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07/10/2005 01:01:00 PM · #1 |
DPC Mentorship – Rules of the Road
Group: Exposure
Mentor: Digital Quixote
Students: cpickett, tjbell05, suemack, Britannica, sheapod, papagei
NON-MEMBERS PLEASE READ, TOO:
1. If you are not an active member of this mentorship group, please feel free to follow this thread. It is not intended to be exclusionary - we hope everyone can learn from it.
2. If you are not an active member of this group but have a question or comment, please send it directly to the moderator by Private Message. The moderator will either answer you directly or post your comment and their response to the thread. Thank you for understanding that we are trying to keep these groups small and on-topic. If this experiment takes off, we plan to start more groups to try to accommodate as many people as we can.
3. Mentors are volunteers with jobs and/or families. They're human too, and may make mistakes on occasion. If you feel the burning need to criticize them, point out a mistake, or point out your own infinately greater knowledge in they subject they are teaching, please do so in a PM to the mentor, not in this thread.
4. Have fun learning!
P.S. To see updated group information, see my profile.
Message edited by author 2005-07-12 16:54:56. |
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07/10/2005 04:22:07 PM · #2 |
Looking forward to learning anything I can. Also, just wanted to thank Prof. Quixote for agreeing to do this.
Message edited by author 2005-07-10 17:49:20. |
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07/10/2005 07:11:45 PM · #3 |
Okay, here we go. I PM'd each member of our little band to see what you all want to focus on, what exposure problems you're trying to solve or exposure objective you want to achieve. For the record, these are the current members:
cpickett
suemack
Britannica
sheapod
papagei
jtf6agent
tolovemoon
bcoble
Digital Quixote (mentor-in-training)
I have received additional requests to join but I'm beginning to worry about workload and losing the personal nature of the group. For now, I don't think we're ready to accept additional members.
I've heard back from 3 of you and am waiting on the rest. I have a couple of assignments in mind which I'll revise when I've heard from everyone. I expect that we will be learning by doing and learning from each other.
In the mean time, I'll share with you how I think about exposure.
When I take a picture, I think about the light falling on the sensor. There are a few things going on with the camera that influence light falling on the sensor. Aperature (how open the lens is), Shutter Speed (how long it's open), and ISO (how sensitive is the sensor). So my job as a photographer is to choose the values for these factors to get the photo I want. Often, I am working with my camera in semi-automatic mode and choosing one (aperature in my case) while the camera does the rest. Rarely will I do it all manually. In any case a light meter (either in the camera or a separate meter) is essectial to getting the exposure I want. And that light meter will have settings I might influence. Is there another camera factor that would influence exposure?
Outside the camera, exposure has to do with the light available to be captured by the camera. The light might be reflected from the subject, from non-subject elements in the field of view or possibly generated from backlights of some kind. So part of my job as a photographer is to evaluate the light available and manipulate the camera settings or my position relative to the subject to control the exposure.
So while I wait to hear back from everyone, here is your First Challenge: 1a Think about how you normally shoot a picture considering the factors above and tell us what's normal for you. Do you shoot in fully automatic mode with the camera making all the decisions? Do you shoot in Aperature-Priority or Shutter-Priority mode so you can control those aspects? Do you choose ISO or do you let the camera choose it? Now, go back to your photos and find one you shot in your normal way that turned out well and one that disappointed you. Upload the straight-from-the-camera photos to your portfolio and post the thumbs here. In the photographer's comment section, share your thoughts about what was good about the one you liked and what disappointed you in that one. And First Challenge 1b: Look at each photo posted by the group's members, and comment on it regarding exposure. Lets not worry about composition or subject, okay? What do you observe about the exposure? What worked well? What didn't? What might you have tried to change? Don't worry about how to change it, okay?
It's Sunday afternoon where I am. Lets see what we can do over the next few days with this, okay?
Message edited by author 2005-07-23 14:27:39. |
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07/10/2005 10:54:06 PM · #4 |
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07/11/2005 04:29:25 AM · #5 |
Originally posted by bcoble:
Can I join this? |
Send a PM to Digital Quixote Bill.
Message edited by author 2005-07-11 04:29:59.
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07/11/2005 04:49:10 AM · #6 |
I'll go first cos I work real late tomorrow night. I'm really looking forward to seeing everyone's work, learning and sharing ideas. Exposure is an area that's pretty hit and miss for me.
At the moment I'm working with the Sony 717 which I usually use in full manual mode. I choose all the settings so unfortunately can't blame anyone (or anything) else for the errors!! These 2 shots were taken end of May at our local Shaggy Dog Day Out.
