EEVblog #937 - Retro Canon Still Camera Teardown!

[EEVblog]

How did you take "digital" photos in the 1980's and early 90's?
With an analog still video camera that stored images on a PAL format 2" video floppy disks, that's how!
A teardown of a 1991 vintage Canon Ion RC-260 Still Video Camera.

[riyadh144]

That was actually fascinating, and how do they get to trim all of these pots? some of them ofcourse have to affect sme of the other at least.

And the number of pictures is not so bad for the time, imagine storing 50 pics on a floppy disk even if each pic was the equivalent of a 100kByte photo that was quite the increase from normal floppy storage.

[mariush]

I'm wondering.. not sure how things were back then in the early '90s ...

Couldn't they have used a bunch of eeprom chips instead of magnetic tape, to store the images? Were eeprom big enough and cheap enough for this back then?
I imagine you'd have extra analogue to digital converters and digital to analogue for playback, and each "floppy" may be a bit more expensive but wouldn't this have saved a lot of space space in the camera? (no need to have door, just slide a thinner card in, no need for read write heads and motors)
My mind goes to Nintendo gameboy cartridges... 

[mikeselectricstuff]

That was actually fascinating, and how do they get to trim all of these pots? some of them ofcourse have to affect sme of the other at least.

Manually using a test station with scopes etc. - VCRs typically had many tens of adjustments - A company like Sony would have designed it to be easy to set up in production, and to avoid interactions.

Couldn't they have used a bunch of eeprom chips instead of magnetic tape, to store the images? Were eeprom big enough and cheap enough for this back then?

No - it was just too expensive.
Remember SSDs and tape-free camcorders have only become viable in the last few years.

On the subject of oddball consumer cameras, this is a curious dead-end tech from Sony - tape based camcorder with non-removable tape.

[EEVblog]

I'm wondering.. not sure how things were back then in the early '90s ...
Couldn't they have used a bunch of eeprom chips instead of magnetic tape, to store the images? Were eeprom big enough and cheap enough for this back then?

Maybe it was possible, but the whole point of a camera like this at the time is how to you replay the images and on what device.
They likely would have ended up with the PAL TV output anyway. Even is you got the CCD image into memory in digital form, what then?. USB wasn't invented yet, neither were any removable media cards. Probably serial port to computer would have been the only way. But then the consumer would have wanted instant playback on a screen, so that means PAL video, there was nothing else.
So the limitation here is the CCD sensor and the PAL output format of the time.
Sony solved this with the Mavica 3.5" floppy camera, it was the world's first removeable media camera.

[timb]

I'm wondering.. not sure how things were back then in the early '90s ...

Couldn't they have used a bunch of eeprom chips instead of magnetic tape, to store the images? Were eeprom big enough and cheap enough for this back then?
I imagine you'd have extra analogue to digital converters and digital to analogue for playback, and each "floppy" may be a bit more expensive but wouldn't this have saved a lot of space space in the camera? (no need to have door, just slide a thinner card in, no need for read write heads and motors)
My mind goes to Nintendo gameboy cartridges...

No. EEPROMs are (compared to flash memory) huge in terms of physical size, slow to write and small in terms of storage.

Gameboy cartridges didn't use EEPROMs; they used mask ROMs. (Essentially a bit pattern is converted to a dedicated IC layout, that is the data is hard wired into the IC and cannot be changed. EEPROM is to FPGA as mask ROMs are to ASICs.)

(For saved game storage most GB games used battery backed SRAM.)

Generally, EEPROM is only available in the sub-Megabit size ranges, which isn't even enough to fully hold a single full resolution image.

[mikeselectricstuff]

..and of course aside from the cost of flash memory,  the silicon to compress and decompress images would have been too large, expensive and power hungry.
Remember this is 25 years ago!

[bktemp]

I'm wondering.. not sure how things were back then in the early '90s ...

Couldn't they have used a bunch of eeprom chips instead of magnetic tape, to store the images? Were eeprom big enough and cheap enough for this back then?
I imagine you'd have extra analogue to digital converters and digital to analogue for playback, and each "floppy" may be a bit more expensive but wouldn't this have saved a lot of space space in the camera? (no need to have door, just slide a thinner card in, no need for read write heads and motors)
My mind goes to Nintendo gameboy cartridges...

