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Sony a7s and MWB

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Hi everyone,

 

I recently start using sony a7s because I needed high iso.

I like the camera and the lens. Superior Sony FE1635 and some Canon optics with metabone.

 

The problem is mwb issue, very often getting error message if I'm trying mwb or I'm getting very poor color with what ever method I try (different PP or without).

So now I'm shooting everything with "underwater auto" which is just ok (getting lot of red with strong light or shallow).

And "Underwater auto wb" tend to change color reproduction (so they call auto) each time when I start record (this is more problematic in post).

I can reduce some red in post and possibly makes them usable but most of time I need throw them to client directly without post-edit.

 

Normally I do mwb on sand or other object and I didn't have any mwb problem with Canon DLSR (7D, 70D, 5D3) or Panasonic GH4.

Do I need more accurate white or grey card for Sony?

Any advice would be greatly appreciated.

 

Ej.

Edited by escape

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Point at the sun maybe? It might help in some cases. When I used to get MWB errors on my Sony Z1P when white balancing against the palm of my hand or something white (usually deeper than 20m), pointing at the sun would often let me get a successful white balance and get me out of trouble.

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Point at the sun maybe? It might help in some cases. When I used to get MWB errors on my Sony Z1P when white balancing against the palm of my hand or something white (usually deeper than 20m), pointing at the sun would often let me get a successful white balance and get me out of trouble.

I'll try it next time.

Thanks for the reply.

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Are you in PP7 (with S-Log)? There's a bug that doesn't allow proper MWB when using PP7. Switch to any other PP, MWB then go back to PP7 if that's what you want. If that doesn't work, then just lock it in a custom profile with a preset (done before hand or custom the color depth). Underwater auto is ok if the shooting conditions don't change, but as you have discovered, any change in light and it adjusts. Worse comes to worst, lock it in daylight and deal with it in post.

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IMHO, the Sony cameras have never been great at MWB underwater. The MWB software seems to be desperately looking for red. You can fudge it with a pink plastic card but it's still a bit hit and miss.

 

Rather that stuff-around with MWB while diving, I prefer to be able to quickly get to a WB that approximates the conditions. The typical conditions are:

  • Light blue colour cast - shallow, clear tropical water
  • Deep blue colour cast - deep, clear tropical water
  • Light blue-green colour cast - shallow tropical water with some suspended plankton
  • Deep blue-green-green colour cast - deeper tropical water and/or lots of suspended plankton
  • Video lights dominate (night, cave, etc.) - use AWB
So I made 4 A4 pages in PhotoShop that approximate each of those colour casts and printed them. Then I put the pages in sunlight and took an MWB off each one, saving one into each of the 4 WB presets of the camera - then saving all the settings into the Custom Sets that I had already created for different exposure / focusing custom sets.
Regards
Peter
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EJ - are you diving with a red filter? I have been using a magic filter + underwater auto WB for <10m and overexposed auto WB for >10m, always in SLOG2. So far I really like my results, but I have not gone very deep or in low light conditions. Overall the XAVC codec holds up will to color correction, even @ 60p, 50mbps

 

I cannot perform a manual white balance with the a7s, especially in SLOG. I am diving in Fiji all next week and will let you if I come up with anything else!

 

Kabir

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I haven't had any success with one touch white balance. Underwater Auto, then pulling out some magenta, seems to be the best strategy I've found too.

 

Peter's suggestion is probably the "best practice", but I'm not usually that well prepared.

 

Kalupa - do you have some samples online of the graded SLOG underwater?

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Oh yes I forgot to add that you should also try overexposing the scene before MWB. This is from the Sony Help guide:


  • Setting [iTU709(800%)] or [s-Log2] may cause an error in the white balance custom setup. In that case, set the exposure bright first and then perform custom setup.

 

If you have the time, switch to a B/W PP, overexpose by 1+ stop then MWB, then switch back to S-Log. It's a stupid bug that still hasn't been fixed but hey, it's still gorgeous video.

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I was told the Sony RX100 IV has MWB issue as well. When would Sony take care of the issue? Does it help if you hold your reference (hand/card) closer?

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All Sony cameras since the NEX series have this issue. I have tried all sorts of white balance tool I even got a whibal card that works wonder on land but fails underwater. I ended up using a filter with auto white balance and applying a tint correction. Usually for URPRO you have yellow cast on other filter you have magenta cast so you need to increase blue or green 1 or 2 on the awb. The resulting colors though never needed any correction for me. I guess this is not the sort of reply that people that do grading like!