This shot I got pretty much right, this is straight from the camera.
2nd shot I got pretty much wrong :( straight from the camera.
One of the major things I need to do is to slow down and check the settings.
I really am looking forward to this whole experience and Chuck.....thankyou so much for taking on the mentor role.
sue
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07/11/2005 02:22:03 PM · #7 |
Alright, at the moment I use mostly the Canon 20d and the Panasonic Lumix FZ20. With the Canon I tend to use the automatic mode more often then not. I freely admit to being intimidated by my first dslr. The only settings I occasionally remember to adjust are the ISO and the WB but I've been trying to work on that, with very mixed results.
I like this shot. I think it turned out pretty well. Taken with the 20d
This one is horrible. The shot is completely over exposed. Taken with the FZ20.
I agree with Sue. I need to slow down and think before I take the picture...at least until it becomes second nature.
I look forward to hearing the opinions of the others in the group.
- Laura
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07/11/2005 02:41:53 PM · #8 |
I'll post my pics and comment more later tonight when I get off work (midnight), but in the meantime could those of you that posted already add what metering mode you used and if the image is cropped or not. The metering mode should be in the exif information if you don't remember.
I think this will be very helpful since at least two of the shots posted seem to have suffered due to metering. The meter always (unless told otherwise) makes what it looks at middle grey, so making some assumptions ...
in this shot, assuming the shot is not cropped and some form of center/spot metering was used (can't know unless you tell us), the white of the dogs head is in the middle of the image and what the meter placed at middle grey -- but it is the brightest spot on the image. The result of exposing as the meter said was right resulted in an underexposure and all the tones are moved down the scale.
This shot is just the opposite as the one above -- the center of the image is black (or at least very dark) but the meter said to expose it as if it was middle grey -- the result is overexposure as all the tones are moved up the scale.
Anyway, I'm out the door but will find and post a couple of shots for you to tear into when I get back. :D
David
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07/11/2005 03:00:36 PM · #9 |
On my shot of the owl the exposure compensation was set at -.33
The metering mode was set on multiple.
It was a very, very sunny morning. Would it have worked better set on spot metering? That seems to make sense to me. Am I wrong?
Thanks for the input.
- Laura |
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07/11/2005 03:27:36 PM · #10 |
Thanks David. Both my shots are uncropped, just resized. Had a look at the exif, it says the metering mode is CentreWeightedAverage on both shots......is that what you mean? Both shot using manual mode.
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07/11/2005 04:47:38 PM · #11 |
I never got a PM, though I am on the list. I joined this because I have problems with the darned sun! All too often, I get blown out photos, but if I start using the EV settings, I will get too underexposed images. Since I cannot see the changes on the screen, how do I know what settings to use? I work in A or S modes.
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07/11/2005 06:13:51 PM · #12 |
Originally posted by papagei:
I never got a PM, though I am on the list. I joined this because I have problems with the darned sun! All too often, I get blown out photos, but if I start using the EV settings, I will get too underexposed images. Since I cannot see the changes on the screen, how do I know what settings to use? I work in A or S modes. |
I have a copy of the PM I sent you. I am wondering if your email address with DPC is current. I can resend it if necessary, just let me know. |
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07/11/2005 06:17:46 PM · #13 |
| To our members. I would like you all, in addition to posting your own pictures, to comment on each photo (as a comment on that specific photo rather than in the thread). That way it will be easy to keep the comments and the photos together. This is part 1b of the first challenge. I'll be looking at and commenting this evening hopefully. |
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07/11/2005 07:57:03 PM · #14 |
Charles, thanks for taking the time to comment on my photos. Your input is greatly appreciated, as were your questions. They really made me think. I'm still thinking actually. I'm not sure I have the answers yet. Are we supposed to answer the questions from your comments here in the forum? Should I include your questions so the others know what I'm talking about? Do you even want answers or are they just intended to make us think? What's the plan here? The questions just keep coming. lol Somebody stop me! I'm off to play with the owl photo is PS while I await your reply.
Hey group members: where are your photos? I'm eager to learn here. :-)
Too eager? Probably!
- Laura
Message edited by author 2005-07-11 20:24:53. |
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07/11/2005 11:02:45 PM · #15 |
I assume we are posting examples of our problems? Here is a typical one on a sunny summer day:
Blown out background...
Backlighting is a problem. I found a bear climbing out of a pool and had no time to even try to figure out how to get him, so I just shot...
