7 ms·
A look inside the chips that powered the landmark Polaroid SX-70 instant camera
- kens 5y agoAuthor here for your Polaroid camera questions :-)
- s800 5y agoSo the integrator circuit implies it determines the exposure time during the exposure? Meaning, the metering is ongoing during the shutter opening?
- kens 5y agoYes. It's a pretty clever circuit. You can think of film as integrating the amount of light that falls on it, so the photodiode integrator is computing the same thing. So the film will get enough light at the same time the integrator gets enough light. By closing the shutter at that time, the film is properly exposed.
- foldr 5y agoThe Olympus OM series had some particularly ingenious integrative metering modes, including metering light reflected off the film itself. https://www.dpreview.com/forums/post/24653220 https://www.dpreview.com/forums/post/24653220
- deleted 5y ago[deleted]
- morpheuskafka 5y agoThat's very interesting. Just picked up an OM-4 the other week as my first film camera, I knew it was one of the first to have multi-spot metering but just assumed it was standard TTL technology.
- grozzle 5y agoNot sure if I'm mis-reading this a surprised reaction, but if so, using light reflected from the film inside the camera body _is_ the standard TTL technology. https://mir.com.my/rb/photography/hardwares/classics/nikonfeseries/fe2/basic9.htm#:~:text=TTL%20flash%20metering%20adds%20a,for%20a%20proper%20flash%20exposure https://mir.com.my/rb/photography/hardwares/classics/nikonfe....
- morpheuskafka 5y agoInteresting. The parent thread in the linked forum said that other bodies used a different method, so I assumed that was the standard. > Yep, it applies to almost every AE SLR ever made. Notable exceptions were cameras like the OM-4 that metered off the film during exposure, or others that meter off the closed shutter curtain before exposure. But the vast majority meter from the focus screen so are susceptible to light entering through the eyepiece.
- boondaburrah 5y agoI have an Olympus XA that similarly has a light meter that's active when the shutter's open and closes it when it's "full." It actually has two light meters, and one of the problems it can have (mine did) is that the light meter that tells you what your exposure will be in the view finder and the light meter inside the body may not agree. The issue was that the internal meter became far slower such that I would see a (correct) value in the viewfinder and then the film would be overexposed by 2 stops. I tested this using slide film and lying to the camera about the ISO by 2 stops and suddenly everything wasn't blown out anymore. There's a potentiometer hidden inside the body that you can use to adjust the internal sensor's timing (fill rate?) and using audacity to measure the ms between shutter clicks I was able to adjust it to match the viewfinder's reading again.
- ravila4 5y agoI have a couple of these cameras. How difficult is it to get an OpenSX70 circuit PCB printed and installed? Is this something achievable by an average tinkerer?
- kens 5y agoI don't know the details of the OpenSX70 boards; I just looked at the Polaroid chips :-)
- jdkee 5y agoWill you be investigating the sonar system developed for later cameras such as the SLR 680?
- kens 5y agoThe sonar system is very cool, but I probably won't be investigating it.
- ochrist 5y agoI inherited a Polaroid Supercolor 635 from my dad, who passed away more than twenty years ago. It's just lying in the basement, and I don't know what to do with it. Is it worth anything? Can you still buy film for it?
- yardie 5y agoI'm impressed that surface mount components existed in the 1970s and in consumer electronics that early. I've taken apart VCRs and game consoles from the 80s and they were DIP mounted and through-hole circuit boards for all of the ones I've come across. I didn't realize the SX-70 was so cutting edge.
- dboreham 5y agoI believe they always existed, but were not widely used until the late 1980s when pressure to reduce size and cost became dominant and pin counts on packages rose above the limit for DIP. I worked in the industry at the time and remember the transition. You had to ask assembly houses if they had reflow capability, automatic pick and place, etc, otherwise they couldn't manufacture SMT.
- kens 5y agoTexas Instruments' surface-mount miniDIP chips were "new and risky but cheap", and one of the innovations that made their second design of the Polaroid circuitry successful. Aerospace had been using a lot of surface-mount in the 1960s, e.g. the Apollo Guidance Computer. But consumer electronics didn't really use surface mount until about 1990. I've wondered if there was any particular reason surface mount wasn't popular sooner.
