Luminous Landscape Forum
Equipment & Techniques => Digital Cameras & Shooting Techniques => Topic started by: vorlich on May 04, 2009, 07:20:51 am
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Hi All,
I'm confused about exposure compensation. I understand that the metering in most cameras will try to expose bright scenes as middle grey, snowy scenes for example. However, what I don't understand is the benefit of using exposure compensation over say, taking a shot, checking the histogram and adjusting the exposure manually by changing the shutter speed to taste. This seems much less fiddly than going into a menu and making the adjustment there.
Am I missing something?
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… However, what I don't understand is the benefit of using exposure compensation over say, taking a shot, checking the histogram and adjusting the exposure manually by changing the shutter speed to taste. This seems much less fiddly than going into a menu and making the adjustment there.
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On most DSLRs, changing exposure compensation is just a matter of turning a wheel or pressing a button. It's not as flexible as controlling exposure via the manual mode (M) but it's quick and you can leave your camera in Av or Tv mode.
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On most DSLRs, changing exposure compensation is just a matter of turning a wheel or pressing a button. It's not as flexible as controlling exposure via the manual mode (M) but it's quick and you can leave your camera in Av or Tv mode.
Ah-ha. Thanks for the speedy response. It makes sense now, I always shoot manual, so I hadn't considered it's use for Av or Tv modes.
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Ah-ha. Thanks for the speedy response. It makes sense now, I always shoot manual, so I hadn't considered it's use for Av or Tv modes.
Exposure compensation means compensate for the automatic meter. If you use manual mode, then you don't need to compensate - yourself -…
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However, what I don't understand is the benefit of using exposure compensation over say, taking a shot, checking the histogram and adjusting the exposure manually by changing the shutter speed to taste. T
Am I missing something?
Well for one, if you're shooting Raw, that histogram is a big fat lie. Its a histogram representing a JPEG if you had the camera set to provide one.
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Well for one, if you're shooting Raw, that histogram is a big fat lie. Its a histogram representing a JPEG if you had the camera set to provide one.
Yes, I'm aware of that. But it's a pretty good guide IME. If in doubt I usually bracket...
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Yes, I'm aware of that. But it's a pretty good guide IME.
I totally disagree, its not at all even a close guide to the Raw data. You're looking at a baked, gamma corrected, white balanced histogram. The Raw histogram is very, very different. Be useful if we could see it.
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I totally disagree, its not at all even a close guide to the Raw data. You're looking at a baked, gamma corrected, white balanced histogram. The Raw histogram is very, very different. Be useful if we could see it.
Of course the RAW histogram would be preferable, but in it's absence, what do you suggest?
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Of course the RAW histogram would be preferable, but in it's absence, what do you suggest?
http://www.digitalphotopro.com/technique/c...ng-for-raw.html (http://www.digitalphotopro.com/technique/camera-technique/exposing-for-raw.html)
My suggestion is to totally disregard the LCD histogram for anything other than focus, composition, etc. IOW, the histogram is just a totally unreliable indicator for exposure unless you're exposing for the JPEG.
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http://www.digitalphotopro.com/technique/c...ng-for-raw.html (http://www.digitalphotopro.com/technique/camera-technique/exposing-for-raw.html)
My suggestion is to totally disregard the LCD histogram for anything other than focus, composition, etc. IOW, the histogram is just a totally unreliable indicator for exposure unless you're exposing for the JPEG.
For those of us who meter in-camera, I'd argue the histogram is still a useful guide, provided the shooter is aware of it's limitations.
I make an exposure, ETTR, and see the histogram shows I'm just clipping the highlights, surely this is good enough, as I have left myself some headroom in the RAW capture. Bear in mind, I'm using an entry level dSLR, which I assume will be closer to the JPG histogram than your 5D. Isn't knowing the characteristics of your camera and how much headroom exists over what the histogram shows, so you can predict the correct exposure, a viable solution in lieu of a RAW histogram?
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Bear in mind, I'm using an entry level dSLR, which I assume will be closer to the JPG histogram than your 5D.
I can't imagine why that would be so.
Isn't knowing the characteristics of your camera and how much headroom exists over what the histogram shows, so you can predict the correct exposure, a viable solution in lieu of a RAW histogram?
