Exposing for the RAW format

[Dominic Cochran]

Threads about this subject are pretty scattered on this forum and on the web in general. Lets attempt to start a comprehensive discussion on this new sub-forum. Links to good articles, etc. would be helpful for all I'm sure.

My background is 15 years in 35/16mm film although we currently own a Sony F350 XDCam (which we've been very happy with so far btw). From what I've read my experience in film will be helpful in thinking about exposure with the Red and RAW, especially as compared to a 3 chip video system.

Looking forward to using my lightmeter again for more than measuring contrast ratios!

 

[Dominic Cochran]

Decent start I suppose:

http://en.wikipedia.org/wiki/Raw_image_format

 

[Rudi Herbert]

Dominic,

To simplify things, which is not as bad as would appear , here's a bit of my thinking when it comes to RAW, which I've been shooting now for about 6 years with DSLR.
- It is better to slightly under expose than over expose with it. Recovering highlights from a seemingly "dark" image is far better than dealing with blown whites.
- If you'll under expose, then it is paramount to use some fill light on the areas that will inevitable go dark. Then again, using bounce cards and boards is far easier, cheaper and more controllable than dealing with high intensity HMI's...
- To emphasise the above point, a little fill light goes a LONG wait in achieving a balanced, acceptable look when dealing with slightly under exposed RAW images.
- RAW allows you to manipulate the looks ad nauseum in post, however, there is no substitute for certain feels and moods. If you want the warm, magical glow of magic hour, then shoot at that time and you'll end up with an image that's already half way there. You can only accomplish so much in post, don't forget that.
- RAW images are, by default, low contrast and low saturation, and that's good. Now, the less you have to push them the better they'll hold up. So, if you dress your actors in bright clothes, choose saturated props, overdo the make up a bit, and in general have a richer than usual color palette before the camera, the less you'll have to degrade the image afterwards trying to achieve the same.
- Try and achieve "dimensionality" or depth separation in your images. In other words, RAW images look a LOT more filmic when the actual physical separation between the spatial layers in the frame is more pronounced. Meaning, put more distance between foreground and background, and everything in between, and you'll end up with far more clear edges that will require less sharpening in post.

and there's plenty more of course, just to get the ball bouncing

 

[number6]

- RAW images are, by default, low contrast and low saturation, and that's good. Now, the less you have to push them the better they'll hold up. So, if you dress your actors in bright clothes, choose saturated props, overdo the make up a bit, and in general have a richer than usual color palette before the camera, the less you'll have to degrade the image afterwards trying to achieve the same.
- Try and achieve "dimensionality" or depth separation in your images. In other words, RAW images look a LOT more filmic when the actual physical separation between the spatial layers in the frame is more pronounced. Meaning, put more distance between foreground and background, and everything in between, and you'll end up with far more clear edges that will require less sharpening in post.

and there's plenty more of course, just to get the ball bouncing

Interesting idea, shooting high saturation reality. I'm curious how this would work in a broun grass location and with actors wearing clothing whose color was highly saturated? Does the color contrast look phony?

 

[Dominic Cochran]

- It is better to slightly under expose than over expose with it. Recovering highlights from a seemingly "dark" image is far better than dealing with blown whites.

This makes sense considering my limited stills experience with DSLRs as well as the thread that mentions that the Dynamic Range of the Red is skewed more toward the shadows than say a 200T film stock.

- RAW images are, by default, low contrast and low saturation, and that's good. Now, the less you have to push them the better they'll hold up. So, if you dress your actors in bright clothes, choose saturated props, overdo the make up a bit, and in general have a richer than usual color palette before the camera, the less you'll have to degrade the image afterwards trying to achieve the same.

Good point, and something I've always tried to achieve In-Camera when shooting film, especially in a commercial workflow with a fast turn-around. I'm glad that we'll be able to push things a little more on set without having to worry about the latitude of our 3 chip camera so much.

- Try and achieve "dimensionality" or depth separation in your images. In other words, RAW images look a LOT more filmic when the actual physical separation between the spatial layers in the frame is more pronounced. Meaning, put more distance between foreground and background, and everything in between, and you'll end up with far more clear edges that will require less sharpening in post.

Good advice for all, film OR video! When space on set allows of course...

Nice post Rudi

 

[Dominic Cochran]

Interesting idea, shooting high saturation reality. I'm curious how this would work in a broun grass location and with actors wearing clothing whose color was highly saturated? Does the color contrast look phony?

It will be good to hear from someone with specific RAW format experience regarding this; but I've always tried to work with the wardrobe and makeup departments to achieve as much of this look as possible in camera. I assume that this will be the best approach whether shooting Film OR Raw.

