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IRND Filter
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May 15, 2022 08:49:44   #
Canisdirus
 
jcboy3 wrote:
Once again, plastic or resin ND filters do not filter IR, which for long exposures at high stops will result in IR contamination of the image.


Yes, and the newer bodies cut the IR...no difference.

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May 15, 2022 08:57:18   #
jcboy3
 
Canisdirus wrote:
Yes, and the newer bodies cut the IR...no difference.


You can keep making that incorrect statement and it won't change the facts.

You can take infrared photos using an IR filter, that cuts visible light, and a long exposure to compensate for the IR/UV filter on the sensor. If the ND filter lets infrared light through, then the image can be contaminated with infrared light if it is a high-stop ND filter. This is the case with plastic or resin ND filters; this is not the case with glass ND filters.

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May 15, 2022 09:05:04   #
rmalarz Loc: Tempe, Arizona
 
Can you provide some reference material regarding the long exposure statement?
--Bob
jcboy3 wrote:
Once again, plastic or resin ND filters do not filter IR, which for long exposures at high stops will result in IR contamination of the image.

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May 15, 2022 09:17:46   #
larryepage Loc: North Texas area
 
This discussion has been pretty comical to read. From what I can tell, everyone has missed the point entirely. I'm fairly new to IR photography and am still working to figure everything out, but from what I can tell, the purpose of an IRND filter is to allow long exposures when taking IR photographs with a properly converted IR-sensitive camera. Period.

By the way...plain glass will filter out ultraviolet light. About a quarter inch of regular window glass will remove more than 90% of it. That's why either quartz or special glass lenses or mirrors are required to capture UV wavelengths. But plain glass is completely ineffective at blocking infrared. That's why a closed car gets so hot sitting in the sun.

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May 15, 2022 09:27:56   #
User ID
 
jcboy3 wrote:
You can keep making that incorrect statement and it won't change the facts.

You can take infrared photos using an IR filter, that cuts visible light, and a long exposure to compensate for the IR/UV filter on the sensor. If the ND filter lets infrared light through, then the image can be contaminated with infrared light if it is a high-stop ND filter. This is the case with plastic or resin ND filters; this is not the case with glass ND filters.

Consider the Source

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May 15, 2022 09:33:58   #
User ID
 
Theres an enormous amount of glass in the lens, as compared to a glass filter, so how could it actually matter whether the filter is made of resin or glass ???

OTOH if glass blocks IR why is there an internal IR cut filter in the camera ???

And if glass really blocks IR then how can IR photography, film or digital, even be possible at all ???

This all smells like confusion with very short wave UV which is blocked by glass and requires non glass optics such as the Zeiss quartz optics for Hasselblad.
.


(Download)

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May 15, 2022 09:40:32   #
JohnSwanda Loc: San Francisco
 
larryepage wrote:
This discussion has been pretty comical to read. From what I can tell, everyone has missed the point entirely. I'm fairly new to IR photography and am still working to figure everything out, but from what I can tell, the purpose of an IRND filter is to allow long exposures when taking IR photographs with a properly converted IR-sensitive camera. Period.

By the way...plain glass will filter out ultraviolet light. About a quarter inch of regular window glass will remove more than 90% of it. That's why either quartz or special glass lenses or mirrors are required to capture UV wavelengths. But plain glass is completely ineffective at blocking infrared. That's why a closed car gets so hot sitting in the sun.
This discussion has been pretty comical to read. F... (show quote)


That doesn't make sense to me. If you are shooting with a converted IR camera, which has had the internal IR cut filter removed, why would you use an ND filter which includes another IR cut filter?

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May 15, 2022 10:06:39   #
Canisdirus
 
larryepage wrote:
This discussion has been pretty comical to read. From what I can tell, everyone has missed the point entirely. I'm fairly new to IR photography and am still working to figure everything out, but from what I can tell, the purpose of an IRND filter is to allow long exposures when taking IR photographs with a properly converted IR-sensitive camera. Period.

By the way...plain glass will filter out ultraviolet light. About a quarter inch of regular window glass will remove more than 90% of it. That's why either quartz or special glass lenses or mirrors are required to capture UV wavelengths. But plain glass is completely ineffective at blocking infrared. That's why a closed car gets so hot sitting in the sun.
This discussion has been pretty comical to read. F... (show quote)


Correct...and newer bodies no longer need these types of filters. It's cut at the sensor...regardless f what filter is on.

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May 15, 2022 11:35:04   #
selmslie Loc: Fernandina Beach, FL, USA
 
jcboy3 wrote:
The IRND filter adds an IR cut filter to the ND filter.

If your ND filter is made of glass, it will attenuate infrared as well as visible light. An IR Cut filter will essentially elliminate infrared, but in my experience is of little use.

If your ND filter is made of plastic or resin, then it will pass infrared light and cause problems with your image. In this case, an IR Cut filter will help. ....

Preposterous and blatantly uninformed BS.

All digital cameras come with both an IR and a UV cut filter over the sensor to block IR and UV wavelengths. But no cut filter is perfect. The all leak a little of the light they are meant to block. An IR filter would block any UV and visible light but let the IR wavelengths pass.

Oddly enough, sensors can record all three colors in the IR range if the IR cut filter is not present.

An IR filter will allow almost no UV or visible light to pass wavelengths to reach the sensor hence the extremely long exposures. In order to capture IR the IR cut filter over the sensor needs to be removed.

I have had both the IR and the UV cut filters removed from an A7 II along with the Bayer array. Plenty of IR coming in now but for normal B&W photography I have to use an IR/UV cut filter over the lens.



Note the RGB colors in the IR range that are normally blocked by the IR cut filter (hot mirror) over the sensor.

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May 15, 2022 12:59:12   #
lamiaceae Loc: San Luis Obispo County, CA
 
JohnSwanda wrote:
Don't almost all current digital cameras have an internal IR cut filter? Then what is the advantage of adding it to a ND filter?


Exactly. Right in front of the sensor IR, UV, and in older and a few newer cameras an AA filter. The lens has no need to block either UV or IR for digital cameras. All sorts of filters had uses for film cameras. Sounds like a gimmick to separate photographers from their money.

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