IR sources

In article , David J.
Littleboy wrote:

I seem to recall that one of the services claims to be able to remove the
Bayer filters as well.

someone on dpreview claims he's bleached the colour filters.

I was originally somewhat interested in that idea for
B&W photography, but I found that the red channel from a demosaiced Bayer
image has a lot more detail in it than the number of red pixels would have
one think it would. My opinion remains that the Bayer filter/demosaicing
trick should be rated the most incredibly brilliant and greatest idea of the
20th century. OK, maybe second to the transistor. But way up there. It's
flipping amazing.

yes it is, and it's amazing how so many people don't understand that,
or how it works.

Savageduck wrote:
On 2011-05-10 08:38:32 -0700, jdear64 said:

There is an IR
filter on most DSLRs, which is a high pass filter ( blocking IR ).

Once more there is no "high-pass filter" on DSLR sensors. If anything
the IR filter might be termed a "midpass filter" this blocks mid-IR
wavelengths, but passes visible light.

I think the word you are searching for is "band-pass". But to
apply, the filter would have to block not only IR but also higher
frequencies than the wanted visible light, say UV.

Unless it does that in a reasonable way[1], it's a high-pass
filter.

-Wolfgang

[1] useful cut-off frequency, useful steepness of the
transmission-curve around that point ...

Savageduck wrote in
news:2011050819453829267-savageduck1@REMOVESPAMmecom:

On 2011-05-08 19:20:22 -0700, Rich said:

Savageduck wrote in
news:2011050219341231729-savageduck1@REMOVESPAMmecom:

On 2011-05-02 12:45:02 -0700, "Pete Stavrakoglou"
said:

"nospam" wrote in message
...
In article ,
PeterN wrote:

With digital you don't need an infrared filter. All you do is
remove the infrared filter from the sensor. It's really a simple
procedure. I converted my CoolPix but didn't feel comfortable
doing it myself. So I went to a local repair guy, who charged me
$70.

for infrared photography, yes you do.

No you don't. With one of my DSLRs I take out the removable dust
protector and I've got an IR camera.

That little rectangle of glass on the sensor might be a "dust
protector" to you, but it is in fact a "low pass" filter. Protection
from dust is secondary, but important.
The $70 your guy charged you for removal of the "Low Pass" filter is
probably a fair charge for his time and labor, but you are left with
a camera with a very dust vulnerable sensor which would still
require filters to obtain the full IR effects.

Once that is removed and not replaced with a specific IR filter on
the filter to act in a dual role for dust protection and IR
filtration.


Nonsense. The CCD is already sealed in a ceramic box with a glass
plate on top of it.

What do you mean nonsense?

That glass plate is not a clear piece of glass. it is a low pass
filter. I have cleaned enough of them to know. That is what is between
the surface of the sensor, be it CCD or CMOS. Once removed the surface
of the sensor is exposed to all the universe can throw at it.

IR conversion services usually remove that low pass filter and replace
it with an IR specific filter. That is what the IR conversion is all
about.

You might want to educate yourself before declaring something
nonsense. http://www.lifepixel.com/
in particular check their various options,
http://www.lifepixel.com/infrared-filter-choices
and since you have a D70 handy take a look at their DIY tutorial for
the D70/D70s.
http://www.lifepixel.com/tutorials/i...ls/nikon-d70-d
70s



Well, in the case of Nikon DSLR's, the AA filter and IR blocking filter
are glued to each other and are removed together. Below is the case and
glass cover above the CCD.

On 5/10/2011 10:59 PM, nospam wrote:
In articlegOmdnb2bQNy2c1TQnZ2dnVY3goSdnZ2d@giganews. com, David J.
wrote:

I seem to recall that one of the services claims to be able to remove the
Bayer filters as well.

someone on dpreview claims he's bleached the colour filters.


sounds like an attempt to get someone else to try and report back.

--
Peter