Swans...well, result on blownout feathers and the bg is still too dark (using EV comp) - can't find an example right now.
Even though I used a polarizer and strong EV comp, Purples blewout to pinks - yuk!
Subjects in light and shadows, using my 70-200, came out fine...
So now you know all my exposure problems!
Message edited by author 2005-07-11 23:10:21.
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07/11/2005 11:24:03 PM · #16 |
I always try to judge my lighting..
I like to use my camera mostly in the manual settings unless I am doing something quick and need the auto for assurance that I may get the shot. I have been known though to leave the settings in the manual to aperature priority because I am still a bit confused to how much I should open the shutter or close it.. I like to play with the settings when time allows like change the EV, try the flash and even change the flash settings. I hope to get something out of this wich I am sure I will.... So heres the first assignment.
These shots I took today and one from the 4th....No editing done just resized for the web...
 
 
I just wanted to add these to show a difference in flash for nighttime photography... 
Message edited by author 2005-07-12 01:47:32.
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07/11/2005 11:56:03 PM · #17 |
Originally posted by sheapod:
Charles, thanks for taking the time to comment on my photos. Your input is greatly appreciated, as were your questions. They really made me think. I'm still thinking actually. I'm not sure I have the answers yet. Are we supposed to answer the questions from your comments here in the forum? Should I include your questions so the others know what I'm talking about? Do you even want answers or are they just intended to make us think? What's the plan here? The questions just keep coming. lol Somebody stop me! I'm off to play with the owl photo is PS while I await your reply.
Hey group members: where are your photos? I'm eager to learn here. :-)
Too eager? Probably!
- Laura |
Yes, grasshopper (LOL). I would like you to answer the questions. And yes, to make you think. Answers as comments to your photo.
Message edited by author 2005-07-12 00:16:17. |
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07/12/2005 12:18:59 AM · #18 |
I generally shoot on completely manual, unless I am doing something where I don't have time to change the settings, then I will use "A-Dep" mode. I'll try and comment on the others tommorow.
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07/12/2005 04:45:59 PM · #19 |
Okay we've heard from 5 of our merry band and we'll give the rest a day or so to jump in.
Where We're Heading
As a next topic, I'd like to spend some time on metering light. Nothing fancy and using just the camera's light meter. The light meter is your friend and used correctly, it will give a great head start on a correctly exposed image. David is going to help me with mentoring this.
Next, I'd like to spend a little time on camera set-up and the choice of using manual, priority, automatic, and themed (probably not the right term -- Sports, Landscape, etc) modes. Several of you use each of these modes.
After that I'd like to spend some time on the trade-offs of Aperature, Shutterspeed, ISO and (maybe) white balance. Many of you expressed interest in this.
After that I have some ideas but let's not get too far ahead of ourselves.
Suggested Collaboration Techniques
We are feeling our way along as to how this will work. I have a few suggestions:
1) Lets keep the dialog about any specific photo in the comments associated with that photo. That way they will all be together and in context.
2) I'll use this thread to post assignments and to make general observations and to draw general conclusions.
3) In my comments on your photo, I may ask you questions. I do this to help you think about something. And I hope you will take time to record (in a comment on your own photo)an answer to the questions. Writing it down will help you be clear in your thinking and will help others learn from your experience.
4) If you want to opt out of our merry band, please let me know. I have a waiting list of folks who want to join.
Edit: Did I mention that I am a perfectionist (my wife prefers the term anal)? If you think I'm worrying over much about things that you don't care about ... just tell me.
For Non-Members
For those who are not members of the mentor group, I welcome you to follow along. This thread is public and you're welcome to follow our progress. The photos and comments are public and you're welcome to read them. If you want to communicate with me or any of the members, I would ask that you us a Private Message (PM) rather than leave a message in this thread or post a comment on a photo. I will certainly respond to any PMs I get, even from non-members and I would value your insights if you think I'm wrong about something or have a suggestion.
If you get tired of seeing this thread among recent forum posts, select ignore from the drop down box at the top and you won't be bothered by it anymore.
Message edited by author 2005-07-12 20:37:55. |
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07/12/2005 08:27:52 PM · #20 |
This is an adjustment made based on the suggestions by Digital Quixote. It's amazing to me how such small adjustments to the brightness/contrast brought her face out more.
Thanks for the tip!
Also, I like the layout of our plans. It sounds like a good way to go.
