|
|
Infrared photography
I want to photograph and video in infrared mode.
I understand that some point-and-shoot cameras provide this style of photography/videography. Alternately, some people have "hacked" a camera by removing the IR filter from in front of the imaging element. There are instructions on-line to DIY this, or to send in your P&S to have it done. Basically, the IR filter is removed and replaced with another (not a procedure for the faint at heart). The replacement filter is $$$. My question is this: is this replacement filter that passes rather than blocks IR available as a gelatin or other commonly available filter that I can source elsewhere other than from these camera-mod services? Or can I just strip off the existing filter and not replace it with anything? I'm looking for quantitative data (the existence of IR) not qualitative data (a pretty picture). What function does the replacement filter provide (other than passing IR data)? To clarify, I want to "see" IR images real-time in the viewfinder, not post-process the image data to reveal the IR. If there's another forum you suggest I should ask this question in, please let me know. Thanks, -- DaveC This is an invalid return address Please reply in the news group |
Infrared photography
"DaveC" wrote in message
obal.net... I want to photograph and video in infrared mode. I understand that some point-and-shoot cameras provide this style of photography/videography. Alternately, some people have "hacked" a camera by removing the IR filter from in front of the imaging element. There are instructions on-line to DIY this, or to send in your P&S to have it done. Basically, the IR filter is removed and replaced with another (not a procedure for the faint at heart). The replacement filter is $$$. My question is this: is this replacement filter that passes rather than blocks IR available as a gelatin or other commonly available filter that I can source elsewhere other than from these camera-mod services? Or can I just strip off the existing filter and not replace it with anything? I'm looking for quantitative data (the existence of IR) not qualitative data (a pretty picture). What function does the replacement filter provide (other than passing IR data)? To clarify, I want to "see" IR images real-time in the viewfinder, not post-process the image data to reveal the IR. If there's another forum you suggest I should ask this question in, please let me know. Thanks, -- DaveC This is an invalid return address Please reply in the news group I don't know much about most of this, but it seems that once you remove the IR filter from the sensor, you could just attach an appropriate IR filter to the front of the lens. Of course, you would need the appropriate filter for each of the lenses that you use. Eric Miller www.dyesscreek.com |
Infrared photography
DaveC wrote:
I'm looking for quantitative data (the existence of IR) not qualitative data (a pretty picture). Isn't that the other way round? Qualitative meaning just yes/no while quantitative in addition tells you how much, e.g. darker or lighter on a b/w IR-image or blue/green/yellow/red/white on a color IR-image? jue |
Infrared photography
Isn't that the other way round?
Qualitative meaning just yes/no while quantitative in addition tells you how much, e.g. darker or lighter on a b/w IR-image or blue/green/yellow/red/white on a color IR-image? jue Quantitative: does it exist? do we have presence or absence? 0 or 0? Qualitative: what are its qualities? But to define in other terms, I want images that show the existence of IR wavelengths. If it's not a pretty picture, that's OK. Please let's not detour into this realm. Those who want to discuss quantitative vs. qualitative please start another thread... Thanks, -- DaveC This is an invalid return address Please reply in the news group |
Infrared photography
"DaveC" wrote in message
obal.net... I want to photograph and video in infrared mode. I understand that some point-and-shoot cameras provide this style of photography/videography. Alternately, some people have "hacked" a camera by removing the IR filter from in front of the imaging element. There are instructions on-line to DIY this, or to send in your P&S to have it done. Basically, the IR filter is removed and replaced with another (not a procedure for the faint at heart). The replacement filter is $$$. My question is this: is this replacement filter that passes rather than blocks IR available as a gelatin or other commonly available filter that I can source elsewhere other than from these camera-mod services? Or can I just strip off the existing filter and not replace it with anything? I'm looking for quantitative data (the existence of IR) not qualitative data (a pretty picture). What function does the replacement filter provide (other than passing IR data)? To clarify, I want to "see" IR images real-time in the viewfinder, not post-process the image data to reveal the IR. If there's another forum you suggest I should ask this question in, please let me know. Thanks, The problem is that you won't see an IR picture per se, as the image requires post processing to be anything but a dark red image. If your camera has a B&W mode, that would be helpful, but the image will still require post processing. |
Infrared photography
On 2008-09-25, DaveC wrote:
