Chroma - Lasercut Acrylic 4x5 Field Camera

Nod said:
Maybe an interlock so the s***ter can't be fired when the arm's down?
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No need to swear ;0)

I'm not sure how i'd interlock the shutter on the lens with the ground glass. Then again, it doesn't matter because you'd remove the ground glass to fit the film holder before taking the actual shot so it's not an issue :0)
 
Maybe a nick in the top of the GG that interfaces with a pin on the sensor and raises it (the sensor) when the GG is removed to insert the film holder?

Needs to be idiot proof - you know what LF users are like!!! :p:p:p:D (Mind you, at £10 or so per shot, it would be a once only mistake IMO!)
 
Nod said:
Maybe a nick in the top of the GG that interfaces with a pin on the sensor and raises it (the sensor) when the GG is removed to insert the film holder?

Needs to be idiot proof - you know what LF users are like!!! :p:p:p:D (Mind you, at £10 or so per shot, it would be a once only mistake IMO!)
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The sensor and electronics are physically built in to the ground glass holder. When you remove the GG, you remove the light meter ;0)
 
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Ah!
 
stevelmx5 said:
While the laser cutter is still out of action (they've gone through 3 tubes now!), I'm keeping my mind active working on the idea of a through the lens light meter. The main benefit of this is that it would take into account bellows extensions/filters etc. Obviously, I could just build it into another plate that drops into place instead of the ground glass plate like previous meters available over the counter but that would be way too simple...

I thought I'd see if I could physically embed all of the electronics into the ground glass holder, with the glass in place, so that the light sensor could swing into place to take a reading then move out of the way (like a Leica CL).

View attachment 105598

The OLED screen is visible on the rear face of the holder, along with 3 buttons (not drawn on here). The short 40mm long arm is connected via an acrylic rod to an arm on the inside face of the holder at 90 degrees to it. The light meter itself (green) is mounted to the end of the internal arm so that it can be swung down into the centre of the frame to take a reading;

View attachment 105599

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Also mounted on the inside face is the main arduino control board, battery (grey) and charge circuit (blue) although I've just realised that I need to switch the arduino and charge circuit around so I can use a micro-usb cable to charge the battery externally.

When fitted to the main camera, the only external indication of the meter is the swing arm (that folds flat into the frame) and the OLED screen.

View attachment 105601

The beauty of building this into the ground glass holder is that it's completely optional and has no impact on the camera build. I'll keep it on the burner for now though :0)
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This is brilliant... just a thought though, the meter reading will presumably need to happen when the dark cloth is in place to avoid light contamination through the ground glass itself?

... and of course I'm expecting the final version to allow the meter spot to be located anywhere on the GG rather than just the centre, for spot metering and easier zone calculations. Being able to spot meter AFTER adding a grad filter would be... there is surely no other word... awesome!
 
ChrisR said:
This is brilliant... just a thought though, the meter reading will presumably need to happen when the dark cloth is in place to avoid light contamination through the ground glass itself?

... and of course I'm expecting the final version to allow the meter spot to be located anywhere on the GG rather than just the centre, for spot metering and easier zone calculations. Being able to spot meter AFTER adding a grad filter would be... there is surely no other word... awesome!
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Lol, you're never happy you are ya ;0)

There's already a magnetic cover built in to the ground glass holder as protection which would also do a good job of shielding light from the back of the glass so there's no need to fiddle about under the dark cloth to take a reading.

I'm not sure about the coverage angle of the sensor. When I actually get around to building one I'll test it out to see how feasible it would be to use as a spot meter.
 
While Sinar did make light meters for their monorail cameras, few of us ever bought them. In practice they were no better than a hand held meter. however they did save calculations when using long extensions and strong filters.

Up to the weston lll you could use the log scales to calculate for the inverse square law due to the extension. Today a digital calculator and a pocket tape measure would be easier. However you meter, you still have to add in a multiplier for reciprocity failure especially for longer exposures.
Exposure evaluation is quite different for large format, if you want consistent results, and there are few short cuts.
 
Just out of interest, have you watched the "How it's made" video on the Walker Titan camera? It shows (very briefly) Mike making the bellows.
 
StephenM said:
Just out of interest, have you watched the "How it's made" video on the Walker Titan camera? It shows (very briefly) Mike making the bellows.
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I think I have seen that one but not for a while. Watching the laser cut the ripstop nylon and inner blackout material in around 30 seconds (total) was awesome! The card bellows took around 6 minutes to cut so still much faster than I can do by hand :0)
 
Terrywoodenpic said:
However you meter, you still have to add in a multiplier for reciprocity failure especially for longer exposures.
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Aha, but @stevelmx5 has a computer in his lightmeter, so it's a SMOP (*) to include reciprocity curves for common films! :)

* Small Matter of Programming... SMOP was a term we used to use in my software development days to slightly undermine the over-enthusiasm for new features... you can see that I've never quite lost that enthusiasm!
 
ChrisR said:
Aha, but @stevelmx5 has a computer in his lightmeter, so it's a SMOP (*) to include reciprocity curves for common films! :)

* Small Matter of Programming... SMOP was a term we used to use in my software development days to slightly undermine the over-enthusiasm for new features... you can see that I've never quite lost that enthusiasm!
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Thanks Chris, make me write a longer code ;0)
 
I've been getting all of the parts together and dry fitting them to check alignments and have to say that I genuinely haven't been this excited to build any other camera!