- Laura |
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07/13/2005 08:04:51 AM · #21 |
This is really interesting, and not easy! I'm not very good at analysing what's wrong with the image. I couldn't have chosen a better area to work in as exposure is probably one of my weakest areas, the one I get wrong most often! The comments are really helping, thankyou :)
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07/14/2005 11:27:32 AM · #22 |
Recap of Exercise 1: The purpose of exercise 1 was to get you thinking about exposure. To help you know good exposure when you saw it. And to get you analyzing and commenting on exposure. I have offered critical comments on your photos. Now it's payback time: Please critique the exposure on my shot below. There are some things right and some things wrong with it. Look at my EXIF data before you comment. You won't hurt my feelings. Use comments on the photo itself, please, not comments in the thread.
If I were going to submit this for a challenge, I would probably crop out the top 2/3 of the photo and crop out the right half of the remaining image leaving the lower left 1/6 of the image.
Also look at my next post as we begin metering.
Message edited by author 2005-07-14 12:16:14. |
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07/14/2005 12:00:14 PM · #23 |
Light Metering
Your light meter is your friend. It measures the light entering your camera and determines an exposure value to achieve when the camera sets the aperture and shutter speed for a given ISO.
Most digital cameras have different ways of measuring light: 1) Using the average of the whole frame (e.g. Matrix for my D70, and Evaluative on the Rebel); 2) Using the whole frame but giving more weight to the center of the frame (e.g. Center weighted on my D70 and Center weighted average on the Rebel); and 3) Metering a small area of the frame (e.g. Spot Metering on my D70 and Partial Metering on the Rebel).
Each type of metering will work best in different situations. Matrix or Evaluative tend to work best for landscapes or where the whole frame has about the same brightness. Center weighted tends to work well for portraits or other subjects that dominate the center of the frame. And spot or partial metering works well for subjects that are significantly brighter or darker than the background.
Choosing the right type of metering and setting your camera before you shoot will improve your chances of getting a good exposure.
Exercise 2a: Set your camera on Automatic. Choose one of the following subjects and take 3 photos of the same subject from the same place, with the same angle and lighting. The only difference would be to use each of the three metering modes.
Subject 1: Landscape with similar light levels in the whole frame, or
Subject 2: Portrait with a single face dominating the center of the frame, or
Subject 3: A small (in the frame) subject that is a lot lighter or darker than the background.
Post your 3 thumbnails here in this thread. Post your camera’s EXIF data with your photos. And comment on your own results.
Exercise 2b: Comment on the exposure of each photo posted by the other members.
David (Britannica) had offered to help with theis topic. See his thoughts quoted below. It's an excellent piece and goes deeper than what I wrote above. Thanks David!
Originally posted by Britannica:
Metering
(Note this is also available (including diagrams) as a PDF download here.
It is often said that photography is about the light and this most true when it comes to exposing the scene. Expose for too little light and the image will be too dark, expose for too much and it will be too light – but, by exposing the right amount of light, the scene is recorded in rich detail for later viewing.
Every photographer wants their photographs to be exposed to just the right amount of light to capture the detail they want, but how are they to know what the ‘right amount’ is? The ‘right amount’ is largely a matter of personal taste, but without some way to measure the available light, the exposure is left completely up to chance. That is the purpose of the light meter built into most cameras today. A light meter measures how much light there is, and provides a means to evaluate what exposure settings will produce the desired results.
In photography light is measured in terms of perceived brightness in units called stops, with each unit of stop being twice as bright as the previous one. This scale is a graphical representation of the progression of brightness with each successive stop added.
Notice the scale goes from black (total darkness) to white (total brightness) with each tone being twice as bright as the one to the left and half as bright as the one to the right. Add a stop more light (stopping up) to an exposure and the brightness of an image moves to the right; reduce the exposure by a stop (stopping down) and the brightness moves to the left.
Now that we know how light is measured, we are in a position to know what a meter does – a meter measures the tone or relative brightness of the available light. The light can be measured as it comes from a light source as an incident light meter does, or it can be measured as it reflects off of some object. This last is done with a reflective light meter, and is the type of meter in most cameras and is where we will concentrate our attention.
Most cameras offer a number of different metering modes, but they all have the above in common, but may not interpret the data given by the meter in the same way. What modes are available, as well as how those metering modes work, vary from camera to camera, and the details of what is available and how it is implemented is best left to the individual camera manuals.
There are a few common characteristics however; the most important is the existence of automatic or manual metering modes.
