snubbr.com

how do you tell if a photo is not correctly exposed
I can tell if a photo is not correctly exposed if it's way too dark or light..

But without comparison, I can't tell if a photo is 1 stop or 2 stop uncorrectly exposed..

Some of you people can tell a photo is like 1/3 overexpose or something. how do you people do that? is there some software to do that?..

Comments (31)

I've learned to estimate under- or over-exposure with experience. Post processing in RAW lets you see what 1/3, 2/3, etc. stops difference makes to an image..

Tim'Be the change you wish to see in the world.' -Mahatma Gandhihttp://www.flickr.com/photos/timskis6/..

Comment #1

Many cameras are equipped to display the histogram for each shot. This graphically displays the levels of exposure for a photo, from the darkest to the brightest areas. Based on this, the photog can make exposure adjustments if needed..

Best regards,Doughttp://pbase.com/dougj.

Http://thescambaiter.comFighting scammers WW for fun & justice..

Comment #2

I remember you did ask a question about the need of metering in manual modes... and did not even try to digest the answers..

New_type wrote:.

I can tell if a photo is not correctly exposed if it's way too darkor light..

How? .

But without comparison, I can't tell if a photo is 1 stop or 2 stopuncorrectly exposed..

Well....

Some of you people can tell a photo is like 1/3 overexpose orsomething. how do you people do that?.

Back to the metering question. Learn to use a meter. Learn what it does and how it does it. You don't need to buy one, you have a perfectly good one in your camera. After you understand this, you'll be able to look at a image and say it's 1 stop underexposed.Basically, one knows how shiny certains things are..

Is there some software to dothat?.

Yep, it's Photography 1.0 Pack. Consists of Basics 1.0, Experience 1.1 and Learning 2.4. It runs on Brain 1.0..

Comment #3

In absolute terms, nothing is over- or under-exposed without a point of reference..

Basically, it's often experience, with life and also photography, that tells us whether something looks too dark or too bright. But don't forget that it's ultimately a matter of the photographer's intent..

Have you seen a car ad where only the grille and headlights can be seen? The client didn't send the photographer back for a re-shoot, as that was the intended result and the client felt it was "right"..

With digital cameras, you have to be careful with highlights because each of the three colour channels has a different capacity, so you get ugly colour shifts as exposure maxes out each at a different threshold. Also the image can lose highlights detail within 1/3 of a stop and less, whereas with film the loss is much more progressive. For quick work such as photojournalism, this is generally ignored but for other work, such as portraits and landscapes, the exposure can be fixed by increasing brightness during development. Doing it this way fixes the hard shoulder and colour shift problems..

Because digital cameras have a higher dynamic range than film, but don't have the soft shoulder for highlights, it is important to take care of preserving highlights, whereas with film you would need to take care of shadows during exposure as this is the part that will be lost...

Comment #4

You still have prejudged over me.

Devnull wrote:.

I remember you did ask a question about the need of metering inmanual modes... and did not even try to digest the answers..

New_type wrote:.

I can tell if a photo is not correctly exposed if it's way too darkor light..

How? .

But without comparison, I can't tell if a photo is 1 stop or 2 stopuncorrectly exposed..

Well....

Some of you people can tell a photo is like 1/3 overexpose orsomething. how do you people do that?.

Back to the metering question. Learn to use a meter. Learn what itdoes and how it does it. You don't need to buy one, you have aperfectly good one in your camera. After you understand this, you'llbe able to look at a image and say it's 1 stop underexposed.Basically, one knows how shiny certains things are..

Is there some software to dothat?.

Yep, it's Photography 1.0 Pack. Consists of Basics 1.0, Experience1.1 and Learning 2.4. It runs on Brain 1.0..

