Chroma - Lasercut Acrylic 4x5 Field Camera

steveo_mcg said:
Could you make a board cheap enough to be the litle not quite the full product reward?
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A lens board is cut as part of every camera from the same 3mm sheet as the other camera components. The only difference would be the shutter diameter in the centre. However, the circle that's cut out of the centre of the lens board is currently an offcut that's discarded but I could simply cut another smaller hole in the centre so a pinhole plate could be bonded behind it.
 
It will probably be a 0.5mm pinhole, going off an online calculator. Just need to sort out a simple shutter.

upload_2017-6-12_15-59-47.png

The brass plate will actually stick the pinhole insert to the lens board so it can be pushed out whenever the photographer is ready to use a proper lens (or they can purchase an additional lens board.
 
stevelmx5 said:
It will probably be a 0.5mm pinhole, going off an online calculator. Just need to sort out a simple shutter.

View attachment 103999

The brass plate will actually stick the pinhole insert to the lens board so it can be pushed out whenever the photographer is ready to use a proper lens (or they can purchase an additional lens board.
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A simple flap shutter would suffice , the Intrepid has no shutter at all.
 
I reckon the best option all round would be to include the pinhole insert with the brass pinhole plate already attached and an included sticker which can be used to stick to the inside of the lens board if you want to use it. The sticker will overlap the pinhole plate and the lens board around it to both hold it in place and act as a light seal. There won't be an included shutter so it will be up to the photographer to either use their hand or the dark slide. I reckon a 0.5mm diameter pinhole will give the best general result. If the front standard is mounted using the thread furthest forward from the rear standard, it will give a 172mm focal length and an aperture of around F350 which should make the hand operated shutter practical for all but the brightest days with ISO800 film!

Potentially it would be pretty simple to change the pinhole plate yourself if you wanted a wider angle result, using the same acrylic insert piece.
 
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steveo_mcg said:
Just don't get into kickstarter creep, keep it simple.
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Good advice. If I'm already cutting out the disk part anyway, it makes sense to repurpose it as a pinhole plate.

I have thought about launching the LightBlock under the same campaign because that's ready to go as well but I think it should be kept under its' own banner. I've still got a day job so don't want to be working 24/7!
 
More good news :0)

I've just been speaking to Chris Gampat (www.Thephoblographer.com) and he's happy to give me some news coverage and other backing;

"Actually the large format camera sounds much better. I absolutely will. I can do:

- News coverage
- An interview with you on the concept and design
- A review "

:)
 
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Cool, an excellent bit of free publicity.
 
I should probably say that we were originally talking about an article for my HolSlo 2D last month but I figured it would be more useful for me to get his thoughts/review of the LF Kickstarter instead!
 
I shoot my portraits/weddings under "Everyday-Photographics" so am thinking about taking the "Everyday" part to keep it friendly/approachable and using the "Chroma" part for the Acrylic/modern styling.
 
Ok, time for another random question. I've been speaking to a few different bellows manufacturers to compare prices. As expected, the UK supplier is around 3 times more expensive than the Chinese supplier I've been working with but I'm not 100% confident in the bellows from China (due to the way they're being made, not the supplier themselves).

At the same time, I'm still looking at my options for manufacturing the bellows in-house. The set I made used the traditional triple layer method;

1) Outer lightproof material (external layer from film changing bag)
2) Middle ribs layer (lasercut from thin plastic)
3) Inner black layer (internal material from film changing bag)

Whilst the bellows function as they should and are light tight, there is a lot of time spent bonding the layers, separating the ribs, folding etc so I'm looking at alternatives. I've got a single layer, thin flexible blackout material that should be strong enough on its' own to retain the folds and am considering cutting a complete template for all of the ribs from 3mm acrylic which could then be laid on top of the material and a liquid rubber 'poured' into the template to form all of the ribs. Once it set, I could remove the template sheet and be left with individual rubberised ribs which would guide the material into shape.

I may be completely off-target with this idea but it would reduce the bellows to a single layer, remove all of the cutting/bonding of the ribs and speed up the production. So my question is, does anyone have experience of a liquid rubber that can be poured then hardened to retain it's shape? An alternative I can think of is fibreglass resin (without the fibreglass sheets inlaid) as that will dry solid and is cheap enough to mix up in large quantities.
 
Silicone rubber probably isn't a suitable choice. I've tried to make castings that are stiff (resistant to compression was what I was after), and it wasn't easy. I first tried adding powdered chalk/marble and then tried fumed silica. The problem with both was that the liquid became almost too thick to pour. With the chalk, I got a reasonable result for what I wanted, but pouring didn't work well - most of it poured, but it didn't settle or level well. With the fumed silica, it was marginal for pouring, but the result was still too soft. All of my test bits were still pretty flexible. Another issue with thickening the stuff up with an additive is that it becomes harder for air bubbles to leave while it's curing. (In professional setups, they use a vacuum chamber to pull the bubbles out.)

