Mating lens from camcorder to a digital backplane - A hack...

Hi folks...
I've crossed this message to the most relevant-seeming rec.photo.*
groups in an effort to maybe "hit" the right person to get a good answer
from. If you're not interested in hardware-hacking, feel free to move
on, as this message is solely concerned with taking the unlikely, and
using it to do the improbable for the sheer entertainment value that
doing the deed offers.

Some background:
X10 (Yeah, the outfit that more-or-less invented the pop-under spam
method) sells a unit they call the "X-Cam2" - a digital video camera
coupled to a 1.4GHz transmitter. I have, through methods not remembered,
but *NOT* involving transacting any business directly with X10, managed
to come into posession of several of these units, and have been playing
with using them to watch wildlife on the property, and other fun stuff.
Neat little beasts for various kinds of tinkering. A motley assortment
of people have done some hacking on these things that has generated the
knowledge needed to some neat tricks with them. I'm looking to become
one of the people creating "even newer and neater" tricks to do with
these relatively cheap (despite being ridiculously overpriced), but
surprisingly functional, wireless digital video cameras.

My own pet hack for these things is trying to hook them up to a better
lens system than what they come with - A fixed lens not much better than
the early versions of the Kodak "fun-saver" type disposable cameras -
Can be manually focused by screwing it into or out of the case, with
what eyeball measurement makes a 2-2.5mm fixed aperture that puts the
focal-plane an estimated 6-8mm behind the rear surface of the lens.

Along with the cameras, I've also managed to collect a handful of lens
systems extracted from from defunct camcorders - A lens doesn't care if
a capacitor dries out, a power supply melts, the tape-transport has
gotten jammed and twisted itself into a reasonable facsimile of a
pretzel, or otherwise turned the camera into junk without breaking the
glass, right?

So what I'm trying to do now is figure out how to mate the image plane
of the X-Cam2 to the lens system from a camcorder. I'm running into a
bit of trouble figuring out *WHERE* to mount it, though - As things
stand, I've got a reasonably decent lens system, complete with
functional motorized zoom, focus, and iris control (All of which I
intend to put to use, eventually, but that's "eventually", not right
now) that I can use as a crude but very effective version of something
real similar to the "room that's a camera" that was used in the early
days for (pardon me if I blow the spelling - I'm a computer and
electronics geek, not a photographic history buff ) Dauggerotype
photography.

My problem is figuring out where to mount the image plane in relation to
the lens - My best success so far has been dragging an in-focus image
out of the camera guts with the aperture wide open, the zoom to max
(Don't know the actual "X" of full zoom) and the focus cranked to the
extreme end of its travel while I hold the imager in place by hand. From
there, however, changing either zoom or focus throws the image
irrecoverably out of focus, and only returning to maximum zoom, and
extreme end of focus range will bring it back. From scavenging the lens
system out of the camcorder, I know that the imaging device was fixed in
relation to the back surface of the lens, so there's clearly a "sweet
spot" that will let me use the full zoom/focus range of this lens
system. Unfortunately, due to the way things were put together, it was
impossible to obtain a measurement to tell me where I should place the
"transplanted" imager to take advantage of this "sweet spot".

So, is there a way (preferably one that doesn't require a degree in
physics to use) for me to figure out a reasonably accurate starting
point for where I should place the image plane in relation to the rear
surface of the lens? I suspect I'll encounter similar difficulty with
each new lens system I try to work with, so an equation that I can plug
values into would help more than a "for this lens system, put it X mm
behind the lens" type of answer.

Thanks in advance for any assistance you might be able to give!

--
Don Bruder - - If your "From:" address isn't on my whitelist,
or the subject of the message doesn't contain the exact text "PopperAndShadow"
somewhere, any message sent to this address will go in the garbage without my
ever knowing it arrived. Sorry... http://www.sonic.net/~dakidd for more info

Wouldn't the distance need to be the same as it was in the camcorder?
YOu could try some sort of bellows or flexible rubber plungercam type of
approach. I've gotten some easy results holding various discarded lenses
in from of a camera for macro work, forward and reversed but that
invariably gives a very limited depth of field with no infinity focusing.

Don Bruder wrote:

Hi folks...
I've crossed this message to the most relevant-seeming rec.photo.*
groups in an effort to maybe "hit" the right person to get a good answer
from. If you're not interested in hardware-hacking, feel free to move
on, as this message is solely concerned with taking the unlikely, and
using it to do the improbable for the sheer entertainment value that
doing the deed offers.