Comment #5

If your camera has a histogram, and it should, then you can tell if the image is overexposed simply by looking at the histogram. the histogram appears as a flat floor with 2 vertical sides at each end the histogram itself is the line that is running left to right between the 2 sides. after taking the pic you check the histogram by looking at the wiggly line between the 2 sides. the important part is on the right side. the line MUST drop to the horizontal floor line BEFORE it reaches the right side or wall. if it does not then this tells you that your highlights are blown and your pic is overexosed..

If this is what you see then you fix the image exposure by using the exposure compensation to reduce the exposure by a 1/3 or 1/2 xtop at a time till the line leaves the wall and goes to the floor before it reaches the right wall..

Later on your pc monitor if the the overall image brightness seems to be too bright, then in pe5-6 or csx simply use auto levels button to change the brightness to the normal level..

If there is a choice of your exposure to blow the highlights or blow the shadows to dark then the correct action is to NOT blow the highlights and simply let the shadows or dark areas fall where they may. though some of the dark areas can be recovered in pe 5-6 or csx. once hightlights are blown and have gone to pure white then nothing can be done about them; they are gone forever..

If you have further questions, ask; I will try to answer them.gary..

Comment #6

The way to tell the exposure is to check the histogram. That will tell you the information that you want also where some of the overexposed parts of the frame. There are many good articles on how to read a histogram if you do not know a lot about this area...

Comment #7

GaryDeM wrote:.

If your camera has a histogram, and it should, then you can tell ifthe image is overexposed simply by looking at the histogram..

This doesn't tell you that your image is over- or under-exposed, merely whether you have used the sensor to capacity in certain frequencies...

Comment #8

Martin Caie wrote:.

Because digital cameras have a higher dynamic range than film,.

Slide film, not negative film, except maybe Fuji S5 Pro...

Comment #9

GaryDeM wrote:.

If your camera has a histogram, and it should, then you can tell ifthe image is overexposed simply by looking at the histogram..

As the other reply said, the camera's histogram will only tell you (within it's limitations) how much of the sensor's range is used..

Thehistogram appears as a flat floor with 2 vertical sides at each endthe histogram itself is the line that is running left to rightbetween the 2 sides. after taking the pic you check the histogram bylooking at the wiggly line between the 2 sides. the important part ison the right side. the line MUST drop to the horizontal floor lineBEFORE it reaches the right side or wall. if it does not then thistells you that your highlights are blown and your pic is overexosed..

It's a subjective choice about whether to blow the highlights for a particular scene. It's not true that you musn't blow highlights. If you don't want to blow highglights, then what you say about keeping the histogram from clipping at the right is true. However, blowing or not blowing highlights is only one consideration in whether an image is correctly exposed..

If this is what you see then you fix the image exposure by using theexposure compensation to reduce the exposure by a 1/3 or 1/2 xtop ata time till the line leaves the wall and goes to the floor before itreaches the right wall..

If shooting RAW, there is scope with some RAW converts to recover blown highlights, especially if only one or two channels are blown..

Later on your pc monitor if the the overall image brightness seems tobe too bright, then in pe5-6 or csx simply use auto levels button tochange the brightness to the normal level..

Auto levels takes away your control over the result you want. Levels or curves with manual adjustments are a better bet unless you don't care so much about the result. Brightness and exposure shouldn't be confused either..

If there is a choice of your exposure to blow the highlights or blowthe shadows to dark then the correct action is to NOT blow thehighlights and simply let the shadows or dark areas fall where theymay..

In some cases that will be true, but it's incorrect to say that the only correct way to shoot is to avoid blowing highlights..

Though some of the dark areas can be recovered in pe 5-6 or csx.once hightlights are blown and have gone to pure white then nothingcan be done about them; they are gone forever..

If you have further questions, ask; I will try to answer them.gary.

Cheers from John from Adelaide, South AustraliaJohn Harvey Photography http://johnharvey.com.auCanon 40D, Canon 20D & Fuji F10..

Comment #10

New_type wrote:.

I can tell if a photo is not correctly exposed if it's way too darkor light.but without comparison, I can't tell if a photo is 1 stop or 2 stopuncorrectly exposed..

