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What’s the best Exposure technique?

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Since photography/videography is the art of capturing light. Deciding the correct exposure is the most critical element in helping us produce beautiful sequence of images. This topic is about exposure and should apply to most cameras. Nevertheless, we can still reference our cameras. We would like to share our experiences to learn from each other. 

The three elements that affect exposure: 

1) Aperture, decides the amount of light (affects depth of field & the sharpness of the image across the frame) The widest the aperture the shorter the depth of filed and the less the sharpness at the edges of the frame),

2) ISO (Sensitivity to light), each camera has a native ISO value where it performers the best. when shooting Log file most cameras have preset values.

3) Shutter speed (the duration the light takes for a given aperture for each frame/shot) For videography usually it is set at 180 degree or double the frame rate.

It is important to mention, that some cameras prefer overexposure than under - especially when shooting RAW - to maximize the dynamic range. Exposing to the right (ETTR) is the technique of adjusting the exposure of an image as high as possible at base ISO (without causing unwanted saturation) to collect the maximum amount of light and thus get the optimum performance out of the digital image sensor (google definition) 

My experience:

 a) when shooting with artificial light:

I used to shoot with a Sony camera in total manual mode. And since I shoot using Slog the ISO preset at 2000 native value which I could not change.  I used to set aperture at the best value to maximize exposure  but avoid clipping highlights and I relied on the camera waveform. This way I can easily recover for lost details in the shadows.

b) when shooting with ambient light:

Currently I use the GH5s using stander profile (I tried vlog but could not get best colors) and I set the camera in Aperture priority mode so I can control which aperture to use. And mostly I use the largest/widest iris to maximize light cause I am shooting in ambient light. I set the ISO to Auto with max at 6400. Cause I am always shooting at widest aperture, the camera will always choose the minimum possible ISO. ( I give vlog another try, with max iso technique) next time we dive after the Corona curfew is lifted. I find ISO 6400 is quite usable with the GH5s.

In general and whenever I change camera or technique, I use a color chart as a reference to make sure I get the right colors and exposure.

How about you guys? What technique do you use?

Stay safe, stay home and I pray to God that the Coronavirus disappears from planet earth for ever in the very near future :)

Here is an article about metering: 

https://digital-photography-school.com/metering-modes-and-how-your-camera-meter-works/

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I shoot mostly with ambient light on a Panasonic GH5

My method:

Resolution & frame rate: Mostly at 4K 50p (8 bit)

Always in Manual Mode for video

Picture profile set to Vivid. I find it helps marginally with better saturated colors

Also, always with a well adjusted manual white balance ofc


Shutter locked at 180 degrees
ISO set at its lowest possible value. I live in the tropics and shoot around here, so mostly set at 200.

Aperture is the biggest variable and this is where I do most of minor corrections through a dive. I mainly shoot with Tokina 11-16mm f2.8 (wide) and Sigma 18-35mm f1.8 (wide/zoom). Both of these lenses adapted to GH5 with Metabones Ultra. They are sharpest at f4 for Tokina & f5.6 for Sigma so for general shots I try to keep them close to there, or if I'm going for shallow dof I try to adjust.
I also use an Olympus 60mm f2.8 for macro, but mostly with artificial lights.

You can watch some of my work here:
 

 

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Posted (edited)

Underwater imaging is constrained by optical quality issue requiring smaller depth of field than you have on land

Typically you set the shutter speed depending on your project: I use 180 degrees so it is 1/48 or 1/50

Aperture is set by acceptable quality and depth of field usually except special circumstances this is f/5.6 can go to f/4 in some situations. On lenses that are not so wide it is possible to shoot at f/2.8 in certain scenarios

With those two variables set I go for the lowest possible ISO and try to expose on the subject if there is one. Usually in scenes with light it is not an issue to shoot at lowest ISO and ideal depth of field

The most challenging shots are reef-scapes with no clear subject as I tend not to trust the camera metering so I once shutter and aperture are set I try to use the lowest ISO possible so that I do not crush the blacks or clip the highlights and hope on the camera DR to deal with the situation. 

