Subject: TL120-55 gauging interest
Date: 2018-03-25 14:43:16
From: John Thurston

In 2007 and 2008, I wanted a stereo camera with wider lenses. Inspired
by the work of Sam Smith, I created a new lens board for the TL120-1.
The result, when combined with three 55mm lenses from the Mamiya
C220/C300 , was the TL120-55. It is a fixed-focus, non-metering camera.
As I recall, I made eight lens boards. I kept one, and sold the others
at 'group buy' prices to list members. It is my understanding that all
of the lens boards eventually made their way onto camera bodies.

At the request of one of our members, I recently blew the dust off the
design documents for the TL120-55 lens board. My guess is I could do a
new run, just like the old run, for about $80/each. This would be cost
plus one or two dollars, shipping at actual postage. If lots and lots of
people wanted one, each would be cheaper.

Look in the list archives for more history of the project, analysis of
the design, and discussion of results.

The questions are:
A) How much interest is there in additional TL120-55 lens boards?

B) I had them milled from aluminum. Technology has changed in the last
decade. Rather than having aluminum boards made, should I redesign it to
be 3D-Printed, release the design document, and wash my hands of it?

--
John Thurston
Juneau, Alaska

Subject: Re: TL120-55 gauging interest
Date: 2018-03-25 15:02:51
From: Bill Glickman

test..

can someone respond to advise this email is working with Yahoo?

thx

Bill G

On Sun, Mar 25, 2018 at 1:44 PM, John Thurston juneau3d@thurstons.us [MF3D-group] <MF3D-group@yahoogroups.com> wrote:

In 2007 and 2008, I wanted a stereo camera with wider lenses. Inspired
by the work of Sam Smith, I created a new lens board for the TL120-1.
The result, when combined with three 55mm lenses from the Mamiya
C220/C300 , was the TL120-55. It is a fixed-focus, non-metering camera.
As I recall, I made eight lens boards. I kept one, and sold the others
at 'group buy' prices to list members. It is my understanding that all
of the lens boards eventually made their way onto camera bodies.

At the request of one of our members, I recently blew the dust off the
design documents for the TL120-55 lens board. My guess is I could do a
new run, just like the old run, for about $80/each. This would be cost
plus one or two dollars, shipping at actual postage. If lots and lots of
people wanted one, each would be cheaper.

Look in the list archives for more history of the project, analysis of
the design, and discussion of results.

The questions are:
A) How much interest is there in additional TL120-55 lens boards?

B) I had them milled from aluminum. Technology has changed in the last
decade. Rather than having aluminum boards made, should I redesign it to
be 3D-Printed, release the design document, and wash my hands of it?

--
John Thurston
Juneau, Alaska

Subject: Re: TL120-55 gauging interest
Date: 2018-03-25 15:12:52
From: Bob Aldridge

If I were investing the money in lenses etc to complete this (And I'm certainly interested, by the way) I would want the lens board to be as rigid and dimensionally stable as possible.

Now, it is quite possible that quality 3D printing could do the job, but I have a feeling that there could be deficiencies with this method, that were not there with the milled aluminium panels.

Of course, I'm not a real expert with 3D printing (mine is a very cheap, Chinese, consumer unit) so there must be 3D printing setups that could do the job, but I'd rather not have to source one :-)

Bob Aldridge

On 25/03/2018 21:44, John Thurston juneau3d@thurstons.us [MF3D-group] wrote:

In 2007 and 2008, I wanted a stereo camera with wider lenses. Inspired
by the work of Sam Smith, I created a new lens board for the TL120-1.
The result, when combined with three 55mm lenses from the Mamiya
C220/C300 , was the TL120-55. It is a fixed-focus, non-metering camera.
As I recall, I made eight lens boards. I kept one, and sold the others
at 'group buy' prices to list members. It is my understanding that all
of the lens boards eventually made their way onto camera bodies.

At the request of one of our members, I recently blew the dust off the
design documents for the TL120-55 lens board. My guess is I could do a
new run, just like the old run, for about $80/each. This would be cost
plus one or two dollars, shipping at actual postage. If lots and lots of
people wanted one, each would be cheaper.

Look in the list archives for more history of the project, analysis of
the design, and discussion of results.

The questions are:
A) How much interest is there in additional TL120-55 lens boards?

B) I had them milled from aluminum. Technology has changed in the last
decade. Rather than having aluminum boards made, should I redesign it to
be 3D-Printed, release the design document, and wash my hands of it?

