You've posted twice here about the same topic and in each of your posts you've been consistent in asking about the camera's exposure controls: the f/stop, ISO, exposure modes - A, S, P, M and scene modes.
You have a very capable camera in fact and it should serve well to do what you want. Here's some help about two different topics: camera exposure and photos of flowers.
Your camera contains a digital sensor -- think solar panels just really really small. Light (photons) fall on the sensor and it responds by generating a charge (electrons). The more photons the more electrons and the stronger the charge; in other words that sensor generates a scaled response to the light striking it. This allows us to create a photograph. We read the electron charge and convert it into numbers. This is skipping a few steps and may be more than you want to know but:
when the processing work is done your photo is made up of pixels and each pixel is a set of three numbers that identify the red, green and blue values for that pixel's color. Above you see a section from your trillium photo blown way up and one of the pixels singled out with it's values in the box.
With the help of tools in the camera you need to expose the sensor to make a photograph. The trick about exposure is to
get enough exposure, but not too much. The sensor has physical threshold limits that we have to respect. Your camera is equipped with a light measuring tool that you rely on to measure the brightness of whatever scene you're photographing and then adjusts or helps you adjust the camera's controls that
get enough exposure and not too much.
The camera has two controls that you can adjust or that the camera software can automatically adjust for you to moderate how much light reaches the sensor based on the measurement the meter takes of the scene. Those two controls are the camera's shutter and the lens's f/stop. This is pretty straight forward: the shutter opens and closes. Closed, there is no exposure. Open, exposure begins and continues to accumulate as long as the shutter remains open. If the shutter is open a long time you can't hold the camera still and you'll get a blurry photo. The camera's viewfinder/lcd should tell you what shutter speed the camera has selected or that you have selected. Consider this table:
That's very general (there are qualifiers) but that should get you started. If your camera's information readout tells you the photo will be taken at 1/4 of a second and you're holding the camera in your hands you're going to get a very blurry photo.
In the lens is an iris just like the one in your eye and it works the same way. Fully open it allows the lens to pass as much light as possible. As the iris opening is adjusted progressively smaller less light passes through to the sensor. We assign numbers to the lens iris opening and call them f/stop numbers. Like so: f/1.8, f/2, f/2.8, f/4, f/5.6, f/8, f/11, etc. That's a standard scale in stop increments but the lens can be set to any value in between those numbers. e.g. f/3.3 or f/4.2. Stop increments are twice as much or half as much light. Note the shutter speed scale above; it is also in stop increments. Let's assume you had the very problem noted above and your camera was informing you that the shutter was set to 1/4th of a second. If your lens f/stop was set (for example) at f/8 you could solve the shutter problem by setting the lens to f/2 which is a 4 stop change. To maintain the exposure the camera would then adjust the shutter 4 stops to 1/60th of a second and you could take the photo (carefully).
We're able to trade off shutter speed against lens f/stop to manage the exposure. We've deliberately built our cameras so that shutter speed and f/stop values adjust the amount of light passed to the sensor by equivalent amounts. It's a juggling act because we're responsible for multiple cause/effect events simultaneously. The sensor needs
enough exposure but not too much and we want to avoid blurry photos and we may also want to influence how much is in focus -- the lens iris does this as well as adjusting exposure. It's a complicated topic called
(D)epth (O)f (F)ield For our purposes right now we just want to understand that if the lens iris is wide open (more exposure) less depth in the photo is in focus and if the lens iris is small (less exposure) more depth in the photo is in focus. See how we're juggling? We can juggle shutter speed (sharp/blurry) with lens f/stop (deep focus/shallow focus) but we must nonetheless always make sure the sensor
gets enough exposure, but not too much.
Your camera's meter that measures light intensity in the scene is linked directly to the camera's controls -- shutter speed and f/stop, and can control them directly. That's what we mean when we talk about a camera as auto, semi-auto or manual. When you've used your camera in auto macro mode the camera took care of all the exposure controls for you. The meter measured the scene brightness and with that variable known the camera applied an algorithm to select a combination of shutter speed and f/stop that would give you a sharp photo with good focus depth. In that process although the camera can select between different combinations of shutter speed and lens f/stop what it can't do is fail this requirement:
expose the sensor enough, but not too much.
