Yes!, That was exactly what I was talking about... Why should we stuck to 180º as a general rule bearing in mind our light problems shooting underwater. I'm sure below -20 you will never use ND filters at all and you will feel happy if you chose a fast lens to open as much as you can.
Why should we consider 180º our way to achieve a "normal" look since things down there behave in different ways?
"Normal" means image playback on a screen will look the same to us as it would if we were sat there underwater with the scene in front of us, ie our eyes are seeing things in a way that our brain expects. It doesn't matter whether you're looking at an underwater scene, your kids playing in the park or a mountain vista with clouds scatting across the sky, your brain still processes that image in the same way. The more you deviate away from 180 degrees, the more the image will have the potential to look odd to your brain, you will add either a smeary effect or a staccato effect, depending on which way you push the shutter... which is why I tend to be stuck to 180 underwater, because I tend to be filming natural environments and behaviour, I don't want to add an effect to the look.
As for trying to gain that extra bit of light by increasing the shutter, I think you need to put that into perspective. If your shooting for PAL land, you'll be running at 25p, so at 180 degree you're shutter is going to be 1/50th. By definition, the maximum you can increase that to is a 360 degree shutter, i.e 1/25th second, which is an increase of just one stop... if you're struggling for light that much, then you're already in trouble. Get some video lights, and/or shoot that scene when conditions are more favourable.... But, with all of that said, 180 degree shutter is no different from all the other rules in photography, they're there to guide you, give you the benefit of the wealth of experience that's out there, give you an idea of what you may expect if you abide by them or ignore them. But at the end of they day, it's your choice, you're the creative that's pointing the camera, play around and see what works for you, see what parameters you are personally happy to work with. That way, if you are ever faced with a low light scene that you know you're unlikely get another chance, and you need to get some more light from somewhere, you'll know whether to flick the gain on or open up the shutter.
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
Yep, that's about the size of it... however the document you're referring to here:
covers the technical standards required for delivering the footage from the edit suite as a completed product to the BBC (and others) when ready for transmission/broadcast, i.e this is what the edit suite needs to render to once they've completed all their clever grading etc.
If you look at the end of Section 1.1 on page 6, the document directs you to standard EBU R118 "to assess the suitability of cameras for HD use", this is the document that the outlines the standards required for cameras
If you have a look through there, you can see that the GH4 spec complies with HD Tier SP (for specialist cameras), and would also comply with other HD tiers in terms of image quality, although it does fall down in other areas (e.g time code/genlock, audio etc).
In terms of your original comment, 4-2-0 codec is acceptable, depending on the bit rate and compression method used (have a look at table 1).
So coming back to my original point, GH4 internally recorded footage doesn't meet their standards, but could be used for broadcast - but only within the 25% percentage of the final project?
Happy to be corrected, as I don't want to be wrong myself nor pass on duff info!
So anything shot on a GH4 would be considered as proper, broadcast quality HD, and would not impact on the 25% allowance for other stuff.... which is just as well, cause some of the stuff we've done on GH4s would have blown that allowance in more than a few shows already
Your subjects don't have a great deal of moving detail, so the bit rate isn't going to be pushed. Try throwing a fairly complex image in front of the camera, e.g back lit water droplets hitting a matt black surface, where you're capturing loads of movement, and the cameras trying to cope with a full range of light and exposure, you may see 50p struggle a bit when you look at each individual frame.
If you take a 50p clip and render it out as 25p, your video file will have half the amount of frames. This will be done either through interpolation of adjacent frames (which can result in a fairly messy output) or by dropping frames. It depends on how you've set your NLE up.
If you render a clip out, the bit rate will be defined by the rendering process, the codec used and the parameters chosen. Throw your AVCHD clip through premier and then output as DNxHD, you'll end up with a 180 Mbps data stream. However you're not going to increase quality.... you can't add data in through the rendering process. As for your intermediary codec, no surprise there at all, each looking at each frame, the 50p footage will have twice as many frames as the 25p.
AVCHD is and 8 bit format and highly compressed. It does a great job, which is why it has become so popular, however it does have it's limitations. 8 bit means the image will struggle in low light and highlight, as priority is given to the mid tones where the majority of the important information is assumed to be. Re the compression, as with JPEG vs raw, if you get it right straight out of the box, and don't need to make adjustments, then you'll end up with a pleasing image, however as soon as you start to try to push the image with any form of grade/colour adjustment, you'll very quickly find yourself hitting problems. But in the general case for an untouched clip, it's unlikley that you're going to notice the difference between 25 and 50p.
In terms of bit rate, put it into perspective. BBC HD is broadcast at around 10 Mbps, and is viewed on a screen much larger than your PC monitor. You'd be hard pressed to notice, picture quality is still good... but you can be assured that the initial delivery was way higher than that in order to give them the latitude to pull the image around and get the look they wanted (minimum delivery for us for broadcast is DNxHD at 180 Mbps or ProRes at 185).
