'Grey' for White balancing isn't a specific 'grey', can by 18%, can be anything really - the main issue for using a grey card for white balancing is that the card is completely Neutral, so the R,G,B values read off of it are the same - The PADI card is indeed pretty neutral - and its a Matte finish too, which helps.
The only issue I would say with the PADI card, is thats its quite dark (for grey) - so some cameras might not like it and refuse to WB off, of it.
Don't forget its a $15 card also - they will not be checking the consistency of the neutrality of their cards, unlike XRite or DSCLabs - but for us underwater I think its pretty close.
From my (mis)understanding I thought the BBC et al (via the EBU standards) have certain minimum requirements for source footage depending on the project, and within the finalised project there could be no more than 25% percentage of footage which could be captured with cameras which do not meet the required standards due to the nature of the shot (environmental, drone, on-car etc etc). The final project would then have to be delivered in the required format
I had the lens behind the zen 170mm dome. So very similar to the 180mm.
Using it for recording 4K, you won't find much wrong with the corners. But for 4:3 photos, where it uses more of the FoV, you will see the blurriness.
If I were buying a dome again, I would look at the 180mm at a minimum - or even the 200 or 230mm (via the n85 to n120 adapter) but they travelling with a dome this size becomes an issue.
One of issues with using WWL lens is that you are using a standard zoom in the flat port. The standard zooms are not very fast (f3.5 at the wide end) Would love a constant F2 .8 zoom lens starting and 14 mm!
Sadly even the 14mm primes you can get, appear from the reviews to be worse than the 14mm end of the zooms - which is odd.
Its heavy (but not much more than a large dome mind) and its slightly fisheye'd compared to the wide angles behind a dome - but only very slightly.
Benefits... Sharp corners, more FoV (130 vs 114), OIS and flexibility to boot.
I can't believe how good the combo is. (So sorry if I sound like a broken record praising it )
If one of your primary goals is for hand off to broadcasters. You will need the Atomos Shogun (or Assassin) also. This will eat $3,500 for the housing alone.
Why do I say you need one? Most of the broadcasters have certain requirements for the quality of their clips (with exclusions for a small % of the final output) which will require unedited 4:2:2 footage at a minimum.
As an example from SKY TV in the UK:
"All HD commissioned content delivered to BSkyB should use the AVC Intra 100 codec. The video should be encoded to the standard using Intra frame at 100Mb/s with 4:2:2 luminance/colour difference sampling ratio, level 4.1 with a 10 bit sampling depth. The 100Mb/s codec also stipulates a full horizontal resolution."
All material delivered for UK HD TV transmission must be:* 1920 x 1080 pixels in an aspect ratio of 16:9* 25 frames per second (50 fields) interlaced - now known as 1080i/25.* colour sub-sampled at a ratio of 4:2:2
The GH4 only shoots 4:2:0 internally.
The other option(s) would be:
An Atomos Ninja2 (in a NA-NINJA2 housing) but you would be restricted to 1080p, but you get the 4:2:2 @ 220 Intra.
Or get a BlackMagic Pocket camera, but again it's limited to 1080.
Most of the broadcast stuff you see is filmed on FS Sony's, Red etc.
Soft corners, you need to go big on the domes - if going for a wide angle lens like the 7-14mm. However due to the 2.2crop (in 4K mode) you will find that this is minimised quite a lot with the GH4.
However I still found it soft, so went with the WWL wet lens and a standard zoom.
There is 3 variants of the Panasonic 14-42mm, all with varying image quality.
The one I'm using is the 14-42mm ASPH f3.5-5.6 Mk II (and for additional confusion there is two sub variants, one metal mounted, one plastic)
For sure its not a 'super' or Pro level lens, but provides nice contrasty images which aren't far off my 12-35mm f2.8 - can't tell them apart. As I've found recently the build quality isn't top notch, but image is fine.
Compared to my Panasonic 7-14mm behind a zen 170mm dome. The 14-42mm and WWL offer to me, a massive difference in corner sharpness. Not to mention the addition of OIS. But as the OP is looking at the EM5ii that's a mute point.
As Espen points out thou, you won't be getting any spilt shots with the 14-42 combo. :-)
Yeah the WWL is heavy in the water. Make sure you got a bit of bungee on it when you detach! Hehe
Another option would be to go for the higher end Olympus f2.8 12-40mm ?? (Or 12-50mm. Confused) in a flat port. And just live with the fact it won't work with the WWL until you zoom to 14mm