Beamshots of many lights. Picture heavy

postalguy

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Outstanding! Confirms that I really do want a Striker VG. That Inova T3 is no slouch either. I wonder if the T4 or T5 can match the Striker?

One question by the new guy, what is a ROP? Unenlightened minds want to know:)

Edit: Nevermind. Got off my lazy az...er, fingers and Googled.
 
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OldNick

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iced_theatre, I salute you. I have been talking, You have acted and created a result based on a standard....it happens to match closely to what I was asking :)

You are then brave enough to admit you need to learn cameras. Is Moonrise's stuff helping?

BTW. 3am! I again salute you! :)

OK. Standards. THESE ARE SUGGESTIONS UNTIL DISCUSSED.
I have taken many shots at many settings
My _probable_ norm (and I really am willing to listen. I tried several nights in a row, and had varying

results.)
- using 15W worth of LED at 6 deg lens.
- based on details I could see "in the real world" ( looking at what I was actually photoing) vs looking at either the camera's LCD or a PC screen (both of which caused me to feel about the same) is :-
Film speed/ ISO / sensitivity :
ISO (ASA) 100
Aperture:
F 2.8
_Equiv_ lens length:
35mm (but 50mm is considered 1:1)
Shutter speed
1 second
WB :
daylight
Focus:
Infinity.
This is based on the fact that we need to see the brightness at something over a couple of metres, and at 50mm lens length, this will start to do.

However, I am happy with 200 ISO, because it makes for faster exposures. But of course then my suggestion is for 1/2 second.

With card setups, I feel we need to discuss how far most of us expect to see stuff ahead in normal conditions. For me, it's MTB work, in the forest, at night on a singletrack. But it would be nice to see the next track marker (fluorescent tape) at 20metres (65'). hmmm...this complicates things. A white card does not match a fluro tape for visibility....however, white cards are a good start.
 
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iced_theater

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The Chameleon on CT5 is supposed to be more momentary, but with as cold as it's getting at night, I have had no problems using it constantly.

The MagLED 3AA has three new Duracell batteries.

The Striker-VG has excellent throw and can dim to a much lower level if you don't need full power. The T3 is an excellent EDC light as it has a good compromise of throw and flood, slightly purple color though.

I haven't yet had a chance to really test anything on my camera as I've been working a lot of double shifts lately *all year* but will do so soon, and test again when I get the four more lights I'm waiting on. I stay up late anyway, so 3 am isn't too bad, bedtime for me is anywhere from 2am-6am. I'll try out some of your settings and see how it works for me.

Soon I'll have a Elektrolumens Tri-Blaster 3XK2-4C, Elektrolumens K2-LongThrow, Streamlight Tasklight 2L, and a Surefire 8NX with KT5 Turbohead to test as well.
 

NewBie

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iced_theater said:
The Chameleon on CT5 is supposed to be more momentary, but with as cold as it's getting at night, I have had no problems using it constantly.


Ah, okay, that explains why it managed to match the Mag 3AA then. Thanks a bunch!

BTW, be careful running your Chameleon on CT5 with rechargable cells, it can damage the cells long term, and could lead to rather dangerous situations.
 

Nubo

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I wonder if CCDs are more sensitive to the bluer end of the spectrum. Seems like the LEDs fare better against the incans than they do in real life? Maybe that's part of selecting the white balance? But I wonder if there also would need to be a conversion factor to more closely approximate the relative sensativity of the human eye to different wavelengths.

Those are the kind of questions that I wondered about when I took some beamshots awhile back. Since I had a fairly simple digicam, my only solution was to select a "standard" light, and to have it included in each shot along with the other variations. So even though the images may not have been visually correct, they still had a chance to give some useful qualitative info by comparison to the "standard" light.
 

Somy Nex

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i don't know if the information is oudated, but from what i read, most digital camera CCDs use a beyer pattern of GRGB, which means that they are twice as sensitive to green as compared to red & blue. of course this may differ between cameras, and in some cases (such as sony which uses a CMYK apparently) may not hold true at all. link here: http://www.dpreview.com/learn/?/key=color_filter_array
 

OldNick

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Colour response of the filter itself _should_ be taken care of by the electronics of fhe camera. They will vary, and you can set _that_ in many cameras, along with saturation etc. To add to this most cameras come from the shop with (often puzzlingly) pre-set non-neutral settings.

This would have occurred with film as well.

However, I am very keen to get agreement on a _basic_ set of parameters. Stuff we should all be able to agree upon within a factor of 1.75. We can refine it from there.

I chose 1.75 because 2/3rd F-stop has often been quoted as the probable range of camera sensitivity disparities. It is still close enough, and far closer than the multiple exposure equivalent differences we are getting.

Moonrise. You have posted a lot of knowledge. Not joking. But you have not opined on a standard AFAICS. I am interested in your opinion on the idea and on your preferred settings to show a "real" representation of a torch beam.

