DIY IR pass filter

[Harshad RJ]

Apparently, it is possible to create a cheap IR pass filter by using camera film:

http://www.diyphotography.net/take_infrared_pictures_with_digital_camera_ir_filter/

​When unexposed film is developed, it is opaque to visible light, but passes IR light.

Was anyone aware of it? ​I am going to try and find some dark developed ​film and go testing.

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Harshad RJ

[Karthik Subramanian]

Wow! This is an awesome find :)

I'd love to see the results of your tests!

K. 

[keerthi kiran]

Harshad,

How will you test it?

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[Harshad RJ]

On Tue, Aug 9, 2016 at 2:44 PM, keerthi kiran <info...@gmail.com> wrote:

How will you test it?

As a quick test, I am trying to find old developed negatives. Cell phone lenses are small enough to just hold a dark patch of the film over the lens​.

I can then snap vegetation in sun-light, or IR illuminate a dark room.

If that works, I will try to get film developed from a studio. The cheapest IR pass filters on amazon / ebay are Rs 1500+

Hopefully, something cheaper (and less quality) is possible.

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Harshad RJ

[Suresh Mohan Neelmegh]

But X ray film is similar to photographic film 

Sent from my iPhone

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[Abhilash .P]

Hello all,
Yep, this works. I used to dabble around with making a night vision camera and once the camera's IR filter is removed, procedure is to use film as the pass filter. Worked splendid for me!

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[Harshad RJ]

​Thanks​ Abhilash and Suresh,

I couldn't find camera film much as I tried. But I did have some Xray results and tried photographing an IR led through the darkest patch in the Xray result.

It definitely passes IR, while blocking visible light. But it doesn't pass 100% IR. More like 25% IR pass. It's still nice to have as a quick and dirty IR pass filter!

​

​I wonder if the Xray result given to patients is the "negative" or the "positive" in terms of normal camera film.​

On Tue, Aug 9, 2016 at 4:51 PM, Abhilash .P <paabh...@gmail.com> wrote:

Hello all,
Yep, this works. I used to dabble around with making a night vision camera and once the camera's IR filter is removed, procedure is to use film as the pass filter. Worked splendid for me!

On 09-Aug-2016 4:47 pm, "Suresh Mohan Neelmegh" <drsure...@gmail.com> wrote:

But X ray film is similar to photographic film

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Harshad RJ

[Arun Venkataswamy]

Harshad, this works. I have used an exposed negative inside a web cam. I put the film between the sensor and the lens to check it. BUT you have to remove the IR block filter in front of the sensor to get decent results. BTW this is same for DSLRs too - you have to remove the IR block filter in front of the sensor.

Incidentally I just received this yesterday from Aliexpress:

http://www.aliexpress.com/item/52-55-58-62-67-72-77-mm-550-590-650-650-580-720-760-850/32654179139.html?spm=2114.13010608.0.54.lWp2af

But I think I made a wrong choice by going in for the 850nm filter. My IR modified 1000D requires 3 second exposure at 800 ISO to get a decent frame under cloudy conditions. Anybody else tried these filters? Is this normal? 

Regards,

Arun

[Arun Venkataswamy]

On Tue, Aug 9, 2016 at 2:44 PM, keerthi kiran <info...@gmail.com> wrote:

Harshad,

How will you test it?

Keerthi, the best way is to point a TV remote at the camera. Magically the IR led transmitter become visible in the camera live view!

Regards,

Arun