As far as looking phony, I haven't had that problem with film (occasionally with 3 chip video though), unless we're going for a hyperreal look where we might embrace it of course. It will be interesting to see more tests from people shoting Red in these high contrast situations.

 

[Jeremy Hughes]

I thought you adjusted gain in RedCine... Are you talking about shooting at a target ISO then exposing through appeture and ND filters correctly?

 

[Dominic Cochran]

Yes, we're discusssing proper in camera exposure, and how to get there.

And yes, you can adjust gain, curves, and saturation levels etc. in RedCine, but setting the right stop is crucial.

 

[Mark Crabtree]

Exposing for RAW

Exposing for RAW

Yes, of course, nobody wants blown highlights. Under exposing, or exposing to the left, however, does generate noise and who wants more noise than is absolutely necessary? Many photogs use a technique called exposing to the right, over exposing according to the display yet still guarding against blown highlights. The reason you can over expose, according to the monitor, and still not blow out the highlights, is that the monitoring system is based not on the RAW file but on a converted encoded file which does not have the dynamic range of RAW. So, in other words, the monitor clips before the sensor does and the only way to really know where that clip point is is to shoot tests at increasing exposures or ISOs. The results can only be viewed in RED Cine or RED Alert. Exposing to the right is, yes, dangerous because you are shooting on the edge of clipping the highlights, however, you acheive a picture with lower noise. Playing it safe and using ISO 320 will probably keep you out of trouble regarding clipping but you will not get the best from the digital sensor. Sometimes exposing to the left means shooting a scene at more than a full stop under exposed. If you increase the fill to compensate for things going dark, you can end up with a flat noisey image. The goal for us shooting with the Red camera is the same goal as for the photogs who shoot with DSLRs, to make great low noise images. And to do that we must test and know the limits of the camera so we can exploit them.

 

[Hans von Sonntag]

Hi,

IMHO I never found digital pictures phoney. Some how different to film for sure, but not phoney. They might look phoney before grading due to the flat gamma. But graded properly skin tone and such come out nicely. When shooting digital I never use extra colourful make up or costumes. I even do not change lighting that much. I do care about higlights as I do care about shadows when shooting negative. BTW flat telecined negative does look "phoney" as well.

My two cents,

Hans

 

[number6]

Hi,

IMHO I never found digital pictures phoney. Some how different to film for sure, but not phoney. They might look phoney before grading due to the flat gamma. But graded properly skin tone and such come out nicely. When shooting digital I never use extra colourful make up or costumes. I even do not change lighting that much. I do care about higlights as I do care about shadows when shooting negative. BTW flat telecined negative does look "phoney" as well.

My two cents,

Hans

Hans, substitute "contrived" in place of phoney in my post.

Hope that makes it more palatable.:whistling:

 

[Hans von Sonntag]

Hans, substitute "contrived" in place of phoney in my post.

Hope that makes it more palatable.:whistling:

Hi

Indeed, it does.

Hans

 

[Hans von Sonntag]

Just to put some thoughts on this:

1. Protecting highlights in a sequence can be impossible. Just imagine a pan from shadow to a backlit sunny area. Highlights will burn out. With negative you have a smooth, pleasing transition from light grey to pure, overexposed white whereas with digital a more harsh, edgy, sometimes over saturated, less pleasing transition will occur. With the latest Sony F900R / F23 they manage this quite well with build in circuits that emulate a negative/film like shoulder. Not really there, but a big improvement though.

2. Shooting RAW with RED just means shooting digital with a high range (11 Stops/66db) barely processed with a third of data required compared to YUV/RGB. Hence you can store picture data with a high fidelity on a comparable small device. This is pretty clever. Downside: you cannot use the data instantly - bad for the ENG folks.

3. REDCIDE does what a traditional video camera is doing inside its body with a lot of circuits. The downside of this conventional workflow: Treating every shot individually is is hardly to achieve, ending up shooting as flat as possible (gamma wise, not lighting wise). Positive for a lot of folks: YSWYG, instant access to the footage , etc...

4. It will be interesting to see how REDCINE can manipulate blown out highlights and make them looking pleasing.

Shooting RAW seems to me nothing special in terms of costumes, make up, etc. I find it cumbersomely to fight possible artificiality with contrived costumes, make up etc. IMHO not the way to make a picture looking less contrived.

Slightly underexposing seems the way to go but this is common sense with any other high end digital camera. Like telecine in film REDCINE or any other CC tool that can read RAW is the bottleneck where all has to go through: To the better or the worse.

Hans

 

[Dominic Cochran]

Shooting RAW seems to me nothing special in terms of costumes, make up, etc. I find it cumbersomely to fight possible artificiality with contrived costumes, make up etc. IMHO not the way to make a picture looking less contrived.