Anyone. Has anyone else tried a preferred range of settings?

ice_theatre's move was very commendable, seriously. But we need to take that next step.

This is my fourth attempt. So far it's come closer to success than the others. It seems to be stumbling.

There are many very accurate ways to measure the brightness of a light. They involve light meters of some sort...but still require standards, such as angles, distances etc. We could use these. We could even simply use the cameras we own to give a series of comparative readings. But most people here want to see a beam shot, for obvious reasons; I mean we are all beam freaks right?:)

I would plump for this...IF we accepted standards. We would need a series of readings. _Then_ we can have field shots, no standards, and guess which ones I reckon will sway people the most! :)

Some have mentioned the idea of a standard light. Fine. But we all need to own that light and maintain its power source very carefully. We also then would have the problem of sort of looking at a picture of two light beams, then looking at our own pictures and trying to "double guess" where the new light fell compared to our own.

I cannot attach stuff at present. I wish I could show you two shots. One is Auto ISO 100 F2.8 Lens 35mm shutter 1 second. By chance, although on Auto, it closest shows what I felt I saw. The other is manual ISO 100 F2.8 Lens 35mm shutter 4 seconds. The difference is amazing. Anyone would pick the second shot if they wanted to be persuaded to buy a torch :)
 

LumenHound

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The Luxogen LR10-3W beamshot looks good for such a small 2¼ inch long flashlight. Are you using a primary CR2 battery or one of AW's rechargeable CR2 cells to power it?
 

MoonRise

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A "standard" exposure for beamshots is a nice idea, but unless the lights being evaluated are all about the same general lumen and brightness range and the 'target' distance is the same as well, then something will be lost when you try to use the "standard" exposure settings for a light outside that range.

Example. Someone want to take some beamshots to compare lights. They want to use a "standard" exposure. Fine so far. Except one light is a really wide flood Lux-V like a Surefire L2, another is a low lumen output older Arc-AAA, then they have a Mag85, another custom experimental incan light putting out 2000+ lumens, and a friend has an HID spotlight. What "standard" exposure will capture that wide range of real light? There is no ONE "standard" exposure that will capture it all. Want to see the corona? The hotspot will be overexposed and burned out with no detail left in that part of the image. Want to see a bright hotspot only? No corona detail. The Arc-AAA at five feet compared to the HID at 500 feet? Apples and bananas being compared.

You might want to take a few beamshots of the different class lights using a 'standard' exposure just to illustrate the huge difference between them, but then you'll have to redo the exposure settings and take some more images to show some more meaningful info about the beams of the lights.

My recommendation for a 'standard' exposure? Don't shoot at the widest aperture, every camera might not have the same max aperture. Same with a really small aperture. Besides, most lenses aren't the best at max or min aperture settings. So you would want some middle-of-the-road aperture, like maybe f/5.6.

Use a WB setting of daylight and use an ISO of 100, as most cameras should be able to do that and it will give at least some sort of common ground for the images. I would also recommend setting the lens to a 50mm equivalent lens length (referenced to a 35mm camera) to be closest to 'natural' of what our eyes see with field-of-view. And set the focus to infinity for outdoor distant targets or the actual main target distance if there is one.

Since we have the WB set at daylight, the ISO set at 100, and the aperture set at f/5.6, the only part of the exposure not yet set is the shutter speed. I would say that for most lights, the shutter speed will be somewhere in the 1 to 8 second range, depending on the light under study and the distance to the target. At a minimum, if the exposure settings are listed for the images, then comparisons can be at least partially made between lights at different exposures because you would -know- that they were made at different exposures and could compensate mentally for that difference.

One clue that the OP images might not have been taken on a fully manual and hence consistent setting is by how many of the different lights all seem to have close to the same exposure of the vertical wood 4x4 post in the left side of the images. The camera sensor was fooled by that 'target' among all that black space puctuated by only a few small areas of white rectangles of varying brightness and hence tried to give a mostly 'correct' exposure based largely on that wooden 4x4. (side note: a camera on auto tries to give an exposure to mostly get to an average 18% grey value in brightness. Fancy camera meters and exposure computers try to take into account that real images rarely have uniform brightness targets, but there is only so far that the camera can 'guess' in auto mode as to what you wanted to be correctly exposed when there are big exposure differences between the bright areas and the dark areas.) I suspect that that particular camera's exposure computer in Night-mode allows for large areas of black background in an image and tries to get only some 'bright' areas to be near an average 18% grey brightness value instead of trying to get the general overall image's (or the metering area) brightness to average out to an 18% grey like it would in 'normal' automatic mode.
 

MoonRise

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OK, I took a couple of quick outdoor beamshots last night with my HDs U60GT on high.

