Learning how to expose properly: the basics

Discussion in 'Photography Techniques' started by mmacleodbrown, Oct 28, 2010.

  1. mmacleodbrown

    mmacleodbrown SC Regular

    197
    Oct 10, 2010
    London
    Ok, I now have a lovely new S95 and want some advice on the best way to proceed?
    I dont want to clutter up the forum as there are going to be so many posts coming this way, so will ask my question here..

    My only previous experience of photography is using the auto and scene modes, and I intend to go fully manual. :eek:
    This will be a steep learning curve, and I imagine a very frustrating experience as Im sure I will lose so many shots due to wrong settings etc, but unless I stick at it, Im going to slip back to the ease of the pre-configured modes/auto and lose so much..
    Im thinking of starting a 'learning manual mode' thread and posting everything in there, some of the stuff will be s95 specific, for instance, I just turned the camera on in manual mode and Im seeing stuff on the display that isn't listed in the manual and I dont understand it straight away.
    I have bought Bryan Petersons book as well (understanding exposure), so hopefully between that and yourselves, I will get there. Im thinking this will be my photographic journey documented on this forum and you will all help me (hopefully), and see my results improve over time...
    What do people think, Im aware that this will probably get noisy etc, but the best way to proceed that you are all happy with?
    I can't emphasise how much of a noob I am at this..

    Martin
     
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  2. Ghosthunter

    Ghosthunter boo! Subscribing Member

    Sep 8, 2010
    London UK
    Real Name:
    Andy
    Rather than dive straight into fully manual try Aperture or shutter priority 1st. I use Aperture priority 95% of the time as i like to set the aperture and let the camera do the shutter speed. I always look and see what the shutter speed is going to be and take the shot accordingly. You could try the Program setting too. The s95 looks like a super camera and better thin features than my old s90. Will I get the s95....hmmmm difficult to say as the LX5 looks nice as does the Samsung EX1 and Sigma DP2s.
     
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  3. mmacleodbrown

    mmacleodbrown SC Regular

    197
    Oct 10, 2010
    London
    Im happy to try that, I was worried that it might be too limiting to use Av or program mode
    Reading Bryan Petersons book, I was inspired by the whole sharp image/fuzzy background and understood that AP was critical in achieving this. If I select the AP and the camera selects the shutter speed, then I will lose control of this or 'creative control' as Bryan puts it?
    Im going to go home tonight, set up a cup or vase on my kitchen table and try a few shots and see where I get, that way I should get an idea of what changing the values actually do.
    Im in London Sat, with 3 batteries and 2 memory cards and I plan on walking around and taking photo's all day, not with the intention of using any, just exploring the difference between the settings and seeing if I can get that 'lightbulb moment'
     
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  4. Ghosthunter

    Ghosthunter boo! Subscribing Member

    Sep 8, 2010
    London UK
    Real Name:
    Andy
    That's the best thing you can do, just try stuff and see what you're happy with. Good luck, Wish i could join you!
     
  5. BillN

    BillN SC Hall of Famer Subscribing Member

    Aug 25, 2010
    S W France
    Real Name:
    Bill
    the auto and program modes are good on the S95

    Getting to know how to use the dial and the ring make life easier in the other modes plus what you assign the S button to can make shooting quick

    Being a Nikon person - I like buttons for shutter speed, Aperture, ISO and exposure comp - that's all you really need on a cam - if they pared the controls to four simple buttons, (or similar), which you can do on the S95 - that's all you need and everything else can be left in the Menu

    just my views
     
  6. wt21

    wt21 SC Hall of Famer

    Aug 15, 2010
    Sadly, to break the bubble a bit, tiny sensors do not give you that whole "sharp image/fuzzy background" bit. The related term to get Out Of Focus (OOF) backgrounds is "depth of field" or DOF. DOF is driven by the physical size of the aperture, and the distance to the subject. One way to get OOF background (shallow DOF) is to get really close to the subject that you focus on. This shrinks the DOF, and then if the background is far away, it will be OOF.

    However, being very close to a subject distorts the perspective (one effect, for example, is it will make people look like they have big noses). So, if you need to step back from your subject, then you need a larger physical aperture opening to shrink the DOF and get those nice OOF backgrounds.

