David Richardson wrote:

> Hello fellow depth fans, The maker of the modified TL-120
> showed a Mamiya modified tri-lens camera. Having long
> wanted to have a wider perspective than the 80mm standard
> camera, I'd like to know more. Is the resultant camera in
> universal focus like the classic super Blad super wides?
> If not, how is focus adjusted. Does anybody have plans to
> produce a limited run of these?

Check the archives on this, David. Go back a couple of years
(early 2008) and you will find some discussion.

I got the idea to put 55mm Mamiya C330 lenses on a TL120-1
from Sam Smith. Sam cast three individual lens mounts and
used them to mount the 55mm lenses on a 3D-World lens board.
An image of Sam's camera can be found at:
http://groups.yahoo.com/group/MF3D-group/photos/album/2033268607/pic/list
He recently posted his lensboard for sale here in February:
http://tech.groups.yahoo.com/group/MF3D-group/message/3364
I haven't heard if he sold it.

Back in 2008, I decided it was cool idea, but San's approach
wasn't scalable. So I designed a replacement lens board
which incorporated the offset mounts for the 55mm lenses.
The idea was that anyone could take this board, mount three
Mamiya lenses on it, and replace the stock lens board to
have a TL120-55. I announced the project here on Feb 16, 2008
http://tech.groups.yahoo.com/group/MF3D-group/message/1606
As I recall, the total build was either eight or nine (I
could look it up if anyone cares), and were shared with
photographers in North America and Europe. This was a
non-profit, shared-risk venture which I did as kind of a
pay-back to the community for all the help and support I'd
received over the years. The boards were sold at cost+$1 to
all participants.

A rendering of the board still exists at:
http://www.alaska.net/~thurston/images/frontofboard.gif
http://www.alaska.net/~thurston/images/backofboard.gif

An image of my TL120 with the lens board installed:
http://www.alaska.net/~thurston/images/IMG_3689.JPG
I had just unwrapped the board. You can see the bubble-pack
next to the camera. It has kind of a "West World" look :)

My project resulted in a fixed-focus, non-metered, TL120-55.

About the same time, Peter Thomson, worked up a plan for
making a focusing wide-angle version of the TL120-1.
http://tech.groups.yahoo.com/group/MF3D-group/message/1641
His design uses the lens-barrel threads as the focusing
element. Each lens is focused independently.

I settled on the fixed-focus approach after doing some
thinking and arithmetic. Unless you are willing to mill some
metal out of the TL120's shutter frame and off the back of
the 55mm lenses, you can't get the lenses close enough to
the film to achieve infinity focus. I wasn't willing to do
that much butchery, and I don't think it is necessary. I
fixed the focus at 3.4 meters and feel I get acceptable
sharpness from 2m-infinity at f/22.

Mike Davis went to the trouble of working some DOF
calculations for the TL120-55 and even made a general
purpose spreadsheet:
http://tech.groups.yahoo.com/group/MF3D-group/message/1856

I frequently use the camera and am always pleased with the
results.

I _think_ I still have the design for the lens board. If I
were to do it again, I would adjust a few things before
again submitting it for manufacture. I don't have any
immediate plans to make any more as I perceive the demand to
be insufficient to make it cost effective. If there _is_
sufficient interest, I would be willing to hunt for the
design-documents and explore the cost of doing another run.

--
John Thurston
Juneau Alaska
http://stereo.thurstons.us

> David Richardson wrote:
>> Hello fellow depth fans, The maker of the modified TL-120
>> showed a Mamiya modified tri-lens camera.

- snip-
John Thurston wrote:

> Back in 2008, I decided it was cool idea, but San's approach
> wasn't scalable. So I designed a replacement lens board
> which incorporated the offset mounts for the 55mm lenses.

...

> As I recall, the total build was either eight or nine (I
> could look it up if anyone cares), and were shared with
> photographers in North America and Europe.

I was optimistic with my memory, David. If you saw a
TL120-55, then you saw one of seven in existence.
________________________________________
John Thurston
Juneau, Alaska
http://stereo.thurstons.us

I haven't sold it. I sent it to one of the people interested but it turns out he has the later version that has wires running to the lensboard. Can't blame him for not wanting to alter the camera. The versions I made it for were the earlier models that have the metering on the prisms instead of the lenses. Not sure why 3DWorld changed this.

