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It is for the same reason that chromatic aberration occurs at all: different wavelengths of light will bend at slightly different angles when passing through the same refractive medium such as a lens element. Chromatic aberration in most well designed photographic lenses will be less severe because the lens has been designed to correct for it at the various ...


27

"Colour" is essentially a property of the distribution of wavelengths of visible light (as perceived by humans). Digital cameras only detect the amount of light at each pixel, they can't measure the wavelength and thus can't record colours directly. Colour images are produced by placing alternating red/green/blue filters in front of each pixel. By placing a ...


18

that purple haze is probably a color cast caused by the glass itself; the welders glass often isn't neutral color. you should be looking at solar filters, or very dark (and probably stacked) ND filters. Thousand Oaks sells solar filters, to name one company.


18

If you only see the effect when the D7500 is turned on but not when the camera is turned off you are almost certainly seeing near-infrared light recorded by the camera taking the photo. It's fairly common for most digital cameras to record such light. The easiest example I can think of are the near countless photos people have posted in various forums of an ...


17

The image we can see from an infrared camera is what is known as a false color image. What this means is that a range of wavelengths in the infrared spectrum are rendered with a corresponding wavelength of visible light. Just as with visible light, a particular wavelength of infrared light can vary in intensity from just above black (shadows) to near ...


16

The ideal lens would cause light beams of every color to come to a focus at the same distance from the lens. That would be the focal length of the lens when the lens is imaging at infinity (∞ as far as the eye can see. When we image objects that are closer than infinity, they come to a focus further away from the lens. That is why we must cause the camera ...


13

Lenses certainly are not optimised for the infra-red spectrum. I know this from pursuing infra-red photography with a converted camera. Chromatic aberration (well wavelength specific aberration, infrared light has no colour) is much worse, resolution is lower and some lenses exhibit "hot spots" a curious type of flair that occurs in the centre of the image. ...


12

The Bayer filter passbands are designed to be make the sensor have a reasonable match to the human eye, while not costing too much. They're fairly leaky even in the visible part of their stop band, and pretty much uncontrolled in the IR. To increase their blocking in the IR a more expensive recipe in a thicker layer would be needed. The thicker layer isn't ...


11

IR light is not bent quite like visible light when it passes through the lenses. This is why you need a separate IR focusing mark in the first place. You have one IR mark for shooting at 24mm, one for 35mm and one for 50mm on this lens. Obviously, IR does not bend consistently at the various focal lengths of the lens either. Neither, strictly speaking, does ...


11

Well, I can tell you I definitely didn't take it with my Sony A7. I think Photoshop pulls the metadata when you lay the images side by side from what it can find. The visible and NIR images were taken with my converted A7. The SWIR camera is from a company that is currently working on a gallium on silicon coating process so they can use somewhat ...


10

These spots are clearly some point-like IR light sources out of focus (When I said sources it may also be some reflecting stuff). You may check that changing the f-number will change the size of the spots. You can see from the left part of the image that some of the spots are in front of the wood wall so they do not originate from the sky. One can conclude ...


9

Because of the 60Da's modification to increase IR sensitivity for astrophotography, if you plan on using the camera for regular visible-light photography, you probably should get an IR cut filter, otherwise you may experience color shifts when the sensor gathers both visible and non-visible light together (magenta cast with synthetic fabrics, and foliage ...


9

This is just the diffused light going through the welder glass. It comes from two sources: the sky and the two welder glass. (These have coplanar surfaces that allows for bouncing the light for long.) You cannot do anything with those either. You need to use optical quality filters (ND filters of high value) to achieve this effect, although then you will ...


9

Is my camera capturing infrared? Yes. All cameras are capturing some infrared. Digital cameras are particularly good at capturing IR, that's why most of them have internal filter that dims out the IR. Can this be fixed internally? No. It cannot be "fixed" at all, because it's not considered a defect. The camera likely already has internal IR filter, but ...


8

Short answer : yes you can. From your update, your NEX is in "full spectrum" mode : the sensor filter has been removed and a glass equivalent has been added to replace it (description of this operation for a NEX 6 available here : http://www.ir-photo.net/ir_nex6mod.html). As your sensor is natively sensitive to a wide range of frequency, it detects now ...