--
John Thurston
Juneau, Alaska

Subject: Re: TL120-55 gauging interest
Date: 2018-03-25 15:17:21
From: Bill Glickman

John, most appreciated all u have done for the MF 3d community.

I am curious, the shots I viewed of yours at 3dCon a few months back, (Spectacular!!!) were they shot with the Mamiya lenses, or the stock TL120 lenses?

Also, if a body is converted to Mamiya 55mm lenses, I assume u can no longer use the stock TL 80mm lenses? Or are the two lens boards interchangeable? Or, u use 80mm TLR lenses as well?

What is approx lens center spacing?

how are the lenses synced? On a stock TLR, when u trip the shutter, do both lenses trip their own shutter? Never used a TLR..

thx

Bill G

On Sun, Mar 25, 2018 at 1:44 PM, John Thurston juneau3d@thurstons.us [MF3D-group] <MF3D-group@yahoogroups.com> wrote:

In 2007 and 2008, I wanted a stereo camera with wider lenses. Inspired
by the work of Sam Smith, I created a new lens board for the TL120-1.
The result, when combined with three 55mm lenses from the Mamiya
C220/C300 , was the TL120-55. It is a fixed-focus, non-metering camera.
As I recall, I made eight lens boards. I kept one, and sold the others
at 'group buy' prices to list members. It is my understanding that all
of the lens boards eventually made their way onto camera bodies.

At the request of one of our members, I recently blew the dust off the
design documents for the TL120-55 lens board. My guess is I could do a
new run, just like the old run, for about $80/each. This would be cost
plus one or two dollars, shipping at actual postage. If lots and lots of
people wanted one, each would be cheaper.

Look in the list archives for more history of the project, analysis of
the design, and discussion of results.

The questions are:
A) How much interest is there in additional TL120-55 lens boards?

B) I had them milled from aluminum. Technology has changed in the last
decade. Rather than having aluminum boards made, should I redesign it to
be 3D-Printed, release the design document, and wash my hands of it?

--
John Thurston
Juneau, Alaska

Subject: Re: TL120-55 gauging interest
Date: 2018-03-25 15:51:13
From: Bill Hibbert

Attachments :

I'm not sure what these boards look like but if they're just 2D cutouts, there's no need to mill them. I recently had some parts laser cut in 6mm stainless steel and it wasn't at all expensive - just the material and a few minutes (maybe even seconds, I'm not sure how fast the laser cuts but it's quick) of laser time.

If you have a suitable digital file - I think I sent them .dxf files but I assume they take most common formats - it should be really quick and cheap. Laser-cutting shops are everywhere these days so anybody with the file can have a copy made locally. You can also choose materials - aluminium for cheap and light, stainless steel for rigid, carbon fibre sandwich for ultimate light weight...

Bill

From: MF3D-group@yahoogroups.com [mailto:MF3D-group@yahoogroups.com]
Sent: 25 March 2018 22:06
To: MF3D-group@yahoogroups.com
Subject: Re: [MF3D-group] TL120-55 gauging interest

If I were investing the money in lenses etc to complete this (And I'm certainly interested, by the way) I would want the lens board to be as rigid and dimensionally stable as possible.

Now, it is quite possible that quality 3D printing could do the job, but I have a feeling that there could be deficiencies with this method, that were not there with the milled aluminium panels.

Of course, I'm not a real expert with 3D printing (mine is a very cheap, Chinese, consumer unit) so there must be 3D printing setups that could do the job, but I'd rather not have to source one :-)

Bob Aldridge

On 25/03/2018 21:44, John Thurston juneau3d@thurstons.us [MF3D-group] wrote:

In 2007 and 2008, I wanted a stereo camera with wider lenses. Inspired
by the work of Sam Smith, I created a new lens board for the TL120-1.
The result, when combined with three 55mm lenses from the Mamiya
C220/C300 , was the TL120-55. It is a fixed-focus, non-metering camera.
As I recall, I made eight lens boards. I kept one, and sold the others
at 'group buy' prices to list members. It is my understanding that all
of the lens boards eventually made their way onto camera bodies.

At the request of one of our members, I recently blew the dust off the
design documents for the TL120-55 lens board. My guess is I could do a
new run, just like the old run, for about $80/each. This would be cost
plus one or two dollars, shipping at actual postage. If lots and lots of
people wanted one, each would be cheaper.

Look in the list archives for more history of the project, analysis of
the design, and discussion of results.

The questions are:
A) How much interest is there in additional TL120-55 lens boards?

B) I had them milled from aluminum. Technology has changed in the last
decade. Rather than having aluminum boards made, should I redesign it to
be 3D-Printed, release the design document, and wash my hands of it?

