Chroma - Lasercut Acrylic 4x5 Field Camera

Updated rise/fall standard with rails either side. There are now two 16x8x3mm acrylic bars that are bonded to both the front and rear frames of the standard which pass through the slots either side of the lens board frame (in silver below but will be the same colour as the camera). These new bars keep the U-shaped surround straight by fixing it to the inner lens board frame. The frame can still move up/down and lock in place using the bolts either side at the top.

Screenshot 2017-07-15 00.26.08.png

Even with the added guide rails and bars, there is still 25mm fall and 75mm rise available.
 
Last edited:
I haven't got any photos because I still need to clean up a few bits of glue etc but I assembled the rear standard and film holder yesterday and, if I do say so myself, it's looking awesome :0)

I've ordered some more acrylic so have to wait until that arrives to carry on the build because I've made a change to the focus mechanism after trying it out for real. My current design uses a rack/pinion gear to move the focus rail but after trying it, I'm concerned about the long-term performance (years not months!) due to possible wear on the pinion teeth as there's no way to adjust it once it's assembled. As a result, I've changed the design slightly to use a friction-based system instead which still uses the same central wheel underneath to adjust focus but now moves the focus rail using a combination of a rubber-edged wheel and rubber inner face on the rail;

upload_2017-7-18_10-8-52.png

The two major benefits of this over a more traditional rack/pinion are that there is no risk of long-term wearing down of teeth so it will stay solid and also it gives completely step-less focusing adjustment. I've also added in a guide block on each side of the focus rail to remove any wiggle at longer focus points and acts as a hard stop which simplifies the original design that had a sprung pin to lock it in place. There will be a pair of felt trims either side of the rail inside the camera to ensure it slides smoothly too. Whilst I'm building the camera to a price point, that doesn't mean it needs to feel like a compromise. There is still the same locking knob built in to the main focus knob below the camera so I can unlock it, focus then lock it again with one hand.
 
Last edited:
I decided to do a dry assembly of the rear standard hinge mechanism so I could see the fit/tolerances in the real-world.







I've got my new acrylic sheet so I can cut the new camera bed/front standard pieces soon then get it assembled properly. I've also found a new nylon material that will be much better for the interior of the bellows as it's considerably thinner without losing any of the blackout properties. There's also a new plastic material I'm going to cut the ribs from to reduce the thickness. I've got a metre of the nylon coming in the post so will cut that at the same time.
 
Status update:

- I've part assembled the new focusing rack to test the alignment. I cut two different sized circular gear wheels that will move the rack, figuring that one would be right. One is 15mm diameter, one is 16mm...I reckon 15.5mm will be spot on (sod's law!). The 16mm wheel is just slightly too tight so will keep the rack under too much tension I think so that's one slight change needed going forwards.

- I haven't assembled it yet but the new front standard design seems much more stable. There's now no flex in the uprights as the lens board surround keeps it square. It also means that there's a hard stop on the rise rather than relying on embedded magnets. That also means a reduction in build complexity as there are 4 less magnets to fit.

- The new bellows material is spot on. It's lightweight, flexible and light tight. I managed to cock up my alignment of the outer orange layer when bonding it all together though so this one doesn't look as neat as my other set (mark 2, 3, 26...I've lost count!) but I was more interested in the overall performance to test them rather than the appearance. Before I build more, I'm going to build a former so it's easier to lay up the material layers and bond them. Another positive is that I'm getting quicker at making them, 20 minutes from end to end :0). I intended to cut the ribs out of the same 320gsm card stock that I used on the others but I realised that I've drawn my plans slightly too large for the sheets of card I've got! Instead, I cut them out of material that's used in pull up advertising boards (a bit like projector screen material) as it's what I had to hand at the laser cutter. As it happens, the ribs work really well. They're not as rigid as card, but they're more flexible without losing their shape. I've got the bellows under a weight overnight to crease the folds so I'll check it for performance tomorrow.

I really just want to get a finished camera out in the field now to try it out for real. I continue to make small design changes as I go along and come across improvements for fit/function/assembly but I'm going to finish the purple version in the current design before I build any others.
 
Last edited:
Oh yeah, Miles Whitehead has sorted out my Angulon 90/6.3 so that's on its' way back to me now and I should have it on Monday. He replaced the main spring as I expected (it was over-stretched) and also had to repair a gear bearing. All good now though so I'm looking forward to some wide angle shooting.
 
Can't wait to see it all assembled Steve!

Sorry Charlotte, there's going to be a small delay on that. Unfortunately, Chroma has claimed its first victim....my left thumb/nail [emoji22]. Do you ever do something even though your head is telling you it's a really stupid thing to do...

