GH2 Dynamic Range?

VidE,

You may not have any more rehearsals to test the settings, but if the dresses are still blowing out even with all the Auto settings on the GH2 I've suggested (and that you've already tried), you can also try (in addition to my suggested settings) to adjust the exposure using the +/- settings until the dresses no longer overexpose. I don't have the camera near me to know what the name of the +/- exposure adjustment is called. But I believe it's in the Quick Menu if you're in Auto. No ISO limit in Movie Mode is a bummer. Unfortunately, Full Auto is no subtitute for a human being behind the camera who knows what the scene is supposed to look like. :-)
skulpt is right, maybe using lenses with lower contrast will help. Are you using the kit lens? Lumix lenses are very contrasty compared to my old Nikons and Canon FD lenses.
 
Yeah, I'm interested in the contrast filter also. The compression in the video example a couple of posts back has terrible compression, so it's pretty hard to tell what is going on there in terms of noise. I would have thought that a low contrast filter would give you a lot more noise in the blacks. If they were that good, surely everyone would be shooting with them.
 
Soldier said:
Yeah, I'm interested in the contrast filter also. The compression in the video example a couple of posts back has terrible compression, so it's pretty hard to tell what is going on there in terms of noise. I would have thought that a low contrast filter would give you a lot more noise in the blacks. If they were that good, surely everyone would be shooting with them.
Click to expand...

Old school cinematographers would regularly utilize contrast lowering techniques (i.e., filmstock flashing, silks, fog machines, high-key lighting, beige-toned clothing) in order to tame the contrasty filmstocks prevalent back in the day. One reason why not everyone uses a LC filter is because it takes more effort to use one in that CC is almost required to get the best results. But if it's something the old pros would do, then maybe it's a good idea to try it out for ourselves.
 
Here is what I would do.

Not saying you should do it, just what I would do.

If the GH-2 is being used for lockoffs then:

Turn all auto settings OFF
Turn the mode dial to Movie Camera M
if you are shooting 60i turn your mode to movie multi
select 60 i
set your shutter at 1/125th
turn the Record Highlights alert on
turn highlight alerts on
Set your ISO to either 800 or 1600 depending on what is acceptable to your eye in the "dark" part of the screen
find the T-Stop where anything that is "blowing out" to your eye sets off highlight alert.
this should help you find your "happy medium"

Auto adjustment will never get it right.
If you are still seeing too contrasty of an image when you get to the edit bay then you should maybe put an 1/8 ultracon, or 1/8 White Pro mist

If it is still too contrasty for you then I'd recommend a different camera for your lockoff shots and maybe use the GH-2 for closeups where you can ride your own iris?
 
dvBrother or anyone else out there-what does that +- exposure compensation thingy actually alter? (Aside from the exposure...duh) How does it change the exposure?

The idea of underexposing with maybe a low-con or white net has appeal but may nt be able to procure and test one before the the next shoot. As to the lighting for this production, trust me when I say theatrical lighting designers think sooooo differently than DP/Gaffers. As an example, the key/fill of film video is replaced by 2 bank of leikos, one angled towards stage left, the other stage right using different colors instead of different luminance levels. Pretty much all light is from leikos(ellipsoidals) and fresnels, ie.e very hard light instruments. No soft/diffuse fill anywhere. I think it's time to check out what Rob Marshall's DP(s) have to say for "Chicago" and "Nine" :-) edit: Dion Beebe, definately one of my favorites.

Dan, having 2 more performances to shoot, at least one is going to be manual and after a brief 'live' test, the bright bits stopped overexposing at f5, the rest of the frame looked better at f3.5. This was at a shutter of 60. I could leave the fstop at (roughly) f3.5 and crank the shutter up to 125, but again, what benefit does the higher shutter speed give?
 
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VidE,

The =/- is a compensation factor for the Auto function. So, if normal Full Auto tries to make everything average out to middle grey, setting the =/- toward minus is going to make the image darker. The more minus you set it, the darker the image. It goes in increments of 1/3 stop. So if you find your white dresses are still blowing out when full auto is engaged, you can adjust the =/- down a notch or two until the bright whites no longer blow out. My guess is that this will work out just fine. Here's why: Those theatrical fresnels and Leikos are putting out quite a bit of light on that stage, so your Auto ISO will be low and noise free. If setting the =/- down 2 notches (2/3 stop) will prevent blowouts, it may cause some scenes to be a little underexposed. BUT...in post you can brighten those back up and it should be fairly noise free because the camera is shooting at such a low ISO because of the bright stage lights.
I would not set my ISO to 800 or 1600 as Dan said. That's too high for bright stage lighting. Also, setting your shutter to 125th doesn't have any advantage. In fact, it will make the image look too strobey and "Saving Private Ryan"-ish with the lack of natural motion blur.

I concur that Dion Beebe is a great DP. Not a huge Rob Marshall fan, though.