Some background:
X10 (Yeah, the outfit that more-or-less invented the pop-under spam
method) sells a unit they call the "X-Cam2" - a digital video camera
coupled to a 1.4GHz transmitter. I have, through methods not remembered,
but *NOT* involving transacting any business directly with X10, managed
to come into posession of several of these units, and have been playing
with using them to watch wildlife on the property, and other fun stuff.
Neat little beasts for various kinds of tinkering. A motley assortment
of people have done some hacking on these things that has generated the
knowledge needed to some neat tricks with them. I'm looking to become
one of the people creating "even newer and neater" tricks to do with
these relatively cheap (despite being ridiculously overpriced), but
surprisingly functional, wireless digital video cameras.

My own pet hack for these things is trying to hook them up to a better
lens system than what they come with - A fixed lens not much better than
the early versions of the Kodak "fun-saver" type disposable cameras -
Can be manually focused by screwing it into or out of the case, with
what eyeball measurement makes a 2-2.5mm fixed aperture that puts the
focal-plane an estimated 6-8mm behind the rear surface of the lens.

Along with the cameras, I've also managed to collect a handful of lens
systems extracted from from defunct camcorders - A lens doesn't care if
a capacitor dries out, a power supply melts, the tape-transport has
gotten jammed and twisted itself into a reasonable facsimile of a
pretzel, or otherwise turned the camera into junk without breaking the
glass, right?

So what I'm trying to do now is figure out how to mate the image plane
of the X-Cam2 to the lens system from a camcorder. I'm running into a
bit of trouble figuring out *WHERE* to mount it, though - As things
stand, I've got a reasonably decent lens system, complete with
functional motorized zoom, focus, and iris control (All of which I
intend to put to use, eventually, but that's "eventually", not right
now) that I can use as a crude but very effective version of something
real similar to the "room that's a camera" that was used in the early
days for (pardon me if I blow the spelling - I'm a computer and
electronics geek, not a photographic history buff ) Dauggerotype
photography.

My problem is figuring out where to mount the image plane in relation to
the lens - My best success so far has been dragging an in-focus image
out of the camera guts with the aperture wide open, the zoom to max
(Don't know the actual "X" of full zoom) and the focus cranked to the
extreme end of its travel while I hold the imager in place by hand. From
there, however, changing either zoom or focus throws the image
irrecoverably out of focus, and only returning to maximum zoom, and
extreme end of focus range will bring it back. From scavenging the lens
system out of the camcorder, I know that the imaging device was fixed in
relation to the back surface of the lens, so there's clearly a "sweet
spot" that will let me use the full zoom/focus range of this lens
system. Unfortunately, due to the way things were put together, it was
impossible to obtain a measurement to tell me where I should place the
"transplanted" imager to take advantage of this "sweet spot".

So, is there a way (preferably one that doesn't require a degree in
physics to use) for me to figure out a reasonably accurate starting
point for where I should place the image plane in relation to the rear
surface of the lens? I suspect I'll encounter similar difficulty with
each new lens system I try to work with, so an equation that I can plug
values into would help more than a "for this lens system, put it X mm
behind the lens" type of answer.

Thanks in advance for any assistance you might be able to give!

Hi Don, how about finding out the sweet spot on a grounded/ matted
glas, like the old large format camera's, glass to be held on the focal
plane of lens under test, maybe you should use an optical bench, i.e. a
rigid construction of: subject,lens and ground glass inline and
explicitly paralel to each other, if sweet spot is found then establish
the measurements.

Don Bruder wrote:
Hi folks...
I've crossed this message to the most relevant-seeming rec.photo.*
groups in an effort to maybe "hit" the right person to get a good answer
from. If you're not interested in hardware-hacking, feel free to move
on, as this message is solely concerned with taking the unlikely, and
using it to do the improbable for the sheer entertainment value that
doing the deed offers.

Some background:
X10 (Yeah, the outfit that more-or-less invented the pop-under spam
method) sells a unit they call the "X-Cam2" - a digital video camera
coupled to a 1.4GHz transmitter. I have, through methods not remembered,
but *NOT* involving transacting any business directly with X10, managed
to come into posession of several of these units, and have been playing
with using them to watch wildlife on the property, and other fun stuff.
Neat little beasts for various kinds of tinkering. A motley assortment
of people have done some hacking on these things that has generated the
knowledge needed to some neat tricks with them. I'm looking to become
one of the people creating "even newer and neater" tricks to do with
these relatively cheap (despite being ridiculously overpriced), but
surprisingly functional, wireless digital video cameras.