For the bellows, the difficulties are compounded because the bits need to be pretty thin to stop the bellows being too bulky for short focal lengths, or when the camera is folded. Given that my test pieces were 5mm thick, and noticably flexible, I suspect a thickness suitable for bellows (1mm max?) will add very little in terms of structural rigidity.

Silicone is also quite heavy with a specific gravity around 1.2 to 1.3 (and some go outside that range), so sag might also be an issue depending out how much flex there is in the light tight material.

That said, Tiranti do a wide range of silicone rubbers, should you be interested...

http://www.tiranti.co.uk/EdgeImpactShop/subcategory.php?Subcategory=51&Content=Silicone+Rubber

I've used them once so far, and found the service very good.
 
Nomad Z said:
Silicone rubber probably isn't a suitable choice. I've tried to make castings that are stiff (resistant to compression was what I was after), and it wasn't easy. I first tried adding powdered chalk/marble and then tried fumed silica. The problem with both was that the liquid became almost too thick to pour. With the chalk, I got a reasonable result for what I wanted, but pouring didn't work well - most of it poured, but it didn't settle or level well. With the fumed silica, it was marginal for pouring, but the result was still too soft. All of my test bits were still pretty flexible. Another issue with thickening the stuff up with an additive is that it becomes harder for air bubbles to leave while it's curing. (In professional setups, they use a vacuum chamber to pull the bubbles out.)

For the bellows, the difficulties are compounded because the bits need to be pretty thin to stop the bellows being too bulky for short focal lengths, or when the camera is folded. Given that my test pieces were 5mm thick, and noticably flexible, I suspect a thickness suitable for bellows (1mm max?) will add very little in terms of structural rigidity.

Silicone is also quite heavy with a specific gravity around 1.2 to 1.3 (and some go outside that range), so sag might also be an issue depending out how much flex there is in the light tight material.

That said, Tiranti do a wide range of silicone rubbers, should you be interested...

http://www.tiranti.co.uk/EdgeImpactShop/subcategory.php?Subcategory=51&Content=Silicone+Rubber

I've used them once so far, and found the service very good.
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Thanks for the real world thoughts. I think the only realistic way to pour the ribs would be the user of fibreglass resin as it will cure to a solid part without being too dense. However, the more I think about it, the more I'm coming round to the fact that I may just need to bite the bullet and build them the traditional way! I could pre-cut the inner layer (3 pass blackout material), outer layer (ripstop nylon) and the ribs themselves (heavy weight card) then bond them with a spray adhesive. If I can design the cutting guides efficiently, it should reduce a lot of the headache.
 
gunnar said:
Will there be a self assembly option for nerds like me? :D
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I was originally building the camera with a kit option in mind but my main concern with that is the consistency of build quality. While the parts are basically laminated and bonded using a liquid that fuses the faces together, it all needs to be kept square and aligned. I'd be worried that if someone who, wasn't so confident or technically able, built it badly it could reflect on the whole brand overall.

I'm not entirely against the idea of a kit option, it would save me a lot of assembly!, but I'll see how quickly I can assemble my updated version first.
 
It strikes me that the ribs do not need to be encapsulated . They could be laid in a mould and the thin rubber compound poured on to them.
The stiffeners could be cut from a perforated plastic sheet. To increase the mechanical adhesion.

Rubber bellows are used in the motor industry and they do not have stiffners at all. However thay are comparatively inflexible and heavy.

I rather doubt that the traditional bellows can be improved upon for their particular function. Square bellows are easier to make, but tapered bellows are more flexible and versatile.
Bellows were made in very large numbers up to the 60's, they must have had ways to make them cost effectively, in some sort of production line.
 
Maybe keep the kit for after your kickstarter release once your sick of building cameras and your friends have all abandoned you :p

I think bellows are one of those bugger things which despite everything are still built the same way they've basically always been for a reason. I don't doubt a better method could be made but whether its cost effective to research is a different matter and if its starting to hold up your project; is it worth it.
 
Both valid points (particularly the bit about getting to the point that I've assembled too many cameras!)

As with everything, trying to keep the material costs down which in turn keeps the selling point down is the priority. I've got no illusion that I'm competing for the same market as Ebony/Chamonix/Gibellini etc so my direct challenge will be Intrepid. They manufacture their bellows in house and I'd assume they've gone through the same sums that I'm doing to get to that point. As above, bellows have been produced for close on 100 years so if there was a considerably faster/cheaper way of doing them, it would be done by now so I think I'm going to have to focus on efficiency using the traditional design.

Annoyingly, the chinese manufacturer I've been working with can only build bellows using a solid paperboard/card inner layer which is then bonded to the outer layer and then they are both folded to create the bellows. Externally, the bellows look great and they hold their shape well but I'm concerned about their flexibility for movements so I've asked the manufacturer if they can use traditional individual ribs instead so that's the next conversation.

