to be done: sinar's field companion (DIY 4x5)

<p>Some small background on my project: I have sinar f1 and need smaller

and lighter camera for field work. Something what I can backpack and walk

for few hours. Just basic movements will do the job. Idea was to keep Sinar's

elements (back with ground glass, bellows and lens board), and to have

vertical movements.</p>

<p><img src="http://www.bellay.com/janko/002_model_pn.jpg" alt="1st 3d

model"></p>

<p><i>The sketch and bigger picture can be seen on my <a

href="http://www.bellay.com/janko/">web-site</a>, however I will link

pictures (will open in new window not to disturb your browsing)</i></p>

<p>On my <a href="http://www.bellay.com/janko/001_sketch.gif"

target="_blank">1st sketch</a> (what is actually version 1.3b :)) you can

see shortest position on the left side (top view and under is side view) for

135mm Symmar. That will be when focused at infinity. Now, I have realized

that it will need to be even shorter if I want to use some movements focused

at infinity (like creating deep depth of field). Maybe to move rear panel in front

of it's base?<br>

On the right side of that sketch is the longest extension possible, 315mm

what should produce 1:2 macro with my 210mm G-Claron. If I move rear

panel in front that will cut my <i>semi-macro</i> to 1:2.5. Bad? I don't think

so. Upper picture on the right side is top view of camera's base. And lower

picture represents side view with higher front base - in such situation it will

be easier to pack my camera and if I will need to level rear and front panels it

will be easy to make with tilting base on tripod and tilting both panels.<br>

Please, tell me all your opinions. Disadvantages, mistakes, ugliness...<br>

<br>

Tnx.<br>

Janko</p>

<p>P.S. On this 3d picture I have used different colors to represent different

parts, but in final products I think I will go for same colors of all

elements.</p>

Try: http://www.icon.co.za/~panfield

Well Ellis, thank you for sharing that link, but again: that link is dead. At least

from my 2 locations: "Communication administratively prohibited by filtering"...

And not only for panfield, but for the whole domain... All I have found is

cashed html on Google, but without images (dead links again). Do you have

any other link or kind of archive?

Looks like the idea of the metal Canhams, very good design... perhaps another point to add rigidity in the rear standard (to avoid tilting) would be great...

If minimal weight is one of your primary objectives, Janko, my suggestion would be to look around to see what might be available, "off-the-shelf", in extruded aluminum stock - something akin to the material used for aluminum sliding window frames, where the ribs/tracks will add rigidity. Once you've found an easy source of the light-weight stock that will work with your basic design, let the stock "tell" you what refinements might be needed in the details of your design. If you use aluminum, you'll likely also need to find a shop that can do some precision (heliarc?) welding for you.

 

One possible area of challenge I see is minimizing the bulk and weight of the central rail block. How that is approached will, I think, be a matter of what machining capabilities you have at your disposal.

See thae attached image, it should be a screen shot of the Panfield website that you

cannot access.

<p><b>Jose:</> Yes, I'm worried about rigidity too, specially for rear

standard which will get many "forces" (inserting film holder under spring

back), but at this very moment I don't know if my "design" will be strong

enough. That is one of the reasons why I have asked this question and why I

would like the rest to discuss problems with me.<br>

And thanks on "Canham tip"... they have some good solutions (my english;)

from where I can learn... only to find one near me :(</p>

<p><b>Ralph:</b> Tnx for response, and yes, you are absolutely right - next

main question is what will someone be able to produce... hopefully, I'm

working in huge complex of press firms (several hunderts of printing engines)

and my small studio is just opposite of the machining department. They have

already made me some adapters, and I will for sure go there to ask them.

Next one chance is one relative of friend of mine who is working as

"small-useful-technical-things designer" for police... (whoa, friend just told me

that few hours ago;))<br>

unfortunately, all that will need to wait for me to get out of bed - meed

summer and I got somewhere some nasty cold... should be fine in less than a

week. In meantime, all I can is read, learn and discuss.</p>

<p>Tnx again<br>

Janko</p>

<p>P.S. The second sketch have been done:</p>

<p><img src="http://www.bellay.com/janko/003_sketch_pn.gif" alt="2nd

sketch" width="500" height="375" border="0"></p>

<p>changes have been described on <a

href="http://www.bellay.com/janko/day_002.php">my site</a> if someone

want to discuss it more...<p>

My first reaction is that your design has a risk of flexing the bed

and giving you unwanted tilt, especially at full extension when

you only have small stubs of the rails in the central block.

 

I would be tempted to turn one or both flat rails so that they are

vertical and move them to the side of the block. That way their

stiffest axis will be resisting the most likely torques. If you turn

and move both, you could even flatten the package a little by

reducing the thickness of the horizontal part of the central block.

 

Having the back and front standards moving away from a central

part was quite a common design among tailboard cameras at

the turn of the last century. Amost always there is something like

a strut or an extra slab of wood to stiffen the side perpendicular

to the boards and stop this sort of flexing. Look at some of the

collectibles on eBay if you want to get some more ideas.

To be honest Struan, I was lazy... at very beginning I thought that I will need

something else than plain cubes which can be distorted to easy. I think that

simplyest form will be triangle, so here is one more detail...<br><br>

<img src="http://www.bellay.com/janko/004_detail.gif"

alt="rail_and_base_detail" width="490" height="152" border="0"><br><br>

I hope that noone will be mad at me because I'm inserting those sketches... I

hope that everyone will learn from this ideas.<br><br>

Tnx.

Is there any reason not to make them hollow tubes? For a given

mass of material, a tube is the stiffest cross section for arbitrary

sideways loading. There used to be bi-rail cameras (Nue Vue is

a name that pops into my head) which, again, appear on eBay

quite often if you want design ideas.

 

Ti tubing is light and relatively easy to get hold of these days.

Since there is no machining of the actual rails involved, this

would be a good application for it.