@JoeCullity Earlier you said sharpness doesn’t matter.
You will see that it does, hang on and I will explain.
I’m shooting with Theta S, FX and DX cameras, and sometimes even with crop 2.7 to get insane spheres.
File size is about the same for all spheres 2-5MB, except the 2.7 crop as they become + 200MP and need about 15MB in size to hold all the information.
(I see that most tutorials want you to crank compression up to 97% of a sphere when manually stiching it, that is not needed at all, but helps if picture is a full of details.)
JPG can compress a more sharp and clear image better and with higher compression ratio without loosing quality.
The more noise you have in an image, the less JPG can compress and you also have to crank up the % to 80 or more to not lose quality.
You can test this yourself, create a white image, same size as your sphere is, compress it at 50% with a photo edit program.
It’s a 14.5MP 53KB white image below here. Scroll…
Take a sphere photo and do the same. Notice the size difference after compression.
The white one should look the same and become quite small in file size 53KB in my case,
while the sphere(original 3950KB) should still be quite big 906KB(at 25%) and now even a bit chunky in the graphic.
Surprisingly my demo failed somewhat, but was a success in another thing. Even at 25% it looks really good.
I cranked it down to 10% and 513KB to get the chunkiness I needed for this experiment. Still it didn’t reach the white image in file size, it’s still 10 times larger at 10%.
This file will show a diner good enough on your phone.
To answer your question about sharpness, yes, it really matters.
What you gain from a sharp image is: Smaller size, faster download and it looks better.
Your 15 sphere tour could be 7.5MB if it was sharper and compressed.
Here we have data plans for our mobile devises, 100MB(3$), 300MB, 1000MB and 3000MB(expensive).
With the 100MB plan I could look at 13 sharp and compressed tours per month.
300MB plan I could look at a tour per day and still have some surf left in my phone.
Your viewers would need a 3000MB plan to be able to do the same.
Hope this experiment was educational
PS, I tried a few low compressions in PTGui for 50MP spheres, managed to get 1MB files that was still looking good and sharp.