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Author Topic: Getting the _right_ exposure with a digital camera  (Read 3968 times)
boku
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« on: March 19, 2005, 06:28:45 AM »
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The premise of exposing to the right is based on shooting raw files. Simple cameras only shoot JPEG.

Shooting to the right implies Photoshop tonal mapping afterwards.
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Bob Kulon

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Bobtrips
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« Reply #1 on: March 20, 2005, 12:10:37 PM »
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With JPG, it's actually sometimes best to underexpose 1/3 stop in order to preserve more highlight detail.
Quite true!

I wish I could program my camera to bracket a couple of underexposed shots (say -1/3 and -2/3).  

I've never found the overexposed bracket useful.
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Bobtrips
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« Reply #2 on: March 20, 2005, 04:01:33 PM »
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Thanks, been there, do that.

I nitpicking.  I'd like the first shot to be '0'.  If the range in the image isn't too great I generally squeeze only the first.  Often I take two - '0' and '- 1/3'.

Setting the exposure value in the camera to -1/3 means taking all three to get 0.

(A minor complaint, given the current state of  the world.  ;o)

I suppose I'm looking forward to the time when we can USB our cameras to our computers and custom design functions.
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Bobtrips
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« Reply #3 on: March 20, 2005, 05:51:35 PM »
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Are you sure you can't take a single (or second) shot when in bracket mode?

I've use a few digitals and with all of them I've been able to release the shutter button after the first or second shot.  

(OK, sometimes I'm not quick enough and get more than I wanted.  But that's no disaster.  Half of my shots are "going to be discarded" brackets anyway.)
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61Dynamic
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« Reply #4 on: March 21, 2005, 09:59:28 AM »
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My 300D can do that too.
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Graham Welland
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« Reply #5 on: March 21, 2005, 01:02:29 PM »
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Avalon, I'm inclined to agree with you that we're not taking advantage of the potential automation functionality that a pro-DSLR could achieve. Being in the software industry myself I can also kind of understand their reluctance too - a small percentage of users would understand & use the feature and so why bother to change the way things are done. I'm sure there's also a trade off in terms of rom space for the code although if you're spending $4-8k on a camera I question if this should be an issue. I can almost visualize those product management meetings where advanced ideas are dismissed under the excuse that an experienced photographer can work it out themselves or bracket & photoshop etc.... (memories of the loss of Canon's DEP functionality & Olympus's multi-spot averaging come to mind)

It would only be a matter of programming to achieve the auto-bracket to auto-expose (AE/TV, even P), calculate optimum exposure to the right, and then maybe take a shadow optimized shot for later blending.

How about extending the automation to enable you to produce multiple views - blocked up shadows, blown highlights and 'optimal' exposure. Or maybe provide an interface so that you can shoot and select a region in the review image and auto-recalibrate the next shot to expose for this value, perhaps setting the desired brightness zone level for it? Maybe an exposure adjustment calculator? etc, etc.

Matrix metering and exposure to the right guestimation is ok but I, for one, still end up manually metering & calculating adjustments in my head to try and get the best exposure at capture time vs. Photoshop compensation/correction. Why not leverage the power of the camera to help out?
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Graham
avalon
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« Reply #6 on: March 19, 2005, 01:39:49 AM »
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In several essays/articles on Michael's web site, he's made mention of the "always expose to the right" philosophy, whereby you capture as much information as possible about the relative lighting conditions available when you take the photo.

However, the practice of doing this and doing this correctly is not quite as simple as is made out because of the "blown highlights" problem if you go too far right.  On top of this it also requires that all of your photos take a trip through photoshop or whatever to get adjusted to the correct numbers.

Considering both of these points, this led me to wonder if a better feature than the traditional +/-n AEB you get would be to have "current + what the camera thinks is best".  So 2 photos rather than 1 or 3 (AEB).  Why two?  Because the idea would be for the camera to look at the photo it has just taken, work out what the maximum speed/aperature it can use to generate the required "most information" photo and then take that.  Well, that's how a DSLR would need to work, a digicam could be expected to just have that setting and be a 1-click & done.

If such a feature were available, would people use it or is there too much risk in the camera adjusting things "wronly" for your chosen exposure to get the 2nd photo right?

There's also a risk that if there are some portions of the shot that are quite bright that it might underexpose too much (giving the inverse of the desired result.)

