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Weird Bloom Problem - Canon 6D and Astronomik UV/IR Clip Filter

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#1 Daniel Dance

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Posted 28 July 2016 - 08:34 AM

Good morning,

 

I am having a strange blooming problem with my full spectrum 6D camera.

I recently had it modified and was doing some test shots last night and it was exhibiting some strange blooming / reflection problem.

 

INFO:

Canon 6D full spectrum

Astronomik UV/IR XL Clip Filter

Canon 24-105mm F4.0L (24mm @ 4.0L)

Exposure:  25 seconds / ISO 1600

Temp:  82 degF

 

IMAGES:
1.  The first image is a widefield shot.  Blooming is shown at the bottom left and a nasty reflection as the upper left.  I originally thought this could be do the bright LED in the foreground on my other camera set-up, but I still see the same blooming / reflection by shooting near zenith (2nd image), and also with the lens cap on.  (3rd image)

 

Anyone have any ideas on this one?

 

Thanks
Dan

bloom02.jpg

bloom01.jpg
 



#2 Daniel Dance

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Posted 28 July 2016 - 08:35 AM

bloom03.jpg Image with the lens cap on.



#3 sharkmelley

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Posted 28 July 2016 - 09:06 AM

I had the same problem with a full spectrum modified Sony A7S. It was caused by an Infrared source in the shutter mechanism. The mod had removed some shielding along with removed filters which allowed the IR to reach the sensor. The solution was to replace the shielding.

Mark

#4 Daniel Dance

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Posted 28 July 2016 - 09:19 AM

I had the same problem with a full spectrum modified Sony A7S. It was caused by an Infrared source in the shutter mechanism. The mod had removed some shielding along with removed filters which allowed the IR to reach the sensor. The solution was to replace the shielding.

Mark

 

Interesting.  That certainly  makes sense and it does get worse with increased ambient temperature.



#5 turnerjs085

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Posted 28 July 2016 - 09:21 AM

My Canon t2i does this if I shoot with the lcd display on. Try turning off live view after focusing and framing your shot?

Jeremy

#6 Daniel Dance

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Posted 28 July 2016 - 04:45 PM

Thanks for the info.  I spoke with the person who modified the camera and they suggested it could be indeed amp glow from having the liveview enabled.  I will try to duplicate the problem this evening using the settings I used last night.

Dan



#7 sharkmelley

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Posted 28 July 2016 - 05:32 PM

My Sony A7S problem looked more like a distinct "beam" of light (image taken with the body cap on the camera i.e. no lens):

 

a7s_weird_dark1.jpg

 

If, as you say, your problem is worse with higher ambient temperature then the source of your problem may well be different. 

 

By the way, when you had the lens cap on was the clip filter still in place?  Does removing the clip filter change things?

 

Mark


Edited by sharkmelley, 29 July 2016 - 12:31 AM.


#8 Jerry Lodriguss

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Posted 28 July 2016 - 08:31 PM

I am having a strange blooming problem with my full spectrum 6D camera.
I recently had it modified and was doing some test shots last night and it was exhibiting some strange blooming / reflection problem.

INFO:
Canon 6D full spectrum
Astronomik UV/IR XL Clip Filter
Canon 24-105mm F4.0L (24mm @ 4.0L)
Exposure:  25 seconds / ISO 1600
Temp:  82 degF

 

It is from the IR LED inside your lens.

 

Jerry



#9 sharkmelley

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Posted 29 July 2016 - 12:30 AM

 

I am having a strange blooming problem with my full spectrum 6D camera.
I recently had it modified and was doing some test shots last night and it was exhibiting some strange blooming / reflection problem.

INFO:
Canon 6D full spectrum
Astronomik UV/IR XL Clip Filter
Canon 24-105mm F4.0L (24mm @ 4.0L)
Exposure:  25 seconds / ISO 1600
Temp:  82 degF

 

It is from the IR LED inside your lens.

 

Jerry

 

 

That's an excellent suggestion.  It can be confirmed (or refuted) by taking an image with the body cap on the camera instead of the lens.

 

Mark


Edited by sharkmelley, 29 July 2016 - 12:32 AM.


#10 Daniel Dance

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Posted 29 July 2016 - 07:37 AM

CONCLUSION:

 

Thank you everyone for your suggestions.  It has been confirmed that the problem is due either an LED backlight or amplifier glow from the rear LCD screen.  With live view enabled, the LCD screen remains off even during the shutter exposure, except it goes to black.  With light adapted eyes, you can see the LCD screen is still "on" slightly (dark subtle glow) during the exposure and that there is likely a leakage light path to the sensor area.  I don't think its amplifier glow, because the problem can be eliminated immediately by turning off the liveview.  I would suspect a thermally hot amplifier would have a much longer thermal time constant and would require a short duration to cool.

 

This was confirmed by taking shots with the live view enabled and by live view disabled right being taking an exposure with no lens and the Canon body cap installed.


Edited by Daniel Dance, 29 July 2016 - 07:38 AM.


#11 turnerjs085

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Posted 30 July 2016 - 08:05 AM

Glad you found it. The same issue drove me nuts with my t2i when I started out. Learned a lot about amp glow and thermal noise, then it occurred to me to turn off the light on the back of the camera... ;)

Jeremy

#12 Gary Honis

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Posted 30 July 2016 - 08:52 AM

Hi Dan,

 

 

..... and that there is likely a leakage light path to the sensor area.

 

As I told you by private email it is not a problem of light leaking from the display, it is amplifier glow.  I know that because it happens on camera models with articulating screens where the display is outside of the camera body, if you don't exit liveview before taking the exposure.

 

Gary


Edited by Gary Honis, 30 July 2016 - 08:53 AM.


#13 Daniel Dance

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Posted 30 July 2016 - 09:16 AM

Hi Dan,

 

 

..... and that there is likely a leakage light path to the sensor area.

 

As I told you by private email it is not a problem of light leaking from the display, it is amplifier glow.  I know that because it happens on camera models with articulating screens where the display is outside of the camera body, if you don't exit liveview before taking the exposure.

 

Gary

 

Thanks for the clarification Gary.




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