    Sadly, an f/stop number does not tell you the size of the aperture (this is a common misconception). An f/stop number is the RATIO of aperture to focal length. With pocket cameras like the S90/S95, they use tiny sensors that use very short focal lengths. The larger the sensor, the longer the physical focal length you need for the same Field of View (or FOV -- FOV is a measurement in degrees of the view in front of you. It would be easier if you wikipedia-ed FOV than to have me explain it here).

    OK, so if you've got an s90, why can't you get good OOF backgrounds and narrow DOF when you are stepped back from your subject (say, a full body shot)? Isn't the f/stop 2.0? Yes, BUT the focal length is something like 6mm on the S90 for that kind of shot. 6mm/2.0 = 3mm. The physical size of the aperture therefore is 3mm wide at those settings.

    Let's look at an Olympus EP1. For the same framing (again, this theoretical body shot), you might use a 25mm lens. If that 25mm lens is at f/2.0, then then size of the aperture is 25/2 = 12.5mm. Four times larger.

    If you use a full frame DSLR, then you use a lens that is 50mm for the same framing. If that lens is f/2.0, then the physical aperture is 50/2.0=25mm! Roughly 8 times larger than the S90!!!

    So, while the S90's f/stop of 2.0 helps you keep the ISO down, and take pictures in lower light, it really does very, very little at all for DOF or OOF backgrounds. The best way to control DOF with the S90/95 is by getting closer to the subject. If you need more OOF background, while stepping away, then you might want to consider moving up to a larger sensor.

    This, of course, is not at all about exposure. But you did mentioned that whole "sharp image/fuzzy background" bit, and I thought I'd help with the learning process a bit around that issue. This will not likely be the first post you have to read to understand these concepts, but if you wrestling with FOV, EV, exposure, DOF and some of these other terms. If you learn these, then you are on your way to technically understanding photography (another important concept to learn is perspective).

    Good luck.
     
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  7. Streetshooter

    Streetshooter Administrator Emeritus S.C. Charter Member

    Jul 12, 2010
    Philly, Pa
    The issue with meters is that they are calibrated to place what is being read in Zone V or 18% gray. So if you do a portrait, the meter places the skin tone to Zone V but should be around Zone VI or there abouts depending on the light.
    In the old daze, we would open 1 stop to get skin to zone VI.
    The meters in these cameras are Reflected meters.
    If you use evaluative, it almost is like an incident meter.
    Most times, an incident reading will place Skin in Zone VI.

    What this all means is, whatever your reading is Tge middle of the scale, dynamic range.
    Try making exposures at different metering settings and pay attention to the exposure.
    Look at the image in your software.
    Our mind will automatically adjust Skin to Zone VI.
    So that can thro the dynamic range out.
    Blown highs.... Lost shadows etc.....
    Ansel's books still apply today. The zone system is alive and well....
     
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  8. mmacleodbrown

    mmacleodbrown SC Regular

    197
    Oct 10, 2010
    London
    Thanks for the comments so far - this is exactly what I was hoping for :smile:

    Martin
     
  9. Martin there is no need for it to be frustrating:biggrin:

    Keep things simple. Remember that exposure is just controlling the amount of light that you let into your camera, and you can only make two adjustments to control that light. The first is to adjust the iris of your lens (also called and f/stop or aperture) The larger the iris the more light it lets in, the smaller the less light. The second is the shutter speed. This controls how long you lens is letting in light.

    When you are doing full manual control you are adjusting both of those things, and most likely using some type of light meter to tell you how to set those controls. Modern cameras have very good built in light meters often called TTL metering or "through the lens" or "on board" metering or "in camera" metering. This will give you a visual display if you settings are correct or not based on the TTL meter.

    So if you are going to use TTL metering there is no reason to use full manual just use the "Aperture" or "Shutter" modes. I use "Aperture" mode 99% of the time. This gives me control over the f/stop and I let the in camera meter set the shutter speed for me. This is a much faster way of shooting in changing light. If I was using full manual mode I would set the f/stop I wanted and then use the meter on the camera to help me set the shutter speed. There is just no advantage to doing so as all this does it take time.

    Now you might be saying "but what if the meter is wrong?" Ahhh there is where the beauty of "exposure compensation" comes in. I am not sure how it works on your S95 but on my Samsung EX1 and my SLRs I have a dial for that that I simply turn up and down. This will cause the camera to over and under expose relative to the meter. For example I almost always turn down my exposures by one stop on my EX1 as I like that metering better.