--
John Thurston
Juneau, Alaska

Subject: Re: TL120-55 gauging interest
Date: 2018-03-25 17:27:32
From: toyturn

I'm absolutely interested but skeptical of 3D printing...
I've had mixed results having my 35mm viewer bodies 3D printed..
depending on the printer, the material used, the humidity, etc...
I know the technology is advancing, and its great if you need to make a
small model of the Statue of Liberty...but my vote would be for aluminum.

My thanks to you John for all your great work with the TL120...
And I would absolutely commit to a TL120-55 lens board if one were available...

Peter B

Subject: Re: TL120-55 gauging interest
Date: 2018-03-25 19:49:06
From: John Thurston

On 3/25/2018 1:17 PM, Bill Glickman bglick97@gmail.com [MF3D-group] wrote:

> I am curious, the shots I viewed of yours at 3dCon a few months back,
> (Spectacular!!!) were they shot with the Mamiya lenses, or the stock TL120
> lenses?

I brought some of each, Bill. So there were certainly some TL120-55
images in the mix.

--
John Thurston
Juneau, Alaska

Subject: Re: TL120-55 gauging interest
Date: 2018-03-25 19:59:58
From: John Thurston

On 3/25/2018 1:51 PM, 'Bill Hibbert' billhibbert@designforlife.com
[MF3D-group] wrote:

> I'm not sure what these boards look like but if they're just 2D cutouts, there's no need to mill them.

It's in the archives, Bill. But I'll help with the leg work.
Here are the basic images I rendered a decade ago:
http://www.alaska.net/~thurston/images/backofboard.gif
http://www.alaska.net/~thurston/images/frontofboard.gif

Sam Smith built his by casting collars to screw to a flat metal lens
board. I built mine by milling a billet of aluminum to space the lens
mounts for hyper-focal distance for the Mamiya 55mm lenses. In the
current design, everything is in one unit. This either needs to be
created as a solid, or assembled from plates and cylinders.

--
John Thurston
Juneau, Alaska

Subject: Re: TL120-55 gauging interest
Date: 2018-03-25 20:11:40
From: John Thurston

On 3/25/2018 1:17 PM, Bill Glickman bglick97@gmail.com [MF3D-group] wrote:

> if a body is converted to Mamiya 55mm lenses, I assume u can no
> longer use the stock TL 80mm lenses? Or are the two lens boards
> interchangeable? Or, u use 80mm TLR lenses as well?

The lens board is held on with 4 or 5 screws. How many depends on the
age of your camera body. I consider it to be a one-way alteration. On
most of the camera bodies, the existing meter circuit is soldered to the
viewing lens. That needs to be separated to install the 55mm lenses.

So I have one TL120-1 and one TL120-55. I try to choose if I want
'standard' or 'wide' before I leave home. Carrying both makes my pack a
bit heavy :)

> What is approx lens center spacing?

Exactly the same as the TL120-1. Call it 'standard'. I don't have my
camera in front of my at the moment.

> how are the lenses synced?

The lenses in the stock TL120-1 have no shutters. The camera body
incorporates 35mm 'focal plane' shutters, and places them immediately
behind the lenses. If you look in the film chambers of a TL120, you will
see the shutter blinds. So the shutters are part of the camera, not the
lenses. The TL120-55 uses the same camera shutters.

The Mamiya lenses from the C220/C330 have leaf shutters. These are
disabled, removed, or ignored when the lenses are used to make a TL120-55.

The apertures on the Mamiya lenses are used for the TL120-55 conversion.
I have my apertures un-synched. I know of at least one with Sputnik-like
lever synch between the two apertures controls.
--
John Thurston
Juneau, Alaska

Subject: Re: TL120-55 gauging interest
Date: 2018-03-25 20:44:56
From: iandvaag

I am likewise interested in a lensboard, however I will defer to other members' experience on the question of materials. I haven't been overly impressed by 3D printed materials that I've seen, but I'm not that familiar with all the options that exist.

Regardless of whether you decide to publish the design document to the list, have several made to order, or neither, I am very grateful for your efforts, John. Thanks! You've done a lot for MF3D.

Subject: Re: TL120-55 gauging interest
Date: 2018-03-25 20:46:27
From: efbaskin

What is the change in field/angle of view from the stock 80mm lenses to the 55mm lenses?