Just do the math:
A full resolution PAL frame has 768x576 pixels, the commonly used digital format is 720x576 4:2:2 resulting in 16bits per pixel. That is 810kBytes per frame!
At that time DRAM was probably the cheapest solid state memory you could easily write to at reasonable speeds. At 1990 you got around 100kBits per dollar, so DRAM for a full resolution PAL frame would have cost 64$!
Ok, you would have saved some money by only storing 1/4 resolution and only 64 grayscales, reducing the size to 1.2MBits per frame, still costing 12$. So an equivalent solid state storage device holding 50 frames would have cost 600$. That is a lot of money.
Flash memory at that time was basically non existing, except EEPROM for storing configuration data (typically a couple of kbits).

The data size of game catriges is quite small, often <128kByte. And they aren't even reprogrammable. So it is non comparable for full frame image storage.

[jonovid]

Sony solved this with the Mavica 3.5" floppy camera

  Sony  3.5" floppy camera https://docs.sony.com/release/MVCFD100-200revision.pdf

[blackbird]

I have to do a search in the attic of my parents house but somewere over there a RC-260 is gathering some dust. A few weeks ago I found some of the PAL 2" floppies sandwiched between 3.5" floppies.

One of the accessories for this camera we have used a lot was a interface card (Canon SV-PC digitizer ISA card)  for the PC. The connector is the same shape as Dave used to capture analog video but this one was connected to a DOS PC and you could save (of even load) GIF images from and to the camera (of better, the floppy in the camera).

I have used this functionality during school to take pictures and imbed them in various reports I'd to write. The teachers could not believe there eyes, the things we take for granted today was unheard of, especially when a 19 year old came with equipement like this....

The picture below is found on the internet so you could have an idea of the capturecard.

[EEVblog]

Sony solved this with the Mavica 3.5" floppy camera

  Sony  3.5" floppy camera https://docs.sony.com/release/MVCFD100-200revision.pdf

[Kleinstein]

How could they get away with fixed focus (two settings with the macro mode) and an F/2.4 lense  ? The sensor is small, but still depth of field must be awful.

[mikeselectricstuff]

How could they get away with fixed focus (two settings with the macro mode) and an F/2.4 lense  ? The sensor is small, but still depth of field must be awful.

Simple -it was that or nothing!

[bktemp]

How could they get away with fixed focus (two settings with the macro mode) and an F/2.4 lense  ? The sensor is small, but still depth of field must be awful.

Analogue video has a rather low resolution compared to modern cameras, especially when stored at reduced bandwidth. What is the effective resolution of that camera? Maybe 400x320 or even lower? So you won't notice if something is a bit out of focus, because the picture is always blurred.

[timb]

Who here remembers the original Connectix QuickCam? 16 glorious shades of grey at 320x240 wonderful pixels! What's all this USB nonsense? QuickCam connects over RS-422 serial (Mac) or EPP parallel (PC) ports!

In 1994 it was mind blowing to be able to buy a *camera* for your *computer* for $100! Ohhh, how I wanted one soooo badly. I wanted to do stop motion animations of my LEGOs and document electronics projects. Alas, it never came to be for me... (I *did* get a Color QuickCam in 1998, right before Logitech bought them out then ruined everything.)

The design was pretty engenious, really. They ran raw CCD data from the "eyeball" down the cable to the connector shell, which contained a PIC16 that converted the data to RS-422 serial (with a clock rate just under 1Mbit). The PC versions had the PIC in the eyeball and sent the SPP bidirectional parallel port data down the cable to the connector; in both versions, the cable split off at the end, one side plugging into your keyboard (of ADB) port (with a pass through) which powered the camera.

[alien_douglas]

OK, I have to fess up. I brought one of these cameras. It was actually the previous model (RC-250) and it did not even have a macro function.
It did produce pretty 'reasonable' still video images. I used an IBM Video Capture/A (That is a microchannel bus card!) to capture its PAL composite video images to a computer.
You also have to remember that most computers were only VGA resolution back in the 90's so the still video image resolution was not such a big issue.