I'm going to assemble it all tomorrow and time myself to give me an idea. Even though I've designed the camera entirely, I'm still a bit nervous about getting all of the spacers/magnets in the right way round. I'm sure I'll get quicker :0)
 
Work and a photographic job got in the way of me completing the build today but I took a couple of photos along the way (pre-cleaning!)

This is the back view of the front standard/lens board with the rear frame piece still be be bonded. It shows the lens with around 20mm of fall

Photo 13-07-2017, 12 33 57.jpg

Same view of the front standard but this time the lens is in the zero rise/fall position and the 3x3x3mm cube magnets have clicked it into place. The magnets are actually strong enough to hold the lens surround/board in place but their main point is to give a definite click stop when adding rise/fall so you know exactly where zero is.

Photo 13-07-2017, 12 34 06.jpg

This is the rear of the ground glass with the cover clicked into place using the 4 5x5x5mm cube magnets in each corner. It's amazing how strong these magnets are so it's not going anywhere unless you want to remove it (I may swap them out for the 3x3x3mm magnets instead but will see how it feels when fitted to the camera.

Photo 13-07-2017, 16 42 15.jpg

Oh, and these are all of the magnets/thread inserts/spring that go into each Chroma :0)

DSC03028-2.jpg
 
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RaglanSurf said:
I can't be the only one on here that's ridiculously excited about this :banana:
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Thanks Nick, I appreciate the support!

Annoyingly, I broke the syringe I was using to apply the snapfix glue (it's like water that melts the acrylic together) so until I get a new one later, I'm going to look at making the bellows today. I'm a bit nervous about them as I've never actually assembled one using the plans I drew up so fingers' crossed!
 
stevelmx5 said:
Thanks Nick, I appreciate the support!

Annoyingly, I broke the syringe I was using to apply the snapfix glue (it's like water that melts the acrylic together) so until I get a new one later, I'm going to look at making the bellows today. I'm a bit nervous about them as I've never actually assembled one using the plans I drew up so fingers' crossed!
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Best of luck Steve hope it all goes to plan.
 
RaglanSurf said:
I can't be the only one on here that's ridiculously excited about this :banana:
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No your not the only one. I was telling a mate in work only 5 minutes ago and I got a bit tingly......
 
Andysnap said:
Less chat, more folding. :D
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aye aye Captain!

Well, it started like this..

First build of laser cut bellows by Steve Lloyd, on Flickr

Then it had these bits stuck to it...

First build of laser cut bellows by Steve Lloyd, on Flickr

Then it had this bit stuck to those...

First build of laser cut bellows by Steve Lloyd, on Flickr

Then it was wrestled into shape..

First build of laser cut bellows by Steve Lloyd, on Flickr

And looks like this on the inside...

First build of laser cut bellows by Steve Lloyd, on Flickr

That's what I like...subtle

First build of laser cut bellows by Steve Lloyd, on Flickr
 
Liked, unliked and reliked, just so I could like it twice! :D
 
Overall I'm pleasantly surprised about how (comparatively!) easy that went. It took about 30 minutes from start to finish and is now being compressed for a while to retain the shape. The only changes I'm going to make are to use a thinner card stock because I bought the thickest I could find (around 320 gsm) and it would be fine with thinner ribs. The blackout material on the inside holds a fold well so won't need much shaping. I'm also going to narrow the joiner strips between each of the ribs as again, they could be thinner.
 
Before I start ringing around, has anyone here ever worked with s supplier for stamped/lasercut metal parts? I'm considering adding a metal u-shaped plate to the back of the front standard where the lens frame rises/falls too prevent any slight flexing so will need something 3mm thick I would imagine.
 
Wan't there something about shocking pink somewhere?
 
mothdust said:
This looks brilliant - and I'm glad the purple/orange colour scheme is working out :D :D :D
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Thanks Charlotte. Compared to my original bellows that I made using a changing bag, the new ones are still a bit too inflexible, especially for shorter lenses, so I'm speaking to a couple of suppliers about their options. When I find something else, I'll make another bellows and try again.
 
stevelmx5 said:
aye aye Captain!

Well, it started like this..

First build of laser cut bellows by Steve Lloyd, on Flickr

Then it had these bits stuck to it...

First build of laser cut bellows by Steve Lloyd, on Flickr

Then it had this bit stuck to those...

First build of laser cut bellows by Steve Lloyd, on Flickr

Then it was wrestled into shape..

First build of laser cut bellows by Steve Lloyd, on Flickr

And looks like this on the inside...

First build of laser cut bellows by Steve Lloyd, on Flickr

That's what I like...subtle

First build of laser cut bellows by Steve Lloyd, on Flickr
Click to expand...

WOW that's clever.
 
Thanks Brian and Trevor. In my ever developing way I've come across a slight problem with the front standard (and a solution!). Due to the front standard only being on 3 sides in a U shape rather than right around, there's a small amount of flex when the lens board is in the highest rise position. The way the securing bolts work, they will cause more flex so I've been wracking my brain to figure out how to add more stability (hence the question about metal fabs above).

However, I've just realised that there's a much simpler option, by having a slot on the front/rear faces of each upright and a guide pin going through the front slot, then bonded through the lens board and out through the rear slot, the front upright surround will stay in place as it's locked to the lens board.

A picture will make more sense so I'll draw it up! It's not a huge change but will make a big difference to the feel of it.
 
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