A low con filter might help you if you can get it. I wouldn't recommend a white net as that will make your highlights bloom, which could make your problem worse. A black net, on the other hand, works like a low con filter. Black panty hose or, better yet, Nude panty hose stretched really tight behind the lens creates a low con effect, but it also creates that soft dream sequence look which I don't think you want. from what I've read, the Ultra Cons seem like the best solution. At the very least, "Smooth" or "Nostalgia" film mode with the contrast dialed down to minus 2 will be your best bet in this situation.
 
If your frame rate is 60 interlaced frames per second 1/125 will give you a 180 degree shutter.
Shutter at 60 is the "open shutter" look as used by Michael Mann in Collateral for instance.

1/120 would be a perfect 180 degree shutter, with 60 being a perfect 360 degree shutter. You won't have a "saving private ryan" look until a 1/250 to 1/500 shutter when shooting 60i. People seem to forget about the correlation between shutter angle and shutter speed sometimes.


Setting your ISO any Lower than 400 would actually be a major disadvantage. This might seem counterintuitive. Iso is not gain. Iso has to do with where the center of your exposure is placed. If you place the center of your exposure too low you will clip your highlights sooner.

You are free to disagree - I've spent a LONG time working with digital cinematography cameras.

What was your iso set at with the highlights clipping below a T5?

This will help me help you determine what to do next.

based on what you are telling me - I'd rate it at 800, and shoot the whole thing at a 3.5 or 4 with a 1/125 shutter. Again - just MY opinion.

When YOU are the person in control of lighting, then I'd recommend rating the cam at 320 or 400 and lighting to achieve your desired stop ;)

Oh - yeah - I'd also use your focus magnification to ~very~ carefully set your focus to a nice stage centered point before rolling at the beginning of the show.
 
Dan,

I guess if you are shooting 60fps then you would want your shutter to be 1/125th to approximate a 180 degree shutter.

I missed that part, since I'm so used to shooting 24fps.

However, since 60i is actually 29.97 fps, then 1/60th is the appropriate shutter speed. 1/60th is the default shutter speed for video cameras. The Michael Mann open shutter would be 1/30th in 60i. Open shutter is 1/24th in 24p.

You are correct that setting the ISO below 400 can be a disadvantage as you lose dynamic range. But if the native IS0 of the GH2 is 400, then setting it to 800 or 1600 is also detrimental to the dynamic range, just in the other direction.

All I know is that, when I shoot plays, I have to ride the iris. There's no way a fixed setting will handle the range of light values from cue to cue. That's why I suggested Auto Everything, as much as that suggestion normally makes me cringe.
 
VidE,

BTW, I've only had the GH2 for a few days (I'm a GH1 owner also), but I've noticed the "Cinema" mode is contrastier than "Smooth" and also has harsher clipping of highlights. I seriously think using "Smooth" will help your image. It will bring detail in the shadows and midtones that aren't present in the "Cinema" setting.
 
I dont have the GH2 with that 14-42 lens but I checked it out a couple of times at my local yokel and the lens feels REALLY cheap. So cheap that I would never buy it or use it ( the lens). I would try other glass. Since I also tried mixing GH1 footage with HVX and have problems matching them in post, ( I am no expert) maybe this problem can be dealt with in post by somebody who knows what he is doing?
 
dvBrother & Dan, you are really helping me understand this kind of camera better. Thanks so much for your continued interest. It sounds as though the +/- compensation uses the iris only to make its adjustments.
I engineer video in multi-cam systems for big convention shows and yes, shutters are (almost) always set at 60. But until recently those cameras were also shot at 60i. The shutter would be at 360 per field. I'm not sure a degree count is relevant though. For film, at a fixed rate of 24 fps, the 1/48 - 180 degree shutter is used to control how much time/motion is exposed per frame, a quicker motion may blur if the length in time of exposure was slower than 1/48th a second, say at 1/24th of a second. Faster than 1/48th and the frame may have crisper images but that would probably be it, because in the end run, the viewing of the final video/film will be determined by the display medium. I think. I'll have to check out "Collateral", but as to the stutter in Private Ryan, I think that involves not only fast shuter but overcranking during production.

Dan, it's true I think of iso as gain, which even in video does involve the native sensitivity of the imager. I like your explanation about where the center of exposure is placed. For this show I was setting it at 800. And dv, I have been shooting at smooth. Part of the problem is that theatrical lights are so much brighter until they falloff at the sides, then they really fall off.

timbook2- if I had more money, yeah, I could be exploring lenses. And while I agree that the kit lenses are built from lighter composites, I don't know that this reflects poor build quality. By the time time I can afford another lens, I'm hoping that Panasonic will be out with the faster, wider zoom lens that has been rumored about.

In the end, I'm hoping to bag a Scarlet fixed, but that may be quite awhile...
 
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