Will this app solve the issue of “shaky image”?
The short answer is: The PylonCam Pro app gives you the flexibility to choose the best possible settings for your specific phone model. Just record a set using each lens on your phone and see which one is best.
The long answer is: Yes and no, and there’s a lot understand about iPhone hardware and software:
Lens Info: Starting with the iPhone 6S, Apple introduced “optical stabilization” on the rear lens that, while improving image stability under “normal,” hand-held use, creates terrible image shake with the hi-frequency vibration of a pylon. This is a physical mechanism in the hardware of the phone and thus there is no way to turn it off or circumvent it via software. The solution has been to use the front/selfie camera instead, which does not have optical stabilization. The downside is that the front/selfie lens is a lower quality lens than the main rear lens.
At the time of the 6S, there was only one rear camera on iPhones. For a while now though, iPhones have 2 or 3 different rear lenses: On regular models there is a main lens, sometimes called a “Wide” lens, and there is an “Ultra-Wide” lens. On Pro models, there is those two lenses plus a third “Telephoto” lens. No matter what model you have, as you zoom in or out, the lenses aren't physically moving and thus aren’t actually “zooming” (called optical zoom) - the phone is just cropping and expanding the image on your screen (called digital zoom), which means the image quality degrades, because after a crop, you have a lower number of pixels occupying the same amount of space. However, with the extra lenses, at certain "break points" the phone switches to a different lens. As you zoom out, it switches to the wide-angle lens. As you zoom in, on regular models it’s all digital zoom, but on Pro models at a certain point it switches to the Telephoto lens, or it seems sometimes Apple does an interesting software mixture of the Main/Wide lens and the Telephoto lens as you zoom in. If you press and hold on your zoom options while in the camera app, you can see this dynamic a little more clearly, with the different lens demarcated. Here’s a screenshot from an 11 Pro, showing the three lenses and their “start points”:
Back to stabilization: On non-Pro models the regular/wide lens has the problematic optical stabilization, and on Pro models the telephoto lens also has optical stabilization and thus unsuitable for pylon recording. On either model, the ultra-wide lens does not have optical stabilization, so as soon as you zoom out to anything less than 1x, it switches lenses to the Ultra-Wide and you “access” a lens without stabilization = no pylon shake.
This seems to solve the “problem” of having to use the selfie camera, except at least on my iPhone 11 Pro, the ultra-wide rear lens isn’t any better quality than the front lens, and the ultra-wide lens is more zoomed out than you need to capture skiing, so if I use the ultra-wide and “re-zoom” the video (which remember, isn’t zooming but just cropping), I end up with slightly lower quality than if I had just used the selfie/front lens in the first place.
However, Apple is perpetually updating their lenses (most models) and stabilization (stabilization was upgraded on the 12 Pro Max and again on the 15 Pro), so with newer models or not-yet-released models, the ideal pylon-recording settings may change. The best thing to do for now is just record a set on each lens of your specific phone and see which is best. To restate the important part: The PylonCam Pro app gives you the flexibility to choose the best possible settings for your specific phone model.
*one final note to understand about lenses: the MP (mega-pixel) size is not the only, or even really a good way, to determine the actual quality of a lens. Sensor-size is a better measure, and you can find that info for some models but Apple doesn’t seem to proactively list it, so it takes digging, and even then, there’s still other factors. So don’t just assume that two lenses with the MP will turn out the same