Again, the JPEG is a baked, gamma corrected, rendered image from the Raw. The histogram is based on that rendering. The Raw histogram if we could see one, would look vastly different. And if we took that Raw into any Raw converter, ever differing setting applied to produce a rendering would produce a differing histogram. Yet the original source histogram in all those examples is the same.
If I "over expose" 1.5 stops past what my meter tells me is "correct", at least on my 5D, I'll see a blown out histogram on the LCD, I'll also see a blow out histogram using a default rendering in say Lightroom. But I can move the Exposure slider such that I "normalize" (using Michael's term) the rendering such that no highlight data is blown out and the resulting histogram looks fine. The histogram on the camera represents just one fixed rendering. Within reason, I can alter that by a huge degree in a Raw converter yet the original source data is what it is.
Histograms are not future predictors. They tell us the data distribution based on some current settings. So I don't see how the one baked rendering of a JPEG I'm not producing is useful in gauging the actual data of the Raw.
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I can't imagine why that would be so.
Again, the JPEG is a baked, gamma corrected, rendered image from the Raw. The histogram is based on that rendering. The Raw histogram if we could see one, would look vastly different. And if we took that Raw into any Raw converter, ever differing setting applied to produce a rendering would produce a differing histogram. Yet the original source histogram in all those examples is the same.
If I "over expose" 1.5 stops past what my meter tells me is "correct", at least on my 5D, I'll see a blown out histogram on the LCD, I'll also see a blow out histogram using a default rendering in say Lightroom. But I can move the Exposure slider such that I "normalize" (using Michael's term) the rendering such that no highlight data is blown out and the resulting histogram looks fine. The histogram on the camera represents just one fixed rendering. Within reason, I can alter that by a huge degree in a Raw converter yet the original source data is what it is.
Histograms are not future predictors. They tell us the data distribution based on some current settings. So I don't see how the one baked rendering of a JPEG I'm not producing is useful in gauging the actual data of the Raw.
The $64,000 question then is how do you consistently get proper ettr exposures without reference to the histogram? My experiance on several cameras is to set the histogram to RGB and the display to blink when clipped. I consistently get good ettr's with mild blinking and a small amount of clipping on the histogram. Just my opinion, the histogram is an invaluable tool for exposure but would be even better if you could select a RAW histogram
Marc
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Isn't knowing the characteristics of your camera and how much headroom exists over what the histogram shows, so you can predict the correct exposure, a viable solution in lieu of a RAW histogram?
If you are really interested in the RAW histogram, why should you put any effort to find out how to _predict_ the correct exposure from a processed RAW, i.e. the JPEG? why not complain at the camera manufacturers that (in a wrong way) think you should not be interested in the RAW histogram?
It's amazing to see how many RAW shooters are not only not unhappy with the JPEG histograms their cameras provide, but glad to see thay can 'recover' information when putting the RAW file into a RAW developer. Come on, complain at those camera vendors that live on the money you put in their products, and don't be so happy trying to predict what the right exposure achieved was, just because some brilliant engineer (or more likely some marketer) that will only take weekend family pictures thought you are not intelligent enough to need or be interested in RAW histograms.
BR
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The $64,000 question then is how do you consistently get proper ettr exposures without reference to the histogram?
If I could copy and paste from another forum, the reply to that question (it boils down to, it depends):
I never shoot JPEG. I never pay any attention to the Histogram or clipping.
If I have control of the situation I'm shooting in, certainly a setup where I'm lighting the scene and have time, I'll implement ETTR based on what I know about the sensor.
I also shoot a lot "from the hip" (just friends at an event, having dinner or something). Usually low light. ETTR just doesn't work as I'm always wanting either higher shutter speeds or depending on the lens, its not fast enough to lose that extra 1.5 stops. The preferred lens I use in these situations is a 35mm 1.4 but more often I'm just taking along one lens, a 24-104mm F4. The new 5DMII certainly helps being at ISO 3200 in some cases. A sharp capture is always preferable to one that isn't even if there's less noise (duh).
If the light is changing a lot and again, I'm shooting quickly and have little control, ETTR isn't going to fly. I don't want to clip highlights! I'd rather have a "normal" meter exposure with more noise in the shadows as opposed to really clipping highlights. I can't get that data back, I can deal with noise.
