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I am working currently on an art project.

My target: I apply around 1000 lumen of light through a key hole of a door lock. The light is supposed to go through the key hole and the outcome of the light on the other side, which is very tiny however visible, must be captured in a photograph, together with the lock and an object next to the lock.

The issue is the amount of weakened light that reaches the other side of the door. This amount must be increased or the source light must be amplified somehow.

To succeed I currently see two options:

  1. I am thinking to increase the power of the light source (to about 3000 lumen).

  2. The light outcome must be amplified/multiplied. I was thinking to use a mirror. After researching online I learned that the mirror will not significantly increase the light amount

I was wondering whether it is possible to amplify the power of light that comes out of the door lock?

enter image description here

Here we go an updated picture: enter image description here

Sathees
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  • Where's the photography involved? – Rowland Shaw May 20 '15 at 16:03
  • My target is to take a picture of the object (see picture) frm the light provided within the dark room – Sathees May 20 '15 at 16:25
  • generally I found out that it is nt really possible to take a good pic just having tht light....therefore I was wondering whether the light might amplified somehow..I havent seen any possiblitly to do that – Sathees May 20 '15 at 16:32
  • If the room you are photographing from is really, *really* dark and the object you want to capture is not moving, you could also try to project the light the comes throught the key hole on a wall/screen in that room. Like this. – agtoever May 21 '15 at 09:53
  • If you could explain what you are actually doing and perhaps show us a better lit image of the setup it would help. You do not say WHY you want to do what you ask or why an alternative is not acceptable. To say that the double keyhole is an important part of things does not tell us much - just sets a riddle. What you tell us is of course your choice, but you could far better explain what you want. Why 1000 lumen,. How close can the source be to the door? Why?> Is the target offset so there ios no parallel path to it etc. What you ask for MAY be trivially easy or not, but we cannot tell. – Russell McMahon May 21 '15 at 10:39
  • @agtoever thx for the link! It is indeed a phenomenal way to capture great pictures; however as I have understood the projection through the small hole is crucial for this kind of photography; In my case the light is significantly weakened through the keyhole so that I doubt a projection can be realized – Sathees May 21 '15 at 10:54
  • @Russel well let me try to explain. It is decided that any light volume (1000 lm was chosen to test) has to go through a key hole of a door which fortunately enlighten an object on the side. This setup is not changeable since there is a theme that I have selected. This is abt a powerful light which gets weakened though its way though the door while still having enough power to light an object (this can be easily referred to human life in a metaphoric sense..) I look for a way to exploit the light though the key hole to the max possible. Currently I even doubt wether my intention is feasible.. – Sathees May 21 '15 at 11:28
  • Several questions above have not been answered and answers are needed to help you: How close can the source be to the door? Why? Is the target offset so there is no parallel path to it etc. What you ask for MAY be trivially easy or not, but we cannot tell. You can focus light from an LED to a point at a distance from say mms to m's from the LED end. A suitably small diameter LED and lens could send most of its light through a keyhole in a diverging or converging cone. We need to know why this would not be adequate. A picture showing light PATH, camera location and object location is needed. – Russell McMahon May 21 '15 at 15:32
  • The light source can be as close as possble to the door; there is no restriction. However I wonder whether a diameter LED with a converging cone lens might convey more light then a very bright led torch? ...give me some time I ll come up with a picture as you asked – Sathees May 21 '15 at 15:49
  • @RussellMcMahon I see the idea u mentioned with a diverging Cone and a lens with a small diameter would do the job to get a significant amoinut of the light thru the keyhole (similar to laser). Considering this I have two questions: 1. what material should the cone made of( i guess it might be reflective?) 2. Are there LED and LENS with such small diameters /such torchlighs? – Sathees Sep 01 '15 at 06:38
  • Doew the door / why does the door have to be thick? If you take off the lock and remove works and replace on room-side coverplate only a light source can be very near hole. A narrow beam angle LED would work fine. Lenses may often be be PMMA = acrylic and can be made any size desired (within reason). A compination of the above should allow the results you want. – Russell McMahon Sep 02 '15 at 05:52
  • @RussellMcMahon I see that acrylic lenses are right ones. Well the door or the keyhole of the lock is 7cm thick...thats all abt getting the light through the hole therefore I cannot remove the lock. But given the narrow light it still might work? – Sathees Sep 02 '15 at 08:20
  • In almost all doors the lock can be removed for repair or modification and has ntop be installed somehow. You can usually reinstall the cover plate and handle on one side only without the mechanism in place and this goives you room inside the door for a light source. | Also, if the photos is what counts you can make a "fake" door from thin wooden sheet or even cardboard with the light near the "keyhole". This does not need to be full door size - just big enough to lool OK in the photo. – Russell McMahon Sep 02 '15 at 14:56
  • @RussellMcMahon the issue is in the article that I need to write together with the photo there I wanted to prove that an LED Light coming thru a keyhole of a door lock,(considered as 'not feasible' to lighten a picture) is realized in a decent manner proven by the picture...therefore I wanna avoid 'faking' the door or the lock... – Sathees Sep 02 '15 at 15:09
  • @Sathees I'm getting somewhat confused as to what the aim is. Who considers the light nop feasible and how big is the picture and how far from the lock and how much power may the LED use? It depends whether you want to prove it can be done or cannot be. Giove me say 1 Watt and a picture up to say 1m x 1m and position of picture somewhat fl;exible and I CAN illuminate it quite well with a single LED with a std keyhole. If you want to prove it cannot be done I never said trhe above :-). – Russell McMahon Sep 03 '15 at 06:18
  • @RussellMcMahon the aim is to take a photo of an object (size 5x10cm&flexible location) that is lightened by an LED torchlight. The keyhole is not supposed to be a barrier to enlighten the object. I want to prove that it can be done. I tested it with a 1000lumen torch to lighten the keyhole. Changing ight source to different positions on certain poisitions more light was viisble then on others and the object was lightened slightly. However the light coming thru was still weak. Therefore I wanna increase the light amount coming thru... – Sathees Sep 03 '15 at 09:03