I want to photograph and video in infrared mode. I understand that some point-and-shoot cameras provide this style of photography/videography. Alternately, some people have "hacked" a camera by removing the IR filter from in front of the imaging element. There are instructions on-line to DIY this, or to send in your P&S to have it done. Basically, the IR filter is removed and replaced with another (not a procedure for the faint at heart). The replacement filter is $$$. My question is this: is this replacement filter that passes rather than blocks IR available as a gelatin or other commonly available filter that I can source elsewhere other than from these camera-mod services? Or can I just strip off the existing filter and not replace it with anything? I'm looking for quantitative data (the existence of IR) not qualitative data (a pretty picture). What function does the replacement filter provide (other than passing IR data)? To clarify, I want to "see" IR images real-time in the viewfinder, not post-process the image data to reveal the IR. If there's another forum you suggest I should ask this question in, please let me know. Thanks, Most digital cameras have some infra-red sensitivity left in - the internal infra-red filters are there to stop most infra-red from getting to the sensors, as it blurs the image (apart from anything else). The infra-red filters sold to go in front of the camera lens do the opposite - the stop most or all of the visible light but not the infra-red, so that you can take pictures using only the IR. but because the intermal filter blocks most of the IR, you need a long exposure (or an uncomfortable amount of IR) to get any image at all. It is possible to remove the internal IR-blocking filter from some digital cameras (but probaly not compacts - the lens/sensor assembly in those is ususally a non-servicable sealed module); usually you would then need to replace it with an element having the same optical qualities in the visible spectrum as the original IR-blocking filter had, or the resulting images won't be usable. With such a camera, to get images using only the IR spectrum, you'll need a filter in front of the lens to block the visible light. All IR images from such a camera are likely to be more or less blurred. There are of course purpose-built thermal-imaging cameras, and IR 'remote thermometers'. Some 'night vision' devices operate using 'passive IR'. Oddly, these seem to tend towards the 'stupidly expensive' end of the price spectrum, being targeted at the armed forces and emergency services, or for industrial or medical uses. This site might be useful http://www.wrotniak.net/photo/infrared/#CAMERA. -- -- ^^^^^^^^^^ -- Whiskers -- ~~~~~~~~~~ |
OT: qualitative/quantitative (WAS: Infrared photography)
DaveC wrote:
Isn't that the other way round? Qualitative meaning just yes/no while quantitative in addition tells you how much, e.g. darker or lighter on a b/w IR-image or blue/green/yellow/red/white on a color IR-image? Quantitative: does it exist? do we have presence or absence? 0 or 0? Qualitative: what are its qualities? That is opposite to what I learned in science, especially in chemistry. There a qualitative analysis tells you _which_ components are present in a sample (yes/no). And a quantitative analysis tells you _how much_ (what quantity) of each component can be found. Wikipedia seems to support this view: "A quantitative attribute is one that exists in a range of magnitudes, and can therefore be measured. Measurements of any particular quantitative property are expressed as a specific quantity, referred to as a unit, multiplied by a number. Examples of physical quantities are distance, mass, and time." Please let's not detour into this realm. Those who want to discuss quantitative vs. qualitative please start another thread... Ooops :-). "Subject" adjusted as requested. jue |
Infrared photography
In article .net,
DaveC wrote: I want to photograph and video in infrared mode. I understand that some point-and-shoot cameras provide this style of photography/videography. Alternately, some people have "hacked" a camera by removing the IR filter from in front of the imaging element. There are instructions on-line to DIY this, or to send in your P&S to have it done. Basically, the IR filter is removed and replaced with another (not a procedure for the faint at heart). The replacement filter is $$$. yea, and the price has dramatically increased in the past year or so. My question is this: is this replacement filter that passes rather than blocks IR available as a gelatin or other commonly available filter that I can source elsewhere other than from these camera-mod services? sure. generally it's 2mm thick optical glass that's typically a 2" or 3" square piece and you'll need to cut it to fit the camera. Or can I just strip off the existing filter and not replace it with anything? I'm looking for quantitative data (the existence of IR) not qualitative data (a pretty picture). What function does the replacement filter provide (other than passing IR data)? you can, but the focusing might be adversely affected. To clarify, I want to "see" IR images real-time in the viewfinder, not post-process the image data to reveal the IR. that's exactly what you'll get. |
Infrared photography
In article
, Pat wrote: The other option is to just buy the right camera, something like the old Canon EOS 20Da. The "a" designates it as a astronomy camera and it doesn't have the filter. I think it's been discontinued but you can probably find one if you sniff around. or the fuji uv/ir camera If you go IR, you might also want to buy an older lens. Some of the older ones had an IR mark on the focus ring so you could adjust the IR focus (which isn't the same as the visible light focus). that helps too |
Infrared photography
In article , bino
wrote: The problem is that you won't see an IR picture per se, as the image requires post processing to be anything but a dark red image. If your camera has a B&W mode, that would be helpful, but the image will still require post processing. false. |
Infrared photography
"nospam" wrote in message
... In article , bino wrote: The problem is that you won't see an IR picture per se, as the image requires post processing to be anything but a dark red image. If your camera has a B&W mode, that would be helpful, but the image will still require post processing. false. You got some facts jackass? Experience? I've shot IR film and IR digital. The red filter makes the color sensor see red. Period. |
Infrared photography
