I'm _still_ not done with the installation of my Mamiya 55mm
lenses on my TL120. But the work I've been doing brings me
to the question:

Is anyone else interested in putting 55mm Mamiya
lenses on their TL120?

One of the paths I'm thinking about taking involves having a
monolithic lens board machined to take the 55mm lenses
directly. Once I've done the measurements, design and
layout, making a couple more is dead simple and not much
more expensive. Is anyone else interested in one or should
I keep planning on a production run of one?
--
John Thurston
Juneau Alaska
http://stereo.thurstons.us

> Is anyone else interested in putting 55mm Mamiya
> lenses on their TL120?

> One of the paths I'm thinking about taking involves having a
> monolithic lens board machined to take the 55mm lenses
> directly. Once I've done the measurements, design and
> layout, making a couple more is dead simple and not much
> more expensive. Is anyone else interested in one or should
> I keep planning on a production run of one?

Hi John!
Of course, I would be interested!!!
How do you plan to fix the Mamiya lenses on this lens board after you
finished the work on the board?
Best regards, Chris

chrisjachner wrote:

> How do you plan to fix the Mamiya lenses on this lens
> board after you finished the work on the board?

The lenses I'm using are Mamiya 55mm f/4.5 from the
C220/C330 family of TLRs. These lenses are rather like large
format lenses. They are held to the lens board with a
threaded retaining ring installed from the back.

My TL120 board would use the same retaining ring. The lenses
would be mounted to the board before the board is screwed to
the TL120.
--
John Thurston
Juneau Alaska
http://stereo.thurstons.us

Hi John,

> My TL120 board would use the same retaining ring. The lenses
> would be mounted to the board before the board is screwed to
> the TL120.
> --
> John Thurston

Hi John,
I am already somewhat down this path and have done some lense
matching test films with several pairs of lenses with great results.
I have to point out that the lenses don't merely mount onto the lense
board as is, as they have a different focal point. They in fact have
a hyperfocal setup.
They require being mounted 10-12 mm forward of the lense board
depending on what distance you are desiring to have the preset focus
to be set. Even so, the rear of the lense still hits the focal plane
shutter body (at least on my late model TL120)by about 1-1.5 mm,
requiring some of the rear lense body to be removed, or, (heaven
forbid) removing the shutter and using the shutters in the lenses via
a coupling link. Personally, I am using the camera's own shutter with
the shutters on the lenses locked open.
I am not finished yet, but I will be happy to share drawings &
dimensions etc, even if others want to hold this info close to their
chest. After all, this is what this forum should be about, sharing.

Happy MF3Ding, Peter

Peter Thomson wrote:

>> John Thurston wrote: My TL120 board would use the same
>> retaining ring. The lenses would be mounted to the
>> board before the board is screwed to the TL120.

> They require being mounted 10-12 mm forward of the lense
> board depending on what distance you are desiring to have
> the preset focus to be set. Even so, the rear of the
> lense still hits the focal plane shutter body (at least
> on my late model TL120)by about 1-1.5 mm,

Really?
We should compare measurements (gawd, this is starting to
sound like all the other spam I shovel out of my mailbox!)
as what I have found indicates that I'll be clear of the
shutters by about 2mm. I'll try to make my data coherent and
get it posted this evening.

> I am not finished yet, but I will be happy to share
> drawings & dimensions etc, even if others want to hold
> this info close to their chest. After all, this is what
> this forum should be about, sharing.

IMHO, the community of MF3Ders is far too small to try to
keep secrets, and I don't think I've ever met any who wanted
to!
--
John Thurston
Juneau Alaska
http://stereo.thurstons.us

> We should compare measurements (gawd, this is starting to
> sound like all the other spam I shovel out of my mailbox!)
> as what I have found indicates that I'll be clear of the
> shutters by about 2mm. I'll try to make my data coherent and
> get it posted this evening.

Hi John, at the time of writing my last post I had not seen your post
with the CAD image. Nice work ! I obtained a plate from 3D World for
my project and machined some industrial nylon mounting blocks for the
lenses. After measuring the thickness required by viewing through the
viewfinder, I machined the taking lense blocks accordingly. [See
http://tech.ph.groups.yahoo.com/group/MF3D-group/photos/view/9855?b=1
Then to my surprise, when I put the taking lenses in, they were up
against the shutter housing before seating in the blocks! I took some
films this way and found the focus to be around 18-20 ft.
I am working on a method to quickly push-pull / pack-out the lenses
to either of 2 set focus points for near or "not-so-near", as one
can't always get f22 realistically, and I'm not a fan of the 400 ISO
film.
Nothing malicious meant by my other comments, just an observation,
and certainly not about you.
Love to see your project take off.