I was using a nice sharp (luckily!) Stanley knife to separate the old front standard I assembled last week to harvest the magnets from it and managed to slip and slice into my thumb/nail. After a relatively short trip to A&E (as I expected it to need gluing) I've come back with a steri-stripped and strapped thumb so no more assembly tonight!

The good news is that I managed to complete the assembly of the camera bed and new focus mechanism and that's awesome so not a completely wasted evening!
 
Ouch!

How long before it's safe to use?
 
You mean to say you didn't take it all to A&E to have something to do while you were waiting? Tsk Tsk!
 
I managed to work through the horrendous pain last night for the greater good of mankind to continue the build ;0)

My new focus mechanism is working nicely. I've bonded the focusing wheel to the axle using epoxy and have updated my design to include a 2mm rod that will bond through both the acrylic axle and the wheel to add extra strength.

My new front standard design is much more rigid than my original design too so that's a big improvement. For the assembly process, I've just drawn in more support blocks so they will align the layers exactly and also add even more rigidity. I had to align the parts by eye last night so a couple are frustratingly out by <1mm but I'm annoyed that they're not perfect! It will also speed up the assembly as the parts will lock together.

I'm toying with laminating the three sheets that make up the camera bed using a number of bolts and embedded threads in the bottom part rather than bonding them. The main reasons for that are;

- Much simpler to assemble as the bolts will align up with the threads and can be screwed together.

- This makes it a serviceable part if there was ever a requirement to repair the rear standard hinge supports or the focusing rack. Whilst bonding them gives a neater external finish as there are no visible fixings, I'm trying to plan ahead for future support.

The bolts would have countersunk heads so will be flush with the surface and will also be mostly covered by the bellows so I think it's a sensible approach.
 
A less positive update is that my shutter came back from Miles Whitehead yesterday but when I tested it, it's still jamming when fired :0(. I spoke to him this morning and he said that he'd had to repair a gear pivot in the M delay mechanism so it could be that shifted again. He hasn't got any donor shutters to take a part but I'm going to send it back to him to see if he can do anything :0(

One good thing is that my Olympus OM 35/2.8 Shift should be arriving tomorrow. Going by my luck this week, it will probably be completely knackered but fingers' crossed eh!
 
I managed to work through the horrendous pain last night for the greater good of mankind to continue the build ;0)

My new focus mechanism is working nicely. I've bonded the focusing wheel to the axle using epoxy and have updated my design to include a 2mm rod that will bond through both the acrylic axle and the wheel to add extra strength.

My new front standard design is much more rigid than my original design too so that's a big improvement. For the assembly process, I've just drawn in more support blocks so they will align the layers exactly and also add even more rigidity. I had to align the parts by eye last night so a couple are frustratingly out by <1mm but I'm annoyed that they're not perfect! It will also speed up the assembly as the parts will lock together.

I'm toying with laminating the three sheets that make up the camera bed using a number of bolts and embedded threads in the bottom part rather than bonding them. The main reasons for that are;

- Much simpler to assemble as the bolts will align up with the threads and can be screwed together.

- This makes it a serviceable part if there was ever a requirement to repair the rear standard hinge supports or the focusing rack. Whilst bonding them gives a neater external finish as there are no visible fixings, I'm trying to plan ahead for future support.

The bolts would have countersunk heads so will be flush with the surface and will also be mostly covered by the bellows so I think it's a sensible approach.

Are you going to cut threads in the acrylic, or sink nuts in to it? or use standard threaded insets.? Threaded inserts are perhaps the strongest and neatest alternative.
 
If anyone would like an acrylic 4x5 field camera I'll be launching one out of the window soon.....aaaaarrrggghhh!!!!!

I've been finishing the assembly of the front standard/focusing rail today and it feels like I'm taking 3 steps back for every one forward :mad: I'm concerned that the current design of the front standard is too complex for its' own good (and assembly) and that bonding layers runs the risk of strength issues down the line. I've already changed the design slightly to incorporate plates that will align the layers and add some further rigidity but I'm wondering if it might be better laminating everything with bolts/embedded nuts. As well as speeding up the assembly, it would mean that I don't need to use glue on each layer and wait for it to dry before moving on. I may need to make the frames of the standard slightly wider to allow for it but they would still be no wider than the rear standard.

I'm also having an ongoing fight with the focusing wheel and bonding the acrylic axle to it for adjustment. As I've only got 3mm of depth to play with, any method I use to bond the acrylic axle rod to the wheel is inherently weak. I've used a combination of heat molding around a metal rod for strength and araldite and I'm still not 100% happy with its' long-term strength. I'll come back to that one!
 
