Go Back   Steve's Digicams Forums > Digicam Help > General Discussion

Reply
 
Thread Tools Search this Thread
Old Jan 23, 2010, 12:02 PM   #1
Junior Member
 
Join Date: Jan 2010
Location: North Carolina
Posts: 11
Default How I balance exposure - is this acceptable?

I hope to explain a technique I’ve been using to balance exposure with my camera, and hopefully get some feedback how I might improve in this area …

A little about the camera … Kodak Z1012is - includes manual mode, shutter priority mode, aperture priority mode, and a long list of other features. It seems the full aperture range is f/2.8 – f/8.0 but is limited in this range dependent upon other settings such as zoom level. It seems the full shutter range is 1/1000 – 16.0”, ISO range of 64 – 3200, exposure compensation range of +/-2.0 EV with 1/3 EV steps, and lastly a flash compensation range of +/-1.0 with 1/3 steps. (Note: I disable the flash altogether … haven’t found a scenario outdoors that I would want a flash)

I graduated from “auto” mode just a couple of months ago. I spent some time using the Program mode which allows adjusting ISO and exposure compensation only, and the camera automatically selects aperture and shutter speed. Using the Program mode (or only adjusting ISO and exposure compensation) for a while gave me a pretty good sense of how to balance exposure.

More recently I’ve been spending all my time in the manual mode and learning how all of the adjustments have an affect upon the other components. Manual mode on this camera allows adjustment of aperture, shutter speed, ISO, and flash compensation – and the camera automatically adjusts exposure compensation.

How I’m using the manual mode: Since I mentioned the manual mode automatically adjusts exposure compensation, this is the indicator I’ve been using to determine if my shot is “properly” exposed (or meets my taste). For instance, I may decide upon a particular aperture and ISO – let’s call it f/3.2 and ISO 100. If I set shutter speed at 1/125, I notice the camera decided to adjust the exposure compensation to -6.7 EV. I already know this shot will be underexposed; what to do?? If I’m determined to have f/3.2, the only thing I can do is decrease shutter speed or increase ISO to brighten the exposure. I may have to decrease shutter speed all the way to 0.5”, or increase ISO to 3200 so the camera will adjust exposure compensation to the neighborhood of -1.0 to -1.3 EV. As of today, my personal preference would be to leave ISO at 100, and decrease shutter speed to 0.5”. Had I decided upon f/8.0 to begin with, obviously the numbers would have been different but I would have taken the same approach to adjust the EV towards a setting I know provides a better light/dark balance.

This camera does provide an exposure histogram but frankly I don’t get it. I have never been able to satisfy this histogram!

So that's the best way I can describe the technique I've learned (or taught myself). Is this a normal means of making adjustments (or compromises) with exposure settings? My impression is this camera is, to some degree, SLR inspired. I feel some SLRs would behave in the same manual mode.

Thanks for taking time to read this! I would appreciate any experience you could share with similar technique!
__________________
Kevin Childress
http://www.panoramio.com/user/2367993
Kevin Childress is offline   Reply With Quote
Sponsored Links
Old Jan 23, 2010, 1:32 PM   #2
Senior Member
 
Join Date: Aug 2009
Location: NYC
Posts: 1,990
Default

So that's the best way I can describe the technique I've learned (or taught myself). Is this a normal means of making adjustments (or compromises) with exposure settings? My impression is this camera is, to some degree, SLR inspired. I feel some SLRs would behave in the same manual mode.

Thanks for taking time to read this! I would appreciate any experience you could share with similar technique![/QUOTE]


"My impression is this camera is, to some degree, SLR inspired."

Well, if the camera, and not you, adjusts exposure compensation, I would find this a serious fault. Are you sure such is the case? Are you sure you cannot disable this?

I generally shoot full manual, but will, from time to time, use spot metering, and then lock the camera onto that exposure, move my focus point to the desired subject and shoot. So, even though in such cases I'm in one form or another of auto, I can still control the exposure.

Dave

Last edited by Chato; Jan 23, 2010 at 4:11 PM. Reason: Typos
Chato is offline   Reply With Quote
Old Jan 23, 2010, 4:09 PM   #3
Senior Member
 
VTphotog's Avatar
 
Join Date: Mar 2005
Location: Extreme Northeastern Vermont, USA
Posts: 4,214
Default