Ultimately, whenever the situation allows, I bracket! There's never any downside there. That would mean something that allows the time to do so without losing a shot (so no, I would never bracket shooting people or something moving that might result in the better shot being poorly exposed).
Sometimes I'm using an external meter (a Sekonic that has both spot and incident capabilities) but quite often, I am traveling light and use the camera meter.
Again, it would be really useful if the feedback on the LCD were based on what I'm actually shooting for, the Raw data. I'm not sure why the camera manufactures don't provide this option, seems easy to do.
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I totally disagree, its not at all even a close guide to the Raw data. You're looking at a baked, gamma corrected, white balanced histogram. The Raw histogram is very, very different. Be useful if we could see it.
A totally raw histogram without gamma encoding or logarithmic encoding would not be that useful, since (as Bruce Fraser and others have noted) the data would be scrunched up on the left side of the histogram. It is true that the camera histogram represents data from the JPEG preview and is affected by the color space and tone curve of the camera settings. However, if one uses a normal or low contrast tone curve, the camera histogram often gives a reasonably accurate indication of exposure to the right (ETTR). The tone curve affects chiefly the mid-tones and has minimal effect on the highlights. I have done experiments with my Nikon D3 and have found that the camera histogram is slightly conservative, but gives a good approximation of ETTR. In his seminal article on ETTR, Michael Reichman recommended using the camera histogram and that is what most photographers do.
I posted my results in the Adobe ACR Forum (http://forums.adobe.com/thread/311679). Unfortunately, the illustration links are no longer valid, but the text is still there.
IHMO, an ideal camera histogram would reflect raw data with log base 2 encoding so that each division on the histogram would represent 1 f/stop. Lacking such an ideal, the current histograms give valuable data if one has done tests and knows how to interpret them.
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A totally raw histogram without gamma encoding or logarithmic encoding would not be that useful, since (as Bruce Fraser and others have noted) the data would be scrunched up on the left side of the histogram.
I don't recall Bruce saying it would not be useful, can you find a reference? Yes, it would be all scrunched up to the left, especially if plotted like a gamma corrected Histogram. And yes, users would need to learn to read a histogram that way. And yes, the manufacturers could do something useful like put some line or reference to the right of this scrunched up histogram that indicated based on some testing, where full sensor exposure overload happened so we could adjust to just shy of that point. And yes, that would be real useful IMHO!
It is true that the camera histogram represents data from the JPEG preview and is affected by the color space and tone curve of the camera settings. However, if one uses a normal or low contrast tone curve, the camera histogram often gives a reasonably accurate indication of exposure to the right (ETTR).
Accurate by how much? You have some data to share? 1/10 a stop? 1/2? I've fooled around with my Canon's and 1.5 stops is more like it. Now maybe you consider that an accurate amount to extrapolate but I'd like a bit more precision.
I posted my results in the Adobe ACR Forum (http://forums.adobe.com/thread/311679). Unfortunately, the illustration links are no longer valid, but the text is still there.
I posted mine here:
http://www.digitalphotopro.com/technique/c...ng-for-raw.html (http://www.digitalphotopro.com/technique/camera-technique/exposing-for-raw.html)
Maybe Canon's are way, way different from Nikon.
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A totally raw histogram without gamma encoding or logarithmic encoding would not be that useful, since (as Bruce Fraser and others have noted) the data would be scrunched up on the left side of the histogram
This is nonsense, no matter who noted it. The histogram is very lop-sided if the shot was underexposed by several stops. If the shot is underexposed by one stop, then already half of the histogram is occupied.
A log-based histogram would be better, but we don't have it.
The gamma encoding is very disturbing in ETTR, when judging how much exposure can be added without clipping: the histogram appears close to the right edge - but how much is the distance in terms of EV?
Accurate by how much? You have some data to share? 1/10 a stop? 1/2? I've fooled around with my Canon's and 1.5 stops is more like it
The flashing clipping indication with my 40D is accurate within the adjustibility, i.e. 1/3 EV (the histogram is accurate as well, but not as useful). However, the price is, that all my shots are greenish, i.e. the preview JPEG and the thumbnails are good for nothing but identifying the shot, and I always have to (would have to) think of an extra shot for WB if the scenery itself does not offer anything for picking WB.