Subject: Re: TL120-55 gauging interest
Date: 2018-03-26 04:27:34
From: Bill Hibbert

Attachments :

John

Thanks for the pics. I'm not in the market for one of these, hence my laziness in archive searching - my comment was just on the surprising (to me at least) economy of laser cutting. I've just checked, and the 6 (only 2 alike) chunky parts I had cut (in 5mm not 6mm SS) cost me a total of £40. Not bad for a one-off, I thought, and it would have dropped to half that if I'd ordered 5 sets. I dread to think what conventional milling would have cost.

After a quick glance at your drawings it looks as though a couple of flat plates and 3 rings could be sandwiched together, but it's probably a bit too complicated to make like this. If it could be adapted to one thick plate and one thin plate though, that might well work.

Bill

From: MF3D-group@yahoogroups.com [mailto:MF3D-group@yahoogroups.com]
Sent: 26 March 2018 03:01
To: MF3D-group@yahoogroups.com
Subject: Re: [MF3D-group] TL120-55 gauging interest

On 3/25/2018 1:51 PM, 'Bill Hibbert' billhibbert@designforlife.com
[MF3D-group] wrote:

> I'm not sure what these boards look like but if they're just 2D cutouts, there's no need to mill them.

Subject: Re: TL120-55 gauging interest
Date: 2018-03-26 11:23:11
From: John Thurston

On 3/25/2018 6:46 PM, efbaskin@hotmail.com [MF3D-group] wrote:

> What is the change in field/angle of view from the stock 80mm lenses to the 55mm lenses?

Coming from someone else, I'd suspect a trick question. But seeing as
how it's you, I'll go out on a limb and expose my ignorance.

I don't see how being a stereo camera would make the calculations any
different, so I just grabbed some numbers from an old cheat-sheet for
half-cameras. The horizontal FOV for an 80mm lens on a 60x60 piece of
film is a touch more than 40-degrees. The same number for the same film
with a 55mm lens is right about 57-degrees.

This is where Chuck Holzner would chime in and let us know wide taking
lenses without matching viewing lenses will result in a sub-optimal
stereo experience. In my defense, I do have a viewer with 65mm viewing
lenses. Making a viewer with 55mm lenses is impossibly expensive for me,
so the 65mm must serve that need.

I miss Chuck.
--
John Thurston
Juneau, Alaska

Subject: Re: TL120-55 gauging interest
Date: 2018-03-26 11:30:45
From: John Thurston

I dug through my notes from the last decade and found a relatively
complete synopsis I made of the project:
https://groups.yahoo.com/neo/groups/MF3D-group/conversations/messages/4109

It has links to earlier notes on the mailing list, and explicit notes
regarding DOF and the fixed-focus nature of the camera.

I also found some notes I made to myself of deficiencies I noted while
working with my board to build my TL120-55. They were relatively minor
and I think they would be easy to adjust.
--
John Thurston
Juneau, Alaska

Subject: Re: TL120-55 gauging interest
Date: 2018-03-26 12:28:52
From: Bill Glickman

Capturing an image is the same regardless if 3d, 2d, digital....i.e as it relates to HFOV...

Its an easy calc, as its just right angle triangle, simple trig.

Here is a quick n easy HFOV determination method...

when lens fl = capture medium horiz distance,
this represents 53 deg HFOV.

While the relationship is not perfectly linear, its close if you dont stray to far from reasonable fl's.

Using the new norm of 50mm horiz usable film area in the viewer..

a 50mm lens would equal 53 deg HFOV

If we go to 55mm lens, this is 10% fl increase, so decrease 53 deg by 10% (inverse relationship), or 48 deg HFOV.

Its not the capture film size that matters, its the size of the film u will be viewing that matters, specially in 3d, where we view with fixed fl lenses. Unlike 2d viewing a print on the wall, u can move to and fro the image to alter the viewing fl. In a film viewer, we are stuck with a fixed fl.

True Ortho viewing occurs when capture HFOV matches the viewing HFOV. (fl is just one variable here) When true ortho exists, this means, when looking in the viewer, the image formed on retina is identical to the retinal image formed by the unaided eye while standing at the camera capture position. (through a square mask, of course ;)

So a 48 deg HFOV capture in a viewer with 80mm lenses (35 deg HFOV) is very acceptable IMO. From my experience, you can still fully appreciate variance in taking and viewing HFOV up to about 1/3 of taking HFOV. Its not ortho, but our brain can connect the dots very well when taking and viewing variances are reasonable. I have used MF viewing lenses from 45 deg to 80 deg HFOV with no issues. Yes, wider viewing lenses will increase depth effect and visa versa. Of course, ortho is ideal, but, the limitation exists on the viewing fl lenses. So if we settle on ortho, this makes scene captures limited, ie.. with such long lenses. Although for portraits, ortho is VERY desirable.

