Removal of IR Blocking Filter for a Canon 20D

cwjames · #1 02-08-2009, 07:19 PM

Hi All,

I was feeling brave last week so I done a little job that I have been putting off for weeks ! I removed the IR Blocking Filter in front of the CCD to improve the Red Spectral Response of my 20D.

All went well as the camera is still working and I am looking forward to giving it a feild trial on the next new moon, something like the Helix Nebula which I had a lot of trouble with last year due to the poor Red response of the camera.

This weekend I spent some time to document the process to remove the filter for the 20D. If anybody is considering doing this, you can access this document at the url below.

http://www.cwjames.info/astro/howto/ir_removal.htm

I will contact Mike later to see if this is something that he would like on this site as well.

I hope it helps someone in the future.

Thanks

Chris

DavidU (Dave) · #2 02-08-2009, 07:28 PM

Chris, thats a very well done document you have there.
Well done

MrB (Simon) · #3 02-08-2009, 07:37 PM

Nicely done! Will come in handy when I eventually upgrade from the 300D.
My only criticism is that the Canons don't have CCD's.

cwjames · #4 02-08-2009, 08:17 PM

Hi Simon,

Good pick up !

I have correct this by replacing CCD with CMOS Sensor.

Thanks

Chris

leon · #5 02-08-2009, 09:04 PM

Know how you feel Chris, it is a bit nerve racking

but the end result will be well worth it.

I did my own 5D some time ago

Leon

http://www.lifepixel.com/ir-tutorial...structions.htm

cwjames · #6 02-08-2009, 09:10 PM

Hi Leon,

You are even braver doing a 5D, especialy if it was a while ago when it was newer !

Did you use one of Life Pixel replacement filters so you can focus on the focus screen and sensor at the same time ?

Thanks

Chris

leon · #7 02-08-2009, 09:16 PM

Chris, no mate I got mine from a friend here on IIS who ordered them for me from a supplier he uses, I bought 3 from him.

I still have two in my astro cupboard, for the time when my other 5D runs out of warranty, so that I can have a go at it as well.

Leon

citivolus (Ric) · #8 03-08-2009, 02:02 AM

I swapped my 10D filter with the Lifepixel one a couple of years ago. You should have seen my wife's face when she walked in the room and I had the camera disassembled on my desk

The hardest part of the whole process was applying the adhesive to the new filter. I had to redo it several times, and cleaning it off of the glass when I messed up was not easy! In the end it all worked out though.

cwjames · #9 03-08-2009, 08:29 AM

Hi Citivolus,

How did you manage to clean the filter after attempting to put it in then having to remove it again.

That was one thing that put me off putting a replacement filter in, I seemed to have a lot of trouble getting the orginal filter out as the glue was very stubbon and the orginal filter was not looking very pretty at the end of it.

Glad it work out ok for you !

Chris

leon · #10 03-08-2009, 02:37 PM

Chris may I put my two cents worth in here.

Your right the glue is very hard, and you do need a very sharp Stanley Knife or similar to cut around the glued perimeter of the filter housing.

And yes again it gets messy and the original chips falls apart and so on, but you don't need that one anyway so who cares.

Once you have removed the original the actual sensor is exposed, blow any dust off it with a Giotto Hand Blower, and immediately put it into a clean plastic sandwich bag, you know, the ones you buy from the super market to put your lunch in.

This keeps the sensor clean and away from the elements until you are ready to replace the new filter into its housing.
From this point you can do what you like to get the extra crap off the filter housing to get it as clean as possible.

Leon

cwjames · #11 03-08-2009, 05:32 PM

Hi Leon,

When you put the replacement filter in, did you glue it in ?

I have been wondering why Canon glued the orginal filter in. Was it for mechanical reasons or was it to seal the dust out.

I am still gather more background facts to see if I should fit a replacement filter in the orginal position later to enable the focusing to operate in the normal manner.

I guess using the camera in the current configuration will give me a feel for it to see if I need to consider this or not. I normaly dont focus thru the eyepeice, however its good to use the eyepeice to get the scope roughly focused before using DSLR focus.

Some field work with the camera will help me decide if I need to revisit my decesion.

Thanks for the feedback

Chris

citivolus (Ric) · #12 03-08-2009, 06:57 PM

When I did the 10D, I was installing a visual block IR pass filter. I was using black RTV silicone as my adhesive, and got some on the glass when installing. I unfortunately had to remove it, and clean it with solvent. I think I used mineral spirits to remove the uncured silicone. I actually had to do that twice due to my twitchy hands, but it didn't damage the glass or coatings fortunately. I made sure to leave it a few days before installing it so that there would be no off-gassing in the camera.

Had I followed the proper procedure in the first place and applied the silicone using a fine point, this would not have been an issue.

Regards,
Eric