An optics question
 

To all you optics type folks,
I am converting a camera to a full spectrum camera. This mainly
involves removing the IR blocking filter in the camera. This has been
done. But the CCD sensor needs to be kept approximately the same
distance away from the sensor in order for the autofocus to work. I
have two options. Since the filter is partly made from tinted glass
just removing the coating won't work. So another piece of glass the
same thickness could be put in the filter's place. The other option is
to make an aluminum spacer the same thickness as the filter. There is
a rubber gasket that sits on the filter and that the sensor actually
rests against. If I make a frame that is the same dimensions it would
not block any light. I will be using the camera mostly for IR, there
will be a filter at the front of the camera. Since IR light will focus
a little farther away from the lens than visible light should a spacer
be a little thicker than the filter? Or will it make practically no
difference? Since it looks like I might need to make something I might
as well as make it correctly.
Thanks,
Eric

An optics question
 

On Wednesday, April 29, 2015 at 11:50:20 AM UTC-4, wrote:
To all you optics type folks,
I am converting a camera to a full spectrum camera. This mainly
involves removing the IR blocking filter in the camera. This has been
done. But the CCD sensor needs to be kept approximately the same
distance away from the sensor in order for the autofocus to work. I
have two options. Since the filter is partly made from tinted glass
just removing the coating won't work. So another piece of glass the
same thickness could be put in the filter's place. The other option is
to make an aluminum spacer the same thickness as the filter. There is
a rubber gasket that sits on the filter and that the sensor actually
rests against. If I make a frame that is the same dimensions it would
not block any light. I will be using the camera mostly for IR, there
will be a filter at the front of the camera. Since IR light will focus
a little farther away from the lens than visible light should a spacer
be a little thicker than the filter? Or will it make practically no
difference? Since it looks like I might need to make something I might
as well as make it correctly.
Thanks,
Eric

You might try joining the forums at Cloudy Nights (astronomy forum) and asking in the DSLR forum. There are some there who have removed the IR filter from various cameras.

Jim H.

An optics question
 

On Wed, 29 Apr 2015 08:56:55 -0700, wrote:

To all you optics type folks,
I am converting a camera to a full spectrum camera. This mainly
involves removing the IR blocking filter in the camera. This has been
done. But the CCD sensor needs to be kept approximately the same
distance away from the sensor in order for the autofocus to work. I
have two options. Since the filter is partly made from tinted glass
just removing the coating won't work. So another piece of glass the
same thickness could be put in the filter's place. The other option is
to make an aluminum spacer the same thickness as the filter. There is
a rubber gasket that sits on the filter and that the sensor actually
rests against. If I make a frame that is the same dimensions it would
not block any light. I will be using the camera mostly for IR, there
will be a filter at the front of the camera. Since IR light will focus
a little farther away from the lens than visible light should a spacer
be a little thicker than the filter? Or will it make practically no
difference? Since it looks like I might need to make something I might
as well as make it correctly.

Why not just swap out the no-IR glass for an IR-only glass they use
for IR cameras? Just a WAG.

--
"I believe there are more instances of the abridgment of the freedom
of the people by gradual and silent encroachments of those in power
than by violent and sudden usurpations."
--James Madison, Virginia Convention, June 16, 1788

An optics question
 

Larry Jaques fired this volley in
:

Why not just swap out the no-IR glass for an IR-only glass they use
for IR cameras? Just a WAG

Because he stated "all spectrum", and "...be using it _mostly_ for IR..."

Lloyd

An optics question
 

On Thu, 30 Apr 2015 04:54:44 -0500, "Lloyd E. Sponenburgh"
lloydspinsidemindspring.com wrote:

Larry Jaques fired this volley in
:

Why not just swap out the no-IR glass for an IR-only glass they use
for IR cameras? Just a WAG

Because he stated "all spectrum", and "...be using it _mostly_ for IR..."

Oops!

--
"I believe there are more instances of the abridgment of the freedom
of the people by gradual and silent encroachments of those in power
than by violent and sudden usurpations."
--James Madison, Virginia Convention, June 16, 1788

An optics question
 

On Wed, 29 Apr 2015 13:46:02 -0700 (PDT), Jim Hornaday
wrote:

On Wednesday, April 29, 2015 at 11:50:20 AM UTC-4, wrote:
To all you optics type folks,
I am converting a camera to a full spectrum camera. This mainly
involves removing the IR blocking filter in the camera. This has been
done. But the CCD sensor needs to be kept approximately the same
distance away from the sensor in order for the autofocus to work. I
have two options. Since the filter is partly made from tinted glass
just removing the coating won't work. So another piece of glass the
same thickness could be put in the filter's place. The other option is
to make an aluminum spacer the same thickness as the filter. There is
a rubber gasket that sits on the filter and that the sensor actually
rests against. If I make a frame that is the same dimensions it would
not block any light. I will be using the camera mostly for IR, there
will be a filter at the front of the camera. Since IR light will focus
a little farther away from the lens than visible light should a spacer
be a little thicker than the filter? Or will it make practically no
difference? Since it looks like I might need to make something I might
as well as make it correctly.
Thanks,
Eric

You might try joining the forums at Cloudy Nights (astronomy forum) and asking in the DSLR forum. There are some there who have removed the IR filter from various cameras.

Jim H.
Thanks Jim, I think I'll take a look.

An optics question
 

On Wed, 29 Apr 2015 08:56:55 -0700, wrote:

To all you optics type folks,
I am converting a camera to a full spectrum camera. This mainly
involves removing the IR blocking filter in the camera. This has been
done. But the CCD sensor needs to be kept approximately the same
distance away from the sensor in order for the autofocus to work. I
have two options. Since the filter is partly made from tinted glass
just removing the coating won't work. So another piece of glass the
same thickness could be put in the filter's place. The other option is
to make an aluminum spacer the same thickness as the filter. There is
a rubber gasket that sits on the filter and that the sensor actually
rests against. If I make a frame that is the same dimensions it would
not block any light. I will be using the camera mostly for IR, there
will be a filter at the front of the camera. Since IR light will focus
a little farther away from the lens than visible light should a spacer
be a little thicker than the filter? Or will it make practically no
difference? Since it looks like I might need to make something I might
as well as make it correctly.
Thanks,
Eric
The camera is back together. Everything works. The autofocus may be
off. I may not be able to do anything about it because I lack a
special chart and software from Canon to make the adjustment. There is
a possibllity of adjusting the distance of the CCD to the lens
assembly because the CCD assembly is held in place with three screws
against three springs. This allows changing the proximity of the CCD
to the lens assy. I don't know if that will changing anything but I
will give it a try if need be. I'll post pictures to Dropbox when I
get some good ones.
Eric