8

Run this test: Image your IR TV remote while pressing the volume up button. Can you image the IR LED outputting IR?


8

SFX200 is sensitive to light up to 740nm. The Hoya R72 blocks all wavelengths up to 720nm. So, first and foremost, you need to be aware that you are photographing a range that you can't see and your camera can't meter - and it's a very slim range at that. Ilford's Tech Info recommends increasing the exposure by 4 stops over what your meter would say when ...


7

My friend, a fast reply to your answer is that IR wavelength and brands depends only in the kind of colors you want to show in your images and the durability of the filter you want. The brand doesn't matter if you will use the filter a few times per year, so go for the cheapest you could get. But to understand the 650nm, 670nm, 720nm, 850nm, 950nm, 1000nm ...


7

Ok guys, here is an answer. It turns out that the weak point of my IR photography setup is... Zomei IR filter. I bought a high quality Hoya R72 (720 nm) infrared filter. I was shocked by the result. The first photo is made using the Hoya filter. White balance set on green leaves. The second photo is made using Zomei filter with exactly the same settings (...


7

Lenses may have different markings, which include: Lines associated with different focal lengths in various colors.  Such lenses are varifocal zooms, where the focus point changes with the focal length. This is in contrast to parfocal zooms, which maintains focus when focal length is changed. Lines associated with aperture F-numbers in various colors. These ...


6

Why do DSLRs not use infrared instead? If you used an infrared sensor to focus the lens, the image would be out of focus in the visible spectrum. The refractive index of a lens depends in part on the wavelength -- that's why a triangular prism breaks white light up into its component colors, and it's also the cause of chromatic aberration. Lens designers ...


6

Yes, infrared photography does record infrared wavelengths. Usually, a filter is used to make sure no visible light gets recorded. Sensors and films are not based on human eye, so their limitations are different. We can see the infrared light on resulting photographs because it is displayed in some other color(s) than infrared. In photography, colors in ...


6

Not really. If you want to take a hack at it, the first thing you'll need is the transmittance curves of your (presumably Bayer) color filter. Then,if you're lucky, there's an NIR wavelength at which at least two color filters have some responsivity, and those color filters have no overlap in the visible range. In such a case, you could play with sum and ...


5

The best way to shoot IR is with a modified camera, that way you are free to handhold your shots, compose through the viewfinder and focus with AF/liveview. However this requires the infraref filter to be removed and replaced with a visible light blocking filter. You are looking at $300 or so for the conversion, and it's permanent. However there is a very ...


5

The two factors to consider in an infrared filter are; the cutoff wavelength (when the filter starts to block light, which are the numbers you've listed in your question) and the sensitivity of your camera to IR. This question summarises the looks achieved by the different wavelength filters but you need to keep in mind that higher wavelengths require ...


5

There is no infrared wavelength that does not appear in sunlight. You would have to apply a filter to the sunlight, and to any ambient incandescent lighting, to be able to restrict the image to whatever is illuminated by your specific IR source. Note also that most consumer digital cameras have infrared filters in front of the sensor. However they still ...


5

It seems that with the Nikon D3 series (D3, D3x, D3s), the D4 series, the new D5, the Df, the D700, and the D7000 a small infrared emitting diode is used inside the light box while the shutter is open as part of an infrared self-diagnostic shutter monitor circuitry used to confirm shutter timing and function. When the standard IR filter is on the front of ...


5

Based on your question at Mathematica.SE I assume that you simply summed up the integer values for each pixel in the raw file, and the total was greater than what you assume to be the number of incident photons. First, how do you know what is the actual number of incident photons and are you sure your estimate is correct? Assuming that your photon count ...


5

You're not missing anything - some epic post production is pretty much always used to create digital IR images. Life Pixel is a company that does conversions, but they've also put together an extensive list of video How-To's for post. To boil it down, you need to use a program like Photoshop or Gimp and get familiar with the channel mixer. When converting ...


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