Showing posts with label EXPERIMENTS. Show all posts
Showing posts with label EXPERIMENTS. Show all posts
Sunday, 30 September 2012
Sunday, 2 September 2012
Best Exposure Nikon D3100
Exposure Basics: Correctly Expose Your Photographs
by Bryan F Peterson, August 2008 (updated September 2008)Every picture taking opportunity allows you to record no less than six correct exposures!
Perhaps you have already figured it out after reading the above, but if not, you will soon know that most picture taking situations have at least six possible combinations of f/stops and shutters speeds that will all result in a correct exposure; not a creatively correct exposure but a correct exposure. But only one, sometimes two, of these combinations of f/stops and shutter speeds is the creatively correct motion-filled exposure.
Again, let’s review, that every ‘correct’ exposure is nothing more then the quantitative value of an aperture and shutter speed working together within the ‘confines’ of a predetermined ‘ISO’. For the sake of argument we are both out photographing a city skyline at dusk, using a film speed of 100 ISO and an aperture opening of f/5.6 and whether we are shooting in manual mode or aperture priority mode the light meter indicates a correct exposure at 1 second. What other combinations of aperture openings (f/stops) and shutter speeds can we use and still record a ‘correct’ exposure? If I suggest we use an aperture of f/8 what would the shutter speed now be? Since we have cut the lens opening in half (f/5.6 to f/8) I will now need to double my shutter speed time to two seconds to record a correct exposure, (1 sec + 1 sec= 2 seconds.) On the other hand, If I suggested that we use an aperture of f/4 what would the shutter speed now be? Since we have just doubled the size of the lens opening (f/5.6 to f/4) I will now need to cut my shutter speed in half (1/2 second) to record the same ‘quantitative value exposure’.
Easy yet hard, right?
For a refresher on these terms, take a look at Bryan’s intro article on Basic Photo Tips: Aperture, Shutter Speed, and ISO.
The Equations
The following are equivalent:- f/4 at 1/2 second
- f/5.6 at 1 second
- f/8 at 2 seconds
- f/11 at 4 seconds
- f/16 at 8 seconds
- f/22 at 16 seconds
Likewise, if we find ourselves taking an outdoor portrait at the park with our telephoto zoom, we find that with our aperture set to f/16 and with an ISO of 100, a correct exposure is indicated at a shutter speed of a 1/125 second (s). If I suggest we use an aperture of f/8, what would the shutter speed now indicate as a correct exposure? If you said 1/500s, you are correct, which also means that you know at f/22 the correct exposure would be a 1/60s and at f/11 1/250s and at f/5.6 your shutter speed would now be 1/1000s. Again, why all the ‘fuss’; what difference does it really make which combinations of apertures and shutter speeds we use as long as the meter indicates a correct exposure?
Knowing that every picture taking opportunity offers you no less than six possible aperture/shutter speed combinations in and of itself may seem immaterial, but when you consider the impact of the creative possibilities influenced by the shutter speed (freezing actions, implying motion or panning) and aperture (a great depth of field, or a background of muted tones and/or out of focus foregrounds) you will have a much greater appreciation for why you are choosing that particular shutter speed and aperture combination. The reason will not be simply because you want to record a correct exposure, but rather because you want each and every time to record the CREATIVELY CORRECT EXPOSURE! The difference between a “correct exposure” and a “creatively correct exposure” is often huge! Let’s take a look!
Let’s pretend we’ve invited ten other photographers to join us in capturing this scene and we break into three groups:
- One third of the group shot this scene at f/11 for four seconds
- Another third shot the scene at a f/8 for a two seconds
- The remaining third shot the scene at f/5.6 for 1 second.
Now let’s imagine that we all awoke the following morning, once again splitting into three groups and we all head into a flower garden. All of us are armed with our telephoto zooms and we are going to record correct exposures of a single flower bloom.
- One third of the group shoots that lone flower at a correct exposure of f/4 at 1/1000s.
- Another third of the group at f/8 at 1/250s.
- The last third of the group shot that same flower at f/16 at 1/60s.
 Image 1 |  Image 2 |
Let’s take a real world look at just how different a correct exposure is versus that of a “creatively” correct exposure.
