Spot Metering?

tdodd said:
Were you spot metering from the brightest part of the clouds, or something else? It may well be that Nikon's metering is set up a little different to Canon, or maybe that your software is not so good at dealing with highlight clipping, or maybe that you are merely metering off the clouds in general and not spot metering off the brightest part of the clouds. If you looked at my album of exposures of the white shirt....

http://picasaweb.google.com/EezyTiger/Exposure?authkey=Gv1sRgCOui54easIX-LQ#

you would note that Lightroom did a great job of recovering blown highlights, even from an exposure at +4, with no real ill-effects. Of course, I wouldn't recommend pushing things that far on purpose. It won't work every time, and I consider it my buffer zone for little surprises, not something to be used on purpose. Metering highlights at up to +3, when shooting raw, is absolutely fine with any of my bodies.

In fact, the review by DPReview of the D3 suggests that it is more than capable of holding details beyond +3 and there is bags of room for highlight recovery. Take a look at this page and especially scroll down the page to the section on raw headroom....

http://www.dpreview.com/reviews/NikonD3/page20.asp

The highlight recovery on that blown out hair is remarkable.
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I was shooting at the brightest part of the clouds (waggled the focus point about the cloud until I could not get a lower reading). Then took took shots at 9fps from +1EV in 1/3rd EV increments for 9 frames. Imported into camera raw, then adjusted each frame so that they would reach 1EV. Histograms were virtually identical as you would expect, as were the pictures, until you hit +2 2/3EV where the smallest brightest patches of clouds 'stuck' at pure white, then at +3 bigger patches remained white. They weren't noticable if you weren't pixel peeping, BUT after +3EV then the blues in the sky started turning green (the blue channel was absolutely maxed and the others started to hit the limit too).

Not tried light room myself, perhaps it might fare better as a raw convertor?
 
Also I must add that at +3 the images were 99% usable, but the tones were definitely slightly off. The histogram could definitely be pulled down and the histogram was not 'stuck', but I could tell that the tones adjusted in RAW by -1EV were not identical to say an image shot at +2EV. Even at 3 1/3rd and higher the histogram could be pulled down without sticking, but the tones definitely changed.
 
Cheng said:
I was shooting at the brightest part of the clouds (waggled the focus point about the cloud until I could not get a lower reading). Then took took shots at 9fps from +1EV in 1/3rd EV increments for 9 frames. Imported into camera raw, then adjusted each frame so that they would reach 1EV. Histograms were virtually identical as you would expect, as were the pictures, until you hit +2 2/3EV where the smallest brightest patches of clouds 'stuck' at pure white, then at +3 bigger patches remained white. They weren't noticable if you weren't pixel peeping, BUT after +3EV then the blues in the sky started turning green (the blue channel was absolutely maxed and the others started to hit the limit too).

Not tried light room myself, perhaps it might fare better as a raw convertor?
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Cheng said:
Also I must add that at +3 the images were 99% usable, but the tones were definitely slightly off. The histogram could definitely be pulled down and the histogram was not 'stuck', but I could tell that the tones adjusted in RAW by -1EV were not identical to say an image shot at +2EV. Even at 3 1/3rd and higher the histogram could be pulled down without sticking, but the tones definitely changed.
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Just how hard can you make getting a decent exposure with digital? :eek: :thinking:
 
Cheng said:
I was shooting at the brightest part of the clouds (waggled the focus point about the cloud until I could not get a lower reading).?
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OK, but were you SPOT metering off the brightest parts of the clouds? If not then your exposure would have been thrown off by the dimmer parts.
Cheng said:
Not tried light room myself, perhaps it might fare better as a raw convertor?
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I find Lightroom to be very good, but if by "camera raw" you mean Adobe's camera raw then I would think results would be the same, at least with the latest raw engine, since AFAIK ACR and Lightroom are equivalent in terms of raw processing.
 
HoppyUK said:
Just how hard can you make getting a decent exposure with digital? :eek: :thinking:
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Perhaps this is long winded, but if you master the understanding, then you can apply this effortlessly in the field. Don't get me wrong, I won't be doing this for every and any shot, but when I've found that perfect landscape shot, I'll be maxing out every last bit of RAW I can :p Noise free shadows? Yes please!

tdodd said:
OK, but were you SPOT metering off the brightest parts of the clouds? If not then your exposure would have been thrown off by the dimmer parts.

I find Lightroom to be very good, but if by "camera raw" you mean Adobe's camera raw then I would think results would be the same, at least with the latest raw engine, since AFAIK ACR and Lightroom are equivalent in terms of raw processing.
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Yes, spot metering, and from what I understand each of the 51 points can spot meter (I wasn't using the centre point). When I moved the bracket about from light areas to dark the meter changed accordingly. Yes, I meant ACR. I will try again the same with my D300s tomorrow...


Can you confirm that your +4 EVs were identical (or near enough) when underexposed in raw to those that were taken at lower exposures?

For example, I compared +1EV to +2EV (-1EV in raw), +2 1/3EV (-1 1/3EV in raw) etc. and they were absolutely IDENTICAL in the histogram (at the top half at least..small changes in the shadows but I won't discuss them now) and also identical visibly, at +2EV 2/3 (-1 2/3EV) there was the smallest change in the histogram and small white patches visibly, and larger so at +3EV (-2EV in raw).
 
I don't believe it is as simple as simply reversing the increasing exposure by reducing exposure in ACR/Lightroom, because the exposure control in ACR/Lightroom focuses its action upon the brighter tones only, leaving the shadows unmolested. Therefore, while you might get your highlight end to match, I would not expect the shadow end to.

