RX100 IV - Red Filter vs C.Temp White Balance, etc.

[vfrkids]

Hi All, first post - amateur question about red filters.

I'm going diving in the Caribbean in a few weeks with a Sony RX100 IV and Fantasea housing. No strobe or additional lenses/dome, just the camera and housing.

I'm wondering if I should pick up a red lens for the housing, or could the "C.Temp/Filter" white balance setting cranked up to the 'reddest' (9900K) achieve more or less the same effect?

Also/But...the camera has an 'Underwater Auto' white balance setting, so I guess I'm confused about the basics here, as well as how to decide whether to use red filter vs flash.

Appreciate any advice/explanation.

Thanks,
Howard

 

[JamesBon92007]

I don't know anything about the Sony camera but my experience shooting video in the Caribbean says definitely use a medium red filter. Auto white balance won't replace the missing colors. If you use a red filter AND flash it will likely be too red.

 

[tursiops]

Let the camera do it. Shoot RAW, let the camera adjust if it wants, but post-process to get your colors. The principal thing a red filter does is cuts down the amount of light hitting your sensor. With no additional lights, you want as much as possible of the ambient light, especially at depth or away from mid-day.See for example Color Filters vs. Post-Processing. One issue with filters is there are a lot of different colors, each optimized for certain kinds of water (blue, blue-green, green, and every shade in between) so the chances you have the right one are slight, which means you'll do post-processing anyway!

 

[snowdog61]

what he said. Shoot in RAW then adjust the white balance in post processing. If you want, take a picture of anything white (or gray for that matter) at depth then set that white balance as your default in your software. You can 'fix' all your remaining (at that depth) with just a click.

 

[Chris Ross]

If you shoot stills, then definitely choose an UW white balance mode and shoot in Raw. The colour corrections needed are in fact very simple, either a colour temperature to fix blue-yellow balance and a tint to do magenta-green. Once you get close do each channel in levels and that fixes the contrast as well. The UW balance just sets the starting point for the image when you open it in Raw so you are closer to correct balance and conceptually often easier to see which way to go to get the balance right.

 

[rsingler]

What the others have said. I shoot with an RX100 II myself.
Except if you're just starting, you may not want to spend the time with the post-processing of RAW shots. If you're just dipping your toes in the water, the simple answer is to shoot in JPEG like you'd planned (I know, guys, I know...), and try it one way in the morning, and the other the afternoon, and then the third way on day 2 to compare in your hotel in the evening.
The Model IV supposedly has a greatly improved auto white balance, so I'd start with that. Second try would be a manual K° temp setting. As I recall, I used something around 7800° in 30-40' in Bonaire on my last outing. The third option would be to learn the button sequence to manually white balance. Take a white slate down with you (unless you happen to own a waterproof neutral gray card), and then do a manual WB when you reach depth. It may take about 1-2 min of fiddling until you get used to it. I assume that your housing will let you reach those controls. I shoot w/Nauticam, and have to say it was worth every penny.
Once you have a couple of choices, add those to your memorized settings to save time.

Good luck! If you're like us, it's a rapid progression to shooting RAW and then messing with your pics in the evening while everyone else is out drinking and having fun. Strobes after that, lol!

 

[Ash176]

Hi, my apologies for bringing up and old thread and ''hijacking" it. But I have a query that I need some answers. Hopefully someone could shed some light on the matter.

When I bought the Fantasea housing for my RX100IV, the shop told me to put the camera in the housing when flying as the housing will have vacuum and it'll be hard to open the housing afterwards. As far as I know, the cabin of the airplane is pressurized and therefore such thing won't happen but the shop insisted that it can happen.
So my question is, do I leave the camera in the housing and carry it with me in the airplane or should I check-it in? Thank you for all inputs.

 

[Barmaglot]

Hi, my apologies for bringing up and old thread and ''hijacking" it. But I have a query that I need some answers. Hopefully someone could shed some light on the matter.

When I bought the Fantasea housing for my RX100IV, the shop told me to put the camera in the housing when flying as the housing will have vacuum and it'll be hard to open the housing afterwards. As far as I know, the cabin of the airplane is pressurized and therefore such thing won't happen but the shop insisted that it can happen.
So my question is, do I leave the camera in the housing and carry it with me in the airplane or should I check-it in? Thank you for all inputs.

While modern airliner cabins are pressurized, they're not pressurized to sea level - typically, the cabin air pressure, as the airliner cruises at 35000+ feet, is equivalent to about 6000-8000 feet above sea level. On underwater camera housings, the seals are designed to keep stuff from getting in - not for keeping stuff from getting out, so if your housing is sealed while the plane ascends, the air inside will slowly leak out through the seals. However, when the plane descends for landing, and the cabin air pressure returns to sea level, the housing's seals won't let the air back in, and after you unpack your bag, you will likely find out that your housing is very difficult to impossible to open, because the pressure gradient between sea-level air outside low-pressure air inside is applying tens or even hundreds of kilograms of force on the door. Rough calculation - 1 bar vs 0.8 bar, the equivalent of 7k feet altitude, is applying about 200g of pressure to every square centimeter - FRX100 housing is 15.5cm wide by 14.5cm tall, giving you a total area of about 200 square centimeters, multiply by 2 for front + back, multiply by 0.2, and you get 80kg - no mean feat to pry apart when you don't have much to grab on to.

With interchangeable-lens camera housings, it is typically advised to detach their lens port before flying, but FRX100IV does not have a removable port, nor does it have a vacuum valve to equalize the pressure. Therefore, it's best to fly with the housing either fully open, or with the main door o-rings removed, in order to prevent a seal from being formed.

Edit: See this thread for an example of a user caught by this problem - Stupidly locked my case

 

[Chris Ross]

The o- rings should seal fine in either direction, they are not fussy but if you open it in the plane and close it again it's in there till you take it to altitude again unless you have something like a vacuum valve or bulkhead you can remove or open to vent it. But having said that you should remove the o-ring for travel anyway, o-rings eventually take on a set if compressed too long. Just store the o-ring in a clean zip lock bag.

 

[Barmaglot]

The o- rings should seal fine in either direction, they are not fussy.

Not really - o-ring seals rely on external pressure to keep them leak-tight, but when you have (relatively) high-pressure air inside the housing pushing at the door, trying to kick it open, the seals can leak quite easily. Even with no pressure gradient to speak of, rinse tanks floods are notorious because the housing seals are not loaded - an opposite-direction pressure gradient makes this much worse.

I actually forgot to take the main o-rings out of my housing once before flying back from a trip, and upon getting home, I found that it sealed itself good and tight - I was able to pop it open, but it took a considerable effort to do so.