My own pet hack for these things is trying to hook them up to a better
lens system than what they come with - A fixed lens not much better than
the early versions of the Kodak "fun-saver" type disposable cameras -
Can be manually focused by screwing it into or out of the case, with
what eyeball measurement makes a 2-2.5mm fixed aperture that puts the
focal-plane an estimated 6-8mm behind the rear surface of the lens.

Along with the cameras, I've also managed to collect a handful of lens
systems extracted from from defunct camcorders - A lens doesn't care if
a capacitor dries out, a power supply melts, the tape-transport has
gotten jammed and twisted itself into a reasonable facsimile of a
pretzel, or otherwise turned the camera into junk without breaking the
glass, right?

So what I'm trying to do now is figure out how to mate the image plane
of the X-Cam2 to the lens system from a camcorder. I'm running into a
bit of trouble figuring out *WHERE* to mount it, though - As things
stand, I've got a reasonably decent lens system, complete with
functional motorized zoom, focus, and iris control (All of which I
intend to put to use, eventually, but that's "eventually", not right
now) that I can use as a crude but very effective version of something
real similar to the "room that's a camera" that was used in the early
days for (pardon me if I blow the spelling - I'm a computer and
electronics geek, not a photographic history buff ) Dauggerotype
photography.

My problem is figuring out where to mount the image plane in relation to
the lens - My best success so far has been dragging an in-focus image
out of the camera guts with the aperture wide open, the zoom to max
(Don't know the actual "X" of full zoom) and the focus cranked to the
extreme end of its travel while I hold the imager in place by hand. From
there, however, changing either zoom or focus throws the image
irrecoverably out of focus, and only returning to maximum zoom, and
extreme end of focus range will bring it back. From scavenging the lens
system out of the camcorder, I know that the imaging device was fixed in
relation to the back surface of the lens, so there's clearly a "sweet
spot" that will let me use the full zoom/focus range of this lens
system. Unfortunately, due to the way things were put together, it was
impossible to obtain a measurement to tell me where I should place the
"transplanted" imager to take advantage of this "sweet spot".

So, is there a way (preferably one that doesn't require a degree in
physics to use) for me to figure out a reasonably accurate starting
point for where I should place the image plane in relation to the rear
surface of the lens? I suspect I'll encounter similar difficulty with
each new lens system I try to work with, so an equation that I can plug
values into would help more than a "for this lens system, put it X mm
behind the lens" type of answer.

Thanks in advance for any assistance you might be able to give!

--
Don Bruder - - If your "From:" address isn't on my whitelist,
or the subject of the message doesn't contain the exact text "PopperAndShadow"
somewhere, any message sent to this address will go in the garbage without my
ever knowing it arrived. Sorry... http://www.sonic.net/~dakidd for more info

According to camcase :
Hi Don, how about finding out the sweet spot on a grounded/ matted
glas,

I think that the proper term is "ground glass". "grounded"
implies an electrical connection to ground, which is only confusing
here.

You can even get away with projecting onto thin paper, and
observing that from either side.

But set the lens to the infinity focus point, and focus on
something far enough away to count as infinity. The original poster
said something like "and the focus cranked to the extreme", and I'm not
sure which extreme was meant here -- set to closest focus (lens most
distant from the sensor), or set to infinity (lens closest to the
sensor).

like the old large format camera's, glass to be held on the focal
plane of lens under test, maybe you should use an optical bench, i.e. a
rigid construction of: subject,lens and ground glass inline and
explicitly paralel to each other, if sweet spot is found then establish
the measurements.

Agreed. If he has an optical bench, that is the way to go. If
not, some kind of makeshift can be used. I read (was it here, or in
another newsgroup where optical experiments were being discussed) a
suggestion that one should use a section of aluminum channel (an
extruded aluminum used for structural elements with a shape like this
(view with a fixed-pitch font like Courier to avoid distortion of the
image):
/\ /|
/ \_______/ |
/ / / | (Shown way too short to save screen space.)
|\ / /| /
| \/______/ |/
+-----------+

Anyway -- produce some cylinders of wood, plastic, or metal which will
rest nicely on the upward pointed edges of the aluminum channel, all
cylinders of the same design, with holes bored concentrically in them
(this requires a lathe) to mount the various lenses and focusing
screens. The, you can simply rest the parts on the channel, and slide
them back and forth to accomplish focus. Given the size of the original
sensor (and thus the image produced by the lens), I would suggest that
you add another lens to allow you to view the image on the ground glass
or paper, to judge its focus.

