Chroma - Lasercut Acrylic 4x5 Field Camera

mothdust said:
That looks good! I suppose with bikes, there's a bit more danger of a knock or scratch.
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Yeah, definitely. A simpler alternative to dipping is to wrap the panels. My friend with the laser cutters also wraps cars/vans etc and that plastic is much stronger. As well as solid colours they can also print any pattern onto a base colour too. I think the wraps have something like a 5 year guarantee but can be peeled off at any time with heat and an activator.
 
I've looked into the vinyl wrap before! Or the dipping technique - they float a pattern on water and dip individual pieces in to transfer it (can't remember what it's called!). The dipping looks especially good if done well, but I think it's harder to remove.
 
My initial idea for the bellows didn't work as well as I'd hoped (heat-bonded vinyl didn't stick well to the ripstop nylon) but sandwiching the card ribs between two layers of heat-bonded vinyl looks perfect :0). The finished material is flexible, waterproof, lightweight, stretches without losing shape and is completely light tight so positive all round. A single layer of the vinyl is actually light tight so I may try doing away with the inner layer entirely and just leave the ribs uncovered inside the bellows but that's just as an extra option really.

Even better is that the heat-bonded vinyl comes on large rolls in pretty much any colour/design I can think of! I've just been looking at a particularly fetching light camouflage design or chrome for that full on Huggy Bear look ;0)
 
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While total freedom for the customer in terms of colours is a lovely idea, might it not mean that you'll need a rather large stock of assorted materials for bellows. standards etc.? And how far can the customisation be taken? I might like one with each lamination layer being in rainbow sequence... ;) I wonder how well the assorted colours of body that were available for (?) Pentax a few years ago sold.
 
If the ribs are uncovered, is there any chance of either reflections (I assume that the vinyl is smooth/shiny) and would leaving them uncovered result in more crevasses for dust to accumulate in before dropping onto the film to leave dark spots?
 
Nod said:
While total freedom for the customer in terms of colours is a lovely idea, might it not mean that you'll need a rather large stock of assorted materials for bellows. standards etc.? And how far can the customisation be taken? I might like one with each lamination layer being in rainbow sequence... ;) I wonder how well the assorted colours of body that were available for (?) Pentax a few years ago sold.
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Whilst the full on unicorn effect is possible, I reckon I'll be selling the cameras in solid colours only for ease of machining. The design cuts everything out of two large sheets of 5mm / 3mm Acrylic so it makes most financial sense to use them whole. That doesn't rule out special editions though ;0)

The same goes for the bellows. Whilst I could offer a huge choice, I think it makes most sense to limit it to a smaller range.
 
StephenM said:
If the ribs are uncovered, is there any chance of either reflections (I assume that the vinyl is smooth/shiny) and would leaving them uncovered result in more crevasses for dust to accumulate in before dropping onto the film to leave dark spots?
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Good point about leaving them uncovered. You're right in saying the vinyl is Matt/Gloss so I'm planning on bonding the gloss faces together with the ribs in between so I have a Matt finish on the inside and outside.

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(These aren't real ribs, just some card offcuts to test the bond!)
 
So, how do you test the clear bellows for light tightness?
 
The rainbow effect was purely in jest (although it would be quite cool!!!)

I know that bellows are traditionally black on the outside but could a paler colour actually be better to reduce the temperature inside the body? It'll be a fair expanse of radiation absorbing matt black that's exposed!
 
Nod said:
The rainbow effect was purely in jest (although it would be quite cool!!!)

I know that bellows are traditionally black on the outside but could a paler colour actually be better to reduce the temperature inside the body? It'll be a fair expanse of radiation absorbing matt black that's exposed!
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I'm planning on using Matt black for the inside layer, then the card ribs, then any colour on the outside as a single layer is completely lightproof so the external doesn't have to be black.
 
Sweet....
 
CAF! But you need to make sure all the screw heads are aligned so the slots are parallel to the nearest edge... :p
 
Nod said:
CAF! But you need to make sure all the screw heads are aligned so the slots are parallel to the nearest edge... :p
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Don't start me! I'm bad enough as it is for getting everything aligned :0)

I still need to embed the threads into the rear plates before it's all bolted together but I wanted to see how smooth the movement is.
 
