Chroma - Lasercut Acrylic 4x5 Field Camera

Ok, so I drew up the magnetic frame for the 120 rollfilm back last night and was planning to cut it today then realised that I'm making the components much more complicated than they need to be! After thinking about it more this morning, I've re-drawn the magnetic camera back to incorporate standard Graflok fixing plates and a sprung plate for the ground glass so it can be unlocked from the Graflok plates then sprung backwards to allow for a standard DDS holder to slide in beneath it. Once the DDS holder is in place, the ground glass plate will spring back onto it, holding it in place along with the built in friction. The same method will be used for Quickload holders.

If you want to use either a standard rollfilm back or my 612 back, the ground glass plate can be removed entirely (after focusing) by unlocking the Graflok fixing plates and removing two small thumbscrews that secure the sprung frame (not drawn on the render below but will be inserted in the two upper holes on the white spring frame on the back). This then allows for deeper holders to be inserted and secured using the Graflok plates;

GraflokBack.jpg

(Ignore the bed on this image. I've made the focusing rod a little wider and back slightly on my plans now to allow for further movement of the focusing bed and to stop my knuckles getting hit by the front standard...but haven't drawn the updated shape of the bed layers)

Obviously I need to build a physical unit to ensure it works as planned but this should mean that any Graflok compatible back can be used.

Cheers
Steve
 
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Someone should ban Americans from commenting on articles using multi-syllable words... can't believe how many comments there are, getting p***ed off at the use of grams and "4x5" :D
 
mothdust said:
Someone should ban Americans from commenting on articles using multi-syllable words... can't believe how many comments there are, getting p***ed off at the use of grams and "4x5" :D
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I think it's hilarious and it probably stopped the camera getting more negativity because they're getting in a panic over weights, geography and driving on the left hand side!
 
mothdust said:
Someone should ban Americans
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FTFY! :D

On the whole, mainly positive comments. I've always called 10x8 10x8 - not sure why but probably because Dad used to. If the ignorant chap (using ignorant in the sense of not knowing rather than plain dumb...) can't do the conversion, that's his problem.

I just wish I had the patience for LF!

All the very best with it, Steve and with all the future projects associated with it (as well as the inevitable others!)
 
Nod said:
FTFY! :D

On the whole, mainly positive comments. I've always called 10x8 10x8 - not sure why but probably because Dad used to. If the ignorant chap (using ignorant in the sense of not knowing rather than plain dumb...) can't do the conversion, that's his problem.

I just wish I had the patience for LF!

All the very best with it, Steve and with all the future projects associated with it (as well as the inevitable others!)
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Thanks Nod. I've gone through the DPR comments and replied to the valid ones :0)

I do have a few Chroma projects lined up for after the launch is complete (and a few unrelated of course!)
 
I’m doing some simple testing of the effectiveness of a very simple plastic fresnel plate inserted between the ground glass and lens. There’s a whole range of posts around the web about where a fresnel should be placed so as not to affect fine focus but I’ve generally found that putting it in front of the glass has no effect on focusing (even at widest aperture) and the gains in brightness are definitely worth it.

To show a comparison (although both situations are actually brighter than they look but it’s hard to photograph it properly)

1) Top half of ground glass (digital image inverted!), no fresnel, 150/5.6

ORG_DSC04788.jpg

2) Same part of the ground glass, same focus, plastic fresnel in front of gg, 150/5.6

ORG_DSC04783.jpg

This isn’t a scientific comparison, both shots were taken handheld but with the same kit (Sony A7/ OM Zuiko 50/3.5 macro), but is shows a definite improvement in overall brightness.

There are obviously fresnel circles visible through a loupe but they don’t have an impact on focusing (for me, others may not like it). I’m definitely impressed enough to consider building drop in fresnel screens as options.
 
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stevelmx5 said:
Thanks Nod. I've gone through the DPR comments and replied to the valid ones :0)

I do have a few Chroma projects lined up for after the launch is complete (and a few unrelated of course!)
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Excellent responses, very measured and grown up and if it was me answering in complete contrast to my urge to use a liberal sprinkling of the v-sign & w⚓️ emojis :D
 
Back on the Fresnel, could you just clarify the almost permanent ambiguity in the position - does "in front of" mean in front of the ground glass as you focus i.e. between you and the ground glass or does it mean "in front of" the ground glass, which is the surface furthest back on the camera and hence closer to the lens than the ground glass?
 