Other than auto mode you have the semi-auto modes of Aperture priority, Shutter priority and Program shift. Just as with the camera working in full auto those semi-auto modes remain bound to the same overriding requirement:
expose the sensor enough, but not too much. These modes are just variants on getting the same thing done. Let's say your camera on full auto selected an exposure of 1/500th of a second with the lens f/stop set to f/5.6. In (A)perture mode if you forced the f/stop to f/5.6 the camera would set the shutter to 1/500th of a second and you'd get the same exposure. A mode is just letting you lock in the f/stop if you're sure that's what you want. Likewise in (S)hutter mode if you forced the shutter to 1/500th of a second the camera would set the f/stop to f/5.6. You're being given different ways to get to the same place. Let's remind ourselves again what place is that:
expose the sensor enough, but not too much. So for example if I'm photographing a soccer match with running players I may chose (S)hutter mode to make sure I'm stopping/blurring the action as I intend rather than chance it with the camera's auto algorithms.
In full manual you get to force both the shutter speed and f/stop -- the meter will still function and you can use it. Switching the camera to manual or Shutter or Aperture modes however does not in any way remove or lessen this requirement:
expose the sensor enough, but not too much.
So now we need to think about that exposure requirement. Think first about the scenes you photograph and the brightness of those scenes. Consider a bright sunny day for example and your home in the evening. Consider a rainy day. Consider daffodils in the sun and trilliums in deep shade. The brightness of the various scenes you photograph is variable; in fact it changes a lot. This however does not change at all:
expose the sensor enough, but not to much. In fact that's a specific quantity of light X that for the sensor in your camera is fixed and immutable. No matter how bright or dim the scene is you're photographing the camera's job is to measure that brightness and then calculate the shutter speed and f/stop combination that will produce quantity of light X so the sensor will be
exposed enough, but not too much. For however many photos over however many years the sensor always needs the same amount of exposure.
How does the camera know exactly how much exposure the sensor requires? We use the ISO value. The lowest ISO value on your camera specifies the amount of
exposure for the sensor that's enough, but not too much. So why is there more than one ISO value? Because you can't always get what you want. And so when circumstance dictates that indoors for example with the ISO set to 64 and the lens f/stop as wide as it can get at f/3.2 you need a shutter speed of 1/8th second to expose the sensor you're screwed if you're hand-holding the camera. Assume you need at least 1/30th of a second shutter speed to take the photo. If you make that exposure, 1/30th of a second at f/3.2, you will fail this fundamental requirement:
expose the sensor enough, but not too much -- that's a crash and burn. So when we can't get what we want we make do. Raise the ISO value on the camera to 200 and the camera will recalculate the exposure as 1/30th of a second at f/3.2. By raising the ISO value you told the meter to recalculate a reduced exposure. Take the photo. The sensor does not get enough exposure but we have a patch of sorts. The processing software in your camera that creates the final photo will know about the ISO value and compensate for the loss of exposure by brighten the image in software. Some quality loss must occur but in the early stage of this process it's not too bad. Your camera's ISO values top out at 1600, by then the quality loss is pretty bad. BUT a photo is better than no photo.
What should you do specifically.
Put the camera into the auto macro mode and set the ISO to auto. Start paying attention to the settings the camera selects when you take photos. Ask yourself if the camera is making the best decision and see if you can't do better. For example is the camera raising the ISO value above 64 and also setting pretty fast shutter speeds? Could you use a shutter speed lower and reduce the ISO? Then try and hard-set the ISO and see what happens. Think if you could benefit from having the shutter speed or f/stop locked down. If not then there's no reason not to let the camera select both, but pay attention to what values it does select and sign off on those -- you're responsible.
Find this control on your camera: +/- It's typically a small button diagonally split into black/white with plus and minus signs. Learn to use it. It will lower or raise the exposure in 1/3 stop increments. The camera meter will not always measure the brightness of the scene to best advantage because the meter does not know if the scene is predominately light or dark -- it assumes an average. Take the same photo 3 times: +.3, 0, -.3 and compare them latter to see the difference. This can be a useful tool.
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So I photograph a lot of flowers and plants. My wife is a botanist and I've been following her around for nearly 40 years with my camera. The first thing I learned was that there's a difference between pretty pictures and useful pictures. Unfortunately I've been trained to take useful pictures. Here's a useful picture of the first trillium that blooms in our area, it's called a wake robin:
Useful = show the stem, show the leaves and show the environment. To do that I used a macro zoom lens at the wide end of the zoom range. This next photo is less useful and I do get scolded but this also illustrates a tip:
Trilliums tend to hang down. Very hard then to photograph the flowers unless you