Hans

Depends on what you mean by nothing special. I think it's pretty crucial to get much of the look on set in terms of production design, makeup, wardrobe, (and obviously lighting). Most professionals will agree. You really can't underestimate the importance of these departments.

 

[Hans von Sonntag]

Depends on what you mean by nothing special. I think it's pretty crucial to get much of the look on set in terms of production design, makeup, wardrobe, (and obviously lighting). Most professionals will agree. You really can't underestimate the importance of these departments.

Hi Dominic,

no, I am not underestimating any art department. Crucial for story, style, etc. All I am saying is that shooting RAW does not mean that the work of these departments has to be modified in some way just because one shoots RAW.

Regards,

Hans

 

[Billy Summers]

Lighting and Exposure are pretty IMPORTANT...

 

[Emmanuel Cambier]

Just to put some thoughts on this:


4. It will be interesting to see how REDCINE can manipulate blown out highlights and make them looking pleasing.

Excuse me Hans, but I Wouldn't expect RedCine to perform miracles in this domain.
Blown Highlights in digital are just that… blown highlights.

The only miracle here is how low noise the camera is, and that it records Raw.
From there you can underexose to protect highlights and then raise your levels until noise creeps in.

Emmanuel

 

[Floris Liesker]

Excuse me Hans, but I Wouldn't expect RedCine to perform miracles in this domain.
Blown Highlights in digital are just that… blown highlights.

The only miracle here is how low noise the camera is, and that it records Raw.
From there you can underexose to protect highlights and then raise your levels until noise creeps in.

Emmanuel

Yes indeed, it's far better to avoid blown out highlights than to try and fix them in post. Redcine does have a slider for that called 'highlight' which does what the DRX did in Red Alert; it will look at non-clipped channels and compose some info out of that. I find it hard to get it really good but it's something.

I am working on a noise reduction workspace within Combustion to be able to use more of the low end of the sensor without seeing too much noise. It works in the same manner as noise reduction in telecine does, making noise lower and slower-moving without affecting resolution. Maybe there's already a plug in that does exactly that but I dont know it.
I try to make it work in FCP2 too but I'm not very familiar with those yet.
Maybe Graeme already developed such a plug-in?

 

[Steve Sanacore]

Just to put some thoughts on this:

Slightly underexposing seems the way to go but this is common sense with any other high end digital camera. Like telecine in film REDCINE or any other CC tool that can read RAW is the bottleneck where all has to go through: To the better or the worse.

Hans

Underexposing is the most common mistake digital photographers seem to make when starting out. There are a few great books out there on shooting raw and processing the files for DSLRs. There is very specific information on the raw image data and for best dynamic range and color you must expose to the right without over exposing. If you play it safe by underexposing you will give up a lot of color, dynamic range and have more noise in all the shadows when you try and recover shadow detail. According to the experts who write the software that converts raw files in Photoshop, "50% of the image data lies in the brightest F stop captured" (hope I my memory serves me right). So by underexposing only 1 stop - you may give up half of your potential image data, dynamic range and colors.

An accurate histogram is the best way to judge exposure. It is the only way to see exactly where the highlights and shadows will clip. On most DSLR's we can view this in Luminance and for each RGB color. Highlights can usually be recovered even if only one color channel has detail. I just hope that RED's raw converter is on par with what Adobe offers for most pro DSLR's - it is amazing what we do can with raw files. Once you learn how to process them, you will be astounded by the results.

http://www.luminous-landscape.com/tutorials/expose-right.shtml

Here is a link to one of my favorite web sites on the subject of shooting RAW.

I am curious as to how Redcine will work. Can we optimize the raw processing when we make our QT files for editing? And does it retain that information in a sidecar file for each clip when we return to the raw files to output a high res version for the colorist to finish?

 

[Rob Lohman]

An accurate histogram is the best way to judge exposure. It is the only way to see exactly where the highlights and shadows will clip

Make sure you have RGB histograms (so you can see individual channel clipping). This is definitely not the only way and it can't always show you where the clipping is happening exactly. Our camera also comes with a false color exposure meter which can tell you where exactly something is clipping.

I am curious as to how Redcine will work. Can we optimize the raw processing when we make our QT files for editing? And does it retain that information in a sidecar file for each clip when we return to the raw files to output a high res version for the colorist to finish?

I'm not sure I'm following 100%. REDCINE (as does RED ALERT & QT codec) work directly with the RAW data. Changes parameters will work directly on this data, not on a smaller range (through the QT codec this is only possible at the moment by changing settings in RED ALERT and then re-generating the QuickTime files).

REDCINE can save / load sessions that will retain whatever parameters you set for the clips in that session.