Some of you people can tell a photo is like 1/3 overexpose orsomething. how do you people do that? is there some software to dothat?.

If you think you can tell whether a photo is correctly exposed by looking at it, then just take note of how much you need to adjust 'exposure' during PP to get it right, assuming you're using something like ACR where you can see the adjustment amount in stops..

Cheers from John from Adelaide, South AustraliaJohn Harvey Photography http://johnharvey.com.auCanon 40D, Canon 20D & Fuji F10..

Comment #11

Forget about the Fuji; any DSLR has higher dynamic range than 35mm negative film..

BA baracus wrote:.

Martin Caie wrote:.

Because digital cameras have a higher dynamic range than film,.

Slide film, not negative film, except maybe Fuji S5 Pro...

Comment #12

Martin Caie wrote:.

This doesn't tell you that your image is over- or under-exposed,merely whether you have used the sensor to capacity in certainfrequencies..

Agreed, however a luminance histogram is generally a good indication of over exposure if the distribution is at the right limit. RGB histograms will show the relative distribution by the 3 wavelength ranges, and if one of these specific wavelength ranges has exceeded the sensor's capacity. Should a luminance histogram exhibit distribution primarily to the left, with no pixels near the right limit, the shot is most likely underexposed to some degree..

Luminance by itself doesn't tell the whole story, but it can be used in many situations as a rough estimate of exposure, in absence of a light meter or RGB histograms..

Best regards,Doughttp://pbase.com/dougj.

Http://thescambaiter.comFighting scammers WW for fun & justice..

Comment #13

New_type wrote:.

I can tell if a photo is not correctly exposed if it's way too darkor light.but without comparison, I can't tell if a photo is 1 stop or 2 stopuncorrectly exposed..

Some of you people can tell a photo is like 1/3 overexpose orsomething. how do you people do that? is there some software to dothat?.

No, there is no software to do this for you. The histogram is a useful tool but it can only tell you what the exposure *is*, not what it *should be*..

Very good tip from your first respondent, Tim. Use a RAW converter and observe how the histogram changes as you adjust settings, especially exposure..

The more you look, the more you will learn to see...

Comment #14

If the histogram is hitting the right wall then you have the highlights overexposed, period. and the image is overexposed. who cares if some frequencies are overexposed? the idea is to expose correctly so you have NO points overexposed..

This is not horseshoes where you get points for almost. it is either correctly exposed or it is not. if any part of the image is overexposed then it is overexposed. and that point the exposure has to be adjusted...

Comment #15

"In some cases that will be true, but it's incorrect to say that the only correct way to shoot is to avoid blowing highlights".

If you want to expose in such a way that you blow the highlights on your images and still think that this is good exposure, go ahead..

Me, I prefer to get the the image inside the range of the sensor then worry about the effect later. the only possible rreason to let the highlights blow and not care would be if for some reason your interest in the exposure lay in another area of the scene. this of course assumes that you are talking about a single exposure for each scene, and not dealing with blending or hdr..

As far as auto levels is concerneed, you obviously do not know what that is. it is simply a pp control that change the overall brightness of an image to the normal range by raising or reducing the brightness of the entire image. it does not change individual parts of the dark/light sprectrum of light as you are trying to say with curves..

Auto level would be for a situation in which you exposed to the right and later looking at it on your calibrated monitor, (it is calibrated, right?), the overall image appears to be bright than you would like then autolevels would change then overall brightness to the normal amount. the effect also would reduce the noise level. it would not change the dark/light of the light spectrum as curves would..

In any event if your exposure habit and method is to expose so that your light areas all turn pure white due to overexposure be my guest. I will continue to expose my images correctly...

Comment #16

35mm slide film and a dslr have the same, or very close to it, dynamic range. you may have a slight amount of headroom in the shadow side but the highlight area of slide film and digital sensors are the same...