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The flashing clipping indication with my 40D is accurate within the adjustibility, i.e. 1/3 EV (the histogram is accurate as well, but not as useful). However, the price is, that all my shots are greenish, i.e. the preview JPEG and the thumbnails are good for nothing but identifying the shot, and I always have to (would have to) think of an extra shot for WB if the scenery itself does not offer anything for picking WB.
Yup, that's also a severe issue that needs fixing. The LCD previews are so darn useful (for a guy from the old Polaroid days), its a shame those shooting something that isn't a JPEG get penalized. I keep thinking the camera manufacturers will get it some day. But until they figure we're all tired of larger and larger chips to get us to upgrade, I don't hold out much hope.
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Histograms are not future predictors. They tell us the data distribution based on some current settings. So I don't see how the one baked rendering of a JPEG I'm not producing is useful in gauging the actual data of the Raw.
Yes, but if your in-camera histogram is bunched up at the extreme right, your default histogram in the RAW converter will be similar. Of course this can be adjusted or normalised as required (within limits), but the histogram still serves as an indicator (maybe not a wholly accurate one) of where the values have been recorded in the RAW file. I'm surprised you're unable to make this connection.
I won't be abandoning the in-camera histogram any time soon...
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Yes, but if your in-camera histogram is bunched up at the extreme right, your default histogram in the RAW converter will be similar. Of course this can be adjusted or normalised as required (within limits), but the histogram still serves as an indicator (maybe not a wholly accurate one) of where the values have been recorded in the RAW file
1. If your in-camera histogram is bunched up at the extreme right, then your shot is probably worthless anyway.
2. The default histogram in the raw processor will be similar to that displayed in-camera if you are using a raw processor, which applies the setting; the camera makers' own raw processors do, but for example ACR does not (except for the WB).
However, that is again the histogram of the converted image, which is far from the histogram of the raw data.
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1. If your in-camera histogram is bunched up at the extreme right, then your shot is probably worthless anyway.
2. The default histogram in the raw processor will be similar to that displayed in-camera if you are using a raw processor, which applies the setting; the camera makers' own raw processors do, but for example ACR does not (except for the WB).
However, that is again the histogram of the converted image, which is far from the histogram of the raw data.
1. Thanks for those pearls of wisdom. :-/
2. I'm talking LR here. All settings zeroed after import. I see a histogram broadly similar to the in-camera histogram.
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2. I'm talking LR here. All settings zeroed after import. I see a histogram broadly similar to the in-camera histogram.
Ok, pls upload a sample raw file of yours for demonstration (I have several thousands from five dozen camera models beside the tens of thousands of my own, but a demo is best on your own file). Yousendit.com is the best way.
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1. Thanks for those pearls of wisdom. :-/
2. I'm talking LR here. All settings zeroed after import. I see a histogram broadly similar to the in-camera histogram.
Because you're viewing a gamma corrected, rendered histogram. Again, the current histogram is based on the current condition of the data. What you're now seeing isn't the Raw data of course. And those rendering settings may not be anything appropriate for the color and tone appearance you'll end up with.
Make an exposure that is 1 stop brighter than the meter recommends. The LCD should show its over exposed and clipped. The Histogram of the default rendering in LR will show the same. Now use the Exposure slider and move it down minus about 1 stop. You should see a preferable color and tone appearance and histogram. But wait, if the image were really over exposed, you couldn't do that. The image wasn't over exposed, at least as for as the Raw data was concerned. It was for the in camera JPEG generation. So the Raw histogram is what it is. Exposure and ISO affect it this of course. At some point, you really will over expose to the point that you've saturated the sensors and blown out the highlights. But you don't know where that is just shy of happening based on the JPEG generated histogram.
In the URL I provide, I was able to "over expose" (some would say properly expose) 1.5 stops over the meter recommendation while ending up with a final image that wasn't over exposed. So how do we attribute this? The Raw data if visible as a histogram would have shown me that 2 stops indeed clip, 1.5 doesn't. But the histogram on the LCD told me both were over exposed. So which is it? Well for JPEG, that histogram is appropriate because it defines what the camera would hand me based on its rendering. Its not appropriate based on what I ended up doing in Lightroom by adjusting the exposure slider.
