Ants On A Melon RGB Critter BT - Analog vs PWM Settings
- Stephen Knight
- Mar 26
- 3 min read
Introduction
The Ants On A Melon (AOAM) RGB Critter was a revolution in RGB flashlights/torches for light painting photography, as it had an Analog mode for smooth light trails. Most RGB flashlights produced before the Critter had highly visible Pulse Width Modulation (PWM) to mix colours. LED drivers using PWM quickly strobe or pulse Red, Green, and Blue to colour mix. Whilst this is easy to design, and is common in LED lighting, the downside of PWM is that it generally doesn't look great for light painting photography. PWM also becomes more obvious at lower brightness levels as the strobing frequency is slower. As there have been improvements to the LED driver firmware between the AOAM RGB Critter 1 and RGB Critter BT, AOAM asked me to take a look to see how they compare.
Methodology
I tested using the following variables:
Analog vs PWM - Analog 100% brightness and PWM 100% brightness. Some tests with PWM 50% brightness.
Modes - Yellow colour (which would require colour mixing of Red and Green), and Pastel Creamery fade mode.
Light painting tools - 24" Honeycomb Saber, and BitWhip 200.
Camera settings - identical for Analog 100% brightness and PWM 100% brightness, with exposure increased by one stop in ISO for 50% PWM.
Distance from the camera to light trail was fixed 2m, aside from the light tunnel photos using the BitWhip. Identical post processing settings were used for each comparison, using my SK_Light_Painting_Standard Lightroom preset.
Results
Honeycomb Saber
L to R - Analog 100%, PWM 100%.
L to R - Analog 100%, PWM 100%.
The Analog light trail is noticeably brighter than the PWM light trail at 100% brightness. The Analog light trail is also more vivid and saturated at 100% brightness. This is most noticeable for the fade mode than the fixed colour. When zoomed in closely, I cannot see the PWM effect in the light trails from the Honeycomb saber, likely due to the light being diffused.
BitWhip
L to R - Analog 100%, PWM 100%, PWM 50%.
L to R - Analog 100%, PWM 100%.
As with the Honeycomb Saber, when using the BitWhip, the Analog light trail is noticeably brighter than the PWM light trail at 100% brightness. The Analog light trail is also more vivid and saturated at 100% brightness. This is most noticeable for the fade mode than the fixed colour. I also tested PWM 100% vs PWM 50% brightness, and the PWM strobing was more noticeable as the on-time for each PWM pulse was shorter at 50% brightness.
The PWM strobing is difficult to visualise without zooming in to 100%. Thus, the closer the light trail to the camera, the more noticeable the PWM will be. Due to this, I performed an extra test using the BitWhip to create a light tunnel. Focus was set at approximately 30cm from the camera lens.
L to R - Analog 100% medium movement, PWM 100% fast movement.
The light tunnel photo showed a very noticeable difference between Analog and PWM. The Analog photo again has much better saturation in the light trails. The PWM effect is visible at close range, and more pronounced with fast movements of the BitWhip, as per the sample photo. This PWM effect may be highly desirable for flow artists who want trippy tracer effects, but for light painting photography, it is generally undesirable.
Conclusion
My observations from this testing are that:
Analog mode results in brighter and more saturated light trails for light painting photography compared to using PWM.
PWM strobing/pulsing effect is more pronounced when light trails are closer to the camera, with faster movements, or lower brightness settings.
PWM strobing/pulsing effect is only visible with non-diffusing tools such as the BitWhip, Fiber Optic Brush, and Light Blades. It isn't visible with tools that diffuse the light such as Sabers.
The RGB Critter BT offers the best of both worlds - Analog light trails for light painting photographers, and PWM mode for flow artists. I would highly recommend using the Analog setting for light painting photography.
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