In article , bino
wrote: The problem is that you won't see an IR picture per se, as the image requires post processing to be anything but a dark red image. If your camera has a B&W mode, that would be helpful, but the image will still require post processing. false. You got some facts jackass? Experience? I've shot IR film and IR digital. The red filter makes the color sensor see red. Period. except that the blue pixels also pass infrared light and depending on the camera, the white balance, the strength of the infrared filter and the raw processing, the results can be virtually anything. i've used a couple of digital cameras for infrared and modified one of them myself. none of them produce red images out of the camera. on the camera's lcd screen and the jpegs they produce, the result is b/w. if anything, there's a mild greenish cast, perhaps because the camera is boosting green due to the weak response of the green pixels with infrared light. the very same image when shot raw and processed via adobe camera raw has an entirely different appearance than with nikon or canon's software. saying that it will always be red is simply false. |
Infrared photography
In rec.photo.digital bino wrote:
| "nospam" wrote in message | ... | In article , bino | wrote: | | The problem is that you won't see an IR picture per se, as the image | requires post processing to be anything but a dark red image. If your | camera has a B&W mode, that would be helpful, but the image will still | require post processing. | | false. | | | You got some facts jackass? Experience? I've shot IR film and IR digital. | The red filter makes the color sensor see red. Period. Who said anything about a red filter ... in this thread? Actually, I would recommend a IR-passing filter (e.g. type 89) on the lens after the IR-blocking filter is removed. The sensor (with a replacement all-passing filter to keep the optics consistent) will pick up IR in other colors. This is because the color separation of the sensor is not designed to discriminate IR (and hence why an IR-blocking filter needs to be added in the normal case). The red channel will get the most IR. The blue channel will get a lot. The green channel will get some. And these will vary by what IR wavelength is involved. So you will get some false color effects. Directly viewing the image on the camera screen will give some funny reddish colors for sure. Post processing can then give you the effets you want if you were using the correct lens-front filter to begin with (type 29 for some effects, type 89 for others, and type 87 for yet others). In some cases the desired effect is achieved by making everything monochrome. In other cases the desired affect is a color product derived from adding or subtracting the various color channels. Additionally, multiple shooting of a stationary subject with different lens-front filters (the above plus 25, 23, 15, 12, and none at all) can give you multi-channel info to even be able to derive the original visual image unaffected by infrared (with the correct formula). -- |WARNING: Due to extreme spam, googlegroups.com is blocked. Due to ignorance | | by the abuse department, bellsouth.net is blocked. If you post to | | Usenet from these places, find another Usenet provider ASAP. | | Phil Howard KA9WGN (email for humans: first name in lower case at ipal.net) | |
Infrared photography
In rec.photo.digital Pat wrote:
| There are some good step-by-step instruction out there for removing | the filter. You can leave the filter off, but IIRC you need to | replace it with small shims to keep everything in place. | | If you use a IR filter, you then have to have extraordinary long | exposures because you still have the IR filter in place taking out | most of the IR. | | The other option is to just buy the right camera, something like the | old Canon EOS 20Da. The "a" designates it as a astronomy camera and | it doesn't have the filter. I think it's been discontinued but you | can probably find one if you sniff around. | | If you go IR, you might also want to buy an older lens. Some of the | older ones had an IR mark on the focus ring so you could adjust the IR | focus (which isn't the same as the visible light focus). Or you can pay someone else to do the conversion for you: http://www.lifepixel.com/ http://www.spencerscamera.com/ -- |WARNING: Due to extreme spam, googlegroups.com is blocked. Due to ignorance | | by the abuse department, bellsouth.net is blocked. If you post to | | Usenet from these places, find another Usenet provider ASAP. | | Phil Howard KA9WGN (email for humans: first name in lower case at ipal.net) | |
Infrared photography
sure. generally it's 2mm thick optical glass that's typically a 2" or
3" square piece and you'll need to cut it to fit the camera. Seems straightforward (notice the absence of the term "simple"). Can you give a URL for such a piece? The proper thickness of the replacement glass should be...? Should it be the same thickness as the filter removed from the imager? Thanks, -- DaveC This is an invalid return address Please reply in the news group |
Infrared photography
On Thu, 25 Sep 2008 07:44:25 -0700, DaveC wrote:
I want to photograph and video in infrared mode. I understand that some point-and-shoot cameras provide this style of photography/videography. Alternately, some people have "hacked" a camera by removing the IR filter from in front of the imaging element. There are instructions on-line to DIY this, or to send in your P&S to have it done. Basically, the IR filter is removed and replaced with another (not a procedure for the faint at heart). The replacement filter is $$$. My question is this: is this replacement filter that passes rather than blocks IR available as a gelatin or other commonly available filter that I can source elsewhere other than from these camera-mod services? Or can I just strip off the existing filter and not replace it with anything? I'm looking for quantitative data (the existence of IR) not qualitative data (a pretty picture). What function does the replacement filter provide (other than passing IR data)? To clarify, I want to "see" IR images real-time in the viewfinder, not post-process the image data to reveal the IR. If there's another forum you suggest I should ask this question in, please let me know. You could try picking up a Sony F707 or others of that ilk. If my memory serves me right they do have IR capabilities. Eric Stevens |