    Also keep in mind that when you talk about exposure you also need to understand the dynamic range of the scene. This is the difference between the brightest and darkest parts of the scene you are trying to take. Years ago Ansel Adams created what is called the "Zone System" to deal with such things. You can spend a lifetime mastering all the finer points of it but in a nutshell there are 11 zones from 0 to 10. Zero is total black with no detail (think in a cave dark) and 10 is total white with no detail (think stare at the sun bright). There are 9 zones or "stops" in between. Each stop is twice as bright as the one below it, or half as bright as the one above it. Sadly in the internet age the term "stop" in digital photography has drifted away from what it has always meant in the history of photography but in the classical sense your sensor is able to capture about 5 zones or 5 stops of light.

    So why is that important and how do you apply it? Imagine a 10 story building with a basement. The basement represents zone zero and the 10th floor zone 10, and (you guessed it) each floor represents a zone or stop. Now your cameras meter is designed to put everything on the 5th floor right in the middle. Of course you will have different values of light in your scene some of which will be bright and the others will be dark. So what your meter does is average everything out so that as much of the scene as possible will fit on the 5th floor with brighter areas on the 6th and 7th and darker areas on the 4th and 3rd. If the dynamic range of the scene is larger than what will fit on 5 floors like bright mid-day sun with shadows you will get blocked shadows or burnt highlights with no detail. These will either show up as pure black or pure white on your screen.

    At that point you as a photographer have a choice to make. You can either let both of them block or you can shift everything up or down to that the shadows or highlights block up but not both. This is all that exposure compensation is doing.

    So having said all that my advice to you would be to use "Aperture" priority mode to set the f/stop to what you want. Then take a look at the image on your LCD and the "histogram" to give you a good idea of what the exposure looks like. Then if you want it darker dial exposure down, if you want it brighter dial it up. After a while you will get a feel for everything and it will become second nature.

    Also if you are unsure what a histogram is, it is pretty easy. It is simply a graph often broken down into the 5 stops your camera can record but sometimes it is plain. Anyway it shows where each pixel in the image falls along the 5 stops of light. All the way over to the left is total black and all the way over to the right is total white. As each scene is different there is no right or wrong histogram but you generally do not want everything bunched up on one side or the other.

    Lastly keep in mind that your camera's meter can and will get fooled from time to time so don't trust it use your LCD and histogram.
     
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  10. deirdre

    deirdre SC Top Veteran

    652
    Sep 26, 2010
    I found out yesterday that there's spot metering apps for the iPhone! I may learn to meter yet.
     
  11. BBW

    BBW Administrator Emeritus S.C. Charter Member

    Jul 7, 2010
    betwixt and between
    Real Name:
    BB
    Wallace, thank you for taking the time to write out such a helpful and detailed explanation. I think it can be very difficult for someone who has no experience in photography from the film days to get a handle on what it all means. Everyone's posts have been very helpful, however explaining all the basics in such good detail really is worth its weight in gold.

    Martin, if it's any consolation to you - I majored in photography in college back in 1978. When I came along and decided I want to get into digital photography beyond my little true point and shoot (no controls except a zoom) and bought my first serious compact - an Olympus E-P2 in February 2010, I had no idea what "EV compensation" was!:eek: I was clueless and it was thanks to the patient help I received from others that I learned. You'll be surprised how fast you'll "get it" when you take one step at a time - and continue to ask questions. Don't hesitate. Chances are good that if you have a question someone else reading here does, too.
     
  12. mmacleodbrown

    mmacleodbrown SC Regular

    197
    Oct 10, 2010
    London
    I too would like to take the time to thank everyone who has taken the time to write out explanations for me - it is very much appreciated.
    Based on feedback, when I go out tommorrow, I will just try Av mode and see where I get. My camera's manual mode thanks you :smile:
    I was playing with that last night indoors, but as soon as I went over f2.8, I was getting the camera shake warning so I will see what it is like in full daylight.
    I couldn't really see that much difference between the pictures, my test bed was to take a picture of some roses on the table, about 4ft away, with a paper in the background about six foot away. Depth of field stayed the same which bears out what wt21 kindly posted earlier. I think the problem with this test is that it was too narrow, as I couldn't get a sense of what changing the apperture was giving me in real terms, hopefully by the end of tomorrow, I will have a better idea..
    My understanding of 'stopping down' is that it reduces the light going into the sensor and narrows the depth of field. But on a compact with limited depth of field, does this still apply? Are you guys also varying the automatically selected shutter speed as well?
    I plan to walk around and just snap away, and then compare images when I get back in and try and build an understanding of the differences..