Maybe some mirror screw type thingies if such thingies exist for machine screws?
 
Quick question to the LF users. In my current front standard design, I've included a small 1mm deep indent in the Shift axis so you can feel where the zero point is as the locking knob drops into the indent and you have to actively unscrew it further to clear. I know other cameras like the Intrepid just rely on judging the position by eye. If I engraved a circle in the base where the locking knob is central, would that be good enough to not require the indentation? I'm looking at a way to build the frame slightly different and raise the hinge point to the middle of the upright rather than at the base to help balance heavier lenses.
 
:plus1::withstupid::D
 
RaglanSurf said:
Oh FFS hurry up Steve, I'm getting really impatient :eek:
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Sorry for the drip-feeding dude ;0) I don't get much free time so am having to assemble the parts in bits and pieces. The good news is that the rise/fall movement is really smooth now and I've also assembled the light baffles on the back of the lens board frame, ready for the bellows.
 
stevelmx5 said:
Sorry for the drip-feeding dude ;0) I don't get much free time so am having to assemble the parts in bits and pieces. The good news is that the rise/fall movement is really smooth now and I've also assembled the light baffles on the back of the lens board frame, ready for the bellows.
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No problem Steve although I am stupidly excited about the Chroma One I know these things take time and my impatience is almost entirely for comic effect (y)
 
RaglanSurf said:
No problem Steve although I am stupidly excited about the Chroma One I know these things take time and my impatience is almost entirely for comic effect (y)
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I really appreciate the fact that you're interested in it mate, considering you already own an Intrepid. I had a slight flash of inspiration earlier with the front standard which means I can remove one of the laminations which will simplify the build and make it slightly lighter. I've also moved the locking bolts to the rear face of the standard rather than the side. It's easier to see than describe but it basically means that the standard is simple to use but adds more rigidity again. I'm still building this one using the current design and will build another standard once I've got this one in place as they're interchangeable.
 
If you have any problems with acrylic parts let me know, I run a 2mx3m laser and all we cut is acrylic, sometimes mdf, we also have the same size cnc again just cutting acrylic and mdf, and we have loads of off cuts, happy to help.
 
What's the maximum weight of the lens that can be mounted? One of the questions that was asked of Intrepid was whether their camera would support a specific (heavy) lens.
 
StephenM said:
What's the maximum weight of the lens that can be mounted? One of the questions that was asked of Intrepid was whether their camera would support a specific (heavy) lens.
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Funnily enough, my updated front standard design will be much stronger and will be better balanced for heavier lenses but I couldn't give you a definite answer on the weight! Thanks for your direct message too, I'd really appreciate another lens to test the rigidity.

The main changes I've made are;

- Reduced the number of layers making up the lens board frame to 3 by removing one of the inner 3mm layers. - This reduces build complexity and reliance on a pair of internal guide pins to maintain smooth movement.

- Moved the rise/fall locking knobs to the rear face of the upright rather than the side - Means that the remaining 3mm layer can be a single piece rather than having to embed an M5 thread through it for the locking knobs on the side. I've drawn what looks like a pair of horns (!) because I was aiming to keep them large enough to use with gloves on but not not so large that they stick out and get in the way. They will only need to move 90 degrees to lock/unlock the rise/fall so won't get in the way of the bellows (point upwards, unlocked. Point to the side, locked).

- Moved the hinge point for tilt to the middle of the upright rather than the bottom. Originally, I was intending on folding the front standard at the tilt point when closing the camera. However, I've now decided to simply unscrew the shift/swing knob when closing the camera (like the Intrepid) so I don't need to hinge from the bottom any more. By moving the hinge point upwards, the front standard will be much better balanced for heavier lenses and it will also be easier to make small changes to the tilt adjustment as the lens board won't try to fall backwards/forwards so easily.