Hang in there, Steve, this is what the D in R&D is all about (as opposed to the B in R&B, which is probably where you are now!).
 
Hang in there, Steve, this is what the D in R&D is all about (as opposed to the B in R&B, which is probably where you are now!).

Thanks Chris. I'm definitely in the development/booting it in to touch area today.

I've figured out a better way to attach the focusing wheel which will allow me to screw it securely to the knob on the outside which will mean no reliance on bonding. I'm going to make the adjustments and drill some holes on my current Acrylic bed though to save me having to buy more acrylic until I know that the design works.

On a good note, my OM Zuiko 35/2.8 shift arrived today and it's minty mint!
 
Last edited:
I've just heat-set the threads into the focus bed so I could bolt the current front standard in place to test the fit. On the whole I'm happy with it although I'm waiting for another set of bolts to arrive that are the correct length before I bond the knurled Acrylic heads to them permanently.

150mm Fujinon lens at zero rise/fall;

IMG_8356.JPG

Same lens at -25mm fall;

IMG_8358.JPG

Camera folded back. I'm happy with how simple this is. Basically, remove the lens and unclip the bellows from the front standard (4 embedded magnets), loosen the tilt bolts and drop the standard back to the focus bed. Then, loosen the two bolts in the base of the rear standard and fold it forwards over the top of the front standard whilst holding the bellows back against it;

IMG_8359.JPG

IMG_8360.JPG
 
Forgot to add, I've finished the redesign of the front standard so it's now going to be bolted together using M3 brass countersunk machine screws and embedded brass thread inserts instead of being bonded. I've also changed the layout of the parts for the laser cutter so the tolerances will be much tighter.

The major benefit of using screws/threads to assemble the unit is that it will give a much cleaner finish. Even taking the most care, it's still near impossible to get 4 layers laminated together perfectly without getting any glue residue on the external faces (which really bugs me!)
 
Last edited:
I'd imagine screws are certainly neater than glue - time-wise, is it much of a difference? It's looking fantastic!
 
I'd imagine screws are certainly neater than glue - time-wise, is it much of a difference? It's looking fantastic!

I'll still need to heat-fit the threaded inserts into the rear-side parts so that will take a few minutes but the main benefit is no need to glue it all up. The point of using acrylic (as well as being uniquely coloured) is that the surface and edges are smooth and neat. I've got a few marks from the adhesive on mine here and there and it really annoys me! Another side effect of the using screws/threads is that I've made the standard slightly wider (6mm total) to give enough Acrylic around the screws. As a result, the overall unit is also more rigid again.
 
This camera is going to bankrupt me. I've got a new design finalised so have ordered all of the material to build another one, wish me luck!

Think long-term mate, this time next year you'll be a millionaire :)
 
While I'm waiting for my next batch of materials to arrive, I've been thinking about a dark cloth and whether it's something I should consider supplying with the camera or if it's a personal preference choice? Potentially, I could use the already-embedded magnets in the DDS holder plate to attach a cloth and would make the cloth out of the same material I'm using for the bellows. I could even colour-code it with the bellows if someone wanted to go all out with the design ;0)

Any thoughts?
 
Mate, if I can afford the beans to go on my toast it will be a bonus ;0)
I've got a couple of spare tins in the cupboard I could send if your that easily pleased!
 
Since I've not ever used a LF camera - are they always necessary? Maybe have them as an optional extra you can buy with the camera?
 
While I'm waiting for my next batch of materials to arrive, I've been thinking about a dark cloth and whether it's something I should consider supplying with the camera or if it's a personal preference choice? Potentially, I could use the already-embedded magnets in the DDS holder plate to attach a cloth and would make the cloth out of the same material I'm using for the bellows. I could even colour-code it with the bellows if someone wanted to go all out with the design ;0)

Any thoughts?

Kind of cool to have a matching cloth but since most people who have a LF will own a cloth and newbies are generally advised to start with a t-shirt I think its probably just additional cost for the user and much more work for you.
 
Since I've not ever used a LF camera - are they always necessary? Maybe have them as an optional extra you can buy with the camera?

The dark cloth over your head/ground glass improves contrast as it stops any light hitting the front of the ground glass. It's not a necessity for the camera to work but it certainly makes it easier to compose/focus. The last LF camera I built (Polaroid 110a conversion) had a magnetic popup shade that I fitted when focussing so I could potentially do something similar but as Steve says below, you can also just use a large T-Shirt to create a tube of material that goes over your head and the camera.
 
Back
Top