Hey enlightened peoples ,
Hope everyone had a merry Christmas and are staying safe in the nasty weather!
A curious question I have been pondering for a while…
What intensity in lux, lumens, FC values have you ever logged of the brightest part of the hotspot only, and also the approximate size of that hotspot only, of various lights in your collection at a distance of 10 meters or so.
I would love to see some comparison values of various lights showing hotspot intensity and field width rather than the more common cd and associated throw calculation. Although some may comment it’s all the same or relative, and they would be right to a certain point, but my goal is be able to gauge the _*Hotspot
Only field width*_ over a much, much longer distance for my next light.
Any helpful examples would be much appreciated.
Thanks all!
What you actually want to know is the intensity (or intensity distribution) and angle of the spot. Something like the input of parametrek’s beam profiler.
Lumens a measure of total output from source, so can’t be used in the way you’re describing. What you’re looking for, as SammysHP has said, is the distribution of the light. Commercial specifications for lighting often include FWHM which I would like to see more of in the flashlight world.
The evolution of this hobby has been (approximately): Low power LED > High power LED > Warm/neutral CCT options > specific tint at ones chosen CCT.
I hope for the future, more discussion revolves around beam measurements and light distribution.
I may not have made my point of the question correctly
based on the two responses received above thus far…
So I have linked a web page with an image (link below) which will help to illustrate the kind of data I am looking for …and most likely help others on the site as well who are planning to purchase a particular flashlight in the future.
For me the hotspot data is the most important data in a flashlight in use .
The main point I am hoping some of the members here will actually *physically *perform*this test with a flashlight that they own and share their findings, Not raising my voice , maybe a more clear picture this time .
The linked graphic shows a ceiling light which for our purposes of this test will represent your flashlight, the floor in the graphic will represent a wall 10 meters away from the flashlight…the data I need and think is important to myself and others ,is the *measured intensity ,in lumens or lux , or foot candles, and physical size in inches of the represented center circle (30 degree circle shown in the graphic )which would now be showing as the hotspot and physically measured with a ruler or tape measure ,on the wall in front of you, measure the diameter. The diameter measurements will most likely be very different on various lights you have, as well as the lumens out the front ,lux ,or FC , or intensity , as we all know calculators are readily available on line to convert
hotspot beam size in inches /Cm ,as well as hotspot intensity is the data I am asking for.
No actually I want you fine people to take out your light meter and a flashlight of your choice, put it on a table or chair aim it at the wall in the dark and take the 2 measurements I precisely outlined above as well ,as the call for others to share their results if they perform this test
note : this requires physical effort, do so at your own risk ( snarky comment)
Here I will go first: no spill or other data please
10 meter measurement on wall or similar
Unbranded (al-express) : Reflector/ Cree Xhp.70 Emitter
Hotspot only diameter: 31 inches
Hotspot only intensity: 431 Lux
Is this beyond doing?
Post the name of the light and data here. I will compile it all and post that here after a bit.
Maybe your 10 minutes of time will provide us and yourself with something new you didn’t know yesterday!
Why do you want exactly 10m? Finding a warm room more than 10m long is a problem now. I do not know what the accuracy of the luxmeter will be at –10 degrees Celsius outside. There is also a problem with distance. To see the light meter readings, I have to walk towards it while I walk back and forth, the readings can change due to the cold, but the big problem is a lot of ambient light on street, this will make the readings even more inaccurate
This is not a scientific measurement for NASA or to be used for a college graduate thesis …
My light meter measures in lux or Footcandles ,to get candela I use a reputable online calculator …sooo same thing ,same end result ,no need to mince words.
There is room for tolerance as well
Just measure and record the center hotspot as outlined using any light meter you choose, I’m not looking for random roadblock answers on here, just please perform the test and share the data. Or choose not to participate, your choice
Thanks
Mine is 9 feet distance to wall,center hot-spot is 9inches diameter
Ultrafire HD2010,18650.
I don’t have a light meter and I don’t know the angle of the smooth reflector.
So,if it’s 9 inches at 9 feet,would that equate to 90inches at 90feet?HB
You talk about tolerance, but you don’t behave like that yourself. Please explain why you need this data, why exactly 10 meters and why you are not interested in the accuracy of measurements?
10 meters is just about far enough for most flashlight beams to expand to their fullest, but a further distance would even be better. Shorter not so good as far as all I have read on this forum in various testing heavy posts.
Why do I want this data and why am I allowing for some tolerance in any posted results…well I thought it would be obvious to most ,if you really think about the data asked for…
If you want to really illuminate an empty field you may want spill data ,if you want to illuminate a tower 2 miles away you want tightly collimated beam data,
If you want to illuminate somewhere between the two choices just mentioned above (an area 150 feet wide at 300 yards) you want hotspot data.
the hotspot is really what matters to me, others may care less.
I think this data would be helpful for many who are in need of a large workable area of bright light, and yes a zoomie will do this differently, but I am leaning towards a reflector based light for my future purchase,and I do not trust manufacturer stated claims or most spec. sheets at all.
The way I would do it is ask that specific question as a post of your own ,
Sorry but I can’t help you with that question in a mathematical way . Maybe a cad program?
but you may do a large paper size, scaled down drawing also- just find yourself a protractor or similar measuring device and figure it out like the old timers with a scaled down drafting drawing. Some ratio of your choice.
Birdseye view-scaled down
Represent the light source at the center of a large radius,
Line drawn straight out to large radius circle drawn around center spot
distance to wall measured out from light source center
Draw a 90 degrees (perpendicular to center) line representing scale hotspot size, extend two lines out to intersect the ends of the represented hotspot line,
Continue those lines fully to the outer radius circle and measure 360 degree marks all the way around that outer radius and you have a beam angle measurement between the two fully extended lines
Okay, I got it. If you’re measuring using the metric system the expansion slows down or stops at some point. So basically it makes the math easier to convert to feet and yards.
