GH2 Newbie Exposure Help Needed

[sigamy]

I've searched here and elsewhere, and I've been going through tips and tutorials on this but I can't seem to get anywhere.

I'm confused on how to get proper exposure when shooting video in 24p mode. I can never seem to get a bell curve histogram and if I do get something close, the histogram is always yellow (orange in the user manual).

But if I switch over to iA mode, I see a nice white bell curve. I pressed half on shutter and it seems that shutter speed was over 2000 or something.

My assumption is that I have to keep shutter speed at 50, in order to best match my 24 frames. So, I've been locking shutter at 50. That leaves me Aperture and ISO to play with. Is this correct?

Today is a nice bright sunny day. I was just outside trying to get shots with the Lumix 25mm f1.4. If I'm at anything below f4.0, I get a lot of clipping in the whites. If I go higher, my subject was too dark. I'd like to have shallow DOF as much as possible.

So, do I have to add an ND filter? What type of ND filter?

Is there any way to get the metadata from auto mode so that I can learn what it is doing and then apply that to Movie Mode?

I'm getting a bit frustrated that I can't seem to get solid exposure. Any help is appreciated.

 

[Bruce Foreman]

The histogram is NOT an exposure meter. It is merely a graphic display of the image tones in your scene/picture that shows the "distribution" of image tones.

There is no "right" or "wrong" histogram.

If your scene is composed mainly of darker image tones much of the histogram "spikes" will appear somewhat to the left of the graph, if the tones are very dark like deep woods in dense forest the spikes will literally crowd the left end. If it's something like a snow covered scene the spikes will crowd the right.

To properly use the histogram you must be able to "eyeball" the scene and have some idea of what the image tones will be like and what you are after. Couple that with the histogram display and it will help you understand what you are about to image. Proper exposure can be managed with the meter display at the bottom and by visual judgement of what you see on the LCD or in the viewfinder (assuming you have CONSTANT PREVUE set to "ON").

Outdoors you almost HAVE TO use ND filtration. You do want to keep your shutter speed down to 1/50th (PAL) or 1/60th (NTSC) to avoid "flickering" or "banding" if artificial lighting (especially flourescents) is either in the scene or lighting the scene. I keep Tiffen (brand recommended by Shane Hurlbut) ND filters in my kit, 2 stop reduction, 3 stops, and 4 stops (ND .06, ND .09, and ND 1.2) and I'll be ordering an ND 1.5 (5 stops) soon.

When you need ND you often need a lot of it.

Some are using variable ND filters but reports of image softening, internal reflections (variable NDs are 2 glass flats with 4 reflective surfaces), and unpredictable effects so I'm sticking with single strength filters for now.

Try this: in the Configuration menus set CONSTANT PREVUE to ON, EXPO.METER to ON. Set the mode dial on top to the Movie Camera icon, then in the menus find EXPOSURE MODE. You will have 4 choices, P A S or M; select M for manual exposure.

Then set the camera up on a tripod and either use the EVF or cover your head and camera with a black cloth (see the "making of Genesis" on vimeo to see how they used black cloth). This is so you can really "see" your image on/in the camera. Set shutter to 1/50th, ISO to 160 (assuming on GH2, on GH3 lowest will be 200) and start adjusting aperture until the meter on the bottom of the screen is close zero and the image looks like what you want.

The meter will tell you if exposure is "technically" correct, but if the image is not how YOU WANT that scene portrayed, adjust aperture (or add ND) until it is. Film short sequence to confirm.

Hope this helps.

 

[SuperSet]

Yes to everything Bruce said. You need an ND filter if you want to shoot at 1/50 shutter and low F stop outdoors. I use the Tiffen variable ND filters since it saves me time from using fixed ND filters.

 

[sigamy]

Thank you so much Bruce. Very interesting points on the histogram. The exposure meter is a piece I was missing. I will be shooting with an eye on it and the LCD going forward. I'm going to do plenty of tests before my shoot at end of the month.

 

[maranfilms]

The histogram is NOT an exposure meter.

Sure it is, if it's reading luminance, it tells you whats light, dark, and mid range. Thats the point of a histogram. It's based on 18% grey, It can tell easily tell you if your exposure is correct. I'm not sure why you say there's no right or wrong histogram, if exposure is correct, you should have no lines falling off either edge of the graph. If you spend some time with your camera, and learn to read your histogram based on your exposure from the image, the histogram is a very good tool for getting proper exposure. I couldn't live without it.

 

[Bruce Foreman]

Sure it is, if it's reading luminance, it tells you whats light, dark, and mid range. Thats the point of a histogram. It's based on 18% grey, It can tell easily tell you if your exposure is correct.

The histogram is a pixel map that shows the distribution of light tones, mid tones, and dark tones. While it can help you analyze whether exposure is correct that will really depend on the subject and how it looks in the image. You've learned to interpret it in terms of what you want in your exposure.

I'm not sure why you say there's no right or wrong histogram, if exposure is correct, you should have no lines falling off either edge of the graph.

Several tutorials on histograms state "histograms just are". Here is one:

http://www.luminous-landscape.com/tutorials/understanding-series/understanding-histograms.shtml

As far as having no lines falling off the edges, a histogram for an extremely high key subject may have a thin section of spike "crowding" the right hand edge and just about to fall off with no mid tones or dark tones displayed. The histogram for a performer illuminated only by a very narrow rim light (or accent light) with no fill or main light may show a thin array of spike crowding the leftmost edge with some even falling off.

