me I like to see beams side by side on a large garage door for example from about 25 feet. Something like this for example.

Maratac SS 10440 30.8 lux..........................Preon Ti 10440 39.0 lux


It gives scale, some color, an idea of beam intensity, etc. Most importantly having the two lights gives a direct and relative comparison result. In contrast, if I took a picture of the Maratac beam with a tape behind it one month, then the next month I took a picture of the Preon beam, I really don't know how I'd be helping people very much. Sure, I could stack the two pics or reduce them and put the side by side but it's still inferior to recording the two beams in real time. Not to mention, that ambient light is impossible to control outdoors, even if I remember to set all the camera setting, aperture, shutter, ISO, white balance, and focal length. That means this would only be an indoor beamshot option.

I respect and applaud your desire to standardizebut I don't think it will catch on or work any better than ideas like it in the past have worked. I will always strive to provide CPFers with the very best shot's I can give and limiting myself to 4' will not allow me to provide what I perceive to be as the best data. If this was a full time job for me and I was working in a lab testing lights for people, I'd use some form of your suggestion. But I'd also use 5 other types of photographic methods and locations in an attempt to capture everything that the 4' shot's couldn't. Since time is limited I instead choose to use the best that's available to me. With small LED lights the 25 foot garage door works. For larger LED's that may be my backyard fence, for HID's it might be 335 yard power line tower in a nearby drainage. Many good options.

Still a nice thread and it's always worth discussing. :thumbsup:

i really dont mind either way but,

id say, a beam shot from 4 feet is predictable at 25 feet and at 60 feet and 150. (1500 lumen and over might require more distance )

(a tighter brighter hotspot will throw further, and a wider less intense hotspot @ 4 feet will be more floody, and the spill is also predictable from a standard-ized photo ) not exact, but predictable.

4 feet from a wall with a standard tape measure across the beam anyone can do easily, and it would give everyone the opportunity to predict the beam.


whereas all these completely random beam shots are essentially useless if trying to get an idea of what the beam is like compared to a different light as they are all taken randomly from different distances with no tape measure thru the beam :candle:

i posted because my latest purchase has a much tighter beam that i anticipated, and that got me thinking about standardizing beam shots

i dont care much either way

i love all my lights :twothumbs :nana::devil:

and they all have different beam characteristics.

waddup said:

id say, a beam shot from 4 feet is predictable at 25 feet and at 60 feet and 150.

Click to expand...

Actually, that's not always the case. With smaller lights it is predictable, but with larger ones (and even with some multi-die emitters) it is not. It depends on the beam's focus.

If it were plausible, standardized beamshots would be great, but there are just too many variables to control for. Even the ISO speed of DIGITAL cameras can vary from one model/manufacturer to another (ie, ISO 100 != ISO 100):

http://blog.dpreview.com/editorial/2009/09/sense-and-sensitivity.html

So far, I have found the most useful beamshots to be the ones that include comparisons with lights I am familiar with.

DM51 said:

Actually, that's not always the case. With smaller lights it is predictable, but with larger ones (and even with some multi-die emitters) it is not. It depends on the beam's focus.

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care to enlighten me

light travels in straight lines correct?

i believe physics dictates that in fact the beam profile is predictable at any distance if we have 2 relevant values,

and we have them here,


1. 4 feet from the wall
2. the hotspot diameter. (measured across tape measure)

waddup said:

care to enlighten me

light travels in straight lines correct?

i believe physics dictates that in fact the beam profile is predictable at any distance if we have 2 relevant values,

and we have them here,


1. 4 feet from the wall
2. the hotspot diameter. (measured across tape measure)

Click to expand...

Knowing the hotspot diameter at 1 distance will not allow you to judge its diameter at another, unless the beam travels perfectly paralell. You'd need to know a second distance and diameter to be able to determine what angle those straight lines of light are traveling. ....i think.

waddup said:

care to enlighten me

light travels in straight lines correct?

i believe physics dictates that in fact the beam profile is predictable at any distance if we have 2 relevant values,

and we have them here,

1. 4 feet from the wall
2. the hotspot diameter. (measured across tape measure)

Click to expand...

Your assumptions are too simplistic. It is difficult to demonstrate this without a diagram, and I am no good at drawing. There are probably existing diagrams that will illustrate what I say.

Put simply, light emerges from its source in different radial directions. A reflector is designed to capture as much as possible of the light that is not emitted straight ahead. Some of it escapes from the reflector as spill. A reflector has a focal point, which is usually some/many feet away, the intention being to focus the maximum amount of light on or around that point. With a true parabolic reflector and a precisely positioned light source, that focal point would be infinity.

In practical terms no reflector can achieve that, and no light source is small enough to be focused so precisely: you would need an infinitely large and deep reflector and and infinitely small and bright light source. We CPFers do not yet have those capabilities. Ra's Maxablaster has come closer to it than any so far.

Try this: if you have a light with a diameter larger than say 2-3 inches, try shining it at a wall about 4 feet away, then much closer (a few inches) then much further away (say 100+ feet). You won't see the same beam pattern. It will usually be smoother at longer distances, and have rings or other patterns when closer. That is due to the errant light from the emitter/bulb, and the size, focal length and imperfections of the reflector. It's more noticeable with large lights such as spotlights, but you can still observe it even with small ones such as the Surefire Titan T1A.

Your 4-foot beamshot may be OK for some small lights, but it is not and cannot be regarded as a standard.