If you are shooting 50p, and then retaining the same frame rate in your end delivery, then there will be a minimal increase in quality when compared to 25p. However if you bring the 50p down to 25p, then you will be faced with either dropping frames and losing half'ish of the data, or interpolating frames and quite possibly getting a smeary image as a result.
I would suggest that you approach each shot individually, and choose the appropriate settings. If it warrants slowing down in post, shoot 50P. If it doesn't, shoot 25P.
Fish eye would look ugly in video, however wide angle and macro lens choices would be very similar, so no real issue there...
However the head set would be a struggle. Video, you need to be thinking about the getting the detail, ins and outs, cut aways, GVs, what you've done and what you need to do build the sequence and tell the story. Trying to mix stills into the middle, if you're as feather brained as me, you'll forget where you are with the video, and won't have sufficient time to concentrate on the stills to get good results there either.
The lighten requirements are also very different, as are the settings on the camera... so the more you swap between the two, the more time you'd waste resetting and settling in.
So, I'd say keep it simple. If you're doing a video dive, focus on that, stills then think of stills... and even more than that, dedicate each dive to video wide or video macro, stills wide or stills macro.
I agree the Orca SeaWolf light is a fantastic LED light. Great even light and colour rendering. Clever way to transport and use of high capacity rechargeable batteries. One thing I don't like is the opening and closing of the canister. Two hex bolts and only way of opening is use a blunt flathead screw driver next to bolts. I am going to suggest Orca provide some sort of snap latches or even a thumbscrew. Great light and output is 22K lumen as specified.
OrcaLight have already redesigned the method of opening and securing the lid, have a read of the following for details:
That device is to work on a flat surface. If you go diving on rocks you won't have that. And if you go on sand you can have 4-5-7 20 legs but stability comes out of balance not planting the legs in the sand as if it was an anchor. Even sand contains living organisms and should make sure your impact on the environment is as little as possible. That's my perspective at least. Results matter but after am sure am not demanding more than needed out of the seabed
Thank you Stuart ,yes i have been told the same thing (enigmatic) about mauri but due to the problems with organisation (%50 my fault) i couldnt do it. I wish i can dive to the places you recoment one day
Just for a tease, filmed quite a while ago now, but here's the Southwold
Obviously this needs some extensive testing. I suggest we send a dedicated and unbiased researcher (that would be me) to the Caribbean for a grueling two-week regimen of test dives. I will thoroughly document the testing process and advise you of the results upon my return home. In regard to funding this research, please send a PM and I will send you my paypal address.
Now about this Scotch Mist; does adding lemon peel to a nice whisky really create an enjoyable beverage? I have my doubts but could probably experiment with that as well during the above two-week research project. No additional funding would be required for this. Plus, I could watch for condensation on my glass as I go from an air-conditioned room to the patio and supplement the fogging data.
Can't help with funding, but I'm very happy to supply a pressure cooker (possibly a head to put in it to check for results ), along with a small tub of water, some ice cubes and a copy of Nuffield A-level Physics test book (1987 edition), all obviously essential elements for your tests
Sorry about that Draq! I will try to clearly answer the 2 questions posted in this thread using what little expertise I have in the area as a hyperbaric physician. I will not get drawn into a pettifoggery once again.
Your question if the negative pressure generated by the Nauticam system will make it less likely to flood -the answer is yes, because the o-ring is sucked into the mating surfaces of the housing, preventing blow-by.
watboy, your question if an additional benefit of a vacuum system would be that it would eliminate condensation issues , the answer is no. It will greatly decrease them though. If you close your housing at 30°C and 75% relative humidity, condensation will form when the housing wall reaches 25°C. Under the same conditions, If you pump the housing down negative 10 inches Hg, condensation will form when the housing wall reaches 18°C. Starting conditions will certainly modify the results, but not the manner in which you can calculate the benefit. The explanation is below.
Condensation forms at the dew point which is when relative humidity (RH)= 100%
RH= partial pressure of water vapor (PW) / vapor pressure of water (VP) at a given temp.
Vapor pressure of water at a given temp. (VP) is independent of pressure
When you decrease the pressure by 10 inches Hg, you are decreasing the pressure inside the housing by 30%
Following Dalton's law, decreasing the housing pressure by 30% will decrease the partial pressure of water (PW) by 30% once the temperature equilibrates. Therefore, relative humidity will decrease by 30%
So starting at 30°C and 1atm and a RH of 75%, pumping the housing down to .7atm will yield a RH of 67.5% once the housing equilibrates with the 30°C ambient temp.
Using the dew point curve we know that at 30°C and 75% RH the dew point = 25°C
Using the dew point curve we know that at 30°C and 67.5% RH the dew point = 18°C
So after vacuum there will be a 7°C degree difference in how cold you have to get the housing wall before condensate will form.
I will be happy to answer any questions not originating from Interceptor.
Thanks, good to have a nice summary to cut through all the posture and waffle.