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Ok, pls upload a sample raw file of yours for demonstration (I have several thousands from five dozen camera models beside the tens of thousands of my own, but a demo is best on your own file). Yousendit.com is the best way.
Why don't you illustrate your point with one of your own files?
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I don't recall Bruce saying it would not be useful, can you find a reference? Yes, it would be all scrunched up to the left, especially if plotted like a gamma corrected Histogram. And yes, users would need to learn to read a histogram that way. And yes, the manufacturers could do something useful like put some line or reference to the right of this scrunched up histogram that indicated based on some testing, where full sensor exposure overload happened so we could adjust to just shy of that point. And yes, that would be real useful IMHO!
He made this statement in response to one of my posts (?Adobe Forums or LL forums), where he was trying to discount my advocacy of a camera raw histogram.
Accurate by how much? You have some data to share? 1/10 a stop? 1/2? I've fooled around with my Canon's and 1.5 stops is more like it. Now maybe you consider that an accurate amount to extrapolate but I'd like a bit more precision.
Accurate to about 1/3 f/stop, which is adequate for most practical work. Most camera settings and light meters to not offer finer settings.
To illustrate and prove my assertion here are photos of the D3 histograms for my images 005 and 006 which are shot at 1/20 f/8 and 1/25 f/8 respectively. The camera histogram of the image at 1/20 sec shows clipping of the highlights, while the histogram of the image at 1/25 shows the highlights slightly short of clipping.
[attachment=13466:005_cam_histogram.png]
[attachment=13467:006_cam_histogram.png]
And here are the raw histograms as shown by Rawnalize. The raw histogram of the image taken at 1/20 sec is very slightly short of clipping, while the raw histogram of the image taken at 1/25 sec is about 1/3 stop short of clipping.
[attachment=13468:005_raw_histogram.png]
[attachment=13469:006_raw_histogram.png]
I posted mine here:
http://www.digitalphotopro.com/technique/c...ng-for-raw.html (http://www.digitalphotopro.com/technique/camera-technique/exposing-for-raw.html)
Maybe Canon's are way, way different from Nikon.
Maybe so, but you didn't look at the raw file directly, but used Adobe Camera raw which uses an exposure offset and doesn't really give you a good idea of the actual content of the raw file. To see the actual values in the raw file it is best to use specialized software such as Rawnalize or Iris. When you get some more data, we can discuss the matter further.
Bill
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I agree with Bill that a totally linear histogram would not be so useful as a gamma or EV histogram. Applying a gamma to the encoded data, or plot the X-axis on a log 2 basis is no problem.
The gamma will never blow anything that is not blown in the RAW file and will help visualize better how the information spreads along. The EV divisions can also be plotted in a gamma histogram.
However an EV histogram would be my preferred option, it's conceptually very photographic and allows to find out at a glance the dynamic range of the scene.
Pick the one you like best:
(http://img22.imageshack.us/img22/7052/chicap.jpg)
(http://img22.imageshack.us/img22/3397/histos.gif)
Regards
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Why don't you illustrate your point with one of your own files?
I can show you the raw histogram of many files, but the point is, that you compare it with the histogram of the very same file in-camera and in your choice of raw processor with your settings.
However, do not mix up thing, I was not asking for a favour but offering one, for you don't understand the issues.
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Maybe so, but you didn't look at the raw file directly, but used Adobe Camera raw which uses an exposure offset and doesn't really give you a good idea of the actual content of the raw file. To see the actual values in the raw file it is best to use specialized software such as Rawnalize or Iris. When you get some more data, we can discuss the matter further.
Yes absolutely true. I don't have anything for the Mac (at least I know of nothing) that allows me to look at a Raw histogram. But I did find that 1.5 stops was about the limit over the meter recommendation I could expose to the right for use with that converter. Which begs the question, was the 2 stop really the limit or did I hit an LR/ACR limit (going back to your point that you really want to view that Raw data).
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Yes absolutely true. I don't have anything for the Mac (at least I know of nothing) that allows me to look at a Raw histogram.
DCRaw (http://www.insflug.org/raw/) works with the mac. You can demosaic to a 16 bit TIFF without white balance and then use Photoshop or some other program to view the histogram.