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The easiest answer is "time". You don't need to amplify anything: you just need to collect it for longer. The overall exposure of your photo is the amount of ambient light that is accepted through the camera's aperture for the amount of time the shutter is open.

Presuming that your object doesn't move, simply take either one long exposure or a sequence of shorter ones and combine them together.

Otherwise, you could use some sort of lens to collect more light to send through the keyhole (on the outside, not the inside). A focusing mirror system (not a flat mirror) could also help here. How to do that might be better handled by the people over on https://physics.stackexchange.com/. But this is also not amplifying it, really — it's just making sure that less of it is wasted by hitting the door. And, my strong intuition is that either one isn't really going to be a significant difference, and especially not at any reasonable cost.

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mattdm
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    I see your point considering time! However the amount of light passing the keyhole is currently too low ... I hope that the new light source I have ordered (a 3000 lumen torch) might change that – Sathees May 20 '15 at 21:52
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I really don't understand well what is your experiment.

There are a lot of factors to consider, for example diffraction, which varies depending on the size of the aperture for example.

To "increase" the light source (optimize, actually) I would recommend a parabolic mirror. A headlight of a car could work.

Another option is not to use a led light but a laser beam. But again, I don't really understand what the project is about.

I would not use a lens to focus the light because as I understand you need a parallel light, not a focused one.

Another thing. Do you really need a double keyhole? One entrance and other on the other side of the door?

You can modify the door to appear that it is entering a tunnel keyhole but you can just make a mask.

Diagram showing how a parabolic mirror optimizes the light coming from a source light.

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Rafael
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  • Thanks for your input! Well my experiment is little complicated. However the picture will is based on a gd theme and as 'mattdm' outlined above with an artisic interest.

    I was also thinking abt a laser beam however its volume might be small.

    Yeah, the double keyhole is signifcant part of the experiment.

    Thx for the drawing. Do I understand it correctly, that u suggest the parabolic mirror to be place outside the door. Is there a way to increase the light from inside?