StephenM said:
Back on the Fresnel, could you just clarify the almost permanent ambiguity in the position - does "in front of" mean in front of the ground glass as you focus i.e. between you and the ground glass or does it mean "in front of" the ground glass, which is the surface furthest back on the camera and hence closer to the lens than the ground glass?
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No problem at all. I mean “in front of” the ground glass between it and the lens :0)
 
stevelmx5 said:
Thanks Nod. I've gone through the DPR comments and replied to the valid ones :0)
)
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I’ve been through all the comments and upvoted yours and all the sensible ones, I suggest others do the same.
 
Thanks for that. If I look past the slightly left-field comments, I'm really happy with the overall response to it.

Even more amazing is that Chroma #0 has been backed! This is the one-off £1000 Chroma that will have all proceeds donated to charity. I've been chatting with the guy who's backed it about his requirements and using the camera to shoot portraits at a charity event then auction them off to raise more money. The charity he's supporting is a clean water initiative which will coincide with the UN World Water Day on March 22nd.
 
stevelmx5 said:
Thanks for that. If I look past the slightly left-field comments, I'm really happy with the overall response to it.

Even more amazing is that Chroma #0 has been backed! This is the one-off £1000 Chroma that will have all proceeds donated to charity. I've been chatting with the guy who's backed it about his requirements and using the camera to shoot portraits at a charity event then auction them off to raise more money. The charity he's supporting is a clean water initiative which will coincide with the UN World Water Day on March 22nd.
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Wow! Thats really brilliant Steve, well done.
 
stevelmx5 said:
Thanks for that. If I look past the slightly left-field comments, I'm really happy with the overall response to it.

Even more amazing is that Chroma #0 has been backed! This is the one-off £1000 Chroma that will have all proceeds donated to charity. I've been chatting with the guy who's backed it about his requirements and using the camera to shoot portraits at a charity event then auction them off to raise more money. The charity he's supporting is a clean water initiative which will coincide with the UN World Water Day on March 22nd.
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That's great news Steve, well done that man, whoever he is.
 
stevelmx5 said:
Thanks for that. If I look past the slightly left-field comments, I'm really happy with the overall response to it.

Even more amazing is that Chroma #0 has been backed! This is the one-off £1000 Chroma that will have all proceeds donated to charity. I've been chatting with the guy who's backed it about his requirements and using the camera to shoot portraits at a charity event then auction them off to raise more money. The charity he's supporting is a clean water initiative which will coincide with the UN World Water Day on March 22nd.
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Good man, both of you.
 
Thanks guys. It's nice to be able to do my part and help what appears to be a very worthwhile charity. We're talking over design ideas now and the backer has also asked about the possibility of mounting his Sony A7iii to the Chroma for some digital panoramic shots. He's not the first to ask so I've drawn up a slider back which will fit direct to the rear standard in place of the Graflok back;

FEMount.jpg

FEMount-Landscape.jpg

The back will give 25mm of movement each way when the A7 is mounted which should allow for 3 image panoramics to be taken. I need to build one to find out the best alignment but it looks ok on paper. The whole back can then be rotated (using the same embedded magnets that the Graflok back uses) to shoot horizontal panoramic images. The other back is the 612 holder and the unit to the right is the complete Graflok back with groundglass in place.
 
This waiting for the campaign to end so I can order the materials means that my brain is working overtime! I had a sudden idea at 1am this morning so drew this up;

snapshotalpha.jpg

Still need to work on the shape, but this is basically a pair of plates that can be used to make a fixed ‘snapshot’ Chroma using the front/rear of the existing field Chroma and the bellows in the middle (not drawn on here!). Basically, the entire rear standard of the Chroma is secured to the rear uprights using the thumbscrew and a guide piece. If I remove the thumbscrew from each side, I can remove the whole rear plate (including the film back) and do the same with the front standard. That then leaves the front/rear plates with the bellows connecting them.

The image above shows my 90/6.8 Angulon at infinity so I’m going to add some slots to allow for the lens to move forward to focus closer but I think it could be a good option for a Travelwide-style camera without buying a second camera entirely.
 
Setting it up as a fixed-focus camera could be tricky. If you make adapters to suit the various focal lengths at infinity, the distance to the near focus plane will vary with aperture. You could make plates that allow the lens to film distance to be set for hyperfocal focussing, but that results in a large number of plates to match focal lengths and chosen apertures.

There would likely be crossover of lens to film distances where different focal lengths have the same distance at different apertures, so you could make a set of plates and list which focal length and aperture combinations a given plate will give hyperfocal focussing. However, that would make a given combination effectively fixed aperture, which would potentially impact usability if shutter speeds become slow - assuming a snapshot version is intended to be used hand-held like a press camera.