Here is the result for my 005.nef file whose raw histogram was shown above and repeated here for comparison. I used the following switches in DCRaw: -4 -T -o 0 -r 1 1 1 1. Perhaps Gabor and Guillermo can comment as they are more familiar with these programs. (Note: If anyone notes a change in the histogram, I improved the originally posted Photoshop histogram by cropping out black pixels):
[attachment=13486:PS_histo.png]
[attachment=13472:005_raw_histogram.png]
If you want raw pixel values, you can read them with the eyedropper using 16 bit mode and then divide by two to convert to 14 bit raw values.
For example, here are readings in Photoshop and Rawnalize.
[attachment=13474:PS_info.png]
[attachment=13475:Rawnalize.png]
The raw pixel value of the indicated area is 15908 in Rawnalize and 31384/2 = 15692 in the Photoshop derived method.
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I used the following switches in DCRaw: -4 -T -o 0 -r 1 1 1 1. Perhaps Gabor and Guillermo can comment as they are more familiar with these programs.
That's fine to find out what the RAW histogram looks like (in fact it's what I did 2 posts ago), but it's actually not pure RAW since you are demosaicing (without white balance nor output profile conversion, that's true).
For real RAW histogram you can do:
dcraw -v -D -4 -T -t 0
dcraw -v -d -r 1 1 1 1 -4 -T -t 0
The first is pure RAW data, just decompressed when needed. It's very useful to check fake ISOs and work out RAW saturation points.
The second is 'nearly' RAW data (it clips black point, adjusts saturation point and converts to 16-bit scale). It's very useful to obtain log 2 RAW histograms.
None of them performs demosaicing and can be represented in Histogrammar's RAW mode. Histogrammar has no problem to run on a Mac with Darwine or similar.
BR
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I agree with Bill that a totally linear histogram would not be so useful as a gamma or EV histogram. Applying a gamma to the encoded data, or plot the X-axis on a log 2 basis is no problem.
The gamma will never blow anything that is not blown in the RAW file and will help visualize better how the information spreads along. The EV divisions can also be plotted in a gamma histogram.
However an EV histogram would be my preferred option, it's conceptually very photographic and allows to find out at a glance the dynamic range of the scene.
Pick the one you like best:
Regards
Guillermo,
IMHO, the EV histogram is by far the preferable one.
While we are talking about camera histograms, I should mention that most camera histograms are luminance histograms and may not detect clipping in the blue and red channels. The camera RGB histograms will detect clipping, but are liable to clipping on white balance and will not give a reasonably accurate picture of the raw channels unless UNIWB has been loaded into the camera.
Bill
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DCRaw (http://www.insflug.org/raw/) works with the mac. You can demosaic to a 16 bit TIFF without white balance and then use Photoshop or some other program to view the histogram.
Cool, thanks, I'm on it.
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The in-camera histogram can be made very raw-like, if the camera allows for loading a user-defined curve. My Canon 40D supports this, but unfortunately only with a very primitive curve: I can define only one single point of the curve. I tried to create an "RGB inversion" curve, and this in fact enhanced the displayed histogram (causing the preview become darker), i.e. it is now closer to the raw histogram.
If other cameras support more complex curve specifications, the result can become much better; it should be even possible to achieve a log2 based display.
Note, that the flashing clipping indication does not change by this curve.
ADDED
I am an airhead. I CAN create a curve determined by up to eight points, only that the editor is a bit clumsy, one had to click very accurately on the curve.
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In the URL I provide, I was able to "over expose" (some would say properly expose) 1.5 stops over the meter recommendation while ending up with a final image that wasn't over exposed. So how do we attribute this? The Raw data if visible as a histogram would have shown me that 2 stops indeed clip, 1.5 doesn't. But the histogram on the LCD told me both were over exposed. So which is it? Well for JPEG, that histogram is appropriate because it defines what the camera would hand me based on its rendering. Its not appropriate based on what I ended up doing in Lightroom by adjusting the exposure slider.
[/quote]
When you are making your exposure are you making an exposure based on the "mid tones"? Not for the highlights or dark areas? I often make an exposure for the sky - in landscapes - and set an EV of + 1 or expose for a dark area and set an EV of -1 How would this method fit into the equation? TIA
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Cool, thanks, I'm on it.