     – Sathees May 20 '15 at 18:02
  • It is a way to "optimize it" Not increase it. All (well not all but a lot more) the light that is spilled out of the light source will be used. If you don't use a parabolic mirror more than 50% will be lighting and bouncing on the other side of the door. – Rafael May 20 '15 at 18:10
  • I edited the post showing how a parabolic mirror optimizes the light. – Rafael May 20 '15 at 18:32
  • Thx for the update!! ...After testing different light sources I used with a 1000lumen torch light... however the power was not sufficient...i guess the torch light do not need external parabolic mirror/glass right? – Sathees May 20 '15 at 19:57
  • It has it included. But probably not good enough. – Rafael May 20 '15 at 20:01
  • You might be right! Do you see another way to increase the light volume that comes through to the inside? Can anything be done from the inside?I couldn't find any suggestion on that even after spending lot of time on researching online – Sathees May 20 '15 at 21:20
  • A set of lenses. A movie projector tryes to use the maximum light output on a specific region. – Rafael May 20 '15 at 21:27
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It depends on what you actually need, and what you actually want.

You need some combination of exposure, such that the aperture, shutter speed, and sensitivity can actually capture an image of some kind.

What you want follows from this, and informs your choices.

  • How much noise is acceptable?
  • How much of the object needs to be lit? (i.e., is is acceptable for the object to be partially unlit? If not, how much shadow is acceptable?)
  • From what POV is the object to be photographed?

I'm sure there are others, but my point is that you have a technical problem and a host of artistic interests that are going to intersect.

My immediate thoughts are "Just start exploring." Figure it out. Find out how much light you need to get the object lit somewhat like you are imagining it, and then go from there.

My point is that there is more going on here than some amount of lumens lighting a scene. You can do a lot with high-ISO settings, a single point of light, and reflectors. The question is, what is acceptable for you?

And we haven't even started talking about post-processing!

  • thanks! You are right considering the technical problem. I was wondering whether there might be a way to overcome this isse what I might have disregarded. – Sathees May 20 '15 at 18:03
  • Post-processing is not planed/allowed – Sathees May 20 '15 at 18:04
  • Well, if you are rendering a raw image into JPEG at any point, or if you are using in-camera JPEG, then there is always going to be post-processing of some sort, even if it is app or camera defaults. Assuming you are shooting digital. –  May 21 '15 at 14:17
  • You don't really state what your problem is, actually. You are /assuming/ that you need to throw more light on the subject, but this may not be true. You could use a laser pointer and illuminate the object a huge amount in one place enough to get some exposure. But you might want some sort of overall illumination. Or do you? You don't say what your artistic constraints are. You don't say what your absolute technical constraints are. You don't even discuss where the camera POV is! But, a super-bright LED and some reflectors to the side of the object would be enough to get some valid exposure. –  May 21 '15 at 14:19
  • If it helps, think of your experiment as a small model of objects in space. Your light source is somewhat similar to parallel light from a bright light source that illuminates part or all of a planet or planetoid. Which may also be lit from other angles by a different light source or reflective light from the primary source. Think of how the moon is lit by the sun and seen on Earth, and how an Earth-rise on the moon might look. –  May 21 '15 at 14:26
  • Fair enough I assumed you were meaning post-processing as processing on a software.

    I also thought about a laser pointer. However I guess that the light volume might be too low, right? I will come up with a drawing that will hopefully address some of your questions..

     – Sathees May 21 '15 at 22:45
  • A laser pointer will certainly have enough light to expose part of the object, depending on its size. You could introduce a light spreader of some sort on the other side of the hole form the laser pointer. –  May 22 '15 at 16:55
  • Thx! Well I tried to make use of a magnifying glass with attached reflector....it worked well; however I needed keep the glass with a distance of 7-9 cm from the key hole so that the light was 'amplified' ...now I do look for a glas / lense that does not require such a distance of 7-9 cm from the key hole – Sathees May 25 '15 at 21:52
  • Find an old zoom-type lens and experiment passing light through it and focus/zoom until you get the results you want. The comment upthread regarding projector lenses was a good one. –  May 26 '15 at 14:01