Chroma - Lasercut Acrylic 4x5 Field Camera

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stevelmx5
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Ah, the joys of 3D printing....

Body.JPG

First print was 90% successful. Looks like the model was hollowed below the top deck for some reason and the slicing software didn't add any supports to account for it so it was about 10mm off being finished! I've made some changes to my model and sent it back over to the printer to check it out so hopefully not a terminal issue!
 

Woodsy

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I know this has probably been debated to the n^th degree on the intertubes, and not withstanding the issues it would create with focusing somewhere other than the normal ground glass, but is it possible to make a 617 back for 5x4 on the provision that the film plane is set suitably far back from the normal ground glass plane, thereby allowing the projection from the lens not to clip on the rear standard once the lens is moved back sufficiently? Obviously you'd need a lens which produces a large enough image circle as well...
 
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I know this has probably been debated to the n^th degree on the intertubes, and not withstanding the issues it would create with focusing somewhere other than the normal ground glass, but is it possible to make a 617 back for 5x4 on the provision that the film plane is set suitably far back from the normal ground glass plane, thereby allowing the projection from the lens not to clip on the rear standard once the lens is moved back sufficiently? Obviously you'd need a lens which produces a large enough image circle as well...
Quick answer...yes...I've already drawn one up although I can't find the file at the moment! (and it's only been drawn theoretically on screen, I haven't tested the idea with a real lens)

Long answer...it moves the focal plane back by around 150mm, as far as I remember, to allow for the image to project through the standard opening and still cover the 170mm wide film, which will also have an impact on the amount of light getting to the glass/film and also bellows movement.. The main issue with this is how far it moves the centre of balance back for the rear standard so increases the risk of flex etc. I never got further than a rough sketch because I wanted to focus on the 6x12 back as a priority but it's certainly something I could come back to in the future. I imagined integrating a new ground glass into the 6x17 back, along with the removable film holder. Now I've got the basic design complete for the 6x12 back, it should be a relatively simple step to adjust the design to gain 25mm on each side but I'll get this one sorted first :0)
 

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Quick answer...yes...I've already drawn one up although I can't find the file at the moment! (and it's only been drawn theoretically on screen, I haven't tested the idea with a real lens)

Long answer...it moves the focal plane back by around 150mm, as far as I remember, to allow for the image to project through the standard opening and still cover the 170mm wide film, which will also have an impact on the amount of light getting to the glass/film and also bellows movement.. The main issue with this is how far it moves the centre of balance back for the rear standard so increases the risk of flex etc. I never got further than a rough sketch because I wanted to focus on the 6x12 back as a priority but it's certainly something I could come back to in the future. I imagined integrating a new ground glass into the 6x17 back, along with the removable film holder. Now I've got the basic design complete for the 6x12 back, it should be a relatively simple step to adjust the design to gain 25mm on each side but I'll get this one sorted first :0)
Don't make me use P.Fry again... :D
 
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StephenM

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Thanks for that. I haven't a clue what Futurama is, but I can Google that...
 
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...it moves the focal plane back by around 150mm, as far as I remember, to allow for the image to project through the standard opening and still cover the 170mm wide film, which will also have an impact on the amount of light getting to the glass/film and also bellows movement..
The amount that the lens moves back to get the projected image to clear the frame depends on the focal length of the lens. A wide lens projects its image cone at a more oblique angle, so moves back less, while a long lens has it at a more acute angle and has to move back more. For example, a 90mm moves back about 26.5mm; and a 150 about 44mm.

There is no difference to the amount of light hitting the film in the sense of losses from using extension tubes or the like because the distance from the lens to the film is the same for a given focus setting. In effect, the only thing that's moving is the frame at the back of the camera that's normally used to support the film holder. That said, there is a chance of increased fall-off / vignetting when using the 17cm width.
 
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The amount that the lens moves back to get the projected image to clear the frame depends on the focal length of the lens. A wide lens projects its image cone at a more oblique angle, so moves back less, while a long lens has it at a more acute angle and has to move back more. For example, a 90mm moves back about 26.5mm; and a 150 about 44mm.

There is no difference to the amount of light hitting the film in the sense of losses from using extension tubes or the like because the distance from the lens to the film is the same for a given focus setting. In effect, the only thing that's moving is the frame at the back of the camera that's normally used to support the film holder. That said, there is a chance of increased fall-off / vignetting when using the 17cm width.
Thanks for the clarification, particularly correcting me about light fall-off. Now you've described it, that makes perfect sense! Cheers
 
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Second test print is much more successful;

LidFitted.png

This is the lid (left) fitted to a test print of the top 10mm of the main body (right). The alignment looks spot on and should give a good light seal so the printer is going ahead with another full print of the body.
 