Comment #17

I'd say that if you can't tell then it's correctly exposed. One should know and manage as many technical aspects of photography as one can, but one should never forget that this shouldn't be a "straight-jacket" quite the oposite. Such a thing as correct exposure without considering the objective of the photo just doesn't exist..

Trouble is that modern digital cameras as wonderful as they are. Aren't the best option for learning. What you need is a totaly manual SLR, focus included, with a 50mm equivalent lens. and set it to B&W (to avoid colour temperature issues).

Part 1,.

Set 100 iso, look at the sky and decide an aperture & speed (film usualy came with a rough guide depending on conditions) look at the front of the lens and you should see an f-stop guide on the focus ring, put the infinity simbol on your selected f-stop and the other one should tell you your minimun focusing range. This is the Depth of Field, famous DoF. Now just go around shooting. Don't change settings just shoot..

Now have a look at the photos you took, if you had a good aperture/speed setting quite a few of your photos will be ok, but many will be over or under exposed, try and decide why, what do they have in common. Try and group them in categories..

Part 2,.

Go out again and do the same, but this time try and decide before hand how the exposure will work out, will it be okish, overexposed, underexposed, a lot, a little. Then you can decide to do one of two things either change the speed or change the aperture, but beware if you change the aperture you will have to change the focus..

This is just a short and limited exposition, but should be a good start. Note on the focus: this works on a similar principle as the other, try to guess the distance of what you want in focus and just set the ring by looking at the meter and the DoF ring. Only use the viewfinder to frame..

You'll take much worse photographs than by setting your camera on A but in the end you'll train your eye and develop instinct that will allow you to know when and why you want to override the automatic setting in your camera...

Comment #18

As correct exposure, only taste..

And that is subjective to say the least. Anyone that says there is, is telling porkie pies!.

Obviously, there are certain situations where a certain exposure would not be very appealing. But thats about it really.

A histogram is just a guide, and gives you information. Again..shoot to your taste, not the histogram .

Image control:Zoom outZoom 100%Zoom inExpand AllOpen in new window.

Clint is on holiday! Soon to return! ..

Comment #19

If you want to expose in such a way that you blow the highlights onyour images and still think that this is good exposure, go ahead..

Well... sometimes it's necessary, unless your camera has a remarkably high dynamic range. For example, highlights generated by sunlight reflecting off a shiny surface are inevitably going to be blown if the rest of the image is correctly exposed..

Even on an ordinarily sunny day the difference in brightness between highlight and shadow will exceed the DR of modern sensors. if your subject is in the shade and you expose for that correctly, the highlights will be blown; if your subject is brightly lit and you expose for that correctly, you will lose shadow detail. It depends what you are exposing for. So, yes, sometimes it is necessary to allow highlights to be blown to get a good exposure. Of course it's best avoided as far as possible....

Best wishesMike..

Comment #20

Barry Fitzgerald wrote:.

As correct exposure, only taste.. shoot to your taste, not the histogram .

Very true. Another aspect to consider is shooting to your equipment. My tastes are very simple; I always want my pictures to give as close an approximation to what I saw with my own eyes as possible (for exposure considerations, that means overall brightness level and which parts of the scene lose highlight and/or shadow detail), but that doesn't mean the same exposure that works for camera A is best for camera B. Camera B might have more limited dynamic range and a steeper tonal curve than Camera A. For example, on a bright, sunny day, I might have to give camera B less exposure than camera A to retain the detail I can see in brightly lit areas, then bring up the shadows and restore midtones in post-processing (even with exif data available for digital capture, field notebooks are great for helping me remember what the tonal values should be)...

Comment #21

Unless you see the scene, at the same time the photo was taken, cannot really tell. even then, it's subjective..

Example: for 30 years, a friend who taught at the local community college, would take his class outside andhave them shoot a building. he always tried for a sun filled day, building having lots of shade. he would position some in sun, some in shade. etc..

