Dimmers and auto-iris lenses
Bookmark this page:
 Yahoo!
 Google
 Windows Live
 del.icio.us
 digg
 Netscape
|
|
||||||||||||||||||||||||||||||||||
|
Posted by Robert Green on March 8, 2007, 5:34 pm
Please log in for more thread options Boodle. I monitor the crate with an auto-iris IR cam and therein lies the problem. It's very hard to tell remotely whether the light is barely dimmed or dimmed 90% because the autoiris compensates for the dimming. All you see when you hit the DIM button on the X-10 controller is a slight "flaring" of the image as the light dims and the iris open up. I thought sharpness might be a cue, but the auto-iris probably isn't an iris in the traditional mechanical sense. I'm betting it's electronic because as it adjusts there seem to be no corresponding depth of field changes. The camera's got enough resolution to usefully image a 3" dial thermometer in the heated water bath along the side of her crate so I thought I'd get a solar cell and small electrical meter with a dial I could see via the remote cam and a potentiometer to calibrate lo and hi ranges. That setup would consume no power, but it's probably going to be hard to read. Any suggestions cheerfully accepted. In the meantime I'm going to search the junkbox. -- Bobby G. | ||||||||||||||||||||||||||||||||||
|
Posted by Ian Shef on March 9, 2007, 2:33 pm
Please log in for more thread options How about an LED (or even a nightlight) that is within the image. Its own brightness is constant, so an open iris (due to dim lights) makes the LED look bright. A closed down iris (due to bright lights) makes the LED look dim. Dim LED implies bright room lights. Bright LED implies dim room lights. The LED could blink to reduce battery drain if battery powered. Blinking LEDs for decorative purposes can be picked up in many places. I don't know if there is going to be an interaction between the duration of the blink and the scanning period of the video camera. Could be cheap but consumes more power than your solution. -- Ian Shef 805/F6 * These are my personal opinions Raytheon Company * and not those of my employer. PO Box 11337 * Tucson, AZ 85734-1337 * | ||||||||||||||||||||||||||||||||||
|
Posted by Robert Green on March 9, 2007, 6:12 pm
Please log in for more thread options >
> > I've got an odd issue monitoring the dog crate for my little bad-eyed
> > Boodle. I monitor the crate with an auto-iris IR cam and therein lies > > the problem. It's very hard to tell remotely whether the light is > > barely dimmed or dimmed 90% because the autoiris compensates for the > > dimming. All you see when you hit the DIM button on the X-10 controller > > is a slight "flaring" of the image as the light dims and the iris open > > up. I thought sharpness might be a cue, but the auto-iris probably > > isn't an iris in the traditional mechanical sense. I'm betting it's > > electronic because as it adjusts there seem to be no corresponding depth > > of field changes. > > > > The camera's got enough resolution to usefully image a 3" dial > > thermometer in the heated water bath along the side of her crate so I > > thought I'd get a solar cell and small electrical meter with a dial I > > could see via the remote cam and a potentiometer to calibrate lo and hi > > ranges. That setup would consume no power, but it's probably going to > > be hard to read. Any suggestions cheerfully accepted. In the meantime > > I'm going to search the junkbox. > > > > -- > > Bobby G. >
know
> How about an LED (or even a nightlight) that is within the image. Its own > brightness is constant, so an open iris (due to dim lights) makes the LED > look bright. A closed down iris (due to bright lights) makes the LED look > dim. > Dim LED implies bright room lights. > Bright LED implies dim room lights. > > The LED could blink to reduce battery drain if battery powered. Blinking > LEDs for decorative purposes can be picked up in many places. I don't > if there is going to be an interaction between the duration of the blink
> and the scanning period of the video camera. > > Could be cheap but consumes more power than your solution. Thanks, Ian. I've got a *very* old Lafayette meter calibrated from 1 to 50ma that's just about exactly what I need except the damn needle is too small to see via the camera! I hooked it up to a solar panel salvaged from a garden lamp and it responds to the range of illumination provided by the lamp. After I read your note I realized that's almost enough power to light up an LED so it might turn out that a fusion of our techniques will fill the bill. I'm going to the LED junk box right now to see if I can generate enough power to light one. A nicer design would be to light up a row of LEDs to correspond to the lighting level but I'll take a single LED if I can calibrate to fire before the camera's internal IR LEDs fire because that seems to wake up the dog. [Time passes] Great! I just checked out the panels. While one didn't do the trick (they put out about 1.3V each) three of them easily power a flashing red LED http://www.allelectronics.com/cgi-bin/category/340200/Flashing.html quite nicely under full output with no power other than the room light. I've got a whole box of these recycled solar panels got some time back from Allectronics so ganging them together will make something a little bigger than I would like, but will allow me to determine when the camera's IR illuminator is about to come on. Red LEDs show up VERY nicely when imaged via IR cameras, so