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dreifish

Member Since 25 Oct 2013
Offline Last Active Sep 21 2016 05:45 AM
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Posts I've Made

In Topic: Atomos Flame Housing

10 September 2016 - 10:56 PM

That's quite the contraption you've got yourself there, Trickster! Hehe..zoom-through wet lenses do sound good in theory. How do you find managing switching them underwater?

Recently I've started to notice I have trouble composing with the monitor of my A7rii underwater. I suppose it's mainly an issue of needing a prescription mask, but the idea of having a large external monitor I can position at different angles and use for critical exposure/ focus definitely appeals to me. If it's practical.

On the other hand, I totally hear what you're saying, bubffm. But what options do we really have for a large sensor interchangeable lens camera for underwater use? A Red raven runs 20k+ once you add a housing and the reports i hear are that the sensor isn't so good out of the box with the red channel.An FS7 is probably 15k with a housing and you going even get raw without an external recorder. None is nagging housings for the FS5 or Ursa Mini as far as I know..

I'd love to have a camera that I can take underwater that does 4k at 60p in at least a 10bit 4:2:2 broadcast approved codec, but there isn't anything at the prosumer level at the moment.

In Topic: Atomos Flame Housing

10 September 2016 - 05:13 AM

Interesting. Yeah, I heard from Scubacam in Singapore that Nauticam was producing this, but it seems Nauticam hasn't been doing much publicizing. Did you own the Shogun housing before, Trickster? What refinements are you referencing? Is the size/weight similar?


In Topic: Sony a7s II underwater use -- All parameters

10 September 2016 - 04:53 AM

Well the deep shot is so defective with its magenta color that I don't think anything could help it.  The question is, if it had been shot in a sLog profile, would it be easier to correct?

 

Thanks for taking the time to do that.

 

No, it would be even harder to correct. SLOG is meant to solve issues with dynamic range -- i.e. a very contrasty scene where the brightest part of the image and the darkest parts of the image are more than 7-8 stops apart. The scene you filmed isn't one of those situations. It's easy to tell -- just put up the histogram when recording the video or a waveform monitor in your video editor. Most likely, when shooting with no picture profile, you'll find that neither your blacks nor your whites are clipping. So you can easily represent all of the image in 7-8 stops of the standard no picture profile. All SLOG will do is compress those 7-8 stops of contrast into 3-4 instead.  

 

After further testing over the past two days, I've basically found no situations where you NEED more than 7-8 stops shooting ambient light underwater. Think about it -- all those particles in the water strip away contrast resulting in a very flat image. That's why the most important rule of underwater photography/videography is to get as close to your subject as possible. The only situation where the scene has greater contrast than that is if you're shooting directly into the sun AND you're trying to preserve detail in the highlights AND the shadows (as opposed to just silhuetting whatever you're shooting against the sun). How often do you find yourself doing this with ambient light underwater?

 

SLOG only helps you preserve more luminance detail. It does not help you preserve more color detail. In fact, because it compresses the luminance range, it actually preserves less color detail. So no.. color correction of SLOG footage is never going to be easier than color correction of non-slog footage. 

 

I will try to post some more of the tests I've done, including some UAWB tests in the 10-12 meter range and using all the different picture styles to see which creates the best colors over the next few days (or weeks.. I have a busy week next week). In the meantime, I'll leave you with another screen grab from a video shot today. No picture profile, picture style standard, 3m, underwater auto white balance. Attached File  20160910-.jpg   152.43KB   8 downloads


In Topic: Sony a7s II underwater use -- All parameters

09 September 2016 - 05:15 AM

This are the 2 jpeg I took from the slog clips once I graded them...

16446aa97a307885f5d0026c83a0e095.jpg



Soooo now I will have to try SLOG at -20m to see how it works...

 
Not bad, Taxidiver. But to my eyes, the water is a bit too purple, and the coral too flat. Overall, I don't think it's any better than the no picture profile footage. Here's a JPEG taken from the no picture profile footage with a very straight-forward grade -- levels/contrast and desaturating the green/aqua a bit.

 

I think you'll find that your problem at 20m isn't the gamma profile, it's the white balance. UAWB pretty much falls apart around 10-12m. And I don't think the manual white balance (which requires a filter at those depths) is any good either.

 

As for overexposure, I think I shot this footage in auto-ISO mode, wide metering mode,  EV set to 0. While there might be some slight clipping in the areas where the sunlight is reflecting off the sand, I don't find this at all distracting or unnatural personally. Sure, I could've exposed a stop lower to save those highlights, but that would've meant the midtones of the coral would've been underexposed. So I would have had to boost that in post at the expense of noise in those areas. A bit of highlight clipping isn't always bad. It creates more contrast in the scene.  

 

Attached File  20160907--1.jpg   148.96KB   14 downloads


In Topic: Sony a7s II underwater use -- All parameters

08 September 2016 - 05:06 AM

Any password ?? Cant download...

Oops.. updated the link with the decryption key. Should work now?