gobiodon

On 14 March, the number of confirmed infections had increased to 4,585, including nine fatalities (Germany). Luckily it arrived later to Germany but that time we already had evidences and seriousness from the cases in Italy. Your quoted 25.000 peoples dying from the flue is also incorrect. It's approximately the total reported cases (2018) and only a small fraction died. We can see clearly already now that the death toll of SARS-CoV-2 is much higher. It's not a simple influenza virus.

Try rather the Hawkeye Firefly 8SE 90 degree first. It has an older sensor and it's noisier than a gopro, but you can even refocus the lens for macro work. (it costs less than the lens you want to use) In this video, there are some footages (wide angle was with Yi4K) with the macro modification:

You're probably wrong with your numbers: https://www.rki.de/DE/Content/InfAZ/N/Neuartiges_Coronavirus/Situationsberichte/2020-05-12-en.pdf?__blob=publicationFile

In the past I have some interesting experiments with a 30mm macro lens together with a fisheye adapter (SEL30M35 lens combined with the fisheye adapter (VCL-ECF1) with APS-C (sony )) Unfortunately I never had a chance to try it underwater but on land it gave quite interesting CFWA results. I have some very old blog post might be interesting for this topic: http://fiberstrobe.blogspot.com/2014/08/sel30f35-vcl-ecf1-lens-combo.html http://fiberstrobe.blogspot.com/2014/08/praying-mantis.html http://fiberstrobe.blogspot.com/2015/09/freelensing-versus-30mm-macro-with.html http://fiberstrobe.blogspot.com/2014/09/put-sel30m35-lens-into-perspective.html Cheers Marcell

Another older freshwater video (sorry again for the German text)

Excellent photos. I can only contribute with videos, because in the last few years I'm switched from photography. Sorry for the German text but it was a submission to a German underwater video competition. The footages were taken in German lakes close to Leipzig.

Hydronalin, a German on-line shope sells weefine products: https://www.hydronalin.eu/weefine-smart-snoot-1000-wf069-fokuslicht-fuer-unterwasserfotografie/a-696372/

Some are. This one has 56 cores (of 0.75 mm fiber): https://www.lichtdekor.de/Lichtfasern-Endlicht/Lichtfaser-in-der-Ummantelung/Lichtfaserkabel-PMMA-56-x-0-75mm-391-392.html But now I've read the whole thread again and you meant more and finer cores with a sum diameter of 1 mm

This might help: https://www.lichtdekor.de/Lichtfasern-Endlicht/Lichtfaser-in-der-Ummantelung/ I've ordered single non-jacketed ones and they were good.

Do you have any suggestion for rivers close to Istanbul?

Actually I thought it's Azmak Creek close to Susuzmüsellim

Unfortunately not. I've seen some of your other videos on youtube, the placed look familier, that's why the guess. I have a business trip planned to Istanbul this year. I'm considering to visit this nice river.

First I thought that it's Azmak Creek

Is there any dive base nearby?

Very nice. It's interesting that there are no fish in the water.