Is the camera actually adjusting the exposure comp, or is it just informing you that that is what it reads the scene as? If you shoot manual and the picture is over or under- exposed, the camera isn't doing any adjusting, just giving its opinion of the proper exposure. Reading a histogram can take some time and experience. The graph is simply showing you the percentage of the scene (the vertical axis) from dark to light (the horizontal axis). You don't have to satisfy the histogram, you adjust camera settings to make the histogram change to satisfy you. You really can't change the overall shape of the graph (unless you use flash or other artificial lights), but you can change the position of the graph on the horizontal axis by adjusting exposure.
In order to understand better how the various controls affect your picture, you might want to try taking several shots of the same scene, starting in auto, switching to program and making a change - look at what the camera then changes in response. Then move to manual and change the aperture, to see the effect on shutter speed and ISO. Or change shutter speed and see how aperture is affected. And so on. If your camera has an aperture priority mode, try using it to control your depth of field and watch what happens with shutter speed and ISO.
There is no magic to proper exposure, just experience and judgement for how you want the final result to look.

brian
VTphotog is offline   Reply With Quote
Old Jan 23, 2010, 8:30 PM   #4
Junior Member
 
Join Date: Jan 2010
Location: North Carolina
Posts: 11
Default

Quote:
Originally Posted by VTphotog View Post
...Is the camera actually adjusting the exposure comp, or is it just informing you that that is what it reads the scene as? If you shoot manual and the picture is over or under- exposed, the camera isn't doing any adjusting, just giving its opinion of the proper exposure.
Quote:
Originally Posted by Chato View Post
...Well, if the camera, and not you, adjusts exposure compensation, I would find this a serious fault. Are you sure such is the case? Are you sure you cannot disable this? ... I generally shoot full manual, but will, from time to time, use spot metering, and then lock the camera onto that exposure, move my focus point to the desired subject and shoot.

Dave and Brian, You both mention something that suddenly made a lot of sense. You both point out the camera is not actually changing the exposure compensation, but is in fact displaying its "read on the scene" - this combined with the comment of "spot metering" ... ... I take your point exactly.

So assuming my original scenario ... by "spot metering", you mean pointing the camera in a direction that drives the EV to a more acceptable reading, pressing the shutter button half way to retain this setting, then capturing the photo?
__________________
Kevin Childress
http://www.panoramio.com/user/2367993
Kevin Childress is offline   Reply With Quote
Old Jan 23, 2010, 9:21 PM   #5
Senior Member
 
Join Date: Aug 2009
Location: NYC
Posts: 1,990
Default

Quote:
Originally Posted by Kevin Childress View Post
Dave

So assuming my original scenario ... by "spot metering", you mean pointing the camera in a direction that drives the EV to a more acceptable reading, pressing the shutter button half way to retain this setting, then capturing the photo?
Yes. Part of this comes with experience. Keep in mind that your camera often meters the entire frame, while your subject might very well be much lighter or darker.

However, I've never heard of a camera which adjust exposure compensation. Sounds odd to me, but then again, I am constantly being surprised by how manufacturers set up their products...

Dave
Chato is offline   Reply With Quote
Old Jan 24, 2010, 11:11 AM   #6
Senior Member
 
Tullio's Avatar
 
Join Date: Jan 2006
Posts: 7,370
Default

Quote:
Originally Posted by Kevin Childress View Post
How I’m using the manual mode: Since I mentioned the manual mode automatically adjusts exposure compensation, this is the indicator I’ve been using to determine if my shot is “properly” exposed (or meets my taste). For instance, I may decide upon a particular aperture and ISO – let’s call it f/3.2 and ISO 100. If I set shutter speed at 1/125, I notice the camera decided to adjust the exposure compensation to -6.7 EV. I already know this shot will be underexposed; what to do?? If I’m determined to have f/3.2, the only thing I can do is decrease shutter speed or increase ISO to brighten the exposure. I may have to decrease shutter speed all the way to 0.5”, or increase ISO to 3200 so the camera will adjust exposure compensation to the neighborhood of -1.0 to -1.3 EV. As of today, my personal preference would be to leave ISO at 100, and decrease shutter speed to 0.5”. Had I decided upon f/8.0 to begin with, obviously the numbers would have been different but I would have taken the same approach to adjust the EV towards a setting I know provides a better light/dark balance.

This camera does provide an exposure histogram but frankly I don’t get it. I have never been able to satisfy this histogram!
Well, it seems like you got an understanding of how the three settings that affect exposure, work. Now we need to fine tune it a little. First, let me state that there will be lots of situations where your preferred settings will simply not work, period. Why, because of the ambient light conditions you are shooting in.

Let's start with the ISO since you were emphatic about keeping it at 100. This is an ideal ISO value to keep noise (created by high ISO settings) non-existent (or very close to it depending on the camera). However, shooting at this ISO requires a lot of light. Or does it? Well, not necessarily...that will takes us to the second setting, shutter speed.

If you don't want to increase the ISO and wish to shoot wide open (or close to it depending on the camera lens - we will cover aperture next), you still need light but not as much since the wide open aperture will assure that a lot of light reaches the sensor. However, you also want to keep the shutter fairly fast (1/125) and now all of a sudden the combo may not work unless you have a lot of light not just some light. Why? Because even though the aperture is wide open (or close to), the ISO is very low which requires more light and the shutter being too fast is not allowing enough light in.

