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Re: Infrared photography

 
 
Eric Stevens
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      09-26-2008
On Thu, 25 Sep 2008 07:44:25 -0700, DaveC <(E-Mail Removed)> wrote:

>I want to photograph and video in infrared mode.
>
>I understand that some point-and-shoot cameras provide this style of
>photography/videography. Alternately, some people have "hacked" a camera by
>removing the IR filter from in front of the imaging element. There are
>instructions on-line to DIY this, or to send in your P&S to have it done.
>
>Basically, the IR filter is removed and replaced with another (not a
>procedure for the faint at heart). The replacement filter is $$$.
>
>My question is this: is this replacement filter that passes rather than
>blocks IR available as a gelatin or other commonly available filter that I
>can source elsewhere other than from these camera-mod services?
>
>Or can I just strip off the existing filter and not replace it with anything?
>I'm looking for quantitative data (the existence of IR) not qualitative data
>(a pretty picture). What function does the replacement filter provide (other
>than passing IR data)?
>
>To clarify, I want to "see" IR images real-time in the viewfinder, not
>post-process the image data to reveal the IR.
>
>If there's another forum you suggest I should ask this question in, please
>let me know.


You could try picking up a Sony F707 or others of that ilk. If my
memory serves me right they do have IR capabilities.



Eric Stevens
 
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carlislestamford
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      09-26-2008
On Fri, 26 Sep 2008 17:11:35 +1200, Eric Stevens <(E-Mail Removed)> wrote:

>On Thu, 25 Sep 2008 07:44:25 -0700, DaveC <(E-Mail Removed)> wrote:
>
>>I want to photograph and video in infrared mode.
>>
>>I understand that some point-and-shoot cameras provide this style of
>>photography/videography. Alternately, some people have "hacked" a camera by
>>removing the IR filter from in front of the imaging element. There are
>>instructions on-line to DIY this, or to send in your P&S to have it done.
>>
>>Basically, the IR filter is removed and replaced with another (not a
>>procedure for the faint at heart). The replacement filter is $$$.
>>
>>My question is this: is this replacement filter that passes rather than
>>blocks IR available as a gelatin or other commonly available filter that I
>>can source elsewhere other than from these camera-mod services?
>>
>>Or can I just strip off the existing filter and not replace it with anything?
>>I'm looking for quantitative data (the existence of IR) not qualitative data
>>(a pretty picture). What function does the replacement filter provide (other
>>than passing IR data)?
>>
>>To clarify, I want to "see" IR images real-time in the viewfinder, not
>>post-process the image data to reveal the IR.
>>
>>If there's another forum you suggest I should ask this question in, please
>>let me know.

>
>You could try picking up a Sony F707 or others of that ilk. If my
>memory serves me right they do have IR capabilities.
>
>


Correct, the Sony F707, F717, F818, H3(?), and H9 all have this capability, and
they all do it very well. Real-time hand-held IR photography and videos are a
feature of all of them. No need to hack or alter any camera, just flip a switch
to their "Night-Shot" mode.

According to my add-on lenses and things, I would have to go with a 62mm filter
size to make it the most adaptable to the most situations (including for use
with my 35mm film gear). When looking at IR filters I was shocked at the prices
so I went in search of an affordable alternative.

The Kodak Wratten Gel Filters come in 3"x3" sizes. I could cut one of those up
into a circle and put it inside of an inexpensive filter-ring holder. But
they're prone to water-damage, humidity, etc. And they're still about $25-$30
depending where you get them, that's probably not worth the hassle and care for
the few dollars savings.

Then I found some 3"x3", Lee Polyester IR filters at B&H for only $14. Durable,
worth the cost for an experiment. I didn't want near-infrared, I wanted infrared
only, so I opted to go with the Wratten #87. $14 for the filter, and $10-$15 for
a cheap skylight filter (to dismantle for the mount, I couldn't find a source of
empty filter-ring holders), and I'd be good to go for under $30. If you have an
old filter that you can dismantle for the filter-ring, more power to you, then
you can get into IR photography for only $14.

Here's those Lee filters at B&H Photo & Video if anyone else wants to go this
route:

http://www.bhphotovideo.com/bh4.sph/...ID=F5261AD1470

Normally a decent IR filter of the size needed can run you upwards of $70-$130,
you can see the kind of savings attained by doing it this way.

A problem with all these Sony cameras is that Sony stupidly listened to some
sexually-insecure puritanical idiots at one point and crippled the shutter
speeds and apertures that may be used in their Night-Shot mode. They were
concerned that some people were using them to shoot through certain swim-wear
fabrics at the beach, fabrics transparent to IR. For daylight IR photography you
have to lower the IR levels to those required for shooting in the dark. I
experimented and found out that a Wratten Green filter (for b/w photography)
lowered the levels just right. I found an inexpensive Hoya G (XI). In total you
are using a two filter stack, IR + Wratten Green.