For me, lens spacing is the biggest deterrent... much less tolerance in lens spacing vs. eye spacing, vs. "taking vs. viewing HFOV". Hence why the 55mm taking fl on the TL120, with viewing fl from 50mm to 80mm is very appealing... its also why I was trying to find out the lens spacing on the Mamiya lenses...or.... maybe... the lenses are removed from the TLR lens board, and placed individually into the Thurston designed lens board?

Bill G

On Mon, Mar 26, 2018 at 10:24 AM, John Thurston juneau3d@thurstons.us [MF3D-group] <MF3D-group@yahoogroups.com> wrote:

On 3/25/2018 6:46 PM, efbaskin@hotmail.com [MF3D-group] wrote:
> What is the change in field/angle of view from the stock 80mm lenses to the 55mm lenses?

Coming from someone else, I'd suspect a trick question. But seeing as
how it's you, I'll go out on a limb and expose my ignorance.

I don't see how being a stereo camera would make the calculations any
different, so I just grabbed some numbers from an old cheat-sheet for
half-cameras. The horizontal FOV for an 80mm lens on a 60x60 piece of
film is a touch more than 40-degrees. The same number for the same film
with a 55mm lens is right about 57-degrees.

This is where Chuck Holzner would chime in and let us know wide taking
lenses without matching viewing lenses will result in a sub-optimal
stereo experience. In my defense, I do have a viewer with 65mm viewing
lenses. Making a viewer with 55mm lenses is impossibly expensive for me,
so the 65mm must serve that need.

I miss Chuck.
--
John Thurston
Juneau, Alaska

Subject: Re: TL120-55 gauging interest
Date: 2018-03-26 13:34:39
From: John Thurston

Attachments :

On 3/26/2018 10:28 AM, Bill Glickman bglick97@gmail.com
[MF3D-group] wrote:

> Mamiya lenses...or.... maybe... the lenses are removed from the TLR lens
> board, and placed individually into the Thurston designed lens board?
> Bill G

Yes, Bill. The lens board, which is the heart of the
TL120-55 conversion, has three empty holes. One must buy
Mamiya C220/C330 TLR lens pairs, remove the individual
lenses from their original lens boards, and mix & match to
find a pair of well-matched lenses.

The taking lenses need to be well-matched*. The viewing lens
can be any ol' thing. If I recall, I worked through three or
four TLR lens-pairs. From those, I matched up three pairs of
well-matched taking lenses. 'course, my memory is probably
faulty. It seems like a lot of lens pairs to monkey with,
and a lot of test shots.

Because the Mamiya TLR lens pairs have identical
viewing/taking lenses, two lens pairs will give us six
possible pairings. That's six opportunities to find
"well-matched" lenses.

Those lenses are then mounted in the holes on the board, and
those holes are already positioned to coincide with the
centers of the original lenses. The flanges on the lens
board are already positioned to place the 55mm lenses at the
hyperfocal point**. The taking lenses need to have their
Mamiya shutters. The TL120-55 uses the apertures of those
assemblies. The shutters in those assemblies must be
disabled, removed, or blocked open; we use the shutters in
the camera body instead.

* As with defining "acceptably sharp" when discussing
circles of confusion, we each get to define "well matched"
when discussing these lenses.

** If you want to focus, the TL120-55 is not for you. It's a
fixed-focus camera, suitable for 2m-infinity at f/22. At
f/16 the optimal range is 2m-12m, but I've yet to have
anyone call me out on a soft-infinity on my f/16 images.

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

Subject: Re: TL120-55 gauging interest
Date: 2018-03-26 14:50:36
From: Bill Glickman

thx for info John...

I wouldn't doubt u had to shuffle that many lenses to find a decent matched pair...

When I was building my custom 3d cameras, the only way I could get a matched pair of Schneider Digitars was to advise the factory in Germany. When they made a run of my fl lenses, during QC, they would laser test and record each lens that came off the assembly line (of a fl I needed, mainly 80mm and 47mm), if a pair matched within .1% fl, they set them aside and sold them to me. I got on average, 2 pair per year. The good news was, I did not have to pay for the laser fl testing...

After having a lot of lenses designed for my 3d projects years ago (insane years), I learned, interestingly, that based on the specifics of the lens design, the fl's between samples can be very tight, to waaaay apart, like 10% !