ETTR: is based on lowest ISO and requires you to widen aperture or reduce shutter. Shutter is fixed and aperture has optical limits so it is not relevant to any underwater imaging. Increasing the ISO is NOT ETTR and will reduce dynamic range and increase noise

The biggest issue in underwater imaging is that light meters are set for 18% grey and skin tones and none of those really exist underwater so metering is usually off

Edited by Interceptor121

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With my GH5 I would normally:

4K @ 30p for output on a 24p timeline (so you gain some free slomo)
Shutter: 1/60
Aperture: f5.6 (on the 14-42mm II)
ISO: AutoISO up to 6400
Profile: Scenery 
Metering: Center Weighted

 

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I use an AX700 so a bit different from the Panasonics.

My shutter speed is set to 1/125. I formerly used 1/60 but find that action is a bit crisper at 1/125. The only time I'd be tempted to go back to 1/60 would be an ultra low light situation.

Your thoughts?

Tom

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I think there is some confusion here between settings and exposure

Settings are one thing what you expose to are another...

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I discussed this topic on a webinar last Tuesday for Atlantis Philippines. Link below - feel free to check it out 

 

 

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54 minutes ago, tubestance said:

I discussed this topic on a webinar last Tuesday for Atlantis Philippines. Link below - feel free to check it out 

 

 

Uhm not really we are still going around settings here and photos. Possibly the histogram is the less reliable source of information to expose video and to a good extent also for photos

 

Histogram is an average of the average of the images does not know what is subject and what is not. False colour and waveforms give you that and to a lesser extent zebra but here we are talking about what does zero mean on the meter vs other tools

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Posted (edited)

I'm late to the party, sorry :drink:

I usually film subjects in deep water with little ambient light.
Those few times I filmed in shallow water I realized that shooting with the scene lit entirely by the lights is much, much easier. Especially if you have a pair of Keldan ;)

That said, reading your posts I think I'm the latest Jedi again: histograms, waveforms, zebra & co...

  • I had the histogram on the display for years only to find out that I never looked at it but it just annoyed me by taking up space on the screen: removed
  • Waveforms, where I can find them?  I've always been too poor to afford an external monitor and other gadgets...
  • Zebra is the only function I find really useful.

But the truth is, I've always relied on what I see on the camera monitor and I've never been wrong. Those who know me know that I am a long-time Panasonic user: GF1, GH2, GH3, GH4 and now GH5.I may be a simpleton but the clips always reflected what I saw on the display. I've burned the high lights sometimes but with the zebra, I'm fine. Sorry to admit I'm a WYSIWYG guy.
About ETTR for my empirical experience with Panasonic, I much prefer underexposed than overexposed clips. I've nev been able to fully recover an overexposed clip but maybe it's me again.

Just one question to @thani you wrote several times that you choose the widest aperture. Why? 

I shoot only in the Mediterranean sea and in a sunny day in 5/10 meters I have the exact opposite problem: @200 iso I have to close to F11/16 to expose correctly. I understand that you have murky water but you film in the tropics, don't you?

 

Have a good quarantine guys

 
Edited by Davide DB
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On 4/23/2020 at 4:09 PM, wydeangle said:

My shutter speed is set to 1/125. I formerly used 1/60 but find that action is a bit crisper at 1/125. The only time I'd be tempted to go back to 1/60 would be an ultra low light situation.

Your thoughts?

I think thats a really valid point - I remember a few years ago playing with 1/100 (for pal 25p) and it giving great results also. 

 

7 hours ago, Davide DB said:

Waveforms, where I can find them?  I've always been too poor to afford an external monitor and other gadgets...

Have a good quarantine guys

The waveforms on the GH5 i find too small, but they are within the video settings under Wave/Vector. :)

Quarantine - gee man, Italy and Spain we are really locked in eh! Not sure my kit will still work when it gets wet again!

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8 hours ago, Davide DB said:

I'm late to the party, sorry :drink:

I usually film subjects in deep water with little ambient light.
Those few times I filmed in shallow water I realized that shooting with the scene lit entirely by the lights is much, much easier. Especially if you have a pair of Keldan ;)

That said, reading your posts I think I'm the latest Jedi again: histograms, waveforms, zebra & co...

  • I had the histogram on the display for years only to find out that I never looked at it but it just annoyed me by taking up space on the screen: removed
  • Waveforms, where I can find them?  I've always been too poor to afford an external monitor and other gadgets...
  • Zebra is the only function I find really useful.

But the truth is, I've always relied on what I see on the camera monitor and I've never been wrong. Those who know me know that I am a long-time Panasonic user: GF1, GH2, GH3, GH4 and now GH5.I may be a simpleton but the clips always reflected what I saw on the display. I've burned the high lights sometimes but with the zebra, I'm fine. Sorry to admit I'm a WYSIWYG guy.
About ETTR for my empirical experience with Panasonic, I much prefer underexposed than overexposed clips. I've nev been able to fully recover an overexposed clip but maybe it's me again.