One other thing, you have to make a rubber gasket to cover up Sony's own IR
emitters in the lens housing, that the camera uses to take photos in complete
darkness. Otherwise the IR from those bounces off the back of the filter stack
and into your lens, ruining your shots with nasty light reflection artifacts in
the glass layers.

Here's a quick sample of a hand-held daylight IR shot from one of these cameras

http://farm4.static.flickr.com/3085/...e6058929_o.jpg

 
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carlislestamford
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      09-26-2008
On Fri, 26 Sep 2008 07:45:14 -0700, DaveC <(E-Mail Removed)> wrote:

>
>I'm unclear whether you hacked your camera. Did you remove the IR filter from
>the image sensor? Or did you just add IR filters to your lens?


No need to remove any internal filter or hack these cameras. Just screw-on
standard IR filters to the front of the lens to cut out any visible light. They
come with a built-in infrared photography mode in them. Along with the usual use
for a digital camera, these were designed with their "Night Shot" mode. When you
turn the switch to that mode the camera flips its internal IR filter out of the
way, the one that everyone else has to hack out of their camera and end-up
destroying it for normal photography. The camera then readjusts the focusing
distance to account for IR wavelengths only and turns on some high-power IR LEDs
in front to illuminate subjects in the dark. You can then see, photograph, and
video-record in the total dark with it. I recall during a night-hike one time
that my headlamp batteries went out so I used my Sony camera like a night-vision
scope to find my way down a precarious outcrop of rock. Looking through the
camera's viewfinder for my next safe perch to land on.

These are also the only cameras that can quickly auto-focus in complete dark.
Along with their "Night-Shot" mode they also have what is called their "Night
Framing" mode. It uses the IR mode with its IR LED floods for you to focus and
frame a shot in the total dark, undetected, but then fires the flash for
properly exposed full-color images.

I also obtained two inexpensive (~ $30-$40 USD) high-power IR floods that Sony
sells for their "Night Shot" capable digicams and videocams. Model # HVL-IRM.
They attach to the hot-shoe but also come with an extender plate so you may
attach it to the tripod socket and have it alongside of instead of on top of the
camera, or use it to stack/gang more than one. They use the same Li-Ion battery
as used in the camera or you can use 2 AAs with them, a switch on the IR flood
to select which power source you want. A full charge, when using either battery
source, seems to last forever. They also have a continuous adjustment dial for
how much IR light level you want. I use those two floods (along with the
camera's built-in IR LEDs) to photograph and take videos of nocturnal wildlife
from as far away as 60 ft. in the total dark. The animals see and hear nothing
while being recorded but you can see your subject clearly in the viewfinder by
the IR light alone. It's the only way to photograph and take video of nocturnal
wildlife without your presence changing their natural behavior. If you put the
ISO mode to Auto then when in "Night Shot" mode the camera will crank up the
gain to ISO3200 when needed. It is grainy but perfectly acceptable for an IR
night photo. It looks like using high ISO film. Images at ISO3200 also clean up
very nice with good noise-removal software. Since it will be a B&W image when
done any color noise is averaged out. You can of course still use all the
manually set low ISOs too for noise-free IR images at night. You would use
ISO100 or 200 for daytime IR photography.

One interesting aspect of IR photography that I didn't know. I was photographing
some vast forest fires in the Rocky Mountains. The haze from the smoke for
hundreds of miles was making seeing the tops of any distant mountains impossible
during the many weeks that we were camping/hiking/kayaking in the area. Putting
on that filter-stack on my Sony camera, clicking the camera into "Night Shot"
mode in the daytime, I could then look through the camera's viewfinder to see
all the invisible distant mountain-tops and glaciers right through all that
dense haze. Appearing just as crisp and clear as if there were no fires. It was
pretty neat to be able to see what nobody else could see at the time. It
afforded some unique images that nobody else could get. Photos of the forest
fires right along with the usual majestic mountain scenery and glaciers.
Everyone else was just getting shots of fires, dense smoke, and nearby hazy
hills that could have taken place nearly anywhere on the planet. My photos
clearly showed where these fires were. They also look all the more artistic and
interesting with the mountain peaks towering over their immense fires below.

While hunting on the net just now for something, I notice that this year's Sony
Cybershot DSC-H50 also has "Night Shot" mode in it, for about $350.

Clipped from that page online:

Sony Cyber-shot DSC-H50 Digital Camera (Black)
9.1 Megapixel
15x Optical Zoom
3.0" Tilt-up LCD Display
Super SteadyShot Image Stabilization
Face Detection with Smile Shutter
High Sensitivity (ISO 3200)
NightShot Infrared System
HDTV Compatibility

 
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