In the meantime, I've also sent out RFQs to two other manufacturers to see what kind of price they come back with.
 
If my maths is correct...

upload_2017-6-14_16-42-35.png

I can cut all three of these pieces on the laser and the ribs can be bonded to the material in one piece which will remove all of the manual work involved with separating them.
 
Big night tonight, I'm ready to cut out all of my parts for the (final) "Chroma"

Chroma-Front.jpg

Chroma-Rear.jpg

I can't find any thumb screws that I'm happy with so I'm going with my original plan of cutting my own. This gives a few extra minutes of assembly per camera but in the long run I'm much happier with the functionality and appearance overall.

After going backwards and forwards over names/branding, I'm sticking with Chroma but dropping the 4-5 naming as it's pretty obvious that it's not a 35mm rangefinder ;0)

The first 10 "Earlybird" cameras on Kickstarter will be numbered like the one above. I was going to do "1 of 10", "2 of 10" etc but prefer the simplified text instead so they will have "one", "two", "three" etc. The name and numbers will be etched into the plastic rather than cut right through.

The only other change I've made is to use (more!) magnets to secure the ground glass rather than just friction. The plastic DDS holders are made from softer plastic so are fine holding in but the ground glass is cut exactly to size and gives a cleaner fit with magnets.
 
stevelmx5 said:
Big night tonight, I'm ready to cut out all of my parts for the (final) "Chroma"

View attachment 104187

View attachment 104188

I can't find any thumb screws that I'm happy with so I'm going with my original plan of cutting my own. This gives a few extra minutes of assembly per camera but in the long run I'm much happier with the functionality and appearance overall.

After going backwards and forwards over names/branding, I'm sticking with Chroma but dropping the 4-5 naming as it's pretty obvious that it's not a 35mm rangefinder ;0)

The first 10 "Earlybird" cameras on Kickstarter will be numbered like the one above. I was going to do "1 of 10", "2 of 10" etc but prefer the simplified text instead so they will have "one", "two", "three" etc. The name and numbers will be etched into the plastic rather than cut right through.

The only other change I've made is to use (more!) magnets to secure the ground glass rather than just friction. The plastic DDS holders are made from softer plastic so are fine holding in but the ground glass is cut exactly to size and gives a cleaner fit with magnets.
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This is just awesome, cant wait for this to become a reality.
 
RaglanSurf said:
This is just awesome, cant wait for this to become a reality.
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Thanks Nick, me too!

Unfortunately, the tube in the laser blew yesterday so I couldn't cut anything tonight :0(. The good news is that they should have a new tube tomorrow so can get on with the pieces :0)

While I was there, my friend estimated the cut time for each of the parts and thinks it should take around 30 minutes for all of them;

600x400 3mm Acrylic
600x400 5mm Acrylic
A3 2mm Acrylic
5mm closed cell foam
1mm rubber sheet

Once he actually cuts them he'll have a definitive time which will then give me a price for cutting them all which I can factor into the materials list.
 
In my quest for suitable bellows material I think I might have just struck lucky. I got in touch with a company that manufacture marquees that have a blackout internal lining for hosting functions etc and had a chat to them about their material. I got a sample of the material in the post today and it's lightweight, thin (around 0.5mm), appears to hold a crease and, most importantly, it's completely light tight. I've just held a bright LED torch directly against the material in a pitch black room and it blocked all of the light so I reckon that's a success :0)

I'm going to pick up an A1 sized sheet of 300gsm black card stock over the weekend then cut out the ribs on the laser next week. If my plan works, I may even get away with just using a single layer of black material with the ribs bonded to the underside to build the bellows. As well as keeping weight and complexity down, it also minimises the assembly time. Alternatively, I've also been looking at using a layer of ripstop nylon for the outer material. The nylon is very thin/light weight so offers no light blocking but it's also water-repellant and comes in numerous colours;

Chikara_sample2.jpg


Again, I need to build a bellows to test it but I could use the blackout material as the inner layer (which does all of the work blocking light), then bond the ribs, followed by an outer layer of nylon to give the bellows their colour and water protection.
 
Just asking...

Ever since I read an article which quantified flare from various sources I've been aware of reflectance; will the new material absorb any light as well as block it? I use a black plastic curtain to prevent light leaks around my darkroom door, but it's so reflective that it would be useless in bellows, although 100% light proof.
 
StephenM said:
Just asking...

Ever since I read an article which quantified flare from various sources I've been aware of reflectance; will the new material absorb any light as well as block it? I use a black plastic curtain to prevent light leaks around my darkroom door, but it's so reflective that it would be useless in bellows, although 100% light proof.
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Good question. The sample bellows I had made in China came with a fablon type clear plastic material stuck to the inner layer so created a lot of reflections/flare. Looking at this material, on the windowsill, it doesn't appear to reflect much light at all so I think it would be ideal.
 
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