Chroma - Lasercut Acrylic 4x5 Field Camera

So...

what's the differences between the Adventurer and the "standard" Chroma? is it just the weight or are there other differences with movements etc.?

Asking for a friend :)
 
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sirch said:
So...

what's the differences between the Adventurer and the "standard" Chroma? is it just the weight or are there other differences with movements etc.?

Asking for a friend :)
Click to expand...

Apart from the main material (Advanced45 is acrylic, Adventurer is carbon fibre), the Adventurer also has the following additional benefits;

1) Sliding rear standard, to allow for lenses down to 53mm flange depth (with a flat lens board), without the focusing bed encroaching in the bottom of the image.

2) Main printed components are made from ABS, which is slightly more dense than PLA and has better UV stability.

3) Interchangeable rear standard, allowing the removal of the entire 4x5 rear standard, so it can be replaced with a dedicated 6x17 back/bellows, as well as a dedicated 5x7 back/bellows. - This is a WIP at the moment as I haven’t had any beta builds printed, but it’s next on my list.

At the moment, I’m not taking any more orders for the Advanced45, as I’m working through my current batch of cameras and have had to wait for the laser cutting company to open up again post-lockdown. I’m still taking orders for Carbon Adventurers and SnapShots though.

Cheers
 
As well as building all 3 camera models, I’ve also been working with another photographer to develop an electronic shutter he designed a while back. I wanted to supersize his design, and build it into a removable shutter unit, that attaches to the back of the front standard using the same embedded magnets as the bellows (which then attach to the back of the shutter).

I’m still waiting for some of the components to arrive on a slow boat, but while I’m waiting I’ve been developing the code, and moving to a small OLED screen to keep the size, and battery usage as small as possible. The finished unit will have an integrated USB charged battery, along with a remote shutter release button (cabled). This is where the coding is at the moment;

https://www.dropbox.com/s/35q2ha2m3ergmn6/Video 19-06-2020, 17 29 44.mov?dl=0

I haven’t shown the shutter itself on that video, but there are no moving parts, and I’m hoping I can get up to 1/1000th, but need to test out the larger panels when they arrive.

This is a shot I took with the smaller test unit, mounted in front of an OM Zuiko 35/2.8 on my Sony A7. It was taken at 1/25th and f2.8. Not the most exciting subject (looking out the door of my workshop!) but it’s progress [emoji6] (the light refraction in the middle is the result of the unit being blu tac’d to the front of the lens [emoji23])

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The shutter itself is going to add around 2 stops, as there’s a small amount of filtering, even when ‘open’. For large format I’m thinking this won’t be a major issue! I’m also hoping to use it with an Aero Ektar first, so 2 stops will actually help me shoot it wide open.
 
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https://www.dropbox.com/s/9zfv7d6y0gj0n7s/Video 27-06-2020, 09 26 35.mov?dl=0

[emoji3]

Next step, once my mini Arduino board arrives, is to setup the internal lipo battery/usb charger module and make the shutter unit standalone.

With the current circuit, I’m getting good results up to 1/60th. I’m still working on the design of the circuit, and the shutter panels block 2 stops of light when open, so this shouldn’t be a major issue.
 
I received all but the last printed parts for the first 5x7 rear standard on my Carbon Adventurer;

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The final build will have an aluminium/carbon u-frame like the standard Adventurer but for this beta build I’ve got a printed version on the way.

Next job is to design the bellows, and cut an extended replacement focusing bed.
 
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I got the final beta part today, the printed uframe for the rear body;

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I drew up the new bellows last joint too, so they’ll be getting cut early next week, along with a new longer focus bed that will push out the focus range to 60-380mm.
 
What will the range be with the 10x8 back fitted? :exit:

:film:
 
Sorry to interrupt the flow of this thread but a question , probably for stevelmx5.

I've found a 3D .stl files for a couple of Horseman 80x80 lens boards, one in Copal #00 and the other plain (no hole). Can you suggest somewhere I could get a small batch of these printed for a reasonable cost. I read a suggestion that ABS is the best material, opaque obviously.

I can't find equivalent boards second hand. The actual Horseman aluminium boards seem only to be in sizes 0, 1 and 2. Also they can be very expensive.
 
PeterSpencer said:
Sorry to interrupt the flow of this thread but a question , probably for stevelmx5.

I've found a 3D .stl files for a couple of Horseman 80x80 lens boards, one in Copal #00 and the other plain (no hole). Can you suggest somewhere I could get a small batch of these printed for a reasonable cost. I read a suggestion that ABS is the best material, opaque obviously.

I can't find equivalent boards second hand. The actual Horseman aluminium boards seem only to be in sizes 0, 1 and 2. Also they can be very expensive.
Click to expand...

Hi Peter. If you send me the STLs I can print some for you. It will be in PLA, not ABS, but it’s opaque [emoji1303]
 
That's very generous of you. You must let me pay for the materials and postage at ther very least. What is the best way of getting them to you?
 
stevelmx5 said:
View attachment 284475

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The shutter unit has integrated magnets in the front/rear plates which allows me to fit it in between the bellows/front standard.
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I’ve decided to develop the electronic global shutter as a universal fit, rather than Chroma specific. I’m hoping to start working with a quite well known analogue camera retailer in Liverpool soon (not agreed yet so can’t really name them), and am hoping to start offering some more generic accessories as well as my cameras.