When I used to shoot with the Seitz 220VR round shot, it was critical to program the EXACT fl into the camera so it knew the exact speed of rotation for both the film and the lens. Using some of the best lenses from Mamiya, Nikon, Zeiss, I would see fl swings from +/- 10% vs. nominal fl... to some, that were within .3%. There was a very unique test that was performed to determine such. Today, an optical laser tester can determine this in a few seconds. However, a couple of lenses would prob. cost $50+ each to test...but if there was 50, prob. half that.... again, low volume anything is costly...

I think fixed focus at f16 would be fine, specially if u moved the near out maybe to 8-9ft, which is ideal for reduced disparity....
Anyway, the appeal for me, is the friendly hand-holding ergonomics of the TL120 vs. other MF 3d rigs... AND, the no hassle shooting, just get SS right, and fire away...

Bill G

On Mon, Mar 26, 2018 at 12:34 PM, John Thurston juneau3d@thurstons.us [MF3D-group] <MF3D-group@yahoogroups.com> wrote:

On 3/26/2018 10:28 AM, Bill Glickman bglick97@gmail.com
[MF3D-group] wrote:
> Mamiya lenses...or.... maybe... the lenses are removed from the TLR lens
> board, and placed individually into the Thurston designed lens board?
> Bill G

Yes, Bill. The lens board, which is the heart of the
TL120-55 conversion, has three empty holes. One must buy
Mamiya C220/C330 TLR lens pairs, remove the individual
lenses from their original lens boards, and mix & match to
find a pair of well-matched lenses.

The taking lenses need to be well-matched*. The viewing lens
can be any ol' thing. If I recall, I worked through three or
four TLR lens-pairs. From those, I matched up three pairs of
well-matched taking lenses. 'course, my memory is probably
faulty. It seems like a lot of lens pairs to monkey with,
and a lot of test shots.

Because the Mamiya TLR lens pairs have identical
viewing/taking lenses, two lens pairs will give us six
possible pairings. That's six opportunities to find
"well-matched" lenses.

Those lenses are then mounted in the holes on the board, and
those holes are already positioned to coincide with the
centers of the original lenses. The flanges on the lens
board are already positioned to place the 55mm lenses at the
hyperfocal point**. The taking lenses need to have their
Mamiya shutters. The TL120-55 uses the apertures of those
assemblies. The shutters in those assemblies must be
disabled, removed, or blocked open; we use the shutters in
the camera body instead.

* As with defining "acceptably sharp" when discussing
circles of confusion, we each get to define "well matched"
when discussing these lenses.

** If you want to focus, the TL120-55 is not for you. It's a
fixed-focus camera, suitable for 2m-infinity at f/22. At
f/16 the optimal range is 2m-12m, but I've yet to have
anyone call me out on a soft-infinity on my f/16 images.

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

Subject: Re: TL120-55 gauging interest
Date: 2018-03-26 15:36:20
From: John Thurston

On 3/26/2018 12:50 PM, Bill Glickman bglick97@gmail.com
[MF3D-group] wrote:

> I think fixed focus at f16 would be fine, specially if u moved the near out
> maybe to 8-9ft, which is ideal for reduced disparity....

Ahh, well, that is a nice theory. And in theory, there is no
difference between theory and practice. . . but in this case
there is.

Because the TL120-1 uses shutters (designed for 35mm
cameras) behind the lens, they are placed nearer the lenses
than the focal plane. Putting them nearer the film would
mean the small-sized shutters would cause vignetting. The
camera was designed for 80mm lenses. The lenses on the
TL120-55 are about as close to those shutters as they can
go. In my example, I can slip a piece of paper between the
back of the lens barrel and the frame of the shutter
assembly. To move the focus point out, we'd need to bring
the lenses closer to the film, and there just isn't space to
do it.

Ok. There _is_ space if you make the space. I know one
person who shortened the mounting barrels on the rear
element of the lenses. This let the glass stand just a
little proud of its metal rings. He gained a little more
space by taking a dremel to the shutter assembly, and
grinding a divot in the plate holding the shutter blades.
This divot, when combined with the now-reduced length of the
lens barrel, let him push the focus farther out. I wasn't
willing to take a dremel to my shutter assembly, and haven't
missed the focus distance I chose :)

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

Subject: Wide angle Sputnik
Date: 2018-03-27 07:48:40
From: efbaskin

Attachments :

Starting a new thread so that I don't hijack John's thread, but this is a follow up to my angle of view question.

I need some math help here. I'm trying to do some calculations for a Sputnik that I attached some wide angle lenses to and I don't know what I'm doing.

Measuring left to right, it looks like the attached lenses create roughly a 20 percent gain horizontally in the scene. The wide angle lenses only needed 46mm to capture on film what the regular lenses did with 55mm. With the 75mm Sputnik lens, I'm thinking that the 20 percent increase translates to something like a 60mm lens?