Sam

--- In MF3D-group@yahoogroups.com, John Thurston wrote:
>
> David Richardson wrote:
> > Hello fellow depth fans, The maker of the modified TL-120
> > showed a Mamiya modified tri-lens camera. Having long
> > wanted to have a wider perspective than the 80mm standard
> > camera, I'd like to know more. Is the resultant camera in
> > universal focus like the classic super Blad super wides?
> > If not, how is focus adjusted. Does anybody have plans to
> > produce a limited run of these?
>
> Check the archives on this, David. Go back a couple of years
> (early 2008) and you will find some discussion.
>
> I got the idea to put 55mm Mamiya C330 lenses on a TL120-1
> from Sam Smith. Sam cast three individual lens mounts and
> used them to mount the 55mm lenses on a 3D-World lens board.
> An image of Sam's camera can be found at:
> http://groups.yahoo.com/group/MF3D-group/photos/album/2033268607/pic/list
> He recently posted his lensboard for sale here in February:
> http://tech.groups.yahoo.com/group/MF3D-group/message/3364
> I haven't heard if he sold it.
>
> Back in 2008, I decided it was cool idea, but San's approach
> wasn't scalable. So I designed a replacement lens board
> which incorporated the offset mounts for the 55mm lenses.
> The idea was that anyone could take this board, mount three
> Mamiya lenses on it, and replace the stock lens board to
> have a TL120-55. I announced the project here on Feb 16, 2008
> http://tech.groups.yahoo.com/group/MF3D-group/message/1606
> As I recall, the total build was either eight or nine (I
> could look it up if anyone cares), and were shared with
> photographers in North America and Europe. This was a
> non-profit, shared-risk venture which I did as kind of a
> pay-back to the community for all the help and support I'd
> received over the years. The boards were sold at cost+$1 to
> all participants.
>
> A rendering of the board still exists at:
> http://www.alaska.net/~thurston/images/frontofboard.gif
> http://www.alaska.net/~thurston/images/backofboard.gif
>
> An image of my TL120 with the lens board installed:
> http://www.alaska.net/~thurston/images/IMG_3689.JPG
> I had just unwrapped the board. You can see the bubble-pack
> next to the camera. It has kind of a "West World" look :)
>
> My project resulted in a fixed-focus, non-metered, TL120-55.
>
> About the same time, Peter Thomson, worked up a plan for
> making a focusing wide-angle version of the TL120-1.
> http://tech.groups.yahoo.com/group/MF3D-group/message/1641
> His design uses the lens-barrel threads as the focusing
> element. Each lens is focused independently.
>
> I settled on the fixed-focus approach after doing some
> thinking and arithmetic. Unless you are willing to mill some
> metal out of the TL120's shutter frame and off the back of
> the 55mm lenses, you can't get the lenses close enough to
> the film to achieve infinity focus. I wasn't willing to do
> that much butchery, and I don't think it is necessary. I
> fixed the focus at 3.4 meters and feel I get acceptable
> sharpness from 2m-infinity at f/22.
>
> Mike Davis went to the trouble of working some DOF
> calculations for the TL120-55 and even made a general
> purpose spreadsheet:
> http://tech.groups.yahoo.com/group/MF3D-group/message/1856
>
> I frequently use the camera and am always pleased with the
> results.
>
> I _think_ I still have the design for the lens board. If I
> were to do it again, I would adjust a few things before
> again submitting it for manufacture. I don't have any
> immediate plans to make any more as I perceive the demand to
> be insufficient to make it cost effective. If there _is_
> sufficient interest, I would be willing to hunt for the
> design-documents and explore the cost of doing another run.
>
> --
> John Thurston
> Juneau Alaska
> http://stereo.thurstons.us
>

Sam Smith wrote:

> I haven't sold it. I sent it to one of the people
> interested but it turns out he has the later version that
> has wires running to the lensboard. Can't blame him for
> not wanting to alter the camera.

So someone who wants to use wide angle lenses on their
TL120-1 still has a chance :) This is excellent news. I can't
believe you haven't had people beating down your door for
this board with lenses, Sam.

I'd be willing to help someone put a connector in the wire so
they could swap back and forth, but if the hang-up is they
don't want to modify the camera at all... can't help that.

> The versions I made it for were the earlier models that
> have the metering on the prisms instead of the lenses. Not
> sure why 3DWorld changed this.

I've said this before and I'll say it again:
The only way the metering has changed among the various
models of TL120 is how the information is passed to the meter
circuit. None of the TL120-1 models will meter without their
prism finder. There are no light sensors in the lenses.

In early cameras, the light sensor was in the prism and there
was a two or three-pin electrical connection between the body
of the camera and the prism.

In later cameras, the light sensor is on the body of the
camera and light is collected in the prism and transfered to
the sensor by a fiber-optic bundle.

In both cases, the prism is essential to the operation of the
meter circuit. The meter lights may light without the prism
being attached, but the information the lights present is
_useless_.

I have pictures of these differences at:
http://stereo.thurstons.us/updates.htm

The wired connection from the lens board to the camera body
is to transfer the aperture information to the meter-circuit.
In all cases, the finder-lens remains at f/2.8 but there is
an electrical wiper inside the lens barrel. As the aperture
is changed on the coupled lenses, the resistance between the
ends and the middle of wiper change. These resistance values
are passed back to the meter-circuit through these three
wires so it is aware of what aperture has been selected.

The amount of light comes from the prism, the chosen aperture
comes through these three wires, and the selected shutter
speed is taken from the dial on the top of the camera. The
meter-circuit compares these these three values and lights
the appropriate +/0/- LED on the edge of the finder.

On earlier cameras, this required aperture information was
still passed to the meter circuit (you can't determine
exposure without aperture information). The difference is
that the connection was done with three spring-loaded pins on
the camera body pressing against three contact-pads on the
back of the finder lens.

An early model with the pin connection can be seen in the
images at:
http://stereo.thurstons.us/TL120-inside.htm
The pins making the connection can be seen top-center in:
http://stereo.thurstons.us/tl120/TL120_interior.JPG
The three pads on the finder-lens can be seen at:
http://stereo.thurstons.us/tl120/TL120lensboard.JPG
On a later-model camera, there will just be a wire running
between the two. As I recall, the wires are soldered to the
finder-lens.

________________________________________
John Thurston
Juneau, Alaska
http://stereo.thurstons.us