Exercise 1: Flower Composition
Head outside with your camera set to 200 ISO and a telephoto lens, say a 200mm, and frame up a flower. Once you focus on the flower, shoot six correct exposures, each one using a different aperture and shutter speed. For example, with the aperture set to f/4, you get a correct exposure indication at 1/1000s. Shoot this one exposure and than move on to f/5.6 and then shoot another at 1/500s, f/8 at 1/250s and another at f/11 at 1/125 second, f/16 at 1/60s and finally another at f/22 at 1/30s. You will soon see that all six exposures are correct in their quantitative value, but radically different in their “visual weight”. Note in just these two examples where the first image was shot at f/5.6 at 1/500 second and the second image shot at f/22 at 1/30s. They are the “same” exposure in their quantitative value, but oh my, look at how much busier the background is in the correct exposure taken at f/22 versus the much cleaner and more isolated flower composition of the correct exposure taken at f/5.6 at 1/500s.  Image 3 |  Image 4 |  Image 5 |
Image 3 was taken at f/5.6 at a 1/500 second, Image 4 was taken at f/11 at 1/125s and Image 5 was taken at f/22 at 1/30s. Again, their quantitative values are identical, which is to say that the volume of light that passed through the lens and the amount of time that light was allowed to render an image on the CCD or film was the same. When I composed all three of these images, they looked exactly the same inside my cameras viewfinder. Yet when I reviewed these same three exposures on the camera’s digital monitor, they were clearly different and that difference in this case was with their backgrounds.
In Image 3, the background is limited to subtle out-of-focus tones, color and very few shapes. In Image 4, the background begins to offer up a bit more information in both shapes and sharper tones and by Image 5, it’s ‘clear’ that the background, consists of other nearby flowers due to the much greater defined shapes and tones that are presented. All three are the same exposure, but as is often the case, only one, and sometimes two, are the “creatively” correct exposure.
Use of Motion
When capturing this simple composition of an S-curve on Interstate 5 approaching downtown Seattle, I was presented with six possible options of recording a correct exposure, three of which you see here (Images 6, 7, and 8). In terms of their ‘quantitative value’, all three of these images are exactly the same exposure, BUT one can clearly see that they are vastly different in their creative exposure, with the creative emphasis on the use of motion. It has and will always be my goal to present motion-filled opportunities in the most motion-filled way and more often than not when there is a motion filled scene, the longer the exposure time, the greater the motion is conveyed. In our first example, Image 6 was captured at f/4 for 1/2s, Image 7 was shot at f/8 for 2s and Image 8 was shot at f/16 for 8s. All three of these exposures were made with my Nikon D2X and Nikkor 200-400mm zoom at the focal length of 400mm, mounted on tripod with my ISO set to 100 and my WB set to Cloudy.  Image 6 |  Image 7 |  Image 8 |
Going to Extremes with Shutter Speed
As you begin to digest more and more this simple rule of exposure, it will soon become clear that the need to pay attention to what aperture choice or shutter speed choice will in fact lead you to conclude that there is but one truly creatively correct exposure most of the time and this is particularly true as you begin to notice that the world offers up an unlimited supply of motion-filled opportunities. When capturing these motion filled opportunities you will find yourself, more often than not, on either end of the shutter speed spectrum; using fast shutter speeds to freeze the action in crisp sharp detail or using slow shutter speeds and the resulting blur to suggest or imply the motion present. There is rarely a ‘middle ground’ when it comes to the motion-filled world and with that in mind, it won’t be long before you discover that most of your time is being spent on action-filled scenes between 1/500s and 1/1000s OR between 1/4s to 8s.  Image 9 |  Image 10 |
Recording a correct exposure will always be your responsibility, so why not make it a point to make the most deliberately and visually compelling ‘creative’ exposure possible!?
Exercise 2: Motion-Filled Exposures
One of the best lessons I know of is one that I have offered up to countless students over the years in my on-location workshops and at my on-line photography school www.ppsop.net. It is a very revealing lesson and not surprisingly will lead you further into the world of creatively correct motion-filled exposures. Choose a moving subject, such as a waterfall or a child on a swing or shoot something as simple as someone pounding a nail into a piece of wood.With your camera set to Aperture Priority Mode, your ISO set to 100, (or 200 ISO if that is the lowest your camera offers) and your aperture set to wide open, (f/2.8, f/3.5 or f/4) take an image of the action before you. You have just recorded an exposure at the fastest possible shutter speed based on the ISO in use, the light that is falling on your subject and of course your use of the largest lens opening. Now stop the lens down one full stop, (if you started at an aperture of f/2.8 then go to f/4 and if your lens starts with f/4 then go to f/5.6) and once again take another exposure of the action filled subject. Repeat this each time with the aperture set next to f/8, then f/11, then f/16 and finally f/22. Each time you change the aperture by what is called a ‘full stop’, your camera does a quick recalculation and offers up the ‘new’ shutter speed to maintain a correct exposure and since you are stopping the lens down with each full stop change in aperture, (making the hole in the lens half as big as it was before) your shutter speed has now doubled in time to compensate, or in other words, your shutter speed is becoming progressively slower. The slower your shutter speed the more likely it is that your action filled subject before you is showing signs of ‘blurring’, since the shutter speed is too slow to ‘freeze it’.