I'm going to try to attach a photo as well as add it to the photo section. Left to right is the camera with the lenses attached, a photo of my house with the wide angles lenses attached, and my house taken with the regular 75mm lenses.

Subject: Re: Wide angle Sputnik
Date: 2018-03-27 08:00:12
From: efbaskin

I can't seem to post a photo and I can't see attachments in any messages, including my own.

Subject: Re: Wide angle Sputnik
Date: 2018-03-27 08:50:30
From: Timo Puhakka

I see the attachments.

There seems to be more contrast in the Sputnik lenses.

Timo

On 2018-03-27, at 10:00 AM, efbaskin@hotmail.com [MF3D-group] wrote:

I can't seem to post a photo and I can't see attachments in any messages, including my own.

Subject: Re: Wide angle Sputnik
Date: 2018-03-27 11:01:38
From: John Thurston

On 3/27/2018 5:48 AM, efbaskin@hotmail.com [MF3D-group] wrote:

> I need some math help here. I'm trying to do some calculations for a Sputnik that I attached some wide angle lenses to and I don't know what I'm doing

I can see your attached images. No problemo.

Are these wide-angle "teleconverters", or have you grafted
new lens elements on to your shutter bodies?

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

Subject: Re: Wide angle Sputnik
Date: 2018-03-27 12:19:09
From: efbaskin

The wide angle lenses are converters. I'm not smart enough to get more sophisticated than that. I replaced the Sputniks lens rings with those from later Lubitels. I think they support 40.5mm attachments/filters/etc? The auxiliary lenses come in a telephoto and wide angle pair. I actually bought 4 sets of these over the years. I haven't tried using the telephoto lenses.

With the wide angle lenses attached, I have to focus the camera at around 2 meters in order to bring infinity into focus. It makes me wonder if the telephoto lenses will even be able to focus.

They're easy to put on and take off. I didn't move the tripod for the comparison pair that I uploaded. I think it's a usable setup even though they were made for a 35mm camera. I have four of these wide angle lenses and I'm going to set up one Sputnik to sell with a set of them. I'd like to be able to state with some level of confidence what the attached lenses give in terms of a comparable focal length.

Subject: Re: Wide angle Sputnik
Date: 2018-03-27 12:32:10
From: Bob Aldridge

I see some distortions in the corners on the wide-angle shots - especially on the left side... Also, some vignetting.

Not sure how much would be inside the masks, once mounted, of course - and it's hard to really analyse your attachments...

So, have you tried mounting up the pairs and viewing critically in a quality viewer?

Bob Aldridge

On 27/03/2018 19:12, efbaskin@hotmail.com [MF3D-group] wrote:

The wide angle lenses are converters. I'm not smart enough to get more sophisticated than that. I replaced the Sputniks lens rings with those from later Lubitels. I think they support 40.5mm attachments/filters/etc? The auxiliary lenses come in a telephoto and wide angle pair. I actually bought 4 sets of these over the years. I haven't tried using the telephoto lenses.

With the wide angle lenses attached, I have to focus the camera at around 2 meters in order to bring infinity into focus. It makes me wonder if the telephoto lenses will even be able to focus.

They're easy to put on and take off. I didn't move the tripod for the comparison pair that I uploaded. I think it's a usable setup even though they were made for a 35mm camera. I have four of these wide angle lenses and I'm going to set up one Sputnik to sell with a set of them. I'd like to be able to state with some level of confidence what the attached lenses give in terms of a comparable focal length.

Subject: Re: Wide angle Sputnik
Date: 2018-03-27 13:04:27
From: efbaskin

The digitized pair of house photos that I uploaded were taken with my phone as they sat on a cheap light table that has noticeably less light towards the edges. Also, the wide angle chip was a little curled on the left side and didn't sit flat which resulted in that corner appearing softer. It isn't like that on the film.

They look fine in a viewer and they're matched up pretty well. Regardless, I'm going to do some more tests to see if I can get better focus as well as determine which of the four lenses work best together. I didn't keep track of which lens I used (and on which side) for this test.

Subject: Re: TL120-55 gauging interest
Date: 2018-04-17 13:18:16
From: coronet3d

Do you know what kind of equipment is used to determine focal length by laser? Such equipment would be very helpful in determining FL in cameras one is looking to match.