Or what if you could program the camera such that you could tell it what % of the histogram you wanted for each section?  i.e. be able to tell the camera how you want the histogram to look and let it work out how to take the photo to make that happen rather than take a photo, review, adjust, etc.

Granted the average John Doe on the street isn't likely to want something like this...but even if a simple camera took a photo to maximise information and then adjusted that for what would be the correct exposure, would this be better than what we see today?  Now that I ask that, how do I know that doesn't happen anyway?
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61Dynamic
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« Reply #7 on: March 20, 2005, 01:20:18 AM »
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ETR does not work for jpg shooting because as soon as the info clips in the camera-made jpg it's gone for good. RAW gives more latitude and is why ETR only works when shooting RAW.

With JPG, it's actually sometimes best to underexpose 1/3 stop in order to preserve more highlight detail.
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Digi-T
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« Reply #8 on: March 20, 2005, 03:01:17 PM »
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Quote
Quote
With JPG, it's actually sometimes best to underexpose 1/3 stop in order to preserve more highlight detail.
Quite true!

I wish I could program my camera to bracket a couple of underexposed shots (say -1/3 and -2/3).

I've never found the overexposed bracket useful.
You can and I sometimes do this. If, for example, you set your exposure baracketing to +/- 1/3 stop then just make your original exposure -1/3. Then you will end up with these three exposures: -2/3, -1/3 and 0. Remember the exposure bracketing is based on the original exposure that you set whether it is over or under exposed.

With the current dslr's and now many digicams you can see a histogram with your images so it already is pretty easy to take a single exposure and check to see if it has the kind of histogram that you are looking for.

T
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Digi-T
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« Reply #9 on: March 20, 2005, 04:38:14 PM »
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Bobtrips, I finally understand what you are saying and it is a good point. I'm still using a digicam for my digital work and whether it is in exposure compensation mode or burst mode it takes all three shots at once so I don't have a choice of only squeezing off a single shot when I want. What you are asking for seems like a valid feature and should be easy enough to implement. Just program the exposure compensation function to make the first shot the exposure that is closest to 0. But then I'm no programmer so what do I know?

T
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Digi-T
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« Reply #10 on: March 20, 2005, 11:25:50 PM »
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Yes I'm sure. My camera, the Sony F707, takes all three shots or none in bracketing or burst mode. Others may be different, especially current models, but I think it is mostly a feature specific to dslr's.

T
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Jonathan Wienke
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« Reply #11 on: March 21, 2005, 09:00:47 AM »
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The Canon 1-series DSLRs allow one shot in a bracket to be taken if desired; each shot requires a separate shutter press. You can choose between 0,+,- or -,0,+ shooting order, and also between 3, 5, 7, and 9-frame bracket sequences, with the interval between bracketed frames adjustable in 1/3 stop increments.
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avalon
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« Reply #12 on: March 21, 2005, 10:44:02 AM »
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Sigh, judging by the replies to my original post, I'm not sure if I made the original posting too dense (and hard to understand) or it just didn't interest people at all.  Or maybe people just create tangents and like discussing those instead :)

I'm really not interested in what you can do today, rather, the question I was trying to pose is, should we expect the camera to evolve to a point where it can take a better photo than simply trying to expose 50% grey correctly and if so, why can't this be an option instead (of AEB bracketing)?

Time for the digital equivalent that does it better - taking a raw photo as far to the right as possible, without blowing any highlights, automatically, ready for the best treatment in Photoshop or the camera's internal tonal curve fixing to generate that JPG file many desire.

Or is that too unattractive?  Is this something that, really, only the pro's who are going to spend time getting a photo right with photoshop would appreciate?
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Jonathan Wienke
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« Reply #13 on: March 21, 2005, 07:25:02 PM »
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Time for the digital equivalent that does it better - taking a raw photo as far to the right as possible, without blowing any highlights, automatically, ready for the best treatment in Photoshop or the camera's internal tonal curve fixing to generate that JPG file many desire.

Or is that too unattractive? Is this something that, really, only the pro's who are going to spend time getting a photo right with photoshop would appreciate?
Look here for info regarding how to do thisw with current cameras. What I'd personally like to see is a histogram based directly on the RAW data rather than on camera JPEG interpretations of the RAW. If you have a totally accurate histogram to work with, adjusting exposure and bracketing needs is easy.
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