Maybe it could be done with a plate per focal length, and have a series of fixed positions to set hyperfocal for a reasonable selection of apertures? For instance a 3-position thing that gives hyperfocal at f45, f22 and f11 - if the light changes, move the standards closer together or further apart, reset aperture and change shutter speed to suit.
 
Nomad Z said:
Setting it up as a fixed-focus camera could be tricky. If you make adapters to suit the various focal lengths at infinity, the distance to the near focus plane will vary with aperture. You could make plates that allow the lens to film distance to be set for hyperfocal focussing, but that results in a large number of plates to match focal lengths and chosen apertures.

There would likely be crossover of lens to film distances where different focal lengths have the same distance at different apertures, so you could make a set of plates and list which focal length and aperture combinations a given plate will give hyperfocal focussing. However, that would make a given combination effectively fixed aperture, which would potentially impact usability if shutter speeds become slow - assuming a snapshot version is intended to be used hand-held like a press camera.

Maybe it could be done with a plate per focal length, and have a series of fixed positions to set hyperfocal for a reasonable selection of apertures? For instance a 3-position thing that gives hyperfocal at f45, f22 and f11 - if the light changes, move the standards closer together or further apart, reset aperture and change shutter speed to suit.
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I think that, if I do this, I’ll be basing it around a single lens (eg the Angulon 90) for all of the reasons you’ve given. The Travelwide was based around one lens too for the same reason.
 
117! That's a lot of cameras to build... preferably before October... :)
 
stevelmx5 said:
I think that, if I do this, I’ll be basing it around a single lens (eg the Angulon 90) for all of the reasons you’ve given. The Travelwide was based around one lens too for the same reason.
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Aye, that makes more sense. Sounds like an interesting add-on if it can be retro-fitted to the existing camera.
 
stevelmx5 said:
It's 118 now :0)
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Have you worked out how long it takes to build one? The different colour options will presumably make some "production line" approaches more difficult...
 
ChrisR said:
Have you worked out how long it takes to build one? The different colour options will presumably make some "production line" approaches more difficult...
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The parts for a single camera take around 45 minutes in total to cut. The bellows take around 45 minutes to assemble, fold and glue to the front/rear plates. The assembly of the camera takes around 90 minutes. I’ve spoken with Perspex (who are supplying the acrylic sheets) and they’re supplying them ready-cut into 1000x600mm sheets which is the total size of the laser cutter bed and big enough to cut two separate sets of camera parts. As a result, I can swap materials out half as often so the cutter can be left to cut for longer.

Once the campaign ends and I send out the backer questionnaires, I’ll know how many of each colour I need so can order the 3/5mm acrylic sheets as needed. All cameras share the same black 2mm acrylic parts so they can be nested on a smaller number of sheets and cut in bulk.

Once cut, the parts are going to be placed in their own box (the one that the camera will be shipped in) by the company doing the cutting and I’ll collect them all. Once back in my workshop I’ll basically have a big pile of boxes that will be labelled/numbered so I can work through them one by one.

It’s easy when I write it down :confused:
 
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So you're making the bellows? And are they all to be black?

That does sound like a fiddly job that would be a real PITA to do 120+ times!
 
ChrisR said:
So you're making the bellows? And are they all to be black?

That does sound like a fiddly job that would be a real PITA to do 120+ times!
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Yes and yes and yes :0)

I originally priced up with a few companies making the bellows for me but a UK company wanted around £80 per set and a Chinese manufacturer made a set for me but they weren't suitable. After making around 10 different sets myself, I've nailed down the materials and assembly to get it as streamlined as possible. By laser cutting the ribs (in 4 main parts with each rib joined by a 1mm strip to save having to align 30 ribs on each side of the bellows!) and the outer skin, it makes it much easier to assemble. I've also found, what I hope, to be the perfect material that's completely light tight in a single layer and very lightweight. I've got a roll of black on its' way to me this week but it also comes in around 10 other colours. I asked the manufacturer to test for it's blackout quality and they weren't 100% sure that all colours were as effective but I may get some samples of the other colours to test as well.
 
If anyone is on my Chroma.Camera mailing list, they will have seen in my weekly update last night that I've been working with a new company for scanning my sheet film. I found them by accident and sent over a slide to test their quality (Imacon scan) and have been impressed with the result. Whilst there is is some movement in this frame (came from the extreme testing I was doing with my Chroma on a Manfrotto Pixi tripod!), the overall quality of the scan and turnaround time was good (posted on Saturday, scan sent over to me via WeTransfer on Monday night). The scan I received was a 410Mb TIF file and 9246x7397
(68Mp-ish) resolution.