this will work out quite well. If I can figure out how to vary the flash rate with the illumination levels that would be even better but the flashing LED's I use have the flashing circuitry built into the base of the LED and are not adjustable, I believe. Even without flashing, mounting the LED near the lens will tell me what I need to know about lighting levels. It doesn't need to be in sharp focus, like the meter would, to give me an indication of the light level. Now to see if there's any way to have three LEDs to indicate dim, medium and bright conditions. I'm not sure how to create a circuit that lights additional LEDs in response to an increase in amperage. The voltage on the panels appears to be fairly constant over the range of illumination provided by a 60W lamp. Thanks for the input, Ian! I like the nightlight idea, too, and am going to try one of the little electroluminescent jobs before I finalize on a solution. The amount of electricity used by those panels is negligible and it could be that it images even better than LEDs will. It's certainly easier to implement. -- Bobby G. | ||||||||||||||||||||||||||||||||||
|
Posted by Robert Green on March 9, 2007, 9:42 pm
Please log in for more thread options Ian Shef wrote:
<stuff snipped>
> How about an LED (or even a nightlight) that is within the image. Its own
> brightness is constant, so an open iris (due to dim lights) makes the LED > look bright. A closed down iris (due to bright lights) makes the LED look > dim. > Dim LED implies bright room lights. > Bright LED implies dim room lights. The winner turned out to be an electroluminescent panel nightlight that I got for a couple of bucks a while back. It's got a large plastic border. At first, it didn't quite give me enough data but when I encased it in Smarthome "air" shipping bag with big block lettering, three problems got solved at once. First, the bag makes the unit waterproof which is rather important. Secondly, the lettering disappears as the room lights dim, with the thickness of the letters acting as a very good indicator of the relative lighting levels. As the letters get more backlighting (in relation to roomlighting) the get more washed out, thinner and hard to read. When the room light is out entirely, the lettering vanishes. It turns out to solve another problem - that of the IR LEDS being too bright because the camera is designed for a greater range than I am using. The bag with the lettering is reflective and reflects enough of the IR LEDs back to the unit to cause it to drop about an F stop or so. I'm surprised it doesn't cause feedback flutter, but it doesn't. Now I can see detail in the dog's fur. Even more interesting is that Hotspot's (the nearly deaf JR terrier whose in Boodle's crate now as a "test subject") big brown spot almost disappears entirely when lit only by infrared light. It's pretty remarkable how the brightness difference in the little night light draws your eye to that corner of the frame. Before installing it, you would be aware that the image was pulsing slightly and that some reflections were changing when you dimmed the light. After installing it, when the rest of the scene is seemingly unchanged, the nightlight is becoming conspicuously brighter or darker. Problem solved! I've also discovered, FWIW, that the IR LEDS in the camera are always on, but vary in intensity. I know they go out in bright sunlight, but it's probably never bright enough in the basement to extinguish them entirely. I can always see their reflection now in the bag over the nightlight, no matter what bulb is dimmed or brightened to. Thanks again for the idea, Ian. -- Bobby G. | ||||||||||||||||||||||||||||||||||
|
Posted by Bill Kearney on March 9, 2007, 6:57 pm
Please log in for more thread options Get a dimmer you can monitor. By the time you lash up some hack to work you
could've gotten it delivered UPS ground. | ||||||||||||||||||||||||||||||||||
| Similar Threads | Posted |
| Dimmers and auto-iris lenses | March 8, 2007, 5:34 pm |
| LED bulbs that work with dimmers? | March 13, 2007, 7:30 pm |
| New technology wall switch dimmers? | February 19, 2006, 12:29 pm |
| Using cheap audio DACs as light dimmers | August 10, 2008, 9:34 am |
| Protocol(s) for controlling switches, dimmers and other devices over ZigBee? | August 31, 2006, 2:57 am |
| INSTEON dimmers can respond to both X-10 and INSTEON commands | July 29, 2005, 7:51 am |
> Boodle. I monitor the crate with an auto-iris IR cam and therein lies
> the problem. It's very hard to tell remotely whether the light is
> barely dimmed or dimmed 90% because the autoiris compensates for the
> dimming. All you see when you hit the DIM button on the X-10 controller
> is a slight "flaring" of the image as the light dims and the iris open
> up. I thought sharpness might be a cue, but the auto-iris probably
> isn't an iris in the traditional mechanical sense. I'm betting it's
> electronic because as it adjusts there seem to be no corresponding depth
> of field changes.
>
> The camera's got enough resolution to usefully image a 3" dial
> thermometer in the heated water bath along the side of her crate so I
> thought I'd get a solar cell and small electrical meter with a dial I
> could see via the remote cam and a potentiometer to calibrate lo and hi
> ranges. That setup would consume no power, but it's probably going to
> be hard to read. Any suggestions cheerfully accepted. In the meantime
> I'm going to search the junkbox.
>
> --
> Bobby G.