Conclusion
To re-cap, the fastest possible shutter speed with any given ISO will always be found when you use the largest lens opening and the slowest possible shutter speed (barring the use of any filters) will always be found when you use the smallest lens opening.There is one thing I hope you will never forget after reading this article: correct exposures can be found just about anywhere, but why settle for just a correct exposure when you can in fact record a truly creatively correct exposure each and every time? You really can take charge of your own creative vision when it comes to exposure!
More
- Bryan’s member page
- Bryan’s gallery page
- www.bryanfpeterson.com
- Photo.net Photo Critique Forum
P Mode In Nikon d3100
This chapter is from the book
P: Program Mode
There is a reason that Program mode is only one click away from the automatic modes: with respect to apertures and shutter speeds, the camera is doing most of the thinking for you. So, if that is the case, why even bother with Program mode? First, let me say that it is very rare that I will use Program mode because it just doesn't give as much control over the image-making process as the other professional modes. There are occasions, however, when it comes in handy, like when I am shooting in widely changing lighting conditions and I don't have the time to think through all of my options, or I'm not very concerned with having ultimate control of the scene. Think of a picnic outdoors in a partial shade/sun environment. I want great-looking pictures, but I'm not looking for anything to hang in a museum. If that's the scenario, why choose Program over one of the scene modes? Because it gives me choices and control that none of the scene modes can deliver.
When to Use Program (P) Mode Instead of the Automatic Scene Modes
- When shooting in a casual environment where quick adjustments are needed
- When you want more control over the ISO
- If you want to make corrections to the white balance
- When you want to change shutter speeds or the aperture to achieve a specific result
Let's go back to our picnic scenario. As I said, the light is moving from deep shadow to bright sunlight, which means that the camera is trying to balance our three photo factors (ISO, aperture, and shutter speed) to make a good exposure. From Chapter 1, we know that Auto ISO is just not a consideration, so we have already turned that feature off (you did turn it off, didn't you?). Well, in Program mode, you can choose which ISO you would like the camera to base its exposure on. The lower the ISO number, the better the quality of our photographs, but the less light sensitive the camera becomes. It's a balancing act with the main goal always being to keep the ISO as low as possible—too low an ISO, and we will get camera shake in our images from a long shutter speed; and too high an ISO means we will have an unacceptable amount of digital noise. For our purposes, let's go ahead and select ISO 400 so that we provide enough sensitivity for those shadows while allowing the camera to use shutter speeds that are fast enough to stop motion.
With the ISO selected, we can now make use of the other controls built into Program mode. By rotating the Command dial, we now have the ability to shift the program settings. Remember, your camera is using the internal meter to pick what it believes are suitable exposure values, but sometimes it doesn't know what it's looking at and how you want those values applied (Figures 4.1and 4.2).
Figure 4.1 (left) This is my first shot using Program mode. The camera settings are affected by the large amount of blue sky.
Figure 4.2 (right) By zooming in, there was less sky and more tower to influence the light meter, resulting in a change of exposure.
With the program shift, you can influence what the shot will look like. Do you need faster shutter speeds in order to stop the action? Just turn the Command dial to the right. Do you want a smaller aperture so that you get a narrow depth of field? Then turn the dial to the left until you get the desired aperture. The camera shifts the shutter speed and aperture accordingly in order to get a proper exposure, and you will get the benefit of your choice as a result.
You will also notice that a small star will appear above the letter P in the viewfinder and the rear display if you rotate the Command dial. This star is an indication that you modified the exposure from the one the camera chose. To go back to the default Program exposure, simply turn the dial until the star goes away or switch to a different mode and then back to Program mode again.
Let's set up the camera for Program mode and see how we can make all of this come together.
Setting Up and Shooting in Program Mode
- Turn your camera on and then turn the Mode dial to align the P with the indicator line.
- Select your ISO by pressing the i button on the lower-left portion of the back of the camera (if the camera's info screen is not visible, press the info or i button).
- Press up or down on the Multi-selector to highlight the ISO option, then select OK.
- Press down on the Multi-selector to select a higher ISO setting and then press OK to lock in the change.
- Point the camera at your subject and then activate the camera meter by depressing the shutter button halfway.
- View the exposure information in the bottom of the viewfinder or by looking at the display panel on the back of the camera.
- While the meter is activated, use your thumb to roll the Command dial left and right to see the changed exposure values.
- Select the exposure that is right for you and start clicking. (Don't worry if you aren't sure what the right exposure is. We will start working on making the right choices for those great shots beginning with the next chapter.)
Tuesday, 10 April 2012
Wednesday, 21 December 2011
MY EXPERIMENTS WITH PHOTOGRAPHY 21/12
F--4.8--5
iso--auto(3200)
lighting---0 watt bulb
Orchids in my room............
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