Some musings on camera design...

[jb7]

Thanks Colin, yes, I remember that one-
I'm pretty sure I complimented you on it at the time,
very nice looking cameras, and beautifully made-

I had it bookmarked already...

A 4x5 will be smaller, of course, which will lead to its own problems-
when I did the 8x10 conversion, I had expected that my next camera would be bigger than that,
but some recent traveling convinced me that I should really be thinking about making my existing setup less painful to carry around-

Will definitely be having a look at your cameras again-

[athens01]

Yet another (hair-brained) idea for rear movements......It may not be elegant, but if you did design the camera like we talked about earlier.... detachable rear standard, rotating back and bellows for horizontal and vertical options..., you could incorporate different fixed connecting points to enable generalized directional perspective changes (back movements). In other words, fixed tilt and swing positions that buy you just enough angle difference to give the lens and front standard some help. I only say this only in thinking about a design with a detachable standard...if the detachable back is "central" to the design of the camera then why not explore options around that specific design element... hell it may be more irritating to use if you can lock in say a 10 degree tilt but that's all...just an idea..

[Gordon Moat]

http://www.youtube.com/watch?v=MKb4Dkjjmk8

The elegant aspect I find about the Gilde 617 camera is the use of magnets to hold various parts in place. There are also lots of interlocks and movements.

http://www.edmundoptics.com/onlineca...?categoryid=30

You might want to request a catalogue, though if you browse through their Positioning Stages, you might find a few items you could use. Prices are okay if you only want to make one or two cameras, but would be expensive for production.

http://www.edmundoptics.com/onlineca...categoryid=256

I am looking at production, and not just one camera. What I found with small lockdown handles is that I needed to order over 100 in order to get anyone interested in making them. That means I would need to finalize on one design, and then use it throughout the camera. The process has been quite difficult, though if I manage a large order of handles, then the overall price point would stay within reason on the finished cameras (target under $800 US).

The trick on the rack and pinion, with a courser rack, would be to get a larger pinion, or a smaller pinion. The idea is to translate hand (finger) motion to rack motion, and the diameter gives you finer control. I don't see the advantage of a helical, because some for of lockdown would be your device to prevent slippage.

Ciao!

Gordon Moat Photography

[JRFrench]

I have recently finished making my own 4x5 camera, mainly using the CNC mill at my University, as well as the CNC Lathe to make the thumbscrews. I ended up using rare earth magnets for attaching the back to the standard, and most of my movements are a bit different to how you would see them on commercial cameras as I had to design it around the equipment and materials I had available.

The focusing screw is a bit tedious, its very slow and you can't force it by pushing the standard to the rough position like you could with a rack and pinion. Unfortunately I found Rack gears difficult and/or expensive to find over here. If I were to do it again I would try a friction rack and pinion, where a rubber wheel roller on a grippy bar.

At the moment some of the movements require an allen key to unlock, but eventually I will make some lightweight aluminium thumb screws so no tools are required.

Some more photos here: http://www.flickr.com/photos/2744154...7623205328086/

[jb7]

Thanks again for your continued responses-
JR, that's a particularly robust looking camera-
I'm very jealous of your access to CNC-
Detents are a nice touch too, not sure I'd be up to that-
I'm sure I could make them, but would be worried they'd turn up in the wrong place...

There is a solution to your tedious focusing screw,
involving a spring loaded nut that is pushed out of the way for fast, rough focusing-

It looks a bit heavy, have you weighed it?
What are you studying, is this part of your course?

Gordon, I suppose the advantage of the helical drive is in keeping the bed centered,
and perhaps it might run smoother, with less likelihood of binding against the sides-
The smaller modules might allow for lower gearing, more input, less travel-

That 617 looks good, completely beyond me though-
I like the motor drive, from time to time I wonder about how motors can be applied to movements-
Then I pull myself together-
I've seen pictures of an electrically driven 20x24, but it was huge and heavy looking-

Can't help you on the lockdown handles, I'm afraid-
that's the difference between making something for yourself, and making something for production-
the market is far less accepting of my limitations than I would be-
Did you say you were designing a 4x5 camera?
Look forward to seeing something, sounds interesting-

I had a look at those Edmunds bits, don't think you'd hit your price point by shopping there-