OK, when you use Manual mode to adjust these three settings, the Exposure is simply a gauge (a monitor to assist you). In the old film days, cameras had this little needle inside the viewfinder. The needle was placed on the right of the VF with a vertical line running next to the edge. At the top there was a + sign, 0 in the middle and - at the bottom. That was the Exposure meter. As we adjusted the two settings (aperture and shutter speed - remember that in the old days there was no ISO setting. One would buy a fast (400 ASA) or slow (100/200 ASA) film), the needle would move up indicating over exposure or down for under exposure. The ideal was to keep it in the middle for proper exposure. One of the major differences between film and digital technologies is that with film cameras, 99.9% of the time the exposure would be spot on if the needle was right at 0 (in the middle). With digital, that's not the case. Some cameras have the tendency to over expose while others will under expose. As a result, keeping the Ev at 0 may not result in the best image quality for that particular camera. This is something one learns over time as one gets more and more familiar with one's camera. So, in manual mode the camera is really not adjusting the Exposure in any way but telling you what it is based on the settings you chose.

Moving on, let's talk aperture. This is the one setting that differentiates P&S from DSLRs. The reason is because of the difference between the fixed lens vs. swappable lens technologies. The two technologies affect the results of the aperture value in vary significant ways. The aperture is responsible for one primary thing...to let (or not to let) light get into the camera. The more open the aperture, the more light gets in (and vice-versa). The second most important phenomenon caused by the aperture (and let's be sure that we understand that this is not a feature), is the affect in Depth of Field. The wider the aperture, the shallower the DoF (for short). That means, the wider the lens, the blurrier the image will look behind the object being in focus. This is an important effect that will really impact the outcome of a photo. Sometimes the photographer wants to emphasize the subject and nothing else while other times having a clear background is crucial to the composition. The intensity of the DoF effect is determined by the size of the sensor. The smaller the sensor, the less DoF you get. This is the primary reason why P&S cameras don't produce images with a very blurred background, no matter how wide the aperture is. The sensor cropping factor limits that. Full frame cameras on the other hand, offer a very shallow DoF at wide open apertures.

To wrap this up, lets talk about aperture and how it will affect your exposure. Since your camera is a P&S, we know you will not obtain a real shallow DoF, no matter how wide you keep the aperture. In fact, unless this is really your intention, I would not keep the aperture at its widest value because that's not ideal for sharpness. The wider the aperture, the less sharp the image will become. The thing is, in your scenario, you are already bumping against limitations caused by the lack of light so reducing the aperture is not an option. That will leave you with two choices. Increase the ISO or reduce the shutter speed (or a combination of the two). I'd go with option #3. The reason is because the camera has image stabilization, which will save you a couple of fstops. That means, unless you are shooting action, it is safe to bring the shutter down to 1/30. However, that alone is not enough to put the Ev at (or close to) zero. So, you'll have to raise the ISO to 400 or even 800. If 800 is not enough, you are probably in a very low light situation. Reducing the shutter further will eventually produce blurred images due to camera shake (and that you can not fix in PP, unlike ISO noise which can always be cleaned up some). You might want to consider a tripod, which will then allow you to really reduce the shutter speed, keep the ISO to reasonable levels and obtain sharp images.

Hope this helped some.
__________________

Tullio

Last edited by Tullio; Mar 5, 2010 at 7:04 PM.
Tullio is offline   Reply With Quote
Old Jan 24, 2010, 12:54 PM   #7
Junior Member
 
Join Date: Jan 2010
Location: North Carolina
Posts: 11
Default

Tullio,

Wow! What a great description! Thank you for taking the time to convey all of this!

Kevin
__________________
Kevin Childress
http://www.panoramio.com/user/2367993
Kevin Childress is offline   Reply With Quote
Old Jan 24, 2010, 10:26 PM   #8
Senior Member
 
Tullio's Avatar
 
Join Date: Jan 2006
Posts: 7,370
Default

NP. Thanks for taking the time and read.
__________________

Tullio
Tullio is offline   Reply With Quote
Old Mar 5, 2010, 6:01 PM   #9
Senior Member
 
Join Date: Feb 2010
Location: tr
Posts: 224
Default

@Tullio, i was searching forum for locking exposure then i saw this thread and i read it, that is piece of great explanation for a beginner like me. Thank you.
imut is offline   Reply With Quote
Old Mar 5, 2010, 7:07 PM   #10
Senior Member
 
Tullio's Avatar
 
Join Date: Jan 2006
Posts: 7,370
Default

You're welcome, imut. I'm glad it all made sense.
__________________

Tullio
Tullio is offline   Reply With Quote
 
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -5. The time now is 11:03 AM.