Underwater Bubble Blowin' Users Group

[Michael Hastings]

Mike,

Gates writes: "5K Digital Cinema Underwater Imaging", which should probably read something like "Less than 1k Underwater Imaging using 5K Digital Cinema Camera".

The point I was making is that I questioned and not received an answer about the optical performance of their optical ports underwater and believe that they are far from 5k...in fact very far.

On the other hand I have posted a 1:1 corner crop of an low contrast SFR slanted rectangle filmed with the Epic underwater through 15mm Nikonos lens. The corner CA was less than 1 pixel. The MTF was nearly as good as that of a Master Prime in air. If anyone thinks they can match that, I'd like to see it.

I'm curious to try. Can you post how we make the chart and the water and lighting conditions, F stops used etc so I can try to compare?

And to be fair, can you tell us how you came up with the "less than 1K"

Also, my goal is to get optimum performance with much wider lenses - which is always more difficult to maintain sharpness and CA, however to do a proper direct comparison I should use the same Nikon 20mm F2.8 from the mid-80s - if anyone has one please let me know as I would like to borrow it for a test.

Here's the specs:

Nikkor 20mm f/2.8s 12 elements 9 groups close focus 0.25 m 62mm filter size Ai-S, CRC

[Tom Hamilton]

Gates writes: "5K Digital Cinema Underwater Imaging", which should probably read something like "Less than 1k Underwater Imaging using 5K Digital Cinema Camera".

Pawel, there should be plenty of Gates glass dome ports in Australia for you to test, I believe the Deep Red uses the same one as the Deep Epic.

Why don't you borrow one from one of the guys on this forum, do the tests, and publish the results here?

[Pawel Achtel]

I'm curious to try. Can you post how we make the chart and the water and lighting conditions, F stops used etc so I can try to compare?

Hi Mike, All instructions and procedure is set out on Imatest website.

Here is how you do it:
http://www.imatest.com/docs/sfrplus_instructions/

Here is how you interpret the results:
http://www.imatest.com/docs/sfr_mtfplot/

It is very straight forward. At the last Reduser meeting in Sydney I demonstrated and explained the entire process end to end.

And to be fair, can you tell us how you came up with the "less than 1K"

an educated guess :)

Pawel, there should be plenty of Gates glass dome ports in Australia for you to test, I believe the Deep Red uses the same one as the Deep Epic.

Why don't you borrow one from one of the guys on this forum, do the tests, and publish the results here?

Tom, good idea except I do not know anyone in Australia that has one. Gates appears to be mostly American thing...

Currently I had a setback with my measurement tank, which allows for perfect alignment of the chart against the dome and the dome against the lens. It was smashed to pieces by a transport company. I need to replace it first and I will fish for some domes.

However, there is nothing stopping anyone to simply film slanted edge rectangles with their rigs the best you can and post it up. I can run it through Imatest and compare. You do not need to purchase the software. The good thing about Imatest is that the testing is repeatable and everyone can do it. Gates do not need my housing, I do not need theirs, yet we can compare the results in an objective way. My results have been published ages ago. Sadly, no one else posted theirs....not even an old-school zone chart.

[Mark_Thorpe]

Amongst other items including a RED One Camera have just posted an underwater housing for Epic for sale. Any interested parties please see this post for more info.

Cheers,
Mark.

[Mauro Andreini]

Sorry I missed you guys! I’m kind of new to Red but….here I am.

Meanwhile …. happy bubbles !

[Pawel Achtel]

Hello Mauro and welcome to the Bubble Blowers thread. We seem to have two of them now after this thread was resurected from a crash. Here is the other thread:

http://www.reduser.net/forum/showthr...oup-Thread-NEW

[Mauro Andreini]

Cheers for that, I'll go there

[Mark_Thorpe]

Hey all, just wanted to get re-acquainted. It's been a while since my last appearances here as a shooter but hey, c'est la vie' said the old folk. Hoping to be able to share some plans with you soon.

Cheers,
Mark.

[Johnny Friday]

Thorpe---wrong place mate---got the the u/w bubble blowers new....

[Mark_Thorpe]

This one is the Sticky?