He then told everyone what the proper settings were, for exact exposure, according to his very expensive light meter..

All wold take a baseline image, with these settings. then move up one stop, every frame, for 5 frames. then down one fstop from baseline, per frame, for 5 frames..

Resulting in 11 pics, with +\- 5 stop variance..

Develop into prints, then have studens pick out the image that best represented the scene, as they remembered it. once that was done, he would take class back outside, have them stand in same spots as before and review again picking best image..

Swap places with another, then re-pick most representative image..

Rarely was any image out of the series chosen more than once, and few picked the actual baseline frame, the one the meter said was correct.Dave PattersonMidwestshutterbug.com'When the light and composition are strong, nobodynotices things like resolution or pincushion distortion'Gary Friedman..

Comment #22

GaryDeM wrote:.

"In some cases that will be true, but it's incorrect to say that theonly correct way to shoot is to avoid blowing highlights".

If you want to expose in such a way that you blow the highlights onyour images and still think that this is good exposure, go ahead..

Hi Gary. It depends on the scene. Your statement was that you should always avoid blowing highights. That simple isn't a valid way to shoot unless your photography is within a fairly narrow range of lighting conditions. there are heaps of situations where you have bright highlights that don't matter as much as exposing the rest of the scene correctly. Shots at night with street lights or shots inside where you see lights mean you have no choice but to blow highlights unless you don't want most of the detail in the scene to be captured..

In general, I agree with your idea of shooting to the right while avoiding blowing highlights, but only when it makes sense to do so. It just doesn't always make sense to do so. As I said, your statement is absolute when real world scenes don't always allow you to follow that 'rule' while still capturing the image in the best way possible..

Me, I prefer to get the the image inside the range of the sensor thenworry about the effect later. the only possible rreason to let thehighlights blow and not care would be if for some reason yourinterest in the exposure lay in another area of the scene..

Yes, which it often can..

This ofcourse assumes that you are talking about a single exposure for eachscene, and not dealing with blending or hdr..

If you plan to blend or use HDR, one or some of your exposures will blow some highlights so that you capture enough of the less bright parts of your image..

As far as auto levels is concerneed, you obviously do not know whatthat is. it is simply a pp control that change the overall brightnessof an image to the normal range by raising or reducing the brightnessof the entire image. it does not change individual parts of thedark/light sprectrum of light as you are trying to say with curves..

Auto levels doesn't work like that, nor does using curves lock you into having to use it in any particular way. You don't appear to understand how levels and curves work..

Auto levels adjusts the RGB channels individually so that there's a certain amount of clipping of black and white levels, and it also adjusts the levels midpoint to darken or brighten the scene overall. What I was saying with curves (or manual levels) is that you have control over changing the brightness of your image, including black and white points if you so desire, but just as importantly being able to raise or lower a point on the curve to affect overall brightness. Auto levels does the same thing, but just comes up with what it thinks is ok without your intervention, which may or may not be optimal. Only you can decide what's optimal. Auto levels can be a good starting point for further adjustments..

Auto level would be for a situation in which you exposed to the rightand later looking at it on your calibrated monitor, (it iscalibrated, right?),.

Sure is. If you're really interested, check my posting history. I've posted plenty on how that works as most people don't understand it..

The overall image appears to be bright than youwould like then autolevels would change then overall brightness tothe normal amount..

Normal doesn't have any real meaning when it comes to what looks like a correct exposure. As I said, you're letting the application make an automatic adjustment without you deciding what looks right. Auto levels may produce a result that looks right in many cases, but there will be times when you can do a better job by using a manual adjustment with levels or curves..

The effect also would reduce the noise level..

Not necessarily..

Itwould not change the dark/light of the light spectrum as curves would..

If you mean moving the black and white points, then using curves doesn't mean you have to move black and white points. You can if you want to, but that's only a part of what curves is used for. With curves, you can drag a point along the curve up or down, no differently from moving the mid point in levels, or what auto levels does (per channel)..

