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Old Jan 15, 2016, 5:40 PM   #11
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Thanks guys. I don't have anything more to add ...... at this time.
..... john
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Old Jan 19, 2016, 9:44 AM   #12
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Originally Posted by TCav View Post
https://en.wikipedia.org/wiki/Infrared_photography
You're not doing IR photography if you just remove the IR blocking filter, or you remove the IR filter and the Bayer Filter but don't use an IR Passing Filter.

But the camera will still produce color images because it will still presume that the Bayer Filter is in place and providing color information. Converting the images to B&W will get rid of the false color.
Further to TCav's comment, I believe that people use a piece of exposed film to act as an IR passing filter of sorts. Exposed film (like the scrap at the start of the roll that starts out exposed) will filter out all visible light leaving only (mostly) IR.
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Old Jan 19, 2016, 12:29 PM   #13
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Hi Conor,
Yes, I'm aware of that trick. I hear that E6 (colour slide film) is best, apparently unexposed and developed. But I'm not sure I want to fork out the money for a roll of film and developing, probably $40, on a whim. (I've tried many other diy remedies for this problem, that didn't work.) The two cameras that I took the IR block filters out of produce images that have a strong magenta cast and are in colour.
But here's the real question that plagues me. I have a Cybershot F717 which produces infra-red images, if a switch is thrown (that apparently moves the IR block filter out of the light path). Now, these images have only a very light green cast, and NO colour. Why don't they show the heavy magenta cast (and colour images) that the other cameras show when their IR block is removed. I just don't get it. I've been told that all the F717 does to produce IR images is move the IR block out of the light path. Of course the F717 is crippled for daylight use, in IR mode, otherwise I wouldn't be messing around with removing the filters from other cameras.
Thanks for reading this catharsis.
..... john
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Old Jan 20, 2016, 11:51 AM   #14
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I have a Cybershot F717 which produces infra-red images, if a switch is thrown (that apparently moves the IR block filter out of the light path). Now, these images have only a very light green cast, and NO colour. Why don't they show the heavy magenta cast (and colour images) that the other cameras show when their IR block is removed.
My *guess* is that the cameras that show a red cast have an inefficient filter system and some of the visible (red) light near the end of the spectrum is getting though (or all the visible light is getting through)... and on your camera that doesn't show colour, the filters are more precise and are doing a better job of filtering out the visible light.

i.e., My *guess* is that the F717 has a filter for the visible light when the switch is thrown (swapping from an IR filter to a VL filter)... but I have no way of knowing for sure.
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Old Jan 20, 2016, 2:32 PM   #15
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The infrared setting on the F717 is what Sony called 'night shot' mode. It switches out the IR filter and sets the sensitivity to maximum in order to use the IR illuminator built in to the camera. The green cast seems to be something to give the photos the same appearance as night vision scopes.
I don't think you can fit standard filters to the F717, but if you could, or could adapt them, a ND filter might give you what you're looking for.
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Old Jan 20, 2016, 6:02 PM   #16
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Hi Conor,
"My *guess* is that the F717 has a filter for the visible light when the switch is thrown (swapping from an IR filter to a VL filter)... but I have no way of knowing for sure."
Yes, well, you may be right, but that's not what people who have opened this camera to remove the IR block have said. I may have to open her up and have a look.
Hi VTphotog,
I can fit any external filter that I want onto the F717 ..... it has a 58 mm thread. Right now I have a double polarizer on it in order to reduce the brightness to where I can shoot in full sunlight, within the 1/8th to 1/60th second exposure restriction. I've entertained removing the IR block filter, so that I can shoot with no restriction (using the colour modes), but those who have done it say that it's necessary to replace it with glass of exactly the same thickness, or it won't focus properly. So .....
.... john
P.S. Right now I'm on the Public Infragram forum trying to find out how I can modify the point and shoots from which I have removed the IR filter; and they're saying that I have to add a filter (Wratten 87, or developed colour film) that will remove the colour cast and visible colour from the images. So, I'm looking into that.

Last edited by Shinnen; Jan 20, 2016 at 6:11 PM. Reason: addendum
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Old Jan 21, 2016, 12:33 PM   #17
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P.S. Right now I'm on the Public Infragram forum trying to find out how I can modify the point and shoots from which I have removed the IR filter; and they're saying that I have to add a filter (Wratten 87, or developed colour film) that will remove the colour cast and visible colour from the images. So, I'm looking into that.
Best of luck, I'm curious to hear how this goes!
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Old Jan 21, 2016, 2:08 PM   #18
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Here is a page with IR filters that could be a good start.:http://www.adorama.com/l/Lenses/Lens...lter-Size_58mm
The different numbers are the wavelength cutoff ((usually)R72 being 720 nanometers, etc). The R72 will probably allow some visible light, IIRC. It depends on what you want to achieve. There are some sample pictures for each filter, too, to give you an idea of what you'll get.
And a page from B&H: http://www.bhphotovideo.com/c/search...332+4294955252
If you need more confusion, just let us know. Happy to oblige.
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Old Jan 22, 2016, 9:19 AM   #19
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Hi VTphotog,
Yes, I've looked at the R72. The pictures that people shoot on line with it are pretty impressive; but it's fairly pricey. Thanks for the links. I'll have a look at them.
..... john
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