After speaking to the guy who did the scan we've started talking about mutual benefits, so I could negotiate some sort of discounted rate for Chroma users. His standard rate currently is £10 per scan so I would get that down lower. Is this something that anyone would be interested in before I go back to him?

Cheers
 
Possibly interested, but if I'm honest I'm unlikely to take it up for a number of reasons:

1. Scan size. I normally scan larger than that - I assume other scan sizes are available, but at a higher cost?
2. I'd be worried about damage/loss of negatives in the post.
3. I'm never likely to make a direct comparison myself, but an article a few years ago comparing an Imacon scanner with an Epson V750 for 5x4 black and white negatives came to the conclusion that the Imacon extracted more detail, but the downside was visible grain revealed in areas of even tone; and after sharpening, the Epson wasn't much inferior.

The only time I could see myself taking it up were if I wanted to produce an A1 or A0 print, or if I broke the habit of a lifetime and moved into colour.
 
StephenM said:
Possibly interested, but if I'm honest I'm unlikely to take it up for a number of reasons:

1. Scan size. I normally scan larger than that - I assume other scan sizes are available, but at a higher cost?
2. I'd be worried about damage/loss of negatives in the post.
3. I'm never likely to make a direct comparison myself, but an article a few years ago comparing an Imacon scanner with an Epson V750 for 5x4 black and white negatives came to the conclusion that the Imacon extracted more detail, but the downside was visible grain revealed in areas of even tone; and after sharpening, the Epson wasn't much inferior.

The only time I could see myself taking it up were if I wanted to produce an A1 or A0 print, or if I broke the habit of a lifetime and moved into colour.
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Out of interest Stephen, what scanner/service do you normally use to get larger than 68mp results?
 
I use my Epson V700 (now V850, but I haven't rescanned any old negatives). I set it on maximum resolution, and have VueScan do its "4 pixels to 1" averaging to bring down the file size and (hopefully) reduce/eliminate noise. The resulting scans are around 15,000x12,000 pixels in round figures with a reported file size in Windows Explorer of about 341,000 KB give or take 3,000 KB
 
I can't offer a like with like comparison, because I don't have any 5x4 colour photos. If you want to see the Epson V700 full size version of a Mamiya RZ67 6x7 colour negative (Fuji NPS160) you can download the 1.41 gigabyte scan here. This is straight from the scanner.
 
I apologise in advance if this is in the wrong place, but as a digital photographer dipping a toe back in the film world (just bought a 35mm film body), I couldn't help reading this thread, and since then reading a fair bit about large format cameras, and it strikes me that the Chroma would be a very good way to try out the 5x4 (or is it 4x5?? :) ) experience.

As a complete newcomer to this area of photography, I've watched a fair few YouTube videos and have a handle (I think) on some of the basics - front standard, rear standard, movements, process for preparing and making an exposure etc..

What I am struggling to get a handle on is that if I was to look to place an order for a Chroma (or other 5x4 camera), I have literally no idea as to which lens/shutter to look at.

I get that for 5x4, the "35mm focal length equivalent" is around 3 x (so a 105mm is close to 45-50mm in 35mm speak), and that I should look for something with a fairly wide max aperture.

What I'm really struggling with is that you can get different sized shutters - 0,1, or 2, and do you buy the shutter separate from the lens, or is it included? I understand Copal and Seiko are good shutters - possibly slightly more reliable than Compur?
What is the effect of the shutter on the image circle produced by the lens? I understand the image circle needs to be significantly bigger than the size of the film if movements are to be possible without vignetting.

Is there a thread/advice that specifically covers all of this (perhaps with examples of specific lenses/shutters)?

As I say, probably not the right place to ask, but it's been bugging me for a few days now as I think that if I was to place an order for a Chroma, I have no idea at all what I'd do about a lens/shutter (although I guess I'd have plenty of time to further research it before November)!

Any pointers you could give would be very much appreciated.

Thanks.

Conrad.
 
GreenNinja67 said:
50 x 3 was 150 when I was at school.

Ben Thorne swears by the Nikon 150mm.
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D'oh - yes - looks like I can't do basic maths - getting confused with 50mm and 35mm!! :)

When you say "the Nikon 150", is there only 1, what aperture, and what size shutter (or does it come with a shutter)?
 
C&C said:
I apologise in advance if this is in the wrong place, but as a digital photographer dipping a toe back in the film world (just bought a 35mm film body), I couldn't help reading this thread, and since then reading a fair bit about large format cameras, and it strikes me that the Chroma would be a very good way to try out the 5x4 (or is it 4x5?? :) ) experience.