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LidAndBody.png

Top piece is the lid (upside down) showing the inset around the rim and the bottom piece is the test print of the main body showing the 2mm raised lip that runs around it and fits into the inset in the lid. The innermost holes are for securing the lid on (there will be m4 rods embedded into the body that pass through the lid and nuts on the other side), and the outermost holes are for the rods that go into the 120 spindles to wind the film on.
 
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Big moment guys.....the first official unboxing video for a Chroma!


Rich is a really nice guy who I met at the Photography Show at the NEC this year and he received his Chroma this morning. I know he'd really appreciate the views/support if you want to take a look at his first impressions of his shiny (well matte..) new Chroma.
 

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Andysnap

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"Nice bag which will hopefully keep it scratch free"...as he scratches it all over his desk! Heh.
Clumsy oaf, this is why Nikki won't let you have shiny new things ;):D
 

Andysnap

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No no, not me ya daft spoon, the guy in the video a few posts above mine :)
My comment still stands regardless of the facts.:)
 

Nod

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Oh yeah, same as they told me "chicks dig scars" after the last time I fell off the motorbike... I don't quite agree to either of those ;)

I have a few scars, the most visible being the one from ear to ear across the top of me heed. I'm unlikely to be showing the vasectomy scar off and even less likely to be flashing the haemorrhoidectomy one!!!
 

ChrisR

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How is the production process going, @stevelmx5 ? Is it slower than you expected, or are you getting into the swing of it?
 
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How is the production process going, @stevelmx5 ? Is it slower than you expected, or are you getting into the swing of it?
I’m actually sending a backer update later this evening (I’m currently building a new dining set from Ikea!) to let everyone know the progress. I’m currently taking around 5 hours to assemble each camera from end to end, so my original timeframes are going to have to be pushed back a little, sadly. I’ve built/shipped the first 11 Earlybirds (pending an extra lens board for one but it will go tomorrow) and have started on the next block of Kickstarter Specials.

I’m running around 8 weeks behind schedule as a result of the time it’s taking to build, working around my day job, and a far from simple Home life (my daughter, Chloe, has autism and is really struggling to cope during the school holidays due to being out of routine so she’s taking a lot of time/attention from both myself and Hayley). I’ve taken this week off from work with the intention of camping out in the workshop to catch up so will hopefully bring down the delivery dates as much as I can.
 
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that's a cracking combo as well, after the posts about-how scratch resistant to the think the plastic will be mate? some grades/types are way better than others in this regard
The gloss finish is more prone to scratching than the matte although fingerprints are the most obvious! I’m not sure about acrylic grades, the only differences I’m aware of are in surface finish/opacity. I have considered cutting vinyl skin panels as optional extras so may look to do them in the future, including transparent panels to simply cover the most likely parts that could scratch (like the top of the bed).
 
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The gloss finish is more prone to scratching than the matte although fingerprints are the most obvious! I’m not sure about acrylic grades, the only differences I’m aware of are in surface finish/opacity. I have considered cutting vinyl skin panels as optional extras so may look to do them in the future, including transparent panels to simply cover the most likely parts that could scratch (like the top of the bed).
thank you mate, sorry I was referring to different plastic types rather than acrylics in particular. its such I stunning looking camera I think I would be frightened to scratch it, id need "kid gloves" to hold it:eek::D
edit, there are few cycle accessory providers that sell some really good protective stick on clear plastic sheets to protest the frame- dant know if they could/would provide something for you perhaps
 
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thank you mate, sorry I was referring to different plastic types rather than acrylics in particular. its such I stunning looking camera I think I would be frightened to scratch it, id need "kid gloves" to hold it:eek::D
edit, there are few cycle accessory providers that sell some really good protective stick on clear plastic sheets to protest the frame- dant know if they could/would provide something for you perhaps
I’ve been pretty rough with my Chroma’s while I’ve been refining the design and none of them look scratched up or battered so I wouldn’t worry too much about kid gloves :0). I’m going down to see the guy who’s cutting all the acrylic tomorrow. He also cuts vinyl for posters/vehicle wraps so I’m sure he could cut skins (we’ve already talked about it). The company who I bought all the adhesive heavyweight vinyl for the light seals will also do stonechip protection clear vinyl which would be perfect so I’ll check them out.
 

TheBigYin

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The company who I bought all the adhesive heavyweight vinyl for the light seals will also do stonechip protection clear vinyl which would be perfect so I’ll check them out.
other option off top of my head is 3M helicopter tape... iirc it's for protection on the leading edges of rotor blades. I bought some to protect certain high wear bits on my bike and it's amazingly tough.
 

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Andysnap

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This is wrong on so many levels, focus Steve, focus!!!!!

:D
Yes Steve, you can eat off your knees, in fact there's no time for eating...leave that to the chumps who aren't making cameras. :D
 
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