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Seeing the word through a rose-tinted webcam?

Posted: Fri Jun 17, 2016 7:12 am
by rwilkinson
One of our members had been having trouble with a webcam which he'd converted for astrophotography, by fitting it into a 1.25" nosepiece, along these lines:
http://dslrmodifications.com/lifecam/lifecam1.html
But after the modification he found that he couldn't get sensible colours out of the camera.

Fortuntately, just before he slung it in the bin, he gave it to me to look at.
So I fitted it on the back of my 70ED 'scope and pointed it at some foliage in the garden:
noir.jpg
The view through the unfiltered CCD
noir.jpg (15.4 KiB) Viewed 3499 times
Not a pretty sight!

No matter where I set the white-balance slider, the colours were dominated by the red end of the spectrum - which gave me an idea. Looking into the front of the camera, I could see the unprotected CCD sensor, without the usual pink sheen of an IR-blocking filter.
So I screwed one of these filters http://www.telescopehouse.com/revelatio ... -1-25.html onto the front of the nosepiece and took another picture:
irfiltered.jpg
Looking at the same subject through an IR-blocking filter
irfiltered.jpg (15.25 KiB) Viewed 3499 times
Note that as well as giving a horrible colour-cast, the lack of filter would also give a blurred image of astro subjects through refracting telescopes, since they focus IR into a different plane than visible light.

Re: Seeing the word through a rose-tinted webcam?

Posted: Fri Jun 17, 2016 8:06 am
by bbones
Well it was me.....

I'm convinced that I had tested it in daylight and used it for recording video from Jupiter, but being honest I carn't remember.

As I can not find the IR filter I took out I'm going to get the one recommended by Ross.

Bill