Infrared photography
In article .net,
DaveC wrote: sure. generally it's 2mm thick optical glass that's typically a 2" or 3" square piece and you'll need to cut it to fit the camera. Seems straightforward (notice the absence of the term "simple"). if you know how to cut glass it should be fairly easy. however, opening up the camera to replace the filter is usually not easy at all. Can you give a URL for such a piece? here's a few: http://www.alpineastro.com/filters/filters.htm http://www.controloptics.com/product_colorglassfilters.htm http://www.edmundoptics.com/onlineca...cfm?productID= 1918 The proper thickness of the replacement glass should be...? Should it be the same thickness as the filter removed from the imager? it should. if it's not that close, you might lose either infinity focus or close-up focus, but stopping down should compensate for that. depending on the camera, the autofocus might need adjusting. the other problem is the only way to know how thick a filter to get is open up the camera and measure it. it varies depending on the camera, and sometimes it varies with the *same* camera, depending on the revision. i've also heard of using microscope slides to match the thickness. |
Infrared photography
On Fri, 26 Sep 2008 17:11:35 +1200, Eric Stevens wrote:
On Thu, 25 Sep 2008 07:44:25 -0700, DaveC wrote: I want to photograph and video in infrared mode. I understand that some point-and-shoot cameras provide this style of photography/videography. Alternately, some people have "hacked" a camera by removing the IR filter from in front of the imaging element. There are instructions on-line to DIY this, or to send in your P&S to have it done. Basically, the IR filter is removed and replaced with another (not a procedure for the faint at heart). The replacement filter is $$$. My question is this: is this replacement filter that passes rather than blocks IR available as a gelatin or other commonly available filter that I can source elsewhere other than from these camera-mod services? Or can I just strip off the existing filter and not replace it with anything? I'm looking for quantitative data (the existence of IR) not qualitative data (a pretty picture). What function does the replacement filter provide (other than passing IR data)? To clarify, I want to "see" IR images real-time in the viewfinder, not post-process the image data to reveal the IR. If there's another forum you suggest I should ask this question in, please let me know. You could try picking up a Sony F707 or others of that ilk. If my memory serves me right they do have IR capabilities. Correct, the Sony F707, F717, F818, H3(?), and H9 all have this capability, and they all do it very well. Real-time hand-held IR photography and videos are a feature of all of them. No need to hack or alter any camera, just flip a switch to their "Night-Shot" mode. According to my add-on lenses and things, I would have to go with a 62mm filter size to make it the most adaptable to the most situations (including for use with my 35mm film gear). When looking at IR filters I was shocked at the prices so I went in search of an affordable alternative. The Kodak Wratten Gel Filters come in 3"x3" sizes. I could cut one of those up into a circle and put it inside of an inexpensive filter-ring holder. But they're prone to water-damage, humidity, etc. And they're still about $25-$30 depending where you get them, that's probably not worth the hassle and care for the few dollars savings. Then I found some 3"x3", Lee Polyester IR filters at B&H for only $14. Durable, worth the cost for an experiment. I didn't want near-infrared, I wanted infrared only, so I opted to go with the Wratten #87. $14 for the filter, and $10-$15 for a cheap skylight filter (to dismantle for the mount, I couldn't find a source of empty filter-ring holders), and I'd be good to go for under $30. If you have an old filter that you can dismantle for the filter-ring, more power to you, then you can get into IR photography for only $14. Here's those Lee filters at B&H Photo & Video if anyone else wants to go this route: http://www.bhphotovideo.com/bh4.sph/...=F 5261AD1470 Normally a decent IR filter of the size needed can run you upwards of $70-$130, you can see the kind of savings attained by doing it this way. A problem with all these Sony cameras is that Sony stupidly listened to some sexually-insecure puritanical idiots at one point and crippled the shutter speeds and apertures that may be used in their Night-Shot mode. They were concerned that some people were using them to shoot through certain swim-wear fabrics at the beach, fabrics transparent to IR. For daylight IR photography you have to lower the IR levels to those required for shooting in the dark. I experimented and found out that a Wratten Green filter (for b/w photography) lowered the levels just right. I found an inexpensive Hoya G (XI). In total you are using a two filter stack, IR + Wratten Green. One other thing, you have to make a rubber gasket to cover up Sony's own IR emitters in the lens housing, that the camera uses to take photos in complete darkness. Otherwise the IR from those bounces off the back of the filter stack and into your lens, ruining your shots with nasty light reflection artifacts in the glass layers. Here's a quick sample of a hand-held daylight IR shot from one of these cameras http://farm4.static.flickr.com/3085/...e6058929_o.jpg |
Infrared photography
