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Canon 6D mod - full spectrum filter or no filter at all?

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#1 Thomas Ashcraft

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Posted 12 July 2019 - 06:32 PM

Is there a difference in color receptivity between a modded Canon 6D which has had its infrared blocking filter removed and one that has an Astrodon full spectrum filter installed?

 

Would one or the other show good natural blues or purples?  Thanks in advance. 

 

Does having the astrodon filter installed reduce dust specks?  Thomas


Edited by Thomas Ashcraft, 12 July 2019 - 06:35 PM.


#2 Jerry Lodriguss

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Posted 13 July 2019 - 01:24 AM

Is there a difference in color receptivity between a modded Canon 6D which has had its infrared blocking filter removed and one that has an Astrodon full spectrum filter installed?

 

Would one or the other show good natural blues or purples?  Thanks in advance. 

 

Does having the astrodon filter installed reduce dust specks?  Thomas

1. Probably not much difference for bandpass between no filter and a full-spectrum. You would have to look at the transmission curves to be sure. But there will be a lot of difference between the modded camera and a stock unmodded camera in terms of color, especially any color that has any red in it. And none of your color temp settings will work, including auto, with a modded camera. You will have to shoot a custom white balance.

 

2. No. "Natural" color for blue and purple are not going to be accurate either way because you will have more red in those colors (that is the point of the mod, to record more red from Ha emission nebulae).  If color accuracy is the most important thing, then don't use a modified camera. 

 

3. No. if you have dust, it's either going on the replacement filter, or the sensor cover glass.

 

You will have to shim the sensor if you remove the filter and don't replace it with anything, if you want autofocus to work.

 

And with both - no filter, or a full-spectum filter, you're going to have to use a UV-IR blocker with refractive optics (anything with a lens, like a camera lens or refractor) or you will get star bloat from unfocused far red and blue wavelengths.

 

Really, you remove the filter or put a full-spectrum filter to get better transmission of the red Ha emission wavelength.  You don't get any more visible blue from the mod.

 

Jerry


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#3 the Elf

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Posted 13 July 2019 - 03:06 AM

The mod allows for daylight IR photography. This is mono modded T3i with the Hoya R72 on a Canon 35mm f/2:

 

IMG_6019.JPG

 

Not an answer to your question but perhaps something you like to play with at daytime. It never came to my mind until the guy who modde the camera for me posted such images taken with my camera. The filter was available for half price, must be a sign from the gods I thought...


Edited by the Elf, 13 July 2019 - 03:08 AM.

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