Is auto exposure bracketing necessary with RAW ?

[myworkshop]

I just learned how to blend 2 images together in Photoshop in order to

increase the dynamic range beyond what my 5D can capture in one shot. My

question is do I need to use auto exposure bracketing to get the 2 images or

can I just take one RAW image and adjust the exposure down for the first and

up for the second? Also, do all the Canon DSLR's have the same possible

dynamic range?

[mendel_leisk]

If you output 2 images from a single RAW, with exposure adjusted, Photoshop's HDR function will refuse to work with them. Not sure how sensible that is, but apparently there's no advantage to HDR in this case.

 

I used to do just what you're proposing: blended exposure from 2 outputs from a single raw. However:

 

If you are using Photoshop CS3, it's version of Adobe Camera Raw has a slider that allows you to recover shadow detail. I forget the exact name, but it's on the main adjustment tab, with exposure, brightness, etcetera. If you first allow ACR's auto exposure to recover as much highlight detail as it can, and use the shadow recovery slider, and then set contrast roughly equal to the value in the shadow recovery slider, the results are at least as good as blended exposure, and with none of odd brightenings at tone transitions.

[zackojones]

I think you will get better HDR results with images exposed using AEB than you would tweaking the same image multiple times and then merging it.

[JohnMWright]

You don't even need to use AEB, just use manual mode or control dial in auto mode if you choose to use multiple exposures. Unless you want to use AEB for every series of shots, it will take more time to turn on AEB, use it, then turn it off again.

 

Since Canon changes/upgrades the sensors over time, I'm sure the dynamic range varies some, even if it isn't much. I've seen measurements of the various ranges for sensors but I don't remember where, search and you'll find that information.

[johnson_d.]

The point is to capture a scene with greater dynamic range than can be captured with a single exposure. In other words, by definition, multiple exposures are required. If that's not what you are trying to do then HDR really isn't the right tool as Mendel mentioned.

[myworkshop]

I currently only have CS2 and am using layer masks to create the blend. http://www.luminous-landscape.com/tutorials/digital-blending.shtml I got the technique from Luminous Landscape in the above link. I don't know what the HDR function is in Photoshop.

[peter_rowe]

Photoshop HDR functions refuses to work on two images from a single RAW because the EXIF is the same. If you save the two image without EXIF and then use these in Photoshop it will work.

 

As mentioned however it makes no sense to do this - you're RAW reader should be able to do the same thing recovering highlights and shadows. If you instead bracket the shots, say -2, 0, and +2 you have effectively added 4 stops to your dynamic range. If you use just one shot then you have added nothing.

[jason_hall4]

Pete, HDR is where Photoshop(or other software) takes images of different exposure and combines the data for each pixel to creat an image that is well beyond the ability of the camera to capture. YOu need at least two images, however you can use many more(not sure of the max). The result can be so surreal it looks illistrated or it can be toned down to just be in the realm of believable. It is up to you and the number of exposures you have. A tripod is a must and each image must have exact framing(some software will self aline).

 

Imagine an image shooting directly into the sun and still equal detail in the sky and the foreground.

 

Jason

[jason_hall4]

BTW, CS2 will do HDR.

[ronald_moravec1]

Set the camera to auto bracket so nothing moves between shots. Then a tripod so the camera does not.

 

Bracket with shutter, not aperture.

[g dan mitchell]

I'd generally do two separate exposures.

 

On some occasions I've been able to optimize the RAW conversion of a single image - once for

highlights and once for shadows - and then combine the results using layers in PS.

 

But capturing two separate optimized exposures in the camera will give better results. And, yes, there

definitely are circumstances in which the 5D's dynamic range is not enough. I use a tripod and take the

second exposure at the same aperture but different shutter speed.

[znabal]

There are 3 distinct techniques under discussion here, Each has its uses, advantages etc.

 

1. Multiple exposures, or bracketing, with the resulting shots put on layers and masked according to what you want from each shot....basically, "I'll take this part of the frame from exposure #1 and that part from exposure #2" etc

 

2. Multiple exposures combined using HDR...CS2 combines these 16 bit exposures into a 32 bit result. Then using tone mapping, curve adjustments etc to get an image that can be displayed or printed. This technique is used either to a) expand the dynamic range i.e. cases in which any single exposure setting results in either clipped highlights, blocked shadows or both. or b) as a simple way to access tone mapping and strange curve capabilities for weird effects. Most "HDR" stuff you see that is instantly recognizable as HDR...what you are really recognizing is the tone mapping/curve adjustments.

 

3. One RAW file "developed" multiple ways and then again layered and masked according to what you want from each ....again basically, "I'll take this part of the frame from develop v1and that part from v2 etc. This technique is useful for instance in making local color temp. adjustments and corrections for a photo taken in mixed lighting.

 

I'm not proud...I've used (and use) each at one time or another and have even used them in combination....I've even done two different versions of HDR merge, then taken the results and layered/masked those together. Feel free to go to the "personal web page" (my blog) listed on my Photo Net User Page and click on the "photoshop" label. -have fun jeffl

[peterlyons]

Pete, IMO, layer masks are a fine way to do this, and yes, you can do it all from one RAW

exposure. But if you're shooting from a tripod, go ahead and bracket. It's the better way.

That said, I shoot mostly action myself, and will sometimes make two developments from the

same RAW, and then combine them in Photoshop using masking.

[mendel_leisk]

Here's an example of what you can do with Photoshop CS3's version of Adobe Camera Raw. I this case the Fill Light slider was raised to 70, and Contrast slider to 40. Before:<div></div>

[mendel_leisk]

After<div></div>

[mendel_leisk]

With a little more adjustment: exposure bump by +.85 and raising contrast to 60.

 

What I'm finding is CS3's ACR negates the need for blended exposure tactics, for the most part. It's not true multiple exposure HDR, but is convenient and fairly effective.<div></div>

[myworkshop]

Thanks for the photos! I have ordered an upgrade copy of CS3. I take a lot of indoor photos and that top photo is the kind of thing I was blending layers to correct. I can't wait to be able to take care of it in camera raw.