Edited by Interceptor121

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Peter's methodical approach is probably the way to go. I had about a year with the A7s and I am convinced the camera could not MWB consistently. I get inconsistent ambient back ground colour. I would suggest stay away from PP7 and S-log for UW. Even with a Shogun recorder. However this combo works best topside. I almost ruin a day's shoot at Northern part of Palau with this setting. Very washed out but where as on land this would be okay in post but there is something UW I did not anticipated. You need ND to stop-down as the camera ISO is fixed lowest at 3200. Not good on a bright morning and water full of mantas near the surface.

I find the A7s works best close up and with dive lights. Superb results with macro. Set it custom profile that you like and expose properly. Never forget those ND filters. My two cents.

 

cheers

 

David

Edited by CheungyDiver

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I used to put some of that pink styrofoam netting that they put over your duty free bottles in the airport over my white slate when I used sony. I found that took out the magenta cast.

I suspect EJ has some Pink fishnet stockings that will work just as well. :mocking:

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Thanks a lot to everyone for comments.

Maybe I should try Simon's method. :)

Ej.

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White-balance RAW tests I did show a red filter is needed to get accurate MWB for both Sony 5R and 5N under more than 9m/30ft of water. This may be true for A7S also.

Manual WB without filter:
@ 12m/40ft requires 12000K and +150 Magenta
12000K is outside 5R/5N's 9900K maximum color-temperature range which produces an error message. I think +150 Magenta is also outside the camera hue range.

MWB with an Equinox red filter:
@ 12m/40ft requires 6400K and +150 Magenta
Even though 6400K is inside 5R/5N's color-temperature range, I think +150 Magenta is just outside the hue range, resulting in an error message. However, MWB produces very good colors.

MWB with an Equinox red filter:
@ 9m/30ft requires 4600K and +75 Magenta
Both color temperature and hue are within the camera MWB range so no error message.

BTW, shooting AWB with a red filter, NEX-5R and 5N produce strong green cast in backlit situations. Shooting MWB definitely prevents the drastic color shift, which = less headache in post.

Edited by A.Y.

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White-balance RAW tests I did show a red filter is needed to get accurate MWB for both Sony 5R and 5N under more than 9m/30ft of water. This may be true for A7S also.

 

Manual WB without filter:

@ 12m/40ft requires 12000K and +150 Magenta

12000K is outside 5R/5N's 9900K maximum color-temperature range which produces an error message. I think +150 Magenta is also outside the camera hue range.

 

MWB with an Equinox red filter:

@ 12m/40ft requires 6400K and +150 Magenta

Even though 6400K is inside 5R/5N's color-temperature range, I think +150 Magenta is just outside the hue range, resulting in an error message. However, MWB produces very good colors.

 

MWB with an Equinox red filter:

@ 9m/30ft requires 4600K and +75 Magenta

Both color temperature and hue are within the camera MWB range so no error message.

 

BTW, shooting AWB with a red filter, NEX-5R and 5N produce strong green cast in backlit situations. Shooting MWB definitely prevents the drastic color shift, which = less headache in post.

The above is true for all cameras white balance it is limited by default between 2000-10000K.

 

There are cameras of other manufacturers that use Sony sensors and do not produce errors example Canon G7X and Sony RX100 have the same sensor the Canon does not error.

 

Errors should be triggered only when the exposure is off, when the exposure is in range the camera should go as close at it can to the white balance but not come out with weird results which is what Sony cameras do because the custom white balance implementation is essentially faulty.

 

On every white balance card of good quality there is also a way to check you are taking the read correctly, backlit situations for example always create issues when you white balance, filter or not. The light is meant to come from above or behind not frontally

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On my NEX i just use auto WB never have an issue

 

 

Sent from my iPhone using Tapatalk

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On my Sony NEX-5R, I would set a manual WB, shooting usually at sand (that seemed to work best), although sometimes my white card would work (sand actually seemed to work better). I would get an error message, but would just press "OK" -- basically telling the camera that the crazy WB reading was ok, and it would accept it. Additionally, I had a Magic Filter (gel) affixed on the backside of the lens. Those 2 together seemed to get me a decent WB.

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I too am shooting with the sony a7 and getting it to WB is driving me insane, bit of a newbie when it comes to underwater shooting. Have tried to MWB to a slate, hand, sand and nothing works well.

 

From what I'm reading people are saying its best to get a magic filter then also MWB if I'm correct ? or getting specific coloured slates like in the link to the PDF posted and use them ? Does the MWB not have to be white to make it correctly WB ?

 

Cheers,

Trent

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