DaveC wrote:
I want to photograph and video in infrared mode. I understand that some point-and-shoot cameras provide this style of photography/videography. Alternately, some people have "hacked" a camera by removing the IR filter from in front of the imaging element. There are instructions on-line to DIY this, or to send in your P&S to have it done. Basically, the IR filter is removed and replaced with another (not a procedure for the faint at heart). The replacement filter is $$$. My question is this: is this replacement filter that passes rather than blocks IR available as a gelatin or other commonly available filter that I can source elsewhere other than from these camera-mod services? Or can I just strip off the existing filter and not replace it with anything? I'm looking for quantitative data (the existence of IR) not qualitative data (a pretty picture). What function does the replacement filter provide (other than passing IR data)? To clarify, I want to "see" IR images real-time in the viewfinder, not post-process the image data to reveal the IR. If there's another forum you suggest I should ask this question in, please let me know. Thanks, You will not SEE the IR regardless of whether the filter allows a live preview. A filter only allows or blocks a given wavelength- it does not CONVERT it from one wavelength to another. In effect, the digital camera does a conversion, but provides three channels of color info. The read channel does not maintain spectral information. All reds are the same. What the result is is a "false color" picture. You are not viewing real infrared radiation when you view a print or a viewfinder image taken with an IR-enabled camera. |
Infrared photography
You are not viewing real infrared radiation when you
view a print or a viewfinder image taken with an IR-enabled camera. Ah, yes, of course you're correct. Isn't language a trip-up? "No, you misunderstood what I meant to say"... :-) Thanks, -- DaveC This is an invalid return address Please reply in the news group |
Infrared photography
http://farm4.static.flickr.com/3085/...e6058929_o.jpg
CS, Thanks for your reply. I'm unclear whether you hacked your camera. Did you remove the IR filter from the image sensor? Or did you just add IR filters to your lens? Thanks, -- DaveC This is an invalid return address Please reply in the news group |
Infrared photography
In article .net,
DaveC wrote: Seems straightforward (notice the absence of the term "simple"). Can you give a URL for such a piece? The proper thickness of the replacement glass should be...? Should it be the same thickness as the filter removed from the imager? Edmund Optics (the "pro" side of Edmund Scientific) was a recommended source for this sort of optical glass, in one article I read on a P&S IR conversion. http://www.edmundoptics.com/ Yes, you want a piece that is as thick as the "hot mirror" filter that you are removing from the camera's existing optical path. -- Dave Platt AE6EO Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
Infrared photography
"Dave Platt" wrote in message
In article .net, DaveC wrote: Seems straightforward (notice the absence of the term "simple"). Can you give a URL for such a piece? The proper thickness of the replacement glass should be...? Should it be the same thickness as the filter removed from the imager? Edmund Optics (the "pro" side of Edmund Scientific) was a recommended source for this sort of optical glass, in one article I read on a P&S IR conversion. http://www.edmundoptics.com/ Yes, you want a piece that is as thick as the "hot mirror" filter that you are removing from the camera's existing optical path. I haven't got the nerve (or ability, probably) to perform surgery on a camera but how expensive a camera do you need for IR photography? I have been impressed by the artistic quality of many IR photographs but not their sharpness and those were taken with conventional film cameras. -- James Silverton Potomac, Maryland |
Infrared photography
In article ,
James Silverton not.jim.silverton.at.verizon.not wrote: I haven't got the nerve (or ability, probably) to perform surgery on a camera but how expensive a camera do you need for IR photography? I have been impressed by the artistic quality of many IR photographs but not their sharpness and those were taken with conventional film cameras. I've successfully taken some interesting-looking IR photos using inexpensive Nikon Coolpix cameras - specifically, the Coolpix 800 and Coolpix 950. These use a 2.1-megapixel sensor (made by Sony I believe) which has a less-than-efficient hot mirror... enough near-IR comes through to allow IR photos to be taken in daylight with an exposure in the 1/8- second range, as long as an IR-pass/visible-light-blocking filter is added to the lens. I bought these cameras last year via eBay auctions... around $25 for an 800 and around $45 for a 950, if I recall properly. I homebrewed a simple IR-pass filter as a "proof of concept", before buying a good one. The simplest approach is to use several layers of exposed photographic film. Another approach is to go to a plastic store, and buy a scrap piece of black acrylic plastic sheet... this stuff is made with a dye that passes a reasonable amount of IR. In either case, the plastic or exposed photographic film can be mounted to the front of a piece of opaque plastic tubing, which can then be slid over the front of the camera lens assembly. Better quality can be achieved with a purpose-made IR filter... the Hoya RM-72 is the usual suspect. These filters pass more IR than the simple homebrew type, I think. Removing the hot filter from a camera of this sort, and replacing it with clear glass would greatly increase the IR sensitivity and allow for much shorter exposures (you'd still need an RM-72 or similar). Removing the hot filter, and replacing it with a piece of IR-pass filter glass would convert the camera to a high-sensitivity IR-only camera... which is what several commercial camera shops can do for you, for a significant fee. -- Dave Platt AE6EO Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