ISO 100, f/5.6, distance to target about 50 feet, nothing really between me and the target except for the ground. I took a few quick shots at a shutter speed range of 1 to 4 seconds. The first shot was at 4 seconds, it came out OK and showed the large corona and the central hotspot. Changing the shutter speed to 2 and then 1 seconds showed correspondingly less and less brightness in the corona and dimmed the captured brightness of the hotspot as well. All images were 'OK' and usable without really losing highlight or shadow detail, they just captured the image 'differently'.

Indoors at a closer range and with a room in the way and bouncing more light back from the walls and ceiling, I'd probably want less exposure with that particular light. Outdoors at a target farther away I might want a little more exposure. A light with a different lumen output or hotspot brightness would need slightly (or largely!) varying exposure settings as well.

Since our flashlights can vary so much in their output, I really don't think there can be one 'standard' exposure setting for beamshots. But as long as the exposure values are listed with the beamshots, either explicitly or in the EXIF data, then at least someone could look at the exposure data and roughly compare someone else's beamshots to their own and have a general basis for comparison. But for absolute comparisons between lights, then I fully agree that all the variables in the shot except for the lights themselves need to be the same. Same distance to target, same camera settings (on MANUAL), everything the same except for the different lights.
 

OldNick

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Thanks for following up.

My main interest is to show the difference in brightness between two lights. If one is so bright that is saturates everything at 50 metres at our standard settings, then it needs reconsidering, as a different kettle of fish.

I guess my question is, regarding your test, which of those exposures did you feel best represented what you were seeing, just looking at the light on the target?

My idea is to give an impression of how bright a torch is and how spread the beam. If it washes out the whole picture with light, theh it needs reconsidering. But it is still placed into an obviously different category.

If you wish to use 5.6 rather than 2.8 fine. I don't think it will be major. But when I compared what I took to what I saw, using targets, I felt that ISO100, F2.8, 1 second was the closest to looking at the actual screen. So f5.6 2 seconds would be my suggestion for average flashlight shots.

If we have a standard _set_ of targets, at a known distance, which is what I have already asked for, and a standard camera setting, then we can compare the light output of lights at a given set of circumstances. I agree that many shots may well be overexposed.

If you want to show the detail of the beam, which seems important to many, then use Auto, just about <G>....no, then you pick the shot that shows to best advantage, and publish data.

Most of the comparisons I have seen are not between some 2000 cp light and a few hundred.

I have a _claimed_ 10,000,000 cp light. Very bright very narrow. My camera is unavailable unfortunately, for a few days. But I will take shots of that vs my LED lamp and see if I can follow up.
However, maybe there need to be a couple of standards. I still feel that just publishing ghe data may not allow visual comparison of actual brightness.
 

OldNick

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OK. Try again Server too busy.

I guess my question is: Which of those exposures did you feel best represented what you could actually see when looking at the scene? I am happy to work at F5.6 or whatever.

Many of the comparisons I have seen and dealt were between more similar stuff, but I agree that there are going to be standouts if we start to carry the comparison over a long time.

I agree that a really powerful light would wash out the scene and prevent beam characteristcs from being shown. However, if it does that, maybe we can well that's _really_ bright, new category but in the meantime we know we have a really bright light in the current set of tests.

My camera is unavailable for a week or so. I have a "10,000,000 cp" spotty. I will take shots of it and my LED lamp when it's back, and see what happens.

Perhaps we could, as you suggest, post all data. but I would like to see if in the wash it comes out around some are a that we centre on as a standard starting point. The trouble is, people like ice_theatre, who has seen the need for standardisation, are waiting for guidance about settings.

ice_theatre, if you are still there, do you have enough grasp of the ins and outs of aperture etc to try one or two lights, and see if you can say what _you_ think "feels most real"?
 

iced_theater

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I'm still here, I just haven't had much freetime lately to try things with the camera yet. I should be in bed now since I worked a double last night and have to go in 6 more hours.
 

OldNick

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iced_theater said:
I'm still here, I just haven't had much freetime lately to try things with the camera yet. I should be in bed now since I worked a double last night and have to go in 6 more hours.

Sorry guy. Appreciate it. Let's know. ABSOLUTELY no crit intended. Full of praise. Seriously.

Nick (the old)
 

iced_theater

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Alright, taken a few pics to try out your guy's recommendations. I used a Streamlight Tasklight 2L on high and a Mag ROP with MS reflector.

The Streamlight was shot at about 15' with F5.6, 1/1.3, WB day, ISO 100. That was the closest I could get to real life.
P9260016600x449.jpg



The ROP was shot at about 15' with F5.6, 1/4, WB day, ISO 100. Again that was the closest I could get to it.
P9260033600x449.jpg


When I do shoot some pictures again *as soon as I recieve about 3-4 more lights* then I'll do it at that setting except probably 1/2.5 as that would be about the middle. If you have other suggestions, I am open to them as well. I will try out other shutter speeds first before I settle on 1/2.5 though just to make sure.
 
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