Recommendations for a slow motion camera or microscope?

GregAtkinson

I have the homemade light detector with oscilloscope described elsewhere on this forum, and it's been really helpful for me to detect sources of PWM in computers, lightbulbs, cars, etc.

But I feel like I'm missing a piece of the puzzle. I've been thinking about getting a slow motion (960 fps or higher) camera with zoom or a digital microscope. My hope is that the combination of slow motion and zoom would help me to actually see what's happening on the screen, such as pixel inversion.

I've been looking at the Sony RX100 VI (or VII) which films at 1244×420 at 960 fps with an 8x zoom.

Does anyone have thoughts on this model or have suggestions for something else? My budget is in the $1000 range.

Zodios

GregAtkinson why not use iphone + lense to do videos like https://www.youtube.com/watch?v=ieCT17IZp2E ?

GregAtkinson

Zodios Oh that's a great suggestion. I didn't know those clip-on lenses existed. I've ordered one from Amazon (https://www.amazon.com/dp/B074TGMFD3) and we'll see how it works.

My phone only shoots at 60 fps, but surely I can borrow a friend's and maybe get as many as 240 FPS. That should be enough to get started for a tiny fraction of the price.

KM

Is the magnification done by such lenses enough? Notebookcheck was reported to use the microscope mentioned in this thread: https://ledstrain.org/d/1903-gear-used-by-notebookcheckcom
Perhaps they are still using it currently. It has a magnification of up to 250x, which is suitable for high resolution displays like those found in smartphones. Some kind of tripod stand that firmly fixes the camera in place may help a lot to stabilize the video.

GregAtkinson

KM Nice! I've ordered the Carson Microflip as well. I'll report back in the next week or so.

If anyone else has suggestions I'd love to hear them.

One thing I've been able to see in my tests so far is that the monitor that bothers me the most has some pretty serious flickering from pixel inversion. I can see diagonal rows of pixels glow brighter and then dim. Of course the pixel inversion may not actually be what's causing my symptoms, or perhaps it's only one of many triggers. But it's something I can investigate.

GregAtkinson

I was able to capture pixel inversion at 60 fps. This video is slowed down to 1/10 playback speed.

The top row is #A0A0A0 which seems to be a color that's susceptible to pixel inversion. The bottom row is white (#FFFFFF) as a control group. There are other pixels in the frame but they're black.

You can see the pixels along the top row getting brighter and dimmer.

https://youtu.be/4H6bETUx2Lc

BTW the clip-on lens I bought only magnified to 2x, so that obviously wasn't helpful. The Carson Microflip magnifies to approximately 20x. It's advertised at 250x, but that's purely marketing. The phone itself does most of the magnification.

GregAtkinson

GregAtkinson I wanted to fact check myself on the magnification of the Carson Microflip. It actually magnifies about 30x at the 100x setting and 80x at the 250x setting.

I've actually found it pretty useful. And it only costs about $20.