I'm trying to capture small particles at about 20-30 cm distance to the camera at ~60-70 fps. Was using SMD32 LED with rechargeable battery as light source. By using that light source, there was no flicker in the video (almost no light intensity variance between frames), but the scene was a bit dark.
To increase intensity, I tried cheap light bulbs of all kind, such as Philips Classic Tone 60W, and Energy efficient Philips Economy Stick 23W. As expected, intensity levels were quite reasonable, but the flickering was quite obvious and problematic in the captured video. Then I tried 2 LED light bulbs: Wiselite Warmwhite LED A60 8W, and GoldMaster 9W LED. Interestingly, LED light bulbs DID flicker too.
Please note that voltage levels in the region is quite fluctuating, sometimes electrical home appliances stop operating and lights dimming although the electricity is on.
What made SMD32 LED non-flickering compared to LED bulbs? Is it the battery, or multiple light sources, or the type of the LEDs? What should I do for a non-flickering but enough intensity capture environment?
After the responses, I have further investigated the SMD32 LED, by only capturing the light projected from SMD32 LED on to the screen. Fps was variable between 59-61, exposure time was 1.5 ms, CV_8UC1 color scheme (grayscale) was used. I have saved 0th, 40th, 80th, 120th... frames and combined them to build animated gif images. Each gif image consist of 35 jpg images. As side note, each animated gif image below is at 4 fps.
1st animated gif one on the left is captured when SMD32 LED is not plugged into mains power (while it is only using battery power). It is almost steady.
2nd one on the right is captured when SMD32 LED is plugged into mains power. Overall intensity compared to first one increased but the flicker is quite obvious.
Consequently, there is something with the mains power. And I still don't know how to obtain the desired lightning conditions in a cheap way.