    Once again, thank you to everyone that has replied and helped with my understanding...
     
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  13. wt21

    wt21 SC Hall of Famer

    Aug 15, 2010
    Overall, reducing the f/number (from, say f/4 to f/2) lets in more light, and narrows the DOF.

    Opening up the aperture (increasing the f/number from 2 to 4) lets in less light and WIDENS the DOF.

    So, the correlation is: bigger aperture, more light, less DOF (more out of focus); smaller aperture, less light, more DOF (more in focus).

    There will be a difference on an S90, just not nearly as noticeable as with a larger sensor camera (with their correspondingly longer focal lengths and bigger physical aperture openings). The BEST way to control DOF on small sensor cameras is to achieve "separation" between the subject and the background, and to get as close as practical to the subject (closer means less DOF, and with the background far enough away from the subject, it will fall further outside the DOF).

    One other "trick" is to zoom in as much as possible. Zooming in changes the "perspective" of the scene. Try this with your S90 and you'll see what I mean. Zoom out (shortest focal length, or "wide angle") and then get as close to something as you can, so it's still in focus, and very nearly fills the screen. Then zoom out (longest focal length, "or telephoto") and step back so that the object is in focus, but fills THE SAME amount of the shot (this is what we might refer to as "framing" -- how the object is framed in the scene). Here's a simple math trick: this is all linear! If you want the same framing at 30mm equivalent 1 meter from the subject, then zoom out to 90mm equivalent focal length (3X longer) and step back to 3 meters away (3X farther away). Just be careful to maintain the angle of view, so it's best to do this test level on with the subject.

    Do you notice a difference? You should. The background in the zoomed out (wide angle) shot should be busier. The background on the longer telephoto shot should be simpler. The magic thing here is -- YOU moved to keep the framing on the subject the same, but you DID zoom in, which caused the appearance of the background to expand. See these images for what I'm talking about: Picasa Web Albums - w - effect of zoo...

    Do you see how in one shot at 14mm, that mesa in the background looks quite small, yet at 39mm, the mesa has changed quite a bit, even though that charming faceless family is still pretty much the same size? That's perspective (and a good reason to carry a zoom lens when on vacation!)

    Another really good thing to learn here is it works for EVERYTHING in a shot, If you take a shot of a person close up at wide angle, what's the part likely closest to the camera?? Their nose! So their nose looks disproportionality larger. Step back, zoom in and "flatten" that perspective, and shrink their nose back to regular size! (That's why there are focal lengths generally pursued for portraiture, with 35mm being a couple of people, 50mm being about a single body shot, 100mm being about upper body, and 135mm being for head shots. This keeps you at enough distance to the subject to flatten the perspective, but gives you enough wider angle of view to get in more of the scene (group shot) or less (head shot). Of course, in all things rules are made to be broken when creativity demands it).

    How does this help with apparent DOF with small cameras? Well, it doesn't REALLY. DOF is driven by distance to subject and physical aperture opening, so if you stepped back (and assuming the same aperture) wouldn't you have MORE DOF in the telephoto shot? The answer is yes, you do BUT you've simplified the background and "isolated" the subject more, which, although not narrowing the DOF, does still yield the intended effect -- which is isolating and highlighting the subject.

    So, those are some things to think about -- what are you trying to achieve? Truly blurred out backgrounds (and the only real choice with an S90 is to as close as you can to the subject) or to isolate the subject, in which case you can also use zooming and perspective and framing to help you get there.

    Good luck!
     
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  14. mmacleodbrown

    mmacleodbrown SC Regular

    197
    Oct 10, 2010
    London
    Thank you wt21, the examples were quite an eye opener
     
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  15. M5-User

    M5-User SC Rookie

    24
    Oct 23, 2010
    Reply to bold/underline above:

    Not really.
    You DO have control of the DOF, which is a creative aspect of photography.
    But, with a small sensor, your affect will be seen if you do the things I listed below:

    1) Use the longest focal setting
    2) Use the Widest f/stop (f/4.5 or f/5.6 most likely)
    3) Put your subject at around 3-5 feet away
    4) Pick a simple background.... (Make sure your background is at least 25 feet behind the subject), High walls of bushes, or a line of trees. like in a park, or a forest edge.
    will be good, you don't want "Busy" backgrounds.
    5) This will limit what you can take a image of, but, for a head/shoulder capture, it should work.