Happy MF3Ding, Peter

Peter Thomson wrote:

> Hi John, at the time of writing my last post I had not
> seen your post with the CAD image. Nice work ! I obtained
> a plate from 3D World for my project

Hmm, I tried to buy a camera without lenses (and was
understandably declined) but I didn't think to try asking for
just a lens board. Trying to match the curves on that dang
board to make a tight fit is difficult.

> and machined some industrial nylon mounting blocks for the
> lenses.

I was going down this route (using the original lens board)
when I started pricing the machining it was going to require.
I thought maybe it would be the excuse I needed to buy a
lathe but decided I might get some push-back from the House
Finance Committee and learning how to operate the lathe felt
like kind of a long bunny-trail. I think having a monolithic
board made will end up costing me no more than having the
other parts machined. A fringe benefit is that the resulting
product may be reproducable.

> I took some films this way and found the focus to be
> around 18-20 ft.

I've been working on a focus distance of 2.8m. This is kinda
close to where I calculate the hyperfocal distance to be and
exactly how far from the camera it was convenient to mount my
test chart :)

> I am working on a method to quickly push-pull / pack-out
> the lenses to either of 2 set focus points for near or
> "not-so-near", as one can't always get f22 realistically,
> and I'm not a fan of the 400 ISO film.

I've thought of a couple ways to do this, but none are easily
within my grasp right now. Please let us know how this works
out for you.
________________________________________
John Thurston
Juneau, Alaska
http://stereo.thurstons.us

Hi John,

I have a couple of questions regarding your project for a series of
machined aluminum lensboards for the Mamiya 55mm lenses...

a) Are you selling these boards unfinished (bare silver colour) or
will you have them black anodized ?

b) Will it be possible to switch back and forth between this and the
board that came with the camera fairly easily ? (I gather it won't be
possible to switch boards while there is still film in the camera.)

c) How do you deal with focal lenght matching without having several
lenses to choose from ?

Francois

depthcam wrote:

> a) Are you selling these boards unfinished (bare silver colour)
> or will you have them black anodized ?

I dont think I can afford to anodize them. When i checked this
option out it would about double the cost. I'm figuring I will be
painting mine though I've thought about redoing the layout to make
larger flat surfaces to hold some nice red leather :)

> b) Will it be possible to switch back and forth between this and
> the board that came with the camera fairly easily ? (I gather it
> won't be possible to switch boards while there is still film in
> the camera.)

The board is held on with four or five little screws. The shutters
are behind the lenses, so I dont see any problem pulling the board
with the camera loaded but I can't think why I'd bother. Its not
like I'm going to shoot a scene with 80mm lenses and follow it up
with a shot at 55mm. And, with only 6 shots per roll, I'm never more
thn six shots from an empty camera.

> c) How do you deal with focal lenght matching without having
> several lenses to choose from ?

You buy two pairs and pick the best three out of four :)
Or, you figure that whatever you have is close enough.

John Thurston
Juneau, Alaska

There are chemicals available which will blacken (not actually anodize)
aluminum. It is not as good as anodizing but probably preferable to
painting. Checkout the firearms section of a larger sporting goods store or
sometimes Walmart for the chemicals. You want the solutions for aluminum and
not the stuff for steel.

> -----Original Message-----
> From: MF3D-group@yahoogroups.com [mailto:MF3D-group@yahoogroups.com] On
> Behalf Of John Thurston
> Sent: Saturday, February 16, 2008 12:07 AM
> To: MF3D-group@yahoogroups.com
> Subject: Re: [MF3D-group] Re: Anyone interesting in a TL120 lens board ?
>
> depthcam wrote:
> > a) Are you selling these boards unfinished (bare silver colour)
> > or will you have them black anodized ?
>
> I dont think I can afford to anodize them. When i checked this
> option out it would about double the cost. I'm figuring I will be
> painting mine though I've thought about redoing the layout to make
> larger flat surfaces to hold some nice red leather :)
>
> > b) Will it be possible to switch back and forth between this and
> > the board that came with the camera fairly easily ? (I gather it
> > won't be possible to switch boards while there is still film in
> > the camera.)
>
> The board is held on with four or five little screws. The shutters
> are behind the lenses, so I dont see any problem pulling the board
> with the camera loaded but I can't think why I'd bother. Its not
> like I'm going to shoot a scene with 80mm lenses and follow it up
> with a shot at 55mm. And, with only 6 shots per roll, I'm never more
> thn six shots from an empty camera.
>
> > c) How do you deal with focal lenght matching without having
> > several lenses to choose from ?
>
> You buy two pairs and pick the best three out of four :)
> Or, you figure that whatever you have is close enough.
>
> John Thurston
> Juneau, Alaska
>
>
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