Peter, that rotating rear standard and bellows is giving me something to think about-
but I'm wondering is it overkill-
a simpler solution would be to build a camera without it, and use an 'L' bracket to rotate-

The rotation is a good trick, and I like the look of the camera you linked to,
but it would exclude the possibility of rear movements altogether-

My ignorance of the function of rear movements notwithstanding,
(that's sarcasm, unfortunately)
I'm still not completely decided about which, if any, to include-

I had another look at Colin's camera again last night, it makes good reading-
particularly the musings about interlinked three dimensional thinking,
and how components determine other components-

Although there appeared to be a very strong vision about how things worked together,
and the timeline for building it showed very rapid progress,
it was reassuring to know that even Colin had to make time for some head scratching...

[Colin Graham]

Thanks Joseph. Sorry about the redundant posting, couldn't remember if I'd posted a link to it over here or not. I envy you your project, and look forward to seeing your progress with it.

[Gordon Moat]

Thanks again for your continued responses-
.......

Gordon,
........
Did you say you were designing a 4x5 camera?
Look forward to seeing something, sounds interesting-

My test of all this, and what led me to working on a 4x5 camera, was doing a Polaroid conversion. I made the entire lens block movable front standard on a milling machine. The rear film holder was made from one block of aluminum on the same mill. Everything is as compact as possible, and as thin as I could work with the Polaroid body.

What I discovered was that the milled parts are vastly more robust than the Polaroid parts. It made me realize how limited the Polaroid camera design is as a starting point. So I decided to work on a dedicated 4x5, which will probably use the rangefinder mechanism of the Polaroid, though more likely just a platform allowing regular 4x5 usage. Sketches, mock-ups and using Google SketchUp have allowed me to figure out the dimensions.

First hurdle was the bellows dimensions. While a custom design could be made, that would increase costs, so it was decided to use an existing available bellows. Next was the decision to go with Technika style lensboards, since I already have several. Then with the major detail limitations, I have been polishing the design. Unfortunately, I have yet to solve the lockdown handles, and that might mean more changes before I get to a final product. Realistically, I am aiming at about 10 cameras as the break even point, not counting my time involvement.

What I want out of it is a 4x5 camera that can take rollfilm or instant film holders, and use regular 4x5 holders. I want rear swing movement without focus shift, which would allow for things like selective focus (portraits, still life, etc). Weight needs to be light enough to hand hold, and ergonomics so that it feels balanced. Additional movements on the front, in a manner I worked out on the Polaroid conversion (swing, tilt, rise and fall, shift), using only two lockdown handles. Everything with zero detents using threaded slugs that McMaster sell (M4 x.7 thread with 2.5mm ball). Mostly 6061 and 7075 heat treated aluminum for strength and low weight.

Ciao!

Gordon Moat Photography

[JRFrench]

Thanks again for your continued responses-
JR, that's a particularly robust looking camera-
I'm very jealous of your access to CNC-
Detents are a nice touch too, not sure I'd be up to that-
I'm sure I could make them, but would be worried they'd turn up in the wrong place...

There is a solution to your tedious focusing screw,
involving a spring loaded nut that is pushed out of the way for fast, rough focusing-

It looks a bit heavy, have you weighed it?
What are you studying, is this part of your course?

I was happy with how the detents turned out, but apart from the tilt one they aren't really necessary, its easy enough to center the other movements by hand.

I did consider a spring loaded nut, or a lever actuated half nut to disengage the standard, but in the end I have one floating standard that can be dragged around for rough positioning, and one fixed to the screw, so it works pretty well. Its very effective for getting precise focus with a loupe, as its not too touchy.

I havn't weighed it, but my design weight (measured in SolidWorks) always remained under 4lbs, its not immediately obvious but most of the aluminium parts have serious weight reduction on their backs or undersides, the only part I havn't lightened are the 16mm rails, they are still solid. I plan on finding some stainless steel tube to replace them.

I am studying for my PhD in Engineering, unfortunately the camera is not directly related to my course, although getting more experience in design and manufacture is always encouraged.

[JRFrench]

I just weighed it and its bang on 5lbs with everything but a lens, about 2.25kg. Not too bad, could be less with Aluminium thumb screws instead of stainless steel and hollow rails.