Today, if you want to get a picture from your oscilloscope — maybe to send to a collaborator or to stick in a document or blog post — it is super easy. You can push an image to a USB stick or sometimes even just use the scope’s PC or web interface to save the picture directly to your computer. Of course, if it is on the computer, you could use normal screen capture software. But that hasn’t always been the case. Back in the days when scopes were heavy and expensive, if you wanted to capture an image from the tube, you took a picture. While you might be able to hold up your camera to the screen, they made specific cameras just for this purpose.
Of course, these cameras took film. For example, the Contax GCCM in the video below was made for 35mm film. It wasn’t just for documentation, either. You didn’t have storage scopes, so if you wanted to make precise measurements of something that didn’t recur often enough to give you a stable trace, one way to measure it was to grab a photo.
Shake It
The problem with that is that you have to develop the roll of film before you get your results. That’s why most of us used Polaroid scope cameras like the Tektronix ones you can see in this vintage Tektronix brochure on the Vintagetek website.
A typical camera was made to fit around your scope’s CRT and had a “hood.” It locked onto the screen and ended in a standard camera. Often, there was an eyepiece or some other arrangement that let you see the screen. Some of them swung clear when you weren’t using them and some you simply had to pull off the scope’s screen. There were also adapters for normal cameras like the one in the video below.
While you could get backs that took ordinary film, most people used Polaroid backs that took a single piece of Polaroid film — at least, once Polaroid film existed. Once you took the shot, you had to use a smelly squeegee that came with the film to fix the image. Microscope cameras often used this same sort of film.
Lots of Vendors
Of course, Tektronix didn’t have the market cornered. You usually had a camera that matched your scope, like the HP camera in the video below. If you were really decked out, you also had a cart that you could wheel your heavy scope around to where you wanted to use it.
No one uses these today, right? Um, maybe that’s not accurate. If you think CRT oscilloscopes are retro, you haven’t seen these. When we took a lot of scope pictures, we were always glad for that Polaroid film.
I like how the HP has a manual shutter release, not something electronic.
Well, if you know about early HP o-scopes, their triggering was lousy!
was watching emergency! the other day and saw one of the doctors using one of these to get a hard copy of a medical scan.
at work, even our oldest monochrome LCD scopes can snap a screenshot and send it to various storage options, and our newest one’s are running windows… 9 out of 10 times what happens is that someone snaps a pic with their phone
Did they also have movie cameras for recording data, like a kinescope?
I have burned through a lot of Polaroid film capturing a one shot event and then turning on the graticule illumination briefly to double expose it onto the waveform, only to do it over because of a false trigger.
There were also analog storage oscilloscopes. They could take single shot captures and display them for a couple of minutes.
Tektronix made quite a few analog storage scopes that did this. The later ones held their images for a longer time. I don’t recall seeing an image fade.
I also spent a few days working in a display terminal that used the same technology – you erase the display then write what you want and that gets stored. The only way to remove anything strictly to erase the whole display, but I remember there was a way to display a cursor without it being stored – you developed code on the same display! This was in the very early 80’s
Old Tektronix curve tracers are still used today in many electronics labs. The Tektronix 576 is especially popular at semiconductor companies, even though the last one was manufactured in 1990. Tektronix made an attachment for a Polaroid camera, but everyone simply takes a picture with their phone now. Unfortunately, the pictures never look as good as the old Polaroids because of room reflections and glare on the Tektronix screen. To improve the photos, I eventually made a 3D printed attachment. For those who are interested, it can be found here: https://www.thingiverse.com/thing:2096029
We’ve come full circle. If you look at a ‘scope image that’s been posted to any modern online [electronics] forum, it’s almost certainly been taken with a phone camera.
It’s mostly because the user interfaces on the scopes are terrible and getting the data out is a fiddly process that risks losing the image you have on the screen.
In 1982 I used a Tektronix Polaroid camera to capture traces that lasted about a minute. Until I could see the image, I didn’t really know what was happening.
If you have an analog oscilloscope, take a look at this project:
https://hackaday.io/project/171961-a-digital-camera-for-analog-oscilloscopes
Some weeks ago a user from a site I admin had some issue signing-up, so he took a pic of the desktop screen with his smartphone and mailed it to me…
This was not the worst I had though !
Could be worse.
Back around 2005, the company I work for got a support call from a customer using our software. One of the reports kept coming out empty. Not just no data, even the page headers were missing. Basically, a sheet of blank paper popped out of the printer when he ran this one report.
He faxed us a copy of the blank page.
I hope you faxed his paper back to him when you were done with it! /s
I still have six waveform Polaroid photos from my IC lab class four decades ago. I lost the report I wrote, so I can no longer tell you exactly how these waveforms prove that my switched-capacitor filter worked.
But I remember that it did. I was pretty pleased about that. Still am.
I can’t believe it! I have that exact camera, a 35mm Bolsey, shown 30-40 seconds into the second video. It’s an excellent camera as far as quality of build and reliability go, but not high-end in the sense of being SLR and having a fast lens. The only cameras I’ve used on oscilloscopes however were later digital cameras on an analog ‘scope. Works great. I do have an Agilent DSO, but I hate it. That thing is user-HOSTILE! The only reason I’m not using my analog ‘scopes anymore is that their switches need contact cleaner sprayed into them and they’re not accessible.
I remember taking pictures from slow scan APT weather satellites using polaroid camera on tek scope. Prints are still good after 45 years.
This takes me back to the small community college I attended, where we had almost exclusively surplus gear, ‘scopes included. It was all good and working, yes, but needing to take a photo of a trace felt antiquated, even then.
Still, it was that (and we had about six cameras around for the various models of ‘scopes), or drawing it out by hand in our lab books (which we usually did, because nobody wanted to find and pay for the film). To the best of my knowledge, there were no DSOs yet available at the college for students to use at the time. Ah, the bad old days.
Oscilloscope cameras are a bit unique in that they are designed to record a flat object plane onto a flat image plane with minimal distortion and to maintain line pair resolution across the entire image plane. I can only speak for the Tektronix cameras, but they all use BTL (between the lens) shutter systems. Most SLR’s used focal plane shutters which are a bit problematic for oscillography use. The C-50 series of cameras are also very unique in that the shutter and the aperture are both defined by the same shutter leaves. A very tricky thing to try and quite difficult to get those things working properly. The Tek cameras were powered by the contacts on the bezel of the oscilloscope along with a trigger contact. Note the three contacts on the bezel in the photo. The cameras with mechanical shutters still used mainframe power for the focus lights as well as the exposure metering system.
Now you know why it’s called a screen shot.
Sort of a pivot here but the post reminded me of the old days of analog scanning electron microscopes (pre-mid 90’s). A dedicated monitor and camera were used to capture images. To reduce image noise (aka snow), a very slow scan rate was used to drive the electron beam hitting the sample. Essentially, the noise got averaged out by the beams (both in the CRT and in the sample chamber) moving very slowly. Sort of in-pixel averaging. One full raster could take 5 minutes. Single shot Polaroid film packs were usually used for “near instant” photography. I recall them being about $4 each with a lot of wasted shots due to bad focusing of the beam on the sample.
No sentimental nostalgia here.