I suspect that this was in the other newsgroup (or a similar
focus mailing list), as the production of the cylinders will require a
lathe to make sure that the bores are concentric, and the assumption
that any reader would have access to a lathe would be more valid in the
other newsgroup. I wish that I could remember who posted this idea, so
I could give proper credit.

Once you have the lens behaving properly at full zoom and
infinity focus, you can probably use both the zoom and the focus
adjustments to view other distances without serious problems. (Though
the original camera *may* have been designed to continually use the
autofocus mechanism to compensate for shift of focus while zooming, and
thus simplify the design of the zoom lens.) In that case, you are stuck
with having to re-focus when you zoom.

Best of luck,
DoN.
--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

In article , Don Bruder
wrote:

So, is there a way (preferably one that doesn't require a degree in
physics to use) for me to figure out a reasonably accurate starting
point for where I should place the image plane in relation to the rear
surface of the lens?

Don-

As camcase suggested, set up the lens with some kind of optical bench.
That way you can focus it on a matte surface or ground glass mounted
perpendicular to the axis of the lens.

I think the key is to set the lens to infinity and focus an object that is
at a great distance, depending on focal length. The test you described
suggested focus was obtained arbitrarily without regard to a distance
scale on the lens. Therefore zooming caused the focus to shift(?).

This assumes the lens was designed so that focus did not shift while
zooming. Such may not be the case for a lens system that continually
auto-focused while zooming.

Fred

Exuse le mot" grounded", but I elucidated it after the slash "matted",
though I compliment DoN. Nichols with his additionary thorough answer,
only one comment on DoNs motto"Black holes" etc., it seems the
originator of the post needs an astrophysics course after all(joke)


DoN. Nichols wrote:
According to camcase :
Hi Don, how about finding out the sweet spot on a grounded/ matted
glas,

I think that the proper term is "ground glass". "grounded"
implies an electrical connection to ground, which is only confusing
here.

You can even get away with projecting onto thin paper, and
observing that from either side.

But set the lens to the infinity focus point, and focus on
something far enough away to count as infinity. The original poster
said something like "and the focus cranked to the extreme", and I'm not
sure which extreme was meant here -- set to closest focus (lens most
distant from the sensor), or set to infinity (lens closest to the
sensor).

like the old large format camera's, glass to be held on the focal
plane of lens under test, maybe you should use an optical bench, i.e. a
rigid construction of: subject,lens and ground glass inline and
explicitly paralel to each other, if sweet spot is found then establish
the measurements.

Agreed. If he has an optical bench, that is the way to go. If
not, some kind of makeshift can be used. I read (was it here, or in
another newsgroup where optical experiments were being discussed) a
suggestion that one should use a section of aluminum channel (an
extruded aluminum used for structural elements with a shape like this
(view with a fixed-pitch font like Courier to avoid distortion of the
image):
/\ /|
/ \_______/ |
/ / / | (Shown way too short to save screen space.)
|\ / /| /
| \/______/ |/
+-----------+

Anyway -- produce some cylinders of wood, plastic, or metal which will
rest nicely on the upward pointed edges of the aluminum channel, all
cylinders of the same design, with holes bored concentrically in them
(this requires a lathe) to mount the various lenses and focusing
screens. The, you can simply rest the parts on the channel, and slide
them back and forth to accomplish focus. Given the size of the original
sensor (and thus the image produced by the lens), I would suggest that
you add another lens to allow you to view the image on the ground glass
or paper, to judge its focus.

I suspect that this was in the other newsgroup (or a similar
focus mailing list), as the production of the cylinders will require a
lathe to make sure that the bores are concentric, and the assumption
that any reader would have access to a lathe would be more valid in the
other newsgroup. I wish that I could remember who posted this idea, so
I could give proper credit.

Once you have the lens behaving properly at full zoom and
infinity focus, you can probably use both the zoom and the focus
adjustments to view other distances without serious problems. (Though
the original camera *may* have been designed to continually use the
autofocus mechanism to compensate for shift of focus while zooming, and
thus simplify the design of the zoom lens.) In that case, you are stuck
with having to re-focus when you zoom.

Best of luck,
DoN.
--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---