Exposure in Auto and Manual modes

[ksasidhar]

Hi all,

I am new to photography and was learning to use manual mode for correct exposures. I tried taking a pic of my hall. I tried using combination of different shutter speeds, aperture size and ISO to get the correct exposure. However, every time I found the light shaded curtain being over exposed. When I took the same shot using auto mode, I found the exposure to be balanced. But the picture did not have natural white color to it.

The manual mode picture shown here is taken at shutter speed 1/10, aperture f/3.8, ISO 320 and focal length of 24mm on Nikon D7000.

Please follow the link to the pictures and their histogram. Any suggestions for improving the photo shot in manual mode will be helpful. Thanks in advance.

Auto Mode
Auto Mode Exposure
Manual Mode
Manual Mode Exposure

 

[The_Traveler]

The isn't a way to make a single exposure that will give you what you want straight out of camera because any exposure that will correctly illuminate the chairs will blow out the curtains.
As you can see from the histogram, raising the exposure to correctly expose the room ( move the part of the curve that represents the darkness of the room) will blow out the curtains (push that part of the curve that is the windows off to the edge.)

This can be edited simply to raise the exposure on only the midtones and shadows but the light is still very flat and relatively unappealing

 

[ksasidhar]

Thanks for your reply. The picture that you have attached is a shot taken in auto mode. I wanted to see if I can achieve the right light exposure without having to edit it later. So I tried the manual mode with setting explained in the earlier post.

If I understand you correctly, it does not seem possible to achieve correct exposure in either manual or auto mode for this picture.

 

[Overread]

Dynamic range
This is the term which you need to look up as the scene you have exceeds the dynamic range of the camera. Basically dynamic range is the range in values between the brightest and darkest points in a photo. The camera has a limitation as to how wide a range of differences it can put into a single exposure; our eyes have the same limitation however we resample and move our eyes around very fast when viewing a whole scene so we can adapt to solve the solution.

You can tell the dynamic range of a scene by setting the metering mode to "spot" metering and pointing the middle focusing point at the darkest and brightest points; if you keep aperture and ISO fixed (eg in aperture priority mode) and then read the shutter speeds you get for each then the difference in the number of stops between the two shutter speeds should give you a rough idea of the dynamic range of the scene.


Now of course many times you will have this issue so there are a few work-arounds:
1) Reduce the dynamic range of the scene; this might mean add more light to the dark areas; blocklight from the brighter or a combination of the two. A fix in the scene you have here could be to use flash lighting to add light to the interior areas so that the range between those darker indoors areas and the bright outside is less.

2) Accept that there are limits and work within them; typically (esp for digital) this will mean letting some shaded areas go fully black whilst exposing for the highlights (brightest) parts of the scene. Whilst its true that pure overexposure only records white and no detail and pure underexposure only records pure black with no details (on digital - film is different) typically we are more accepting of pure-black shadows than brilliant blown out whites in a scene.

3) Use Tone Mapping or HDR. HDR involves taking a series of shots at different exposures so that you can correctly expose for a range of values within the dynamic range; thus letting you cover the whole range with good exposures. You then use software to blend the resulting shots together.
As such you'd ideally want to keep most settings the same and only vary one; in this kind of shot it would be a case of using manual mode and keeping the aperture and ISO the same and varying the shutter speed (if you do the test I mentioned above to find the shutterspeed for the brightest and darkest spots you can then use those extreme limits and a range of values of shutter speed between them; knowing that you should get the whole scene).

I would suggest further googling on the subjects of:
Dynamic range
HDR (high dynamic range)
Tone-mapping (which is like HDR but involves only one photo and using editing to bright out the darker spots)

You can then go further into lighting methods for rooms and scenes if you so desire

 

[soufiej]

Thanks for your reply. The picture that you have attached is a shot taken in auto mode. I wanted to see if I can achieve the right light exposure without having to edit it later. So I tried the manual mode with setting explained in the earlier post.

If I understand you correctly, it does not seem possible to achieve correct exposure in either manual or auto mode for this picture.

It's quite possible that is a correct statement. You are not at the point, however, that you would have realized this before you tried taking the shot. Experience will teach you why this is a very difficult shot for any camera in any mode.

We have not yet arrived at the point where a digital camera has the same dynamic range as the human eye. (Nor does our camera possess the cognitive abilities which allow our mind to formulate what our eyes send it as data and to create from that data a "perceived" whole. This is, in many ways and in many areas, very important to understand; perception is reality but reality is not perception. In photography, most often you are striving for an acceptable middle ground between the two.)

Any attempt to capture the extreme dynamics of that range will either fail or require other means (normally HDR) to succeed. HDR would take two (or more) otherwise identical shots but using different exposure values and those multiple images would be blended in post production or in (some cases by) the camera's internal electronics into one final image which achieves that middle ground value overall.

I would guess your manual shot is more similar to what you actually saw in the room at the time you took the shot. Your eyes can send a signal to your brain which will result in a perception of the bright window as not blown out but the rest of the image is probably properly exposed. That's really the lesson to take from this sort of image - your camera has set limits - and not anything to do with exposure itself.



First, I find it less helpful for a student photographer to work in full manual mode. If you're still relying on the camera's light meter, then you aren't really understanding much IMO anyway unless you fully understand how the camera operates in each shooting mode. This information is typically well beyond the scope of most students and most lesson plans. What you're probably missing is the manner in which the camera adjusts itself in "auto" and in "manual".

Without trying to insult anyone, full auto mode is for "dummies".

That said, it can be very instructional to the student photographer. You have to admit, you aren't exactly well informed nor are you experienced so, in a sense, you are still a "dummie". By using full auto mode, the camera can take away many of the confusing elements of photography and allow you to focus your efforts on other values.