I put together a first test unit earlier today, with an Aero Ektar fit rear ring;

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The idea is that the main shutter unit will be the same for all mounts, but there will be a clip on rear plate that will offer either a plain ring fitment for the outside of the lens (like this Ektar), or a Cokin P style mount with threaded rings for smaller lenses with filter threads.

Adjustments.JPG

There will be an attached handheld remote unit, which will house the battery/charge circuit, main controller, OLED screen and shutter button. The unit will be charged via USB and use a pair of buttons to adjust the shutter speed, as well as Timed/Bulb options.

I’ve been working with Dave Walker (Open SX70 project) to build the electronics. We’re currently talking about next steps with regards to building out the shutters in volume.
 
Very interested in the shutter Steve.

What weight will the end resulting apparatus be ( approx)?
 
Isn't there an issue with the shutter being on the front? Focus or lens position or something, I half remember reading something about it.
 
steveo_mcg said:
Isn't there an issue with the shutter being on the front? Focus or lens position or something, I half remember reading something about it.
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I need to do some testing once the remote unit is assembled but, as far as I’m aware, it’s no different that holding a hat over the front to expose the film/plate.

The shutter can either be removed for focusing, then fitted for the exposure, or manually opened via the remote to focus through it.
 
I guess optically, provided the surface is flat to a good approximation, there shouldn't be any issue from an "image quality" perspective. It'd be the same as having any other filter on the front when the shutter is open. I'm not talking about dirt, I'm more thinking if there are any significant lensing effects that would cause aberrations on the image. Being what it is though, I doubt this is any issue at all.

Are the air-facing surfaces of the optical element AR coated for visible? Apologies if you've mentioned this already!
 
is it maybe the elements, have you got an adapter to join the front and rear elements of the lens so they've got the same gap as they would with a traditional shutter?
 
I've just worked out what I remembered, it wasn't the location of the shutter it was the iris position the thread I was thinking of was talking about putting f stops in front of the front element and using a drop shutter.
 
steveo_mcg said:
I've just worked out what I remembered, it wasn't the location of the shutter it was the iris position the thread I was thinking of was talking about putting f stops in front of the front element and using a drop shutter.
Click to expand...

That explains it :0)

The shutter unit it essentially acting like a standard filter in front of the lens. The only difference is that I can turn the effect of the filter on and off.
 
I'm thinking more longer term when Miles can't fix my shutters this is going to be very useful but you'll still need even a broken shutter for iris and to hold the legs elements together.
 
Don't suppose they need to be blades lcd Waterhouse stops might work if the screen was a decent resolution.
 
Although the position of the aperture stop is normally part of the optical calculations for a lens (if I remember correctly).
 
I'd imagine some care would be needed if putting a layer of glass (or whatever) inside the lens - the rays will refract through the added layer and thus arrive at the rear group slightly differently than they would if the extra layer wasn't there.
 
Nomad Z said:
I'd imagine some care would be needed if putting a layer of glass (or whatever) inside the lens - the rays will refract through the added layer and thus arrive at the rear group slightly differently than they would if the extra layer wasn't there.
Click to expand...

The shutter is outside the lens, and I’d be looking at the idea of digital Waterhouse stops outside it too.

Although, at the moment, this unit is only a shutter.
 
At the risk of displaying poor taste, those of a certain age will remember Cokin special effects "filters" which were placed in front of the lens and produced all manner of different effects, without anyone really commenting on any adverse optical effects. I usually object to using the word "filter" for this sort of lens attachment, although I am becoming more flexible in my old age - especially after someone pointed out that close up filters work by filtering out light from distant objects :D

With catadioptric lenses which have built in filters, it's common (invariable?) to have a clear "filter" in the light path as part of the optics so as to allow coloured glass to replace it with no effect.
 
I spent a bit of time last night drawing up a basic remote control unit, and printed it today.

I had to make it quite chunky to allow for the buttons I had to fit in (they’re 22mm deep) but I actually quite like the Go-Pro style handling!

Adjustments.JPG

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The white button in the middle is the On/Off. Silver buttons either side are shutter speed up/down, and the silver button with the blue led ring around it is the shutter.

The cover over the OLED screen is actually developed C41 film :0)

There’s a 600maH lipo battery inside, along with a micro USB connection on the side for charging it. I haven’t had it assembled for long enough to do a test of battery life but both the controller and shutter panel are pretty low drain so it should last for quite a while.

I’ve got a quick video of the shutter in use, with the Aero Ektar lens fitted, so I’ll upload it in a bit.
 
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I promise I’ll record a proper video once I’ve got the last few issues ironed out!

www.dropbox.com

Chroma LF Shutter.mov

Shared with Dropbox
www.dropbox.com www.dropbox.com

Just before I recorded this video, I uploaded a new code to the controller which messed up the timings, which explains why a 2 second exposure actually lasted about 4 in the video [emoji23]

That’s all sorted now, along with some minor spacing changes, so it’s pretty much ready to test out.
 
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