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I sorted out the issue of a central 'zero' marker for the shift too. There is a layer of 1mm rubber across the top face of the frame (below the locking knob) which has a circle cutout in the centre. When the front standard is at zero shift, the locking knob will drop into the rebate so you can feel when it's in the middle.
 
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I love these build updates, Steve! My excitement is only dampened when I remember I've never used a LF camera before, so I'd likely receive mine and then spend ages just staring at it all in bewilderment :D
 
This week's bellows build update :0)

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Bit of a faff assembling, because the heat plate that my friend uses to apply the vinyl is only 300mm square so we had to keep the ribs in place with heat tape and then press it a few times. On the whole I'm happy with the final result though. This is two layers of plain black vinyl with gloss sides face to face to give a Matt internal and external finish.

The flexibility is good and the material is slightly rubbery so is wipe clean and waterproof. I've realised how I can improve the ribs design so that the ribs fold even more flat and should also help with the movements too. My mate was trying to get me to use up the gold/snakeskin/camo vinyl he's got so maybe one of them will be next!
 
I made the decision last night to drop the friction fit focusing because I'm not completely happy with how well it functions, especially with a heavier lens mounted, so I've redrawn the parts using a traditional rack and pinion gear instead. I'll cut the slice out of 3mm mdf when I go back down to the cutter in the week before I cut more Acrylic. I did the same with the front standard yesterday so it's currently a combination of transparent Acrylic and Mdf which looks 'unique' ;0)
 
I had some time last night, while I'm waiting for my next batch of Acrylic to arrive, so have drawn up the simplified traditional front standard alongside the technical one. I've kept it as small as possible while still having the same range of rise (45mm) and fall (25mm) as the technical standard. I've also kept the embedded magnets for zero rise/tilt so it's easy to centre the lens.

I know I've asked before but I'm wondering if it would be better to offer both options side by side during the Kickstarter with a reduced price for the simplified standard (as there's less assembly time), or I should just release with the simplified standard and offer the technical one as a stretch goal?
 
Also, I started thinking about the version 2 Chroma with rear movements as well as front. The only way I'm going to be able to do that, and include rise/fall on the back, is to increase the width of the camera by around 30mm to accommodate the film holder in landscape orientation. If just want to include tilt, I could probably use the exiting design and use the current hinge point for closing up the camera as a lockable tilt instead.

I'm not sure if adding just rear tilt is enough of a benefit to redesign the base to accommodate it though?
 
Given the short bellows length, the camera is going to be used with normal and wide angle lenses. The problem with wide angle lenses is that as focal length length decreases, depth of field increases and depth of focus decreases (depth of field being how much you can vary the position of the subject and still have it sharp, depth of focus being how much you can vary the film position and still get a sharp image). Which is why Mike Walker's cameras designed for wide angle photography have fixed backs - to ensure that they are rigidly parallel. On that basis, much as I like having rear movements, I'd omit them on this camera. Were the bellows longer, it would be a different matter.

Rear movements let you adjust the image shape, and at the cost of distortion gain extra tilt/swing capability because on the rear those movements still use the centre of the image circle. This can be useful at times; but the cost is the need for greater care in setting up with a wide angle every time you use one.
 
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StephenM said:
Given the short bellows length, the camera is going to be used with normal and wide angle lenses. The problem with wide angle lenses is that as focal length length decreases, depeth of field increases and depth of focus decreases (depth of field being how much you can vary the position of the subject and still have it sharp, depth of focus being how much you can vary the film position and still get a sharp image). Which is why Mike Walker's cameras designed for wide angle photography have fixed backs - to ensure that they are rigidly parallel. On that basis, much as I like having rear movements, I'd omit them on this camera. Were the bellows longer, it would be a different matter.

Rear movements let you adjust the image shape, and at the cost of distortion gain extra tilt/swing capability because on the rear those movements still use the centre of the image circle. This can be useful at times; but the cost is the need for greater care in setting up with a wide angle every time you use one.
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Thanks Stephen, that's an excellent explanation and confirms my thoughts about the rear being solid and parallel being more important than any movements. I'll leave it fixed for the time being and maybe look again in the future if I build a larger version where there would be more benefit.
 
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