Just one question to @thani you wrote several times that you choose the widest aperture. Why? 

I shoot only in the Mediterranean sea and in a sunny day in 5/10 meters I have the exact opposite problem: @200 iso I have to close to F11/16 to expose correctly. I understand that you have murky water but you film in the tropics, don't you?

 

Have a good quarantine guys

 

I am on the same page for most the problem I have sometimes is that the LCD is unreliable as well.

Of all the tools discussed zebra is the one that appears more useful underwater but due to limitations of camera LCD it can only be used to avoid clipping. The tool that I like the most in general is false colour because I can clearly see how I am exposing my subject frankly I prefer my subject to be in focus than a little highlight in the corner that I can fix later

I have done my LUT for false color on the GH5 LCD and I can see that is working fine the only issue is swapping between the LUTs on the menu maybe I can find a shortcut key

I also wonder how I survived without an external monitor. I think a good monitor can really add value especially for macro but until now I have resisted the purchase due to the bulk and high costs

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11 hours ago, Davide DB said:

I'm late to the party, sorry :drink:

I usually film subjects in deep water with little ambient light.
Those few times I filmed in shallow water I realized that shooting with the scene lit entirely by the lights is much, much easier. Especially if you have a pair of Keldan ;)

That said, reading your posts I think I'm the latest Jedi again: histograms, waveforms, zebra & co...

  • I had the histogram on the display for years only to find out that I never looked at it but it just annoyed me by taking up space on the screen: removed
  • Waveforms, where I can find them?  I've always been too poor to afford an external monitor and other gadgets...
  • Zebra is the only function I find really useful.

But the truth is, I've always relied on what I see on the camera monitor and I've never been wrong. Those who know me know that I am a long-time Panasonic user: GF1, GH2, GH3, GH4 and now GH5.I may be a simpleton but the clips always reflected what I saw on the display. I've burned the high lights sometimes but with the zebra, I'm fine. Sorry to admit I'm a WYSIWYG guy.
About ETTR for my empirical experience with Panasonic, I much prefer underexposed than overexposed clips. I've nev been able to fully recover an overexposed clip but maybe it's me again.

Just one question to @thani you wrote several times that you choose the widest aperture. Why? 

I shoot only in the Mediterranean sea and in a sunny day in 5/10 meters I have the exact opposite problem: @200 iso I have to close to F11/16 to expose correctly. I understand that you have murky water but you film in the tropics, don't you?

 

Have a good quarantine guys

 

All the shooting I've done so far with GH5s is in ambient light with red filter at depth from 20-30 meters. I manually white balance on my gray gloves. Red filters make may lose  around 2 stops. That is why I use the widest aperture possible 2.8-4.0. In videos, too much sharpness is not usually a good thing. And as long as my subject is in focus, I am not worried about my images being a bit softer cause of the wide aperture. I am not sure, but I think a 2.8 on MFT is equivalent to 5.6 in FF. That is why we don’t get the same depth of field.

Definitely, shooting with artificial lights is the way to go for a better exposure. There are situations where lights are not going to help such as when there are many particles in the water, or wide angle shots where the lights cannot cover/reach (wrecks, school of fish, etc...).

When I expose with lights, I manually white balance without a red filter. And my workflow becomes very simple and efficient in Post. Now, because I am thinking about HDR, lights are a must have. That is another topic.

I usually use monitoring tools with a new setup/camera or when I dive new waters. Once I am used to shooting in a given environment, like you I rely on my screen to measure exposure. You can use the waveform on the GH5. It occupies a large part of the screen. I think it is good to assign it a shortcut so it can be turned on/off. I am happy with the DiveandSee monitor, It has good monitoring tools and a battery that will last for a full day of diving.  http://www.diveandsee.com/products/monitors-and-gopro/DNC-5A-underwater-full-HD-HDMI-SDI-Video-Monitor-Live-Video-Waveform-functions

I agree with Massimo that Zebras are useful to avoid clipping highlights.

 

 

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I think the fundamental issue of getting correct exposure with a camera while trusting an exposure meter is the same as it is on land.