Assuming those two examples were the desired result (and I had to produce some like that) the histograms described are "correct" for them.

If you spend some time with your camera, and learn to read your histogram based on your exposure from the image, the histogram is a very good tool for getting proper exposure. I couldn't live without it.

I've spent well over 40 years "with my camera" (33 years of that working professionally), I know a little bit about exposure, learned most of it long before digital and histograms came about. An exposure meter used to have a "match needle" or index reading that got one to an exposure that was mostly correct in most situations. We learned to "vary from" that mark based on film characteristics, development, and often personal judgement.

I used to do very little bracketing but we had no quick image review, no histogram, just the meter in the bag (later on some cameras started having built in "match needle" systems), and judgement. If shooting Kodachromes it was generally a week or two before we got the film back and came face to face with exposure and exposure judgements.

You don't need any education in interpreting histograms and you're obviously using them in a way that may be like using an exposure meter but with one authors "off the cuff" mention of the histogram being the 21st century light meter, most articles and tutorials do not define it as such. In one sense you are right, in that when one has learned to properly interpret the histogram in relation to the subject material and the image it can aid in exposure judgement.

But if a "proper" or "standard" histogram is sought to indicate proper exposure that may not work well at all.

I still advise the OP to set "CONSTANT PREVUE" to ON, his "EXPO.METER" to ON (GH2), and then in either Motion Picture (mode) on the top dial with "EXPOSURE MODE" set to "M", or in Manual mode for still photo, the LCD/viewfinder image will go lighter or darker for him to see with exposure changes. And like the crew on "Genesis" (and like photographers had to do with view cameras in another age) he should get under a black cloth so he can really see and interpret the image.

http://www.makeuseof.com/tag/read-cameras-histogram-perfectly-balanced-images/

 

[maranfilms]

While it can help you analyze whether exposure is correct that will really depend on the subject and how it looks in the image. You've learned to interpret it in terms of what you want in your exposure

This is correct, I agree.

I still advise the OP to set "CONSTANT PREVUE" to ON, his "EXPO.METER" to ON (GH2), and then in either Motion Picture (mode) on the top dial with "EXPOSURE MODE" set to "M", or in Manual mode for still photo, the LCD/viewfinder image will go lighter or darker for him to see with exposure changes. And like the crew on "Genesis" (and like photographers had to do with view cameras in another age) he should get under a black cloth so he can really see and interpret the image.

I agree with this also, although I find the flashing to be somewhat distracting.

But if a "proper" or "standard" histogram is sought to indicate proper exposure that may not work well at all.

It's not as accurate as a light meter, but for shooting digital video, I love it, but to each is their own

 

[GHKAM]

I have found when the histogram on the GH2 flashes white, this has proven to be the correct exposure when later viewing the footage (at least to my eye).

In the GH2 manual, when it gives examples of using the histogram one of the three examples states, "Properly Exposed". Perhaps this function on this particular GH2 camera, (not histograms in general), is designed to get the correct exposure?

I have also found that setting "REC HIGHLIGHT" is very helpful in showing the over-exposed/blown-out areas in the image.

 

[Bruce Foreman]

I have found when the histogram on the GH2 flashes white, this has proven to be the correct exposure when later viewing the footage (at least to my eye).

Funny thing, I never paid any attention to histogram color. I always just made a quick check to see the distribution on image tones and compare that with both the scene as "eyeballed" and as shown on the LCD/viewfinder, then applied "judgement".

So I just got out a GH2 and found that in automated modes the histogram was always white (because the auto exposure function was achieving somewhat "proper" exposure). But in Manual (stills) and full Manual Motion Picture the histogram did indeed turn white when the meter (at the bottom of the screen) indicated "+/-" (or zero). My guess: The turning white is likely generated by the metering circuits themselves indicating "proper" exposure. This could be a real convenience in that it negates having to look down at the EXPO.METER readout for the "zero" reading. However if the histogram is still yellow and you are trying to "tune" exposure the exposure scale tells you which way to go.

In the GH3 it seems to function the same.

In the GH2 manual, when it gives examples of using the histogram one of the three examples states, "Properly Exposed". Perhaps this function on this particular GH2 camera, (not histograms in general), is designed to get the correct exposure?

In one sense they are "oversimplifying". The scene used in the examples is an "average" scene with an average tonal range and average distribution of tones. The "bell curve" shown in the "correct exposure" is correct for that typical type of scene and probably represents the majority of pictures taken outdoors. But that concept begins to fall apart when the scene is predominantly dark or predominantly bright but still contains a specific tonal value that must be rendered correctly, such as skin tones.

That section of the manual seems to confirm that my guess on histogram color being tied to the exposure meter reading may be correct.

I have also found that setting "REC HIGHLIGHT" is very helpful in showing the over-exposed/blown-out areas in the image.

That's what that's meant for and for a lot of folks it can be very helpful. But for myself I keep it turned off, experience gained from decades of shooting Kodachrome and Ektachrome slides has taught me how to "eyeball" a scene and have a good idea what part of it may not be accommodated by the dynamic range available to the media being used.