Re: Sony DSC-V3 for daytime infrared
- From: slidetbone@xxxxxxxxx
- Date: Sat, 22 Sep 2007 18:42:29 -0700
Ok, I got my hands on a DSC-V3 that had a bad lens assembly. The
previous owner really tore into the lens assembly, which is now
useless. But it gave me the chance to look at the mechanics of the
"Nightshot" function. Reading Macona's claim and after reading the
article on modifying a DSC-717 at http://www.pbase.com/nh/image/74486953,
I wonder now how he is managing to focus the camera correctly since
the hot mirror stage assembly on the V3 is very similar to the 717's
http://www.pbase.com/nh/image/74527713 and it does state that without
it, the camera optical circuit will not compensate for the refractive
loss of the hot mirror while in normal modes, making focusing to
infinity impossible. It's placement is between the lens and the CCD,
just like the 717's.
At first, I thought it would be easiest to open the circuit with a
small switch ( based on the fact that I do not have the schematic and,
like you, I had no way to ID the SO-8 H-bridge chip or the
pinouts...lazy, I guess LOL). Activate the Nighshot mode, open the
switch on the solenoid's circuit, then cycle to the normal mode, which
would leave the hot mirror in the Nightshot position. This should
allow IR shooting in the full color modes and with full aperture/
shutter control. So I would have thought...until I read
http://www.pbase.com/nh/image/74486953 :
=====================================================================================
The original hot mirror (left) is a small piece of optical glass, size
11 x 13 x 1.2 mm.
I replaced it with a special optical window that transmits light from
+/- 300 to 2000 nm,
instead of just 400-700 nm for the standard Sony hot mirror. After
modification the F717
will record images with light from +/- 350 - 1100 nm (the sensor/glass
combination will
not work outside this range). This range includes most of the near-
infrared spectrum.
It is VERY important to replace the hot mirror with another optical
window with the same
dimensions (especially thickness, the tolerance is about 0.02 mm) and
refraction index,
otherwide the camera will no longer be able to focus (especially at
infinity /wideangle).
If you do not replace the original hot mirror with anything, the
camera will only focus
in Nightshot mode (this is because the optical window is part of the
optical system).
You can try to make your own window from a microscope slide or other
piece of optical
glass grinded to specifications, but it will require a lot of trial
and error because the
window must be perfectly flat. If it is too thick, it will probably
not fit in the stage
(maximum thickness is about 1.3 mm). Note: microscope slides have no
AR coating,
using uncoated glass will cause extra reflection / hotspot problems.
=====================================================================================
So technically, applying the correct voltage to actuate that solenoid
or my supposed open circuit solution will move the hot mirror out of
the way, but it will not compensate for focusing. RATS!
Macona makes only one mention on focusing on another post:
=====================================================================================
Two days ago I also modded my Sony DSC-V3. This camera has the built
in nightshot but it is limited. It only functions in standard and "P"
modes as well as movie mode. Also you can not use the flash in this
mode. I took apart the camera (much further than I had to.) and found
how the night shot system worked. It is simply that the IR filter is
on a solenoid. The camera moves the filter out of the way in night and
back in normal. Seeing as there is proabably no way to get into the
firmware there had to be a hardware hack. I found that the solenoid is
controlled with a little surface mount (SO-8) H-bridge chip. I
installed a tiny swithc that sends a pulse to the chip which manually
moves the filter out of the way. Just cycle throught the nightshot
modes to return to normal. Now I can use the camera as a normal color
digicam and full IR mode by placing IR pass filter over the lens and
flash. Or even better use the hotshoe or ACC plug to control an
external IR flash. Only problem I have had is that the camera has a
hard time focusing at full wide angle. Fix is just zoom in a bit.
=================================================================================================
I am more prone to trust in the Niek Haak article on the 717 than
Macona's zoom focusing fix. And most all IR mods I have seen replace
the hot mirror in one way or another.
If you are able to find a viable solution, I will commend you. But for
now, I can deal with the slow shutter speeds and the ND8, ND4, CPL
combo with a 950 nm filter.
In the mean time, I got a V3 I can experiment with ( possibly adapting
a manual focus SLR lens ) to see what I come up with!
Laters!
.
- References:
- Sony DSC-V3 for daytime infrared
- From: Chuck Olson
- Sony DSC-V3 for daytime infrared
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