In any event if your exposure habit and method is to expose so thatyour light areas all turn pure white due to overexposure be my guest..

In situations where it makes sense..

I will continue to expose my images correctly..

Good luck with being able to do that without ever blowing highlights. Just be careful about advising people to always do something in a particular way when there are plenty of situations where you'll get better results by doing it a bit differently..

Cheers from John from Adelaide, South AustraliaJohn Harvey Photography http://johnharvey.com.auCanon 40D, Canon 20D & Fuji F10..

Comment #23

LightRoom wrote:.

I'd say that if you can't tell then it's correctly exposed. Oneshould know and manage as many technical aspects of photography asone can, but one should never forget that this shouldn't be a"straight-jacket" quite the oposite. Such a thing as correct exposurewithout considering the objective of the photo just doesn't exist..

Hi LR. I agree..

Trouble is that modern digital cameras as wonderful as they are.Aren't the best option for learning. What you need is a totaly manualSLR, focus included, with a 50mm equivalent lens. and set it to B&W(to avoid colour temperature issues).

No problem with going back to basics, but I think a DSLR makes it much easier to do what you're saying and get ready feedback to make the whole learning process much easier, quicker and more effective. I couldn't have learned nearly as much as quickly as I did by using a film camera and most people I talk to feel the same with their own experiences..

Cheers from John from Adelaide, South AustraliaJohn Harvey Photography http://johnharvey.com.auCanon 40D, Canon 20D & Fuji F10..

Comment #24

Cheers from John from Adelaide, South AustraliaJohn Harvey Photography http://johnharvey.com.auCanon 40D, Canon 20D & Fuji F10..

Comment #25

Some people say this photo is a little overexposed, but it looks fine too me.

Image control:Zoom outZoom 100%Zoom inExpand AllOpen in new window..

Comment #26

Yes. It looks equally good a little darker but that is to a large extent a matter of taste..

The histogram for this pic shows a sharp cutoff at the right hand end, indicating an area of 'blown' (bright white with no detail) highlights. That is obviously the area of roof on the far shoreline just above the middle of the pic. If it was made of reflective material, in bright sunshine, it is not surprising that it looks the way it does. Maybe if you had used a polarising filter, which selectively darkens some types of reflection, this area would not have been overexposed. You can selectively darken it if you like in Photoshop by drawing a lasoo around it, feathering the edges of the selection, and using the 'darken highlights' tool..

Best wishesMike..

Comment #27

First I am talking about normal outside scenes with pics taken during daylight..

No it does not depend on the scene. if the histogram is touching the right wall then it is blown and overexosed, period. what iof any use an overexposed scne has is up to the user. me, I delete them..

You want to shoot some other way so the highlights in your pics turn pure white with no details, go ahead. me, I am not doing this for the exercise. I want to see details in all parts of the image I took..

Why would you even say what you did about blending or hdr? your remarks just donot make sense unless the only purpose is to argue with someone. if you shot a 9shot hdr 1 stop apart 4 of the pics will have blown highlights. this I assume you knew..

Auto levels do work like that. it attempts to change the overall lighimg of a scene back to the 18% normal level. if a scene is brighter, say 36%, then when it it reduced to 18% the light level of the scene goes down. but so does the noise proportionately. if the scene is is darker than 18% and auto level is used then the scene will be actually noisier than it was at the beginning, though the light level will, appear as normal 18%. this is the reasoning for the saying"always shoot to the right".



Normal lighting does have a real definition and that is an 18% reflectance of light falling on it. this is the level to which all light meters are set and auto buttons on the pp software..

Curves are really designed and intended to be used to change parts of the light spectrum. that is why they call it curves. you can pick many points to act as anchors to change the curve from. auto levels changes the whole light level as a unit. I am talking auto levels NOT levels..