    AP mode can be very creative :smile:
    [​IMG]
     
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  16. mmacleodbrown

    mmacleodbrown SC Regular

    197
    Oct 10, 2010
    London
    Ok, so here are a couple of photos that exposed the limitations of my S95 or maybe my understanding.
    I was trying to get that 'creamy' water effect from a water fountain.
    My understanding is that I try to shoot this with the smallest apperture I can (f8) and the slowest shutter speed I can. I used ISO 400, more because I think I forgot to change it from previous shots - doh!

    f/8 1/1200 sec iso 400

    [​IMG]

    OK, but still too frozen, so I tried a longer shutter time to capture the movement of the water

    f/8 1/200 sec iso 400
    [​IMG]

    Better, but not there yet..
    Try a longer shutter speed

    f/8 1/100 sec
    [​IMG]

    Clearly too much light due to the slow shutter - I was getting a red flashing f/8 warning in the display when taking this, I took that to mean that it wanted to decrease the apperture size even more, which was beyond the limit of my camera.
    It's weird, I have spent years just using the auto setting, the first day I step outside my comfort zone, I immediately find limits, which had I stayed on auto I would never had found - its a catch 22, stay safe and just snap normal pictures, or try and be creative and get annoyed at the camera for not being able to!! Can't win sometimes..

    Thought Id open the apperture, more to see what happened than anything else
    f/5 1/1000 sec

    [​IMG]

    Hopefully these examples will help some people understand the difference that varying the shutterspeed has on a photo, it certainly helped clarify for me what others have kindly posted in this thread..

    In response to m5-user, thank you for your post, I did try to play around, but on this attempt it failed
    I was trying to focus on the light on the right and hoping to get some DOF on the cathedral in the background, obviously need to practice this a bit
    shot at f/8 1/250 ISO 100 22mm Focal Length

    [​IMG]

    This is fun, Im immediately wanting to find ways to make pictures work when they fail :smile:
     
  17. BillN

    BillN SC Hall of Famer Subscribing Member

    Aug 25, 2010
    S W France
    Real Name:
    Bill
    Maybe this will help a little - being two DOF extremes

    [​IMG]
     
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  18. deirdre

    deirdre SC Top Veteran

    652
    Sep 26, 2010
    Nice example, Bill!
     
  19. Streetshooter

    Streetshooter Administrator Emeritus S.C. Charter Member

    Jul 12, 2010
    Philly, Pa
    Bill,
    Real good....
    By the way... Great looking fluid....
    My Zippos are getting thirsty.....
     
  20. wt21

    wt21 SC Hall of Famer

    Aug 15, 2010
    Have you gotten down the exposure basics? Do you know what a stop is?

    Your fountain pics are all at iso 400, which is two stops faster than it needs to be. Setting your iso to 100 will reduce that one shot with a shutter speed of 1/200 down to 1/50. Do you see the relationship? One stop is a half or a doubling of iso or shutter speed. So iso 100 doubled to 200 then doubled to 400 is two stops. If iso goes up, shutter speed goes up the same amount. So in that iso example, then shutter speed would double from 1/50 to 1/100 and then again to 1/200. Or, in your example, vice versa..

    But here, again, we hit the limits of tiny sensored compacts. You can't get the aperture down small enough. Is f/8 the smallest the aperture will go on the s95? That's likely the case, because if your focal length is 4mm, then you are talking about an aperture opening of 1/8 of 4mm, or a half mm. It's likely not to get smaller. If you have a dslr, you could get down to certainly 1/16, possibly 1/22 and maybe even 1/32, which would be enough to get the effect you want.

    For these pictures, you will either have to get an ND filter, which reduces the light getting to the sensor, or shooting in the very early or late light, when conditions aren't as bright. Or try a different venue, like a waterfall or stream in the forest.

    Tiny compacts are good at taking full exposure snaps in full daylight. They struggle with creative effects, though plenty of folks take great shots with good framing, but dof control and shutter speed control like you've been trying to do will have limits.

    Could I recommend a NEX3 or m43 camera if you want to try this kind of thing? This is the voice of experience. I went down your path for about 6 months with a Canon G9. It was only when i moved up to a Canon XTi that I learned this stuff, and now there are even smaller bodies like the NEX that can help with this kind of creative control.
     
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