Ahh, such fond memories.

I even brought it not far from you Dave. At a Ted's Camera Duty Free shop in Pitt Street in Sydney. I can't remember the price I paid, but it certainly was certainly quite a few hundred dollars.
It was certainly a big talking point at the time as it was the first camera that most people had seen that did not work with film.

Alien

[chicken]

My boss at my first job had one of these in the mid nineties, including the capture card shown further up.

I borrowed the camera a few times for my trips to demo/copy parties across Europe. Even found some pictures on my hard drive. The one below is from the Wired 1995 party in Mons, Belgium. Good old Norton Commander. One of the few pictures without people to protect the innocent (good thing I stayed behind the camera). We used the pictures in a disk mag. www.pouet.net/prod.php?which=19722

In a bout of nostalgia, I bought one off eBay a few years back and tore it down. It was the NTSC model, but otherwise identical to Dave's.

Everything that starts with CK4 seem to be custom Canon part numbers. Among the few identifiable chips I found delay lines by Sony (CXL5001M, CXL5002M) and a Fujitsu MB88313 television display controller. The AN3387SB near the test points seems very similar to the Panasonic AN3389SB which was a recording/playback amplifier for VCRs. The big TI part is probably the timing generator to drive the CCD.

[kalleboo]

Now I'm curious about the Video Floppy format.

I'm assuming the camera doesn't have a framebuffer (too expensive and too big), and when you're playing back pictures, it's continually scanning the floppy over and over again?

So is it one photo per track? But that would mean that photos stored near the middle of the disk will be worse quality than ones stored near the edge...

Wikipedia doesn't shed a light on any of this, but it does teach us that apparently standalone Video Floppy decks existed and were widely used in endoscopy, dentistry and even TV production!

[Fungus]

Now I'm curious about the Video Floppy format.

I'm assuming the camera doesn't have a framebuffer (too expensive and too big)

It's an analog video signal recorded on the floppy so that's a safe assumption.

So is it one photo per track?

Very probably.

(I don't see how they could do it otherwise)

[bktemp]

PAL has a bandwitdh of around 5MHz, mabe a bit less at reduced horizontal resolution and reduced colour bandwidth. So you need at least 5-10Msamples per second. Assuming the disk rotates once per frame, the required density on the disk is 200-400ksamples per track. 3.5" floppy disks stored 18kbytes of data per track (147456kbits + sectoring information & MFM encoding). That is in the same ballpark, so it sounds plausible to record one photo per track.

[NiHaoMike]

Now I'm curious about the Video Floppy format.

I'm assuming the camera doesn't have a framebuffer (too expensive and too big)

It's an analog video signal recorded on the floppy so that's a safe assumption.

Actually, there is a framebuffer - the CCD itself.

[alien_douglas]

I am pretty sure that it was one photo per track.
While you were playing back an image, the disk was always spinning and the head was not moving.

Alien

[Ed.Kloonk]

Quick question regarding pal and video tape and VCR's. Always wanted to know if somehow doubling the speed of tape in VHS would do much to improve picture or would the existing electronics negate any tape speed increase?

[Fungus]

Always wanted to know if somehow doubling the speed of tape in VHS would do much to improve picture

Yes and no.

Videotapes aren't like old audio tapes. Video uses a flying head that scans across the tape diagonally as it advances. This creates narrow 'tracks' across the tape. The bandwidth of the tape comes from the speed of the head, not the speed of the tape.

If you increase the speed of the tape you won't get any more bandwidth but you will get more separation between 'tracks'. That might help a teeny bit by reducing crosstalk between successive frames of video but I don't think it will be much - the inventors of VHS would have fine-tuned that parameter.

nb. Many VHS machines actually had a "long play" mode that made the tape go past the head at half speed. This halves the distance between tracks on tape. IIRC the loss of quality was visible, but quite small.

[SeanB]

Faster tape speed on VHS was good to improve audio longitudinal tape track performance. Did little to improve video performance, that was locked to drum speed and head angle, which was fixed for the most part by the timing of the video frames.