The question and answer I was replying to was a GENERAL question not a specific one. therefore the answerer, me gives a general answer. you should have know that and omitted the lecture. I do not need it or want it. and why would anyone make such unpleasant remarks on a photography forum is beyond me..

This and the other forums are supposed to help the other photographers with helpfull advice. you seem to have forgotten this...

Comment #28

Devnull wrote:.

I remember you did ask a question about the need of metering inmanual modes... and did not even try to digest the answers.Back to the metering question. Learn to use a meter. Learn what itdoes and how it does it. You don't need to buy one, you have aperfectly good one in your camera. After you understand this, you'llbe able to look at a image and say it's 1 stop underexposed.Basically, one knows how shiny certains things are.Yep, it's Photography 1.0 Pack.

It runs on Brain 1.0.

Come on, lighten up. The original post was reasonable, no need to knuckle rap the poster. I expect that sort of thing on the other brand-specific and pro-user forums, but it's out of place at this level. We're all here to learn and there aren't any bad questions..

It's only rock n' roll after all...Brian..

Comment #29

GaryDeM wrote:.

First I am talking about normal outside scenes with pics takenduring daylight..

Gary, you're limiting the range of scenes that many photographers, including beginners, typically take. Backlit scenes, for example, are a common enough situation to have to deal with and I've seen beginners confused many times about why their images are underexxposed, ie the subject is way too dark. Your rule of thumb about not blowing highlights is great under favourable lighting conditions, but many photographers, including beginners, won't always have those conditions to shoot in..

No it does not depend on the scene. if the histogram is touching theright wall then it is blown and overexosed, period..

If a part of the scene is overexposed, it doesn't necessarily mean the whole scene is overexposed. It depends on the scene. In general, I agree with you that it's better not to blow highlights and for many/most scenes that's a good rule to follow..

What iof any usean overexposed scne has is up to the user. me, I delete them.you want to shoot some other way so the highlights in your pics turnpure white with no details, go ahead. me, I am not doing this for theexercise. I want to see details in all parts of the image I took..

In some scenes, doing that will mean underexposing to the point that you lose/compromise too much darker detail and/or the subject you're really interested in, and you can't always take more than one exposure to blend later..

Why would you even say what you did about blending or hdr?.

My apologies. I misread what you had said. Not arguing for the sake of arguing..

Auto levels do work like that. it attempts to change the overalllighimg of a scene back to the 18% normal level. if a scene isbrighter, say 36%, then when it it reduced to 18% the light level ofthe scene goes down. but so does the noise proportionately. if thescene is is darker than 18% and auto level is used then the scenewill be actually noisier than it was at the beginning, though thelight level will, appear as normal 18%. this is the reasoning for thesaying"always shoot to the right".

This is the level to which alllight meters are set and auto buttons on the pp software..

I've had a closer look with more sample images and what auto levels appears to do is to adjust the black and white points on a per channel basis to the point of clipping black and white in each channel without seeming to move midpoint brightening, although I could be wrong about no midpoint adjustment..

Auto levels on my range of sample images didn't make them an average of 18% grey, regardless of levels option settings. Even images already much brighter than 18% grey were adjusted by auto levels to still clip the R, G and B channels at both the black and white ends of the spectrum. Auto levels made them as bright and contrasty as possible within certain limits set in levels options..

An average of 18% grey in a scene doesn't mean it's correctly exposed, regardless of whether that's what light meters measure. It varies from scene to scene. To 'correct' to 18% grey doesn't necessarily mean the exposure is correct for your output image..

Curves are really designed and intended to be used to change parts ofthe light spectrum. that is why they call it curves. you can pickmany points to act as anchors to change the curve from. auto levelschanges the whole light level as a unit. I am talking auto levels NOTlevels..

OK, but curves can still be used to just change the black and white points, just as levels can be, and as auto levels appears to do. This is how auto levels appears to change the image brightness 'as a unit' without brightening different parts of the spectrum differently, as would happen if you changed the midpoint adjustment in levels, or dragged a point up and down in curves..

