free drawing camera plans

Hi
I have been developing a desktop camera obscura on and off for about 10 years now, and I was asked by some graphic design teachers to produce plans for the current model so they could build some for their students. I have posted the plans on my website available under the CERN-Open Hardware License (a bit like the GPL software license, but for hardware).

Although not strictly a photographic camera (you use a pencil rather than film or paper), I wondered whether any of you in the DIY zone of Photorio might be interested. Next time I get it out I'll take some photos of the prototype and post them on the thread at the top of this forum.

I also have a fixed focus box camera. Interested?

Am I OK to post a url to the zip file of the plans? This is NOT commercial. You are completely free to download these plans, and copy them to whoever you want. The purpose of the license is to keep these plans freely available at no charge:

http://www.clivecatterall.com/Desktop_Camera_Obscura.zip

Have Fun!

Clive

PS Zemax model is available - but it is so simple you could probably model it yourself v. easily. It was the mechanical design that was difficult.

fizzcat said:

I also have a fixed focus box camera. Interested?

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yep.

and welcome to Photrio

fizzcat said:

Zemax model is available - but it is so simple you could probably model it yourself v. easily.

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You may be overestimating the abilities of the Photrio membership in your latter suggestion.
But feel free to upload whatever a Zemax model is (I haven't googled that yet)

I downloaded the plans. Very nicely done. But I always thought that this optical setup was called "camera lucida". A camera obscura is a different concept IMHO.

pdeeh said:

You may be overestimating the abilities of the Photrio membership in your latter suggestion.
But feel free to upload whatever a Zemax model is (I haven't googled that yet)

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He he he
Yes, I assumed that there would be a wide variety of skills in the forum, but perhaps I was a bit optimistic that there would be forum members with optical design skill...

Zemax is a professional optical design system (Code V and OSLO are also good). I use it at work to design scientific instruments, camera lenses, microscope accessories etc.

All I'm saying is that the lens design for the camera obscura is a Woolaston landscape lens - state of the art in about 1812. No colour correction or anything. Works OK though.

tsobota said:

I downloaded the plans. Very nicely done. But I always thought that this optical setup was called "camera lucida". A camera obscura is a different concept IMHO.

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Nope. A camera lucida is where the drawing image and the scene are combined in the eye using a prism or partially silvered mirror (you have a virtual image only). The camera obscura projects the scene onto paper (in the same way a photographic camera does). Camera obscura is Italian for "dark room". The hood shades the drawing so you get a good contrast and the image appears bright.

https://en.wikipedia.org/wiki/Camera_lucida

https://en.wikipedia.org/wiki/Camera_obscura

My design is a "Kepler" type camera obscura

Clive

fizzcat said:

t optimistic that there would be forum members with optical design skill..

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Oh we actually do have a real live lens designer as it happens, - he goes by the forum name of "Nodda Duma" - and I'm sure there are a few others who know the ins-and-outs, while the rest of us make do with school physics lessons-type understanding

I misinterpreted the plans, then, sorry. Yes, I know what both camera lucida and obscura are, I even used a camera lucida with a binocular loupe years ago.
(BTW "camera obscura" is Latin. Italian would be "camera scura", very similar but not quite the same)
I never used Zemax, but OSLO, the free version, I have used for toying with simple lenses and see what happens.

fizzcat said:

He he he
Yes, I assumed that there would be a wide variety of skills in the forum, but perhaps I was a bit optimistic that there would be forum members with optical design skill...

Zemax is a professional optical design system (Code V and OSLO are also good). I use it at work to design scientific instruments, camera lenses, microscope accessories etc.

All I'm saying is that the lens design for the camera obscura is a Woolaston landscape lens - state of the art in about 1812. No colour correction or anything. Works OK though.

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Welcome aboard!

I’m a lens designer by profession (with optics going on ISS next year) and appreciate the Zemax file.

But I don’t think there any other optical designers here.

Regards,
Jason

P.S. Just noticed after posting that pdeeh outed me.

Nodda Duma said:

P.S. Just noticed after posting that pdeeh outed me.

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You're an adornment to the forum, Mr. L, why should I not be proud of you (in a collegiate way)?

Nodda Duma said:

Welcome aboard!

I’m a lens designer by profession (with optics going on ISS next year) and appreciate the Zemax file.

But I don’t think there any other optical designers here.

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Sounds like you are more of a proper lens designer than me (I've never had anything go into space!). My stuff is commercial optical instruments - so taking a lovely optical design from a university and working out what can we remove to reduce cost and still have the instrument *just* meet the specification!

I'll send an archive file tomorrow, but it's just a stop, PCX lens working at FC&D wavelengths and a couple of field angles to see if the circle of confusion was small enough to allow an artist to trace in low light. I don't have any info about the loss of visual acuity at low light

I just analysed the design to see if a maker could get away with a PCX lens rather than a meniscus lens. I only bothered with RMS spot size as it was so far away from diffraction limited performance MTF would be meaningless.

Clive

Hi Clive,

Props to you ... Making optics "good enough", producible, *and* convincing customers that is ok is a skill-set that sets apart great lens designers from all the rest. A big part of that is doing what you do. The space lens is cool, but the designs I'm most proud of are the high-performance optics that can be assembled in 5 minutes, still blow you away in image quality, *and* survive fielding by the US Marines.

Speaking of catalog optics ... it's a real challenge to design decent quality objectives from catalog optics...like really challenging. This is mostly because available glass types really limit color correction, and the vast majority are PCX or PCVs which aren't of help off-axis. The closest I've gotten was a large format (4x5) f/8 Cooke triplet, and which has a thread over on the largeformatphotography.info forum.

Cheers,
Jason

Nodda Duma said:

Hi Clive,
Speaking of catalog optics ... it's a real challenge to design decent quality objectives from catalog optics...like really challenging. This is mostly because available glass types really limit color correction, and the vast majority are PCX or PCVs which aren't of help off-axis. The closest I've gotten was a large format (4x5) f/8 Cooke triplet, and which has a thread over on the largeformatphotography.info forum.

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Most of the optics I do are non imaging. A lot of the problems are to do with stray light as we are measuring very low levels of scattered light in a laser diffraction system. I do love it when I get to do imaging optics.

I tried making an airspaced achromatic telescope objective using acrylic positive and polycarbonate negative spectacle lenses. RI and abbe numbers for Acrylic are crowny and for polycarbonate are flinty. Should have worked but unfortunately didn't. IIRC it was a shape problem (all modern spectacle lenses are meniscus in form - both pos and neg).

Cooke triplet is cool (especially f8 with stock lenses!). I can sort of see how you could do it with PCV neg and mirrored PCX pos shapes, but kudos for finding the appropriate glasses! How did you do the stops? For my box camera I have replaceable slide-in brass plates, but they go in front of the meniscus singlet (like a Kodak brownie I don't need to achromatise the lens as I'm using orthochromic paper negs - print paper). A bit more difficult to seal out the light if you wan to slide them into the lens cell right next to the PCV neg lens. As a mechanical designer I'm intrigued.

My best design is actually a burner for a paper hot air balloon (I wrote a book about them in 2013). Works for 30mins with wax reservoir, adjustable lift, and can be made by a 14 year old from household items!

Clive