As a complete newcomer to this area of photography, I've watched a fair few YouTube videos and have a handle (I think) on some of the basics - front standard, rear standard, movements, process for preparing and making an exposure etc..

What I am struggling to get a handle on is that if I was to look to place an order for a Chroma (or other 5x4 camera), I have literally no idea as to which lens/shutter to look at.

I get that for 5x4, the "35mm focal length equivalent" is around 3 x (so a 105mm is close to 45-50mm in 35mm speak), and that I should look for something with a fairly wide max aperture.

What I'm really struggling with is that you can get different sized shutters - 0,1, or 2, and do you buy the shutter separate from the lens, or is it included? I understand Copal and Seiko are good shutters - possibly slightly more reliable than Compur?
What is the effect of the shutter on the image circle produced by the lens? I understand the image circle needs to be significantly bigger than the size of the film if movements are to be possible without vignetting.

Is there a thread/advice that specifically covers all of this (perhaps with examples of specific lenses/shutters)?

As I say, probably not the right place to ask, but it's been bugging me for a few days now as I think that if I was to place an order for a Chroma, I have no idea at all what I'd do about a lens/shutter (although I guess I'd have plenty of time to further research it before November)!

Any pointers you could give would be very much appreciated.

Thanks.

Conrad.
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Hi Conrad. No problem at all with asking in this thread. Rather than re-type what's already been written by people much more competent with Large Format than me, these are a couple of links that were shared as comments on my campaign;

http://www.alexburkephoto.com/blog/2018/2/13/choosing-a-4x5-camera-and-lenses

http://www.angusparkerphoto.com/blog/2016/3/good-lenses-for-a-4x5-view-camera

For the Chroma specifically, I'd recommend a lens between 120-150mm. These are seen as 'normal' length lenses (between 35-50mm in 35mm terms roughly) and also offer you the most flexibility in movements. Wider lenses will mount to the Chroma but the wider you go means that the lens is placed closer to the rear standard of the camera and your range of movements are decreased as a result.

With regards to shutters, the different lenses will fit into different sized shutters. With Copal shutters for example, these range from Copal 0 to Copal 3 and major difference is the size of the hole required on the lens board;

http://www.skgrimes.com/products/new-copal-shutters/standardcopals

Generally, large lenses use larger shutters as their glass elements are larger. One other obvious difference between shutters is that larger shutters generally have slower maximum shutter speeds. As far as I am aware, the image circle is a direct result of the lens design rather than any result of the shutter size.

Cheers
Steve
 
C&C said:
D'oh - yes - looks like I can't do basic maths - getting confused with 50mm and 35mm!! :)

When you say "the Nikon 150", is there only 1, what aperture, and what size shutter (or does it come with a shutter)?
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Any reasonably modern lens (made since the 60's) will be sharp and most lenses are sold in a shutter. Fast is usually 5.6 but the dof at that aperture means that it's mostly usable for focus and composition, you'll stop down to f16 and up when shooting.
 
C&C said:
What I am struggling to get a handle on is that if I was to look to place an order for a Chroma (or other 5x4 camera), I have literally no idea as to which lens/shutter to look at.

I get that for 5x4, the "35mm focal length equivalent" is around 3 x (so a 105mm is close to 45-50mm in 35mm speak), and that I should look for something with a fairly wide max aperture.

What I'm really struggling with is that you can get different sized shutters - 0,1, or 2, and do you buy the shutter separate from the lens, or is it included? I understand Copal and Seiko are good shutters - possibly slightly more reliable than Compur?
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You're not alone, although I've been shooting film for years (decades, really), I've never thought for LF before. I've just been reading and researching like mad. The web sites mentioned by Steve above are good pointers (I;ve been meaning to mention them on the LF thread here (zero to hero).

One thing I found is that the 120-ish lenses are quite a bit dearer than (some) 150s, indeed I reckon I might be able to get a Fuji 90 and 150 for about the price of a Fuji 125!

Also, most of the lenses are from Japan, need to factor in 7% import duty, 20% VAT on top of that, plus £8 ransom from Royal Fail.

Also, many listings don't tell you the lens board, or mention a lens board I've never heard of. Many don't mention the shutter (ignoring "enlarging lenses" which AFAICS are a different thing).

One thing @StephenM has mentioned: the enlargement from a 4x5 negative to a 16x20 picture on your wall is the same as the enlargement from 35mm to a 6x4 snapshot... ergo the quality of the lens is much less important unless you're going much bigger still. And most of the lenses are supposedly pretty good.

Slower lenses presumably mean dimmer images on the ground glass for focusing, more need of a dark cloth...
 
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