Infrared photography
On 2008-09-26, James Silverton wrote:
[...] I haven't got the nerve (or ability, probably) to perform surgery on a camera but how expensive a camera do you need for IR photography? I have been impressed by the artistic quality of many IR photographs but not their sharpness and those were taken with conventional film cameras. IR rays come to a focus further from the lens than visible rays do, so after visually focusing you need to adjust the distance setting on the lens to compensate for the difference [1]. But if your IR-passing filter isn't restricted to a narrow waveband, there will still be some IR rays with much longer wavelength than others getting through to the film/sensor and they won't all be focused at a single point. Normal camera lenses are designed to overcome this 'chromatic aberration' for visible wavelengths, but they don't do it for UV or IR. So IR pictures are seldom as sharp as those the same equipment can make using only visible light. Using a small aperture can help a little - at the cost of a longer exposure, of course. [1] Some lenses have an IR focus index as well as the visible-light one; after focusing visually, move the focusing ring so that the distance next to the usual focus index is next to the IR one instead. If there isn't an IR index, use the 'closer' depth of field indicator for f/5.6. Of course with an auto-focus-only or fixed-focus compact camera, you're stuck with what the camera does, which will be 'wrong' - but the large 'depth of field' that goes with a tiny sensor might offset the problem somewhat. -- -- ^^^^^^^^^^ -- Whiskers -- ~~~~~~~~~~ |
Infrared photography
On Fri, 26 Sep 2008 07:45:14 -0700, DaveC wrote:
I'm unclear whether you hacked your camera. Did you remove the IR filter from the image sensor? Or did you just add IR filters to your lens? No need to remove any internal filter or hack these cameras. Just screw-on standard IR filters to the front of the lens to cut out any visible light. They come with a built-in infrared photography mode in them. Along with the usual use for a digital camera, these were designed with their "Night Shot" mode. When you turn the switch to that mode the camera flips its internal IR filter out of the way, the one that everyone else has to hack out of their camera and end-up destroying it for normal photography. The camera then readjusts the focusing distance to account for IR wavelengths only and turns on some high-power IR LEDs in front to illuminate subjects in the dark. You can then see, photograph, and video-record in the total dark with it. I recall during a night-hike one time that my headlamp batteries went out so I used my Sony camera like a night-vision scope to find my way down a precarious outcrop of rock. Looking through the camera's viewfinder for my next safe perch to land on. These are also the only cameras that can quickly auto-focus in complete dark. Along with their "Night-Shot" mode they also have what is called their "Night Framing" mode. It uses the IR mode with its IR LED floods for you to focus and frame a shot in the total dark, undetected, but then fires the flash for properly exposed full-color images. I also obtained two inexpensive (~ $30-$40 USD) high-power IR floods that Sony sells for their "Night Shot" capable digicams and videocams. Model # HVL-IRM. They attach to the hot-shoe but also come with an extender plate so you may attach it to the tripod socket and have it alongside of instead of on top of the camera, or use it to stack/gang more than one. They use the same Li-Ion battery as used in the camera or you can use 2 AAs with them, a switch on the IR flood to select which power source you want. A full charge, when using either battery source, seems to last forever. They also have a continuous adjustment dial for how much IR light level you want. I use those two floods (along with the camera's built-in IR LEDs) to photograph and take videos of nocturnal wildlife from as far away as 60 ft. in the total dark. The animals see and hear nothing while being recorded but you can see your subject clearly in the viewfinder by the IR light alone. It's the only way to photograph and take video of nocturnal wildlife without your presence changing their natural behavior. If you put the ISO mode to Auto then when in "Night Shot" mode the camera will crank up the gain to ISO3200 when needed. It is grainy but perfectly acceptable for an IR night photo. It looks like using high ISO film. Images at ISO3200 also clean up very nice with good noise-removal software. Since it will be a B&W image when done any color noise is averaged out. You can of course still use all the manually set low ISOs too for noise-free IR images at night. You would use ISO100 or 200 for daytime IR photography. One interesting aspect of IR photography that I didn't know. I was photographing some vast forest fires in the Rocky Mountains. The haze from the smoke for hundreds of miles was making seeing the tops of any distant mountains impossible during the many weeks that we were camping/hiking/kayaking in the area. Putting on that filter-stack on my Sony camera, clicking the camera into "Night Shot" mode in the daytime, I could then look through the camera's viewfinder to see all the invisible distant mountain-tops and glaciers right through all that dense haze. Appearing just as crisp and clear as if there were no fires. It was pretty neat to be able to see what nobody else could see at the time. It afforded some unique images that nobody else could get. Photos of the forest fires right along with the usual majestic mountain scenery and glaciers. Everyone else was just getting shots of fires, dense smoke, and nearby hazy hills that could have taken place nearly anywhere on the planet. My photos clearly showed where these fires were. They also look all the more artistic and interesting with the mountain peaks towering over their immense fires below. While hunting on the net just now for something, I notice that this year's Sony Cybershot DSC-H50 also has "Night Shot" mode in it, for about $350. Clipped from that page online: Sony Cyber-shot DSC-H50 Digital Camera (Black) 9.1 Megapixel 15x Optical Zoom 3.0" Tilt-up LCD Display Super SteadyShot Image Stabilization Face Detection with Smile Shutter High Sensitivity (ISO 3200) NightShot Infrared System HDTV Compatibility |
