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How to tell type if Canon DSLR mod is full spectrum or LPF2

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#1 arvindsh

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Posted 26 June 2019 - 07:32 PM

Hello Experts:

I have a borrowed modded Canon T2i for imaging but the owner is unsure if the mod performed was the LPF2 or a full spectrum. Is there a quick/simple test to determine the type of mod? If full spectrum, I believe I will have to use an IR/UV cut filter for astroimaging. Right?

Thank you.



#2 Jim Waters

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Posted 26 June 2019 - 07:52 PM

Sometimes its hard to tell.  Can you post a daytime pic?  Also a night-time pic.  Can you achieve focus with a camera lens?

 

If everything has a pink tone to it it "may be" Ha Mod.  If its really extreme its likely Full Spectrum mod.  Who did the mod?

 

EDIT - The correct UV/IR Clip-In Filter will fix the problem if its Full Spectrum.


Edited by Jim Waters, 26 June 2019 - 08:14 PM.


#3 SteveInNZ

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Posted 26 June 2019 - 08:41 PM

Put it into liveview mode and point it at a remote control and press a button. A full spectrum camera will see the IR led as a bright light. A standard or astro modified won't see it (or it will be very dim).

 

Steve.


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#4 Jim Waters

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Posted 26 June 2019 - 08:54 PM

Put it into liveview mode and point it at a remote control and press a button. A full spectrum camera will see the IR led as a bright light. A standard or astro modified won't see it (or it will be very dim).

 

Steve.

Good idea...!



#5 arvindsh

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Posted 27 June 2019 - 12:32 AM

Put it into liveview mode and point it at a remote control and press a button. A full spectrum camera will see the IR led as a bright light. A standard or astro modified won't see it (or it will be very dim).

 

Steve.

 

Brilliant! This worked. Thank you Steve. Light was dim and I conclude this Gary Honis mod at the min has an IR cut filter.  Now here is the surprising part:

1. I was able to compare it with an astromodded T3i with LPF2 removed. The light was bright. I imagine the LPF1 IR cut should have blocked the light. Makes me wonder if this camera is actually full spectrum.

 

2. Also compared with unmodded 60D. The brightness was in-between the Gary Honis mod and the astro modded T3i. I would have expected the unmodded to have the same or less brightness than the T2i. Not sure what's going on. 


Edited by arvindsh, 27 June 2019 - 12:33 AM.


#6 t_image

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Posted 27 June 2019 - 01:40 PM

Brilliant! This worked. Thank you Steve. Light was dim and I conclude this Gary Honis mod at the min has an IR cut filter.  Now here is the surprising part:

1. I was able to compare it with an astromodded T3i with LPF2 removed. The light was bright. I imagine the LPF1 IR cut should have blocked the light. Makes me wonder if this camera is actually full spectrum.

 

2. Also compared with unmodded 60D. The brightness was in-between the Gary Honis mod and the astro modded T3i. I would have expected the unmodded to have the same or less brightness than the T2i. Not sure what's going on. 

Wavelength cut off filters have specific cut-off points.

But do you know the wavelength range of the IR LED in the remote? It seem you are operating on the assumption that the LED light in the remote is only producing wavelength above _nm, say 720 or the like. But is this true?

Many IR LEDs leak visible light as well.

 

If you had an IR pass filter with a know cut-off spectral chart,

then you could put it in front of the remote,

point it at your cameras,

and then research the hotmirror transmittance spectrum graphs of your cameras/filters and determine more accurately "what's going on."



#7 Samir Kharusi

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Posted 28 June 2019 - 01:14 AM

Another way of checking. A full spectrum mod is IMPOSSIBLE to white balance using Custom White Balance. If your camera has any kind of UV/IR-cut filter but passes a lot of Ha you can still white balance well enough to keep grandma happy and thus fully satisfactory for holiday snaps (you do not need any fancy color correction filter to manufacturer's original filtering). Custom White Balance is almost always satisfactory:

118161458.jpg

 

All above have the white post eye-dropper white balanced. Left to right: unmodded camera, full spectrum mod but with a UV/IR blocker passing Ha through, LPS-P2 filter, CLS filter, full spectrum with no filter. The excessive IR in the last is what makes it impossible to color balance no matter how hard you try with the Custom White Balance.




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