Rawnalyze and Iris do work on Macs (Intel only) with CrossOver Mac. No need to install Parallels or Fusion with Windows. CrossOver Mac is available as a demo ( http://www.codeweavers.com/products/cxmac/ (http://www.codeweavers.com/products/cxmac/) ). I haven't been able to run Guillermo's software in CrossOver...
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Hi All,
I'm confused about exposure compensation. I understand that the metering in most cameras will try to expose bright scenes as middle grey, snowy scenes for example. However, what I don't understand is the benefit of using exposure compensation over say, taking a shot, checking the histogram and adjusting the exposure manually by changing the shutter speed to taste. This seems much less fiddly than going into a menu and making the adjustment there.
Am I missing something?
Hi, while the discussion about histograms is quite illuminating, it does seem a bit sideways to your question. First, as a brief intro- the photo school I attended back in the film days taught previsualization and a variant of the Zone System. They also required us to print on an ungraded paper (Ektalure G) and we were not allowed to use variable contrast papers or adjustable contrast paper while printing, thus our exposures had to be 'nuts on' or a high quality print would be impossible.
All that said, exposure compensation is about keeping focused on the scene in front of you and not on your screen as well as developing an understanding of how your equipment is going to work with that scene. That way meters, histograms and such become the tools they are meant to be and not the crutches they seem to have become.
Now that said... exposure compensation is counter intuitive. You have to stop down for dark scenes when you might think you'd want to open up and open up for light scenes when you'd think you'd want to stop down. Note that this has nothing to do with the amount of light but with the overall tonality of the scene. So if you meter snow in heavy overcast or bright direct sun you'd still have to compensate about the same. Likewise for, say, dark lavarock under various lighting conditions.
So, the lesser advantage of exposure compensation is speed. I shot a lot of snow and ice this past winter and it was a matter of moments to use the thumbwheel to dial in an offset. The big advantage is that it encourages you to look more deeply into a scene than your might otherwise do and think about how it will interact with your specific photographic system in order to get exactly the results you wish.
Ed
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When you are making your exposure are you making an exposure based on the "mid tones"? Not for the highlights or dark areas? I often make an exposure for the sky - in landscapes - and set an EV of + 1 or expose for a dark area and set an EV of -1 How would this method fit into the equation? TIA
The exposure were all based on an incident flash meter in these examples.
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Rawnalyze and Iris do work on Macs (Intel only) with CrossOver Mac. No need to install Parallels or Fusion with Windows. CrossOver Mac is available as a demo ( http://www.codeweavers.com/products/cxmac/ (http://www.codeweavers.com/products/cxmac/) ). I haven't been able to run Guillermo's software in CrossOver...
What's the difference, advantage of CrossOver versus Parallels (which I have on one machine)?
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What's the difference, advantage of CrossOver versus Parallels (which I have on one machine)?
As far as I know Parallels (so as Vmware Fusion) are Windows virtual machines that require the installation of the Windows OS. Crossover (and Darwine) are Windows library emulators that allow to run Windows applications without the need to install Windows, and I guess lower degree of compatibility.
BTW francois, I have seen Histogrammar running on Crossover without any problem, maybe you have to do some config adjustment.
BR
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As far as I know Parallels (so as Vmware Fusion) are Windows virtual machines that require the installation of the Windows OS. Crossover (and Darwine) are Windows library emulators that allow to run Windows applications without the need to install Windows, and I guess lower degree of compatibility.
Thanks, I'll check it out. Not having to actually install Windows sounds very handy!
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As far as I know Parallels (so as Vmware Fusion) are Windows virtual machines that require the installation of the Windows OS. Crossover (and Darwine) are Windows library emulators that allow to run Windows applications without the need to install Windows, and I guess lower degree of compatibility.
That's correct, nothing to add.
BTW francois, I have seen Histogrammar running on Crossover without any problem, maybe you have to do some config adjustment.
BR
Thanks for the info, I'll try with different settings. I just tried with default settings and it's very likely that I missed something.
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Thanks, I'll check it out. Not having to actually install Windows sounds very handy!
The drawback is that CrossOver Mac only works with a limited set of apps.