Infrared photography
In article ,
Whiskers wrote: [1] Some lenses have an IR focus index as well as the visible-light one; after focusing visually, move the focusing ring so that the distance next to the usual focus index is next to the IR one instead. If there isn't an IR index, use the 'closer' depth of field indicator for f/5.6. Of course with an auto-focus-only or fixed-focus compact camera, you're stuck with what the camera does, which will be 'wrong' - but the large 'depth of field' that goes with a tiny sensor might offset the problem somewhat. it depends on the camera. a compact digicam which focuses off the sensor itself won't be 'wrong' if there's a bandpass filter in the optical path. |
Infrared photography
On 2008-09-26, nospam wrote:
In article , Whiskers wrote: [1] Some lenses have an IR focus index as well as the visible-light one; after focusing visually, move the focusing ring so that the distance next to the usual focus index is next to the IR one instead. If there isn't an IR index, use the 'closer' depth of field indicator for f/5.6. Of course with an auto-focus-only or fixed-focus compact camera, you're stuck with what the camera does, which will be 'wrong' - but the large 'depth of field' that goes with a tiny sensor might offset the problem somewhat. it depends on the camera. a compact digicam which focuses off the sensor itself won't be 'wrong' if there's a bandpass filter in the optical path. Well, I can imagine an auto-focus system based on signals from the image sensor itself getting focus 'right' for IR if that's all the sensor is getting. Do many, or any, compacts use that approach to auto-focus? (My Samsung Digimax V700 appears to use a near-IR 'electronic rangefinder' external to the image optics). Is http://electronics.howstuffworks.com/autofocus.htm no longer accurate? -- -- ^^^^^^^^^^ -- Whiskers -- ~~~~~~~~~~ |
Infrared photography
In article ,
Whiskers wrote: Well, I can imagine an auto-focus system based on signals from the image sensor itself getting focus 'right' for IR if that's all the sensor is getting. Do many, or any, compacts use that approach to auto-focus? (My Samsung Digimax V700 appears to use a near-IR 'electronic rangefinder' external to the image optics). Is http://electronics.howstuffworks.com/autofocus.htm no longer accurate? it doesn't appear that it ever was particularly accurate. it describes passive versus active, but only mentions contrast detection for passive and cites an slr as an example. unfortunately, slr cameras use phase detection autofocus, not contrast detection. since an slr has a separate optical path for autofocus (via a semi-silvered mirror), there may be a focus error with infrared. as for the digimax, i don't have that camera but from a brief look at dpreview, it looks like it uses contrast detection off the sensor, just as other compact digicams do, not a separate rangefinder. here's a more detailed article: http://en.wikipedia.org/wiki/Autofocus |
Infrared photography
On 2008-09-26, nospam wrote:
In article , Whiskers wrote: Well, I can imagine an auto-focus system based on signals from the image sensor itself getting focus 'right' for IR if that's all the sensor is getting. Do many, or any, compacts use that approach to auto-focus? (My Samsung Digimax V700 appears to use a near-IR 'electronic rangefinder' external to the image optics). Is http://electronics.howstuffworks.com/autofocus.htm no longer accurate? it doesn't appear that it ever was particularly accurate. it describes passive versus active, but only mentions contrast detection for passive and cites an slr as an example. unfortunately, slr cameras use phase detection autofocus, not contrast detection. since an slr has a separate optical path for autofocus (via a semi-silvered mirror), there may be a focus error with infrared. I'm a mechanical type - I understand how a traditional manual-focus SLR works, and I prefer to use a manual range-finder camera because not only do I understand how that works, but also I can actually see it working (my eyesight doesn't go well with SLR viewfinders). I use a point-n-shoot autofocus digicam, but I don't like not being able to focus quickly and accurately for myself, as I can with my beloved (but bulky) range-finder cameras. as for the digimax, i don't have that camera but from a brief look at dpreview, it looks like it uses contrast detection off the sensor, just as other compact digicams do, not a separate rangefinder. It isn't clear from the user manual; the specification only says 'through the lens autofocus' but there is also an 'autofocus lamp' on the camera body. Perhaps that is only there to ensure sufficient illumination for the TTL 'contrast detection' system to work? here's a more detailed article: http://en.wikipedia.org/wiki/Autofocus That certainly reads better than the 'howstuffworks' article. -- -- ^^^^^^^^^^ -- Whiskers -- ~~~~~~~~~~ |
Infrared photography
In article ,
Whiskers wrote: It isn't clear from the user manual; the specification only says 'through the lens autofocus' that's the key. it's off the sensor, not something separate. but there is also an 'autofocus lamp' on the camera body. Perhaps that is only there to ensure sufficient illumination for the TTL 'contrast detection' system to work? yep. |
Infrared photography
If you want to make simple, you could just buy a camera designed for IR.