Consider how you would learn any other skill. If, say, you wanted to learn how to play a musical instrument, would you begin your studies by playing the last exercise in your lesson book? No, you'd be in well over you head when it comes to comprehension of what is on the page and how to translate it to a pleasing result.

You would begin with fairly simple exercises which instruct you in the most basic elements of performance. Where and how to place your fingers. How to control your breathing. How to read music and its notations. How to translate what you are reading into a language which is performance. You would learn individual notes and how they fit into a scale and how a scale fits into a key signature before you began playing chords. Then you would learn how chords fit into a chord progression based on the key.

And so on.

By approaching your camera and your learning process in photography in a similar manner; simple moving to less simple leading to more complex, you will find your education is more complete, more comprehensible and more effective.

Therefore, don't discount the value of working in full auto if, say, you are working on composition. By only looking at what is in the viewfinder and allowing the camera to do the rest, you can more fully comprehend where you need to work in composition.

First, though, you must understand just how your specific camera operates in auto mode and this is seldom spelled out in the owner's manual. It is a fairly safe bet the camera is making adjustments based on the best overall exposure and focus point(s). "Best" has been decided by the software designers based on thousands of shots taken by less skilled photographers' complaints about poor results. The camera meters in a specific way (usually a very broad overview of the frame) and computes the exposure settings for the least objectionable photo. This more or less guarantees fewer bad photos but also restricts the number of very good photos.

You (and others) can take some very good photos using full auto mode but this "averaging" of values tends to produce what eventually will begin to look more and more like the same thing. If you don't mind average looking photos or don't care to delve into the effort required to take more than average looking photos, you can be content with full auto for many years.

If, however, you are looking for a more refined result, you have to learn you will also have a higher number of subjective failures. Your photographic eye is becoming more discriminating and you will notice more defects which you will work to avoid in your next shot and your next lesson. And you will rather quickly notice that every scene presents its own problems and its own promise.



Relating this to your examples, how does full auto relate to what you actually saw in the room at the time you took the shots? If the manual exposure shots show a chair and other features in the room with a more accurate look, then you can tie the results of the full auto mode shots to how the camera adjusted metering. If you knew how the camera metered in full auto, you could probably duplicate the auto results in manual. Of course, if that were your goal, you would simply stay with auto and not bother will all the adjustments manual requires.

Personally, I just don't feel a student needs to worry about fully manual adjustments any more than the student musician needs to worry about playing more complex scores. It will all come with experience if you apply the time and effort to your studies. What the student should learn, IMO, is how the camera works in each available mode. There are reasons for each option your camera designer has provided. They are not to be ignored but used when they are appropriate.

As you can see, your histogram of the auto shot is not really what you want when shooting in a more "creative mode". You've wasted the right side of the graph. You've placed most of the shot's data at the "wrong" end of the graph. Assuming you left the camera in the same position and took the two shots within a few seconds of each other, you can see the results of the camera making these adjustments in auto mode. You have a very "average" shot which takes no chances in any one direction. As a more experienced photographer, you will eventually learn when and how to take those chances.

IMO your learning process should include looking at the histogram to realize what the camera would do on its own and then learning to make adjustments which suit your vision of the scene. You should recognize you have control over the histogram in other than auto mode. Why? because you have control over the metering. If you change metering, you can't expect the camera to turn out identical results.

From there you learn what metering does for you in other than auto mode. When do you select "this" metering and when should you select "that" metering.

Same for focus points.

In auto, your camera will frequently select from a very wide set of focus points. Not always, this is why you have those little icons for landscape and portrait and so forth. By staying in auto mode but instructing the camera to move to another set of pre-selected conditions, you are asking the camera for different pre-selected results.

Or by using the more manually controlled settings, you can select just how the camera operates.

But, in the end, a student using full manual mode is like tossing a non-swimmer into the deep end of the pool. "Sink or swim" teaching methods are about as effective, IMO, as housebreaking your dog by rubbing its nose in the poop you found two hours after the dog relieved itself. You aren't becoming more like the professional photographers by using full manual mode. You are probably just becoming more confused. So is your dog.



What learning system have you been working through? I'm unaware of any modern method which suggests you begin shooting in manual until well after you understand how the camera meters and establishes focus in its auto modes.

 

[The_Traveler]

1390 words.

That might be some sort of record.

 

[Designer]

1390 words.

That might be some sort of record.

I wouldn't ask for it any other way!

 

[soufiej]

1390 words.

That might be some sort of record.

Possibly, though maybe not.

That you actually counted?

Fer'sure!

 

[The_Traveler]

copy/paste in Open Office.

You could save yourself some effort.
One picture is worth a thousand words.
You could actually post a picture and get get 390 words change.

 

[soufiej]

Yes, but one problem with that is I generally work on forums from a Chromebook.

The Chromebook software doesn't allow me access to many of my photos.

 

[The_Traveler]

Yes, but one problem with that is I generally work on forums from a Chromebook.

The Chromebook software doesn't allow me access to many of my photos.

My guess would be that, if you wanted to post photos, you could find a way around that problem.
Lots of people use Chromebooks.
I used a Linux laptop and could easily upload pictures to my site, then grab the hot links.
The Chrome OS couldn't be much less able.

 

[soufiej]

You seem convinced.

 

[The_Traveler]

It is much more helpful to provide exempars for new photographers rather than just streams of words.

 

[soufiej]

Fine, but I have no HDR photos.

Pretty sure I have no full auto photos.

I almost always shoot in RAW.

Chromebook doesn't handle RAW.

I think my words may have to do.

 

[The_Traveler]

You could actually post in other subfora that would match the content.

You are generous with words, why not with images?