I won't bother with individual histograms, but here you can see a simple comparison of my shots at 0, +1, +2, +3, +4 adjusted by nothing more than a -0, -1, -2, -3, -4 exposure adjustment in Lightroom. Clearly something has gone tits up with the +4 image, but there is at least detail that can be recovered. It just might need more sympathetic treatment. Nonetheless, I don't see a colour shift or anything really offensive, just a bit more work in the +3 to +4 region. That's why I propose aiming to set +3 as the clipping point, not more than that. Also, personally, I'm not expecting to get exactly equal results by recovering blown highlights vs an unblown image. I'm aiming to get a usable image that looks good, not an identical twin of a lower exposure.

20100408_221150_LR.jpg
 
tdodd said:
I don't believe it is as simple as simply reversing the increasing exposure by reducing exposure in ACR/Lightroom, because the exposure control in ACR/Lightroom focuses its action upon the brighter tones only, leaving the shadows unmolested. Therefore, while you might get your highlight end to match, I would not expect the shadow end to.

I won't bother with individual histograms, but here you can see a simple comparison of my shots at 0, +1, +2, +3, +4 adjusted by nothing more than a -0, -1, -2, -3, -4 exposure adjustment in Lightroom. Clearly something has gone tits up with the +4 image, but there is at least detail that can be recovered. It just might need more sympathetic treatment. Nonetheless, I don't see a colour shift or anything really offensive, just a bit more work in the +3 to +4 region. That's why I propose aiming to set +3 as the clipping point, not more than that. Also, personally, I'm not expecting to get exactly equal results by recovering blown highlights vs an unblown image. I'm aiming to get a usable image that looks good, not an identical twin of a lower exposure.

20100408_221150_LR.jpg
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Fair enough! I guess our expectations (and thus results!) were different! I expected a 'twin' image, and I am happy to say that for the most part, this can be done with adjustments of 'exposure' and 'blacks' in the raw converter so it's identical visibly and also histogram wise, from +2 1/3rds EV with spot metering. At least that way, I know I am maximising RAW bit space as much as I can and getting the same scene that I would have got, just with less noise. But as I mentioned above, >3EV is certainly very usable, but as it's not identical, it's not what I was looking for! But whatever works for you, and gets the image you need!
 
Well, yes, adjusting the blacks as well should sort out the shadow end, but you didn't mention that earlier, so I simply applied the -ve exposure adjustment as you suggested.

As for achieving identical results, up until +3, which is all I've ever advocated, getting a twin image is easily achievable. It's only once you go above +3 that things begin to go a bit wobbly, which is why I have cautioned against going that far.
 
Cheng said:
Perhaps this is long winded, but if you master the understanding, then you can apply this effortlessly in the field. Don't get me wrong, I won't be doing this for every and any shot, but when I've found that perfect landscape shot, I'll be maxing out every last bit of RAW I can :p Noise free shadows? Yes please!

<snip>
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Yeah sure, I know what you're saying.

What you are describing is Expose To The Right technique for noise free shadows, which is something quite different to spot metering. Although of course it can be part of the method for doing it, amongst others, depending on your preference.
 
I think there are some wires crossed here. I'm sure that all Chen was doing was a one-off exercise to find the acceptable clipping point for his camera. Now that he knows that he can move forward with that figure from now on. There is no need to repeatedly bracket exposures in the future, for safety, or to nudge the histogram to the right. It can all be done in one go, at once, simply by metering the highlights at +x.y stops. In my case, x.y = 3.0. In Chen's case it is probably 2.7 (or is it 2.3?). Either way, there is no need for further experimentation. The results are in.
 
tdodd said:
I think there are some wires crossed here. I'm sure that all Chen was doing was a one-off exercise to find the acceptable clipping point for his camera. Now that he knows that he can move forward with that figure from now on. There is no need to repeatedly bracket exposures in the future, for safety, or to nudge the histogram to the right. It can all be done in one go, at once, simply by metering the highlights at +x.y stops. In my case, x.y = 3.0. In Chen's case it is probably 2.7 (or is it 2.3?). Either way, there is no need for further experimentation. The results are in.
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Sure Tim. I was just wondering about what the OP thinks of all this, or anybody else seeing the opening pic and looking for a solution.

I think the answer there is a bit simpler - don't turn the flippin flash on for landscapes in bright sun!
 
spot...just a spot decided by the camera manufacturer where the exposure reading is taken from
i use spot metering...but only to 'judge' what settings i need for overall good exposure
normally one tries to expose for highlights but they can over darken the shot

its a bit of an art and science using spot metering...but in effect it is what you do with a hand held meter in any event
take some relevant subject readings and interpolate

and of course with the digital camera....a poor reading can be quickly compensated by manual settings or using the +/- device...my favourite...to reset the exposure relevant to the area you are spot reading from

skies are the hardest to read and take effectively being in a lot of cases too bright...so the grad filter can help there
 
Wow what a response, I sure wasnt expecting this hehe!

Im very new to the whole SLR thing and found this whole topic a bit confusing but looking forward to going through it all in my own time! So I appreciate all of your input.

What I can say, is that before this picture was taken, I was stood 180 degrees around where it was a very wooded and undercover location which may of forced the flash to activate for a previous picture, and then remained on?

Since the picture was taken, ive learnt a lot about what settings achieve what and how they all work in tandem.
I swear by having my camera on Program Mode now and only today realised how one can step down the exposure by a 1/3 of a stop at a time in each direction by using the quick dial mode which is very handy isnt it!

James
 
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