Automatic metering modes include Matrix mode, Evaluative mode and Center Weighted Average mode, among others – several are summarized here:
In Matrix metering mode the camera divides the sensor into a matrix, like a tic-tac-toe grid or a checkerboard – the exact number of grids will vary from camera to camera. The light in each grid is measured and placed on a tone scale and the results put thru some form of averaging calculation.
In Evaluative metering mode the camera divides the scene into zones (shades of grey, like the 11-zone scale above), measures each zone and calculates a result. Again, how the results are calculated and how many zones are used depends on the camera. Note that this is different from Matrix metering as the division is tone based instead of grid based.
In Center-Weighted Average metering mode the camera puts a great deal of weight (importance) to the center of the composition. That is, the tonal value within a small area in the middle (usually seen as a circle or such in the viewfinder) is used more when computing the average, with the rest of the scene making up the rest. How much importance is put on the center area varies, but can be as large as 90% of the final result.
As can be seen, the automatic modes can get very complicated while trying to make it easy for the user to take well exposed images in varying circumstances. But they have one fatal flaw – the meter does not know what it is pointed at and the photographer has no control over how the meter makes its computations. As a result the exposure from the automatic metering modes is erratic in all but the most ‘normal’ of situations.
The manual metering modes are Spot and Partial. These modes are very similar in their operation and most cameras will have one and not the other. In the middle of the viewfinder there is usually a small dot or circle or rectangle in the middle of the view. With spot or partial metering the light from this area is all that is measured, nothing else is considered at all. The only difference between the two metering modes is how big the area metered is. Spot metering evaluates an area usually less than 5% of the total area of the view while partial metering is larger – although not usually larger than 10%.
This, at first, sounds strange – why would we not be interested in the entire scene? But by placing the spot over a specific area of the scene the photographer is able measure the light in that small area without tainting the measurement with adjacent areas. That’s right, the photographer decides what is metered, not the camera. Place the spot on a persons face and only measure the light reflected from the face or move it over a bit and measure only the light from reflected from the person’s hair – the choice is up to the photographer.
If you remember from the automatic metering modes the camera measured light from various areas of the scene and then calculated the exposure based on these measurements. With spot (partial) metering mode the photographer measures the areas of the scene he is interested in and determines for himself the appropriate exposure based on these measurements. The photographer is in control.
While the automatic modes are able to give good results under most normal situations, they are not under the control of the photographer. This lack of control can cause the meter to perform poorly from time to time, often in tricky lighting situations when the photographer is most in need of help calculating the exposure. For this reason I will be concentrating on the manual metering modes from this point on since they provide the means for the photographer to meter the scene and determine the desired exposure.
To use the spot meter (includes partial, but won’t be mentioned again) effectively the photographer must know what the meter is telling him and how to use that data to determine the desired exposure. Although determining the correct exposure uses the data from a meter, it is not directly related to meters and metering, and as such will be discussed at length elsewhere. However, knowing the information the meter gives is vital for any photographer that wishes to be able to determine for themselves the desired exposure.
The readings a meter gives are those needed to make whatever is being metered into a neutral (middle) grey tone. Light and dark objects alike are metered to be neutral grey. Try it for yourself; find a light object and photograph it under indirect lighting with whatever exposure settings the meter gives and then do the same with a dark object. Then in an image editing program convert the images to grey-scale and compare the resultant tones. How similar are they?
There is one instance when the meter will give readings that accurately represent the tone of the object it is measuring – when that object is itself neutral grey. This is why photographers have long used grey cards. By metering a grey card the scene is anchored to middle grey, with the lighter tones in the scene being lighter in the photograph; likewise the darker tones in the scene will be darker in the photograph. This gives the same results as an incidental light meter would have if one had been used to measure the light directly.
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Message edited by author 2005-07-15 14:25:23. |
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07/14/2005 03:00:57 PM · #24 |
Hello. I've been having internet troubles but it seems to be working for now. Repairmen just left after tuning the antennae to get me by until the 28th when they plan on replacing/relocating it to permanently fix the problem. The retuning seems to be working, I haven't had an error since they left so hopefully it will be good for the next 2 weeks while I wait for the full repair.
I've started catching up with the commenting and will post my pictures when I get home from work (if I'm able -- grrr!) and finish commenting then as well.
Chuck, the write-up you requested on metering is in the mail -- no, really! ;) I finally got it to send it to you just now after trying half a dozen times yesterday. I hope your review finds it close to what you wanted.
David
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07/14/2005 06:39:40 PM · #25 |
Pattern Mode (eval)
Partial Mode
Average (centerwt) Mode
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