- mulmen 5y agoThe AGC is a fascinating device. It used 60% of the ICs produced in the United States in 1963. If you are interested in the AGC I suggest this excellent video: https://www.youtube.com/watch?v=B1J2RMorJXM&t=454s https://www.youtube.com/watch?v=B1J2RMorJXM&t=454s.
- morsch 5y agoI think he has, in fact, shown a passing interest in the AGC in the past. ;) http://www.righto.com/search/label/Apollo http://www.righto.com/search/label/Apollo
- anonymousisme 5y agoThe film packs included the (flat) battery, and the (non-rechargeable) battery always had plenty of charge left after the film pack ran out. I salvaged those batteries and used them in many electronic projects.
- junon 5y ago"Instant camera" is a phrase I haven't heard in what feels like a lifetime. Amazing how quickly they lost prevalence. Hearing it feels like a fever dream, I had to question if I knew the phrase at all.
- gkop 5y agoFWIW they are still a thing: https://duckduckgo.com/?q=instant+camera&ia=shopping&iax=shopping https://duckduckgo.com/?q=instant+camera&ia=shopping&iax=sho... My subjective, anecdotal sense of trends is that instant cameras were big in the 80s, faded in the 90s, and made a small (but sustained) comeback in the mid-2010s.
- ghaff 5y agoThe dates will differ but a lot of things (think vinyl albums) probably follow some sort of mainstream, obsolete, retro lifecycle.
- stickfigure 5y agoThese were common at Pivotal when I was last there. Everyone gets a snapshot for the pairing board. I bought one and did the same thing at my last company.
- sharikous 5y agoThey are popular today in the privacy conscious world (including people making nudes)
- skhr0680 5y agoGet a Fujifilm Instax and feel the memories come back
- fortran77 5y agoI would love to see the SX-70 remade, exact same folding design and size (and leather!) but with a computer printer inside.
- 5y ago
- Koshkin 5y agoAs a programmer, electronics looks like fun. (After dealing with all kinds of thick and dense infrastructure stacks, it’s refreshing to see how things work at the lowest level - where the “stack” below is just Nature herself.)
- boondaburrah 5y agoThere is a beauty in "these bits will become those bits because physics says they fuckin' will"
- riffic 5y agothere's a promotional film made by Charles and Ray Eames about this camera. https://www.eamesoffice.com/the-work/sx-70-polaroid/ https://www.eamesoffice.com/the-work/sx-70-polaroid/ Watch the film: https://youtu.be/zpv8J8e9gWI https://youtu.be/zpv8J8e9gWI
- madengr 5y agoAs a kid, I acquired three Kodak instant cameras for free, as they were near worthless. Then Kodak lost a lawsuit from Polaroid and was forced to buy them back at $40 each. I made a huge amount of money for that, as a kid.
- adrianomartins 5y agoImpressive how back then was possible and "relatively easy" to understand how microchips would work, and also to see what new possibilities they've opened to the general consumers.
- dreamcompiler 5y ago500 years from now the technology museums will still have special exhibits about the SX-70, because it's one of the most amazing engineering artifacts of the 20th century. Doubly so because it didn't end World War II or fly to the moon; it was a consumer product with Apollo-grade engineering.
- salmo 5y agoThis is pretty cool. My dad was a Polaroid salesman in the 70’s, so I still have 2 of these and the 1 with the sonar autofocus. Have some of the sales material and his travel case for doing demos. Loved my old Polaroid in the 80’s too, even when the company was already a shadow of its former self. It’s sad. They really bet the farm on Polavision[1] and completely ignored video forcing that original vision of instant moving pictures forward. Beta and VHS w/ audio and working on a TV just made the product look dumb. I used to have one of the projectors but it died to attic heat. Then I could rant about how their sales practices killed them as well, but that’s likely full of hearsay bias. [1] https://en.m.wikipedia.org/wiki/Polavision https://en.m.wikipedia.org/wiki/Polavision