Thanks,

Steve

Subject: Re: TL120-55 gauging interest
Date: 2018-04-17 21:45:20
From: JR

Lens design and lens manufacture involve several compromises. Most manufacturers do not consider exact focal length to be a major consideration. The only one that I am aware of that even specifies the amount that they allow is Nikon (35mm, not MF), which specifies + or - 1% of the advertised (engraved on the barrel) focal length. That means that a lens that was engraved as 100mm could actually be either 99mm or 101mm and still pass quality control. As far as I know, none of the MF lenses specifies a percentage.

Chris Condon of StereoVision originally matched lens pairs for use on the 35mm Natural Vision cameras for the 3-D film House of Wax. I matched lens pairs for the StereoVision 10 perf. 65mm camera (approximately MF). These were of several brands, but mainly Schneider and Zeiss. I used a projector that had been fitted with a Panavision mount at Clairmont Camera. The test pattern was a precision grid. For each focal length, I had to test several hundred different lenses just to get a pair that was within 1%.

John A. Rupkalvis

stereoscope3d@gmail.com

On Mon, Mar 26, 2018 at 2:36 PM, John Thurston juneau3d@thurstons.us [MF3D-group] <MF3D-group@yahoogroups.com> wrote:

On 3/26/2018 12:50 PM, Bill Glickman bglick97@gmail.com
[MF3D-group] wrote:
> I think fixed focus at f16 would be fine, specially if u moved the near out
> maybe to 8-9ft, which is ideal for reduced disparity....

Ahh, well, that is a nice theory. And in theory, there is no
difference between theory and practice. . . but in this case
there is.

Because the TL120-1 uses shutters (designed for 35mm
cameras) behind the lens, they are placed nearer the lenses
than the focal plane. Putting them nearer the film would
mean the small-sized shutters would cause vignetting. The
camera was designed for 80mm lenses. The lenses on the
TL120-55 are about as close to those shutters as they can
go. In my example, I can slip a piece of paper between the
back of the lens barrel and the frame of the shutter
assembly. To move the focus point out, we'd need to bring
the lenses closer to the film, and there just isn't space to
do it.

Ok. There _is_ space if you make the space. I know one
person who shortened the mounting barrels on the rear
element of the lenses. This let the glass stand just a
little proud of its metal rings. He gained a little more
space by taking a dremel to the shutter assembly, and
grinding a divot in the plate holding the shutter blades.
This divot, when combined with the now-reduced length of the
lens barrel, let him push the focus farther out. I wasn't
willing to take a dremel to my shutter assembly, and haven't
missed the focus distance I chose :)

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

Subject: Re: TL120-55 gauging interest
Date: 2018-04-18 07:03:15
From: coronet3d

It's been suggested here that there's some sort of laser contraption out there that measures the focal length of lenses. I know on Docter Wetzlar (formerly Will) projection lenses, you will sometimes see a label providing the accurate focal length. My belief is that they were laser measuring the lenses. The only way I know how to match camera focal lengths is to shoot film and compare the transparencies, which is a costly, time-consuming and tedious chore. I was wondering if anyone knew the part # or at least the manufacturer of the laser equipment. I'm sure it's costly but if you lurk on eBay long enough, you can sometimes score expensive equipment that's being sold as surplus and that the seller hasn't a clue what it is.

Steve

Subject: Re: TL120-55 gauging interest
Date: 2018-04-18 09:41:57
From: Bill Glickman

Steve, the lasers that check fl, are relatively new, my guess is, in the last 20 yrs...

Checking fl is only ONE function they perform...

they are used to demonstrate real world MTF data, (vs. computed), distortion, astigmatism, color aberrations, etc.

Its been years since I looked, but prices were 45K to 100K.

In addition, they require calibration, knowledge of use, software, etc.

so the price charged per piece is actually reasonable, unless u are testing batches of hundreds....

Projection, as John mentioned, is the most cost effective and reliable method for the hobbiest. With projection, u magnify the variances, making them easier to measure with conventional methods...

Bill G

On Wed, Apr 18, 2018 at 6:00 AM, coronet3d@yahoo.com [MF3D-group] <MF3D-group@yahoogroups.com> wrote:

It's been suggested here that there's some sort of laser contraption out there that measures the focal length of lenses. I know on Docter Wetzlar (formerly Will) projection lenses, you will sometimes see a label providing the accurate focal length. My belief is that they were laser measuring the lenses. The only way I know how to match camera focal lengths is to shoot film and compare the transparencies, which is a costly, time-consuming and tedious chore. I was wondering if anyone knew the part # or at least the manufacturer of the laser equipment. I'm sure it's costly but if you lurk on eBay long enough, you can sometimes score expensive equipment that's being sold as surplus and that the seller hasn't a clue what it is.
Steve