Personally, I use the Fuji IS-1. By design, it is sensitive to both visible and IR light; you select the spectrum you want and just put on an appropriate filter. It will work pretty well up to 1000nm IR filter or any of the 87 series, or you can do false-color IR using near-IR or visible red or orange filters. -- is Joshua Putnam http://www.phred.org/~josh/ Updated Infrared Photography Gallery: http://www.phred.org/~josh/photo/ir.html |
Infrared photography
In rec.photo.digital DaveC wrote:
| I want to photograph and video in infrared mode. I'd like to know the spectral range possibilities of various sensors, both in how long they can go for IR, and how short they can go for UV (assuming the filter on the sensor is removed or replaced). I have heard figures of 1000nm and 1200nm for IR, but no figures for UV. Are there cameras with special sensors that go well beyond what normal cameras intended for the visible spectrum can do? -- |WARNING: Due to extreme spam, googlegroups.com is blocked. Due to ignorance | | by the abuse department, bellsouth.net is blocked. If you post to | | Usenet from these places, find another Usenet provider ASAP. | | Phil Howard KA9WGN (email for humans: first name in lower case at ipal.net) | |
Infrared photography
|
Infrared photography
In rec.photo.digital carlislestamford wrote:
| UV is a whole other beast to contend with. Most optical glass in nearly all | camera lenses is a good absorption filter for many UV wavelengths. Even the | micro-lens array and Bayer-filter on the sensor is a UV blocking filter to some | extent. Imaging most of the UV bandwidths requires special and EXPENSIVE lenses | that will allow transmission of UV to any electronic sensor. Short-wave UV | transmission is totally obliterated by nothing more than a layer of flint or | crown-glass as thin as the material in a drinking-glass or standard | daylight-filter. In high-resolution UV photomicroscopy, for example, it requires | specialty lens elements made of hard pure-quartz and soft fluorite, throughout | the whole light-path, from subject to recording medium. Due to the high melting | point of pure quartz and the difficulty in figuring soft (and easily | moisture-destroyed) fluorite into the right curves (the reason L-Glass lenses | are so expensive) you aren't going to easily obtain camera lenses that can | transmit a wide bandwidth of UV with most consumer's bank-accounts. Most CCD | cameras will be somewhat sensitive to the long-wave UV spectrum, but only some | of it. Limited by the very optics that are a part of all white-light-imaging | lens assemblies. Long-wave UV, yes, you can reach into that bandwidth somewhat | successfully with standard lenses and common CCD sensors, but don't even think | about imaging in the short-wave UV spectrum with any of the standard glass lens | elements available on the market. Even L-Glass lenses are incapable for this use | because they are a mixture of more-common glasses elements plus fluorite | elements. The standard flint and crown glass components (as archaic examples | only, there are hundreds, if not thousands of modern glass recipes) will quickly | filter-out any short-wave UV that the L-Glass lenses' few fluorite elements | might pass. What about plastic lenses we ordinarily would scoff at? There are some better quality plastic materials these days. Maybe it could be a semi-useful, even if not the best quality, lens specific for shorter UV that you could ever hope to get out of glass, without having to mess with quartz. -- |WARNING: Due to extreme spam, googlegroups.com is blocked. Due to ignorance | | by the abuse department, bellsouth.net is blocked. If you post to | | Usenet from these places, find another Usenet provider ASAP. | | Phil Howard KA9WGN (email for humans: first name in lower case at ipal.net) | |
Infrared photography
|
Infrared photography
In rec.photo.digital carlislestamford wrote:
| There is not a large outcry for UV and IR capable cameras. I would be first in | line to buy an inexpensive tri-bandwidth (IR, Vis, UV) performer, but I'm the | exception rather than the rule. I wish my camera to be able to image in all the | frequencies that could be captured by a CCD array. As well as record audio from | sub-sonic to ultra-sonic frequencies. Your average person has no concern over | what they can't see nor sense, out of sight -- out of mind. They have no | curiosity about something that is beyond their crippled perception of reality. Many years ago I was actually thinking about a design for "an antenna camera" to produce some rough imaging of RF frequencies. It would, of course, have to be a huge array to get anything approaching a "picture" below the microwave frequencies. It might be interesting to do this from a distance "looking" at the downtown area of a major city, and merge the 124000000nm to 120000000nm view with the 700nm to 400nm view to see all the wifi radiation spots. -- |WARNING: Due to extreme spam, googlegroups.com is blocked. Due to ignorance | | by the abuse department, bellsouth.net is blocked. If you post to | | Usenet from these places, find another Usenet provider ASAP. | | Phil Howard KA9WGN (email for humans: first name in lower case at ipal.net) | |
| All times are GMT +1. The time now is 07:15 AM. |
Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
PhotoBanter.com