If you think auto levels changes brightness some other way, then how do you think it does it?.

The question and answer I was replying to was a GENERAL question nota specific one. therefore the answerer, me gives a general answer..

The answer you gave would work for many situations, but not for some, as I've explained. The nature of what each of us shoots determines the split between those photos that make sense to take without blowing any highlights and those where you lose too much if you don't blow any highlights..

You should have know that and omitted the lecture. I do not need itor want it. and why would anyone make such unpleasant remarks on aphotography forum is beyond me.this and the other forums are supposed to help the otherphotographers with helpfull advice. you seem to have forgotten this..

And you really think that it's better for you to unknowingly give incorrect advice than for someone like me to explain things more accurately? You seem to find it unpleasant for anyone to offer an alternative to your own without considering the possibility that the alternative might be right. I don't think I used offensive language, but sorry if I have offended you..

I'm sure you're a nice, helpful guy and I think I am too. We probably both are. You ask why I bothered saying what I did because you're convinced that you're giving the right advice. I thought your advice could be better and I wanted to set the record straight. We're both trying to provide useful information, nothing more..

I'm more than happy to discuss via email if you prefer and I'm more than happy to admit I'm wrong if you or someone else can prove that I'm wrong..

Cheers from John from Adelaide, South AustraliaJohn Harvey Photography http://johnharvey.com.auCanon 40D, Canon 20D & Fuji F10..

Comment #30

Gary, I've looked a bit more at auto levels to make sure I'm understanding what it's doing..

Levels options 'snap neutral midtones' changes the midpoint adjustment on a per channel basis, which is the same as moving a point on curves up or down for each channel..

The first algorithm in levels options, enhance monochromatic contrast, seems to be the only one of the three that doesn't aim to pretty much fill the available spectrum with all three channels, but as far as I can see, it still doesn't try to make the image an average of 18% grey. Maybe I'm missing something obvious. Are you able to show me something that says how to get auto levels to adjust the image to 18% grey?.

I just want to make sure I'm understanding correctly so I use it properly and pass on the right information to others as the situation arises..

Cheers from John from Adelaide, South AustraliaJohn Harvey Photography http://johnharvey.com.auCanon 40D, Canon 20D & Fuji F10..

Comment #31

Click Here to View All...

Sponsored Amazon Deals:

1. Get big savings on Amazon warehouse deals.
2. Save up to 70% on Amazon Products.


This question was taken from a support group/message board and re-posted here so others can learn from it.

 

Categories: Home | Diet & Weight Management | Vitamins & Supplements | Herbs & Cleansing |

Sexual Health | Medifast Support | Nutrisystem Support | Medifast Questions |

Web Hosting | Web Hosts | Website Hosting | Hosting |

Web Hosting | GoDaddy | Digital Cameras | Best WebHosts |

Web Hosting FAQ | Web Hosts FAQ | Hosting FAQ | Hosting Group |

Hosting Questions | Camera Tips | Best Cameras To Buy | Best Cameras This Year |

Camera Q-A | Digital Cameras Q-A | Camera Forum | Nov 2010 - Cameras |

Oct 2010 - Cameras | Oct 2010 - DSLRs | Oct 2010 - Camera Tips | Sep 2010 - Cameras |

Sep 2010 - DSLRS | Sep 2010 - Camera Tips | Aug 2010 - Cameras | Aug 2010 - DSLR Tips |

Aug 2010 - Camera Tips | July 2010 - Cameras | July 2010 - Nikon Cameras | July 2010 - Canon Cameras |

July 2010 - Pentax Cameras | Medifast Recipes | Medifast Recipes Tips | Medifast Recipes Strategies |

Medifast Recipes Experiences | Medifast Recipes Group | Medifast Recipes Forum | Medifast Support Strategies |

Medifast Support Experiences |

 

(C) Copyright 2010 All rights reserved.