The meter does averages and depending on the metering mode different averages of part of the frame. As such the meter has no idea what is subject and what not. This may be acceptable for landscape shots as long as there is something the meter can identify with middle grey, this may not always be the case underwater.

The exposure meter is the worst exposure tool, next is the histogram that will tell you  the average signal distribution the histogram is useful to see if you are clipping. Zebra are only useful for highlights as typically you don't have less than 0% zebra so they work under the assumption you don't crush the blacks

Ultimately the only tools that are context sensitive are false colour and waveforms. I find reading a waveform complex so my favourite tool is false colour. I have developed a LUT for the GH5 to have false colour in V-LOG on my screen. Otherwise there is no way to have false colour on my LCD

I would think an external monitor is the single most important tool to have correct exposure for video underwater and anything with at least false colour will do. If you can have false colour in camera even a dumb screen would help to see what you are doing

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On 5/4/2020 at 12:29 PM, Interceptor121 said:

I think the fundamental issue of getting correct exposure with a camera while trusting an exposure meter is the same as it is on land.

The meter does averages and depending on the metering mode different averages of part of the frame. As such the meter has no idea what is subject and what not. This may be acceptable for landscape shots as long as there is something the meter can identify with middle grey, this may not always be the case underwater.

The exposure meter is the worst exposure tool, next is the histogram that will tell you  the average signal distribution the histogram is useful to see if you are clipping. Zebra are only useful for highlights as typically you don't have less than 0% zebra so they work under the assumption you don't crush the blacks

Ultimately the only tools that are context sensitive are false colour and waveforms. I find reading a waveform complex so my favourite tool is false colour. I have developed a LUT for the GH5 to have false colour in V-LOG on my screen. Otherwise there is no way to have false colour on my LCD

I would think an external monitor is the single most important tool to have correct exposure for video underwater and anything with at least false colour will do. If you can have false colour in camera even a dumb screen would help to see what you are doing

I haven’t used false color before but it does make sense hence this tool can help you set exposure correctly for the main subject while managing the under/over exposed parts of the scene. @Interceptor121do you have the false color LUT always on your screen while recording? or do you expose using it and then disable the LUT?

Here is in-depth video by wolfcrow explaining the sweet spots for GH5 for vlog recording. He does rely on false color tool at 22:00 for measuring exposure. It is a long technical video at the beginning but it is worth watching, I think. 

 

 

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16 minutes ago, thani said:

I haven’t used false color before but it does make sense hence this tool can help you set exposure correctly for the main subject while managing the under/over exposed parts of the scene. @Interceptor121do you have the false color LUT always on your screen while recording? or do you expose using it and then disable the LUT?

Here is in-depth video by wolfcrow explaining the sweet spots for GH5 for vlog recording. He does rely on false color tool at 22:00 for measuring exposure. It is a long technical video at the beginning but it is worth watching, I think. 

 

 

False colour is based on standad rec709 IRE in V-LOG the IRE levels differ so you need your monitor to be able to understand how to interpret those. I do not know if the dive and see can do that but for sure you can apply a standard v709 LUT to the camera and then apply it to the HDMI output and then use the native functionality of your monitor

This is what I do on land and works wonders. I have also a LUT I have adjusted myself to give me false colour on the LCD that I would like to test when eventually I go diving again as currently I dont own an underwater monitor

Of course this is when you have a clear subject and you need to be able to have a skin tone or something you know is grey. Underwater skin tones are not that popular but you can use a grey card like the one you have in your xrite

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1 hour ago, Interceptor121 said:

False colour is based on standad rec709 IRE in V-LOG the IRE levels differ so you need your monitor to be able to understand how to interpret those. I do not know if the dive and see can do that but for sure you can apply a standard v709 LUT to the camera and then apply it to the HDMI output and then use the native functionality of your monitor

This is what I do on land and works wonders. I have also a LUT I have adjusted myself to give me false colour on the LCD that I would like to test when eventually I go diving again as currently I dont own an underwater monitor

Of course this is when you have a clear subject and you need to be able to have a skin tone or something you know is grey. Underwater skin tones are not that popular but you can use a grey card like the one you have in your xrite

@Interceptor121 I might have misread your earlier comment, are you enabling false color on your external monitor or on the GH5 screen itself?

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[mention=34353]Interceptor121[/mention] I might have misread your earlier comment, are you enabling false color on your external monitor or on the GH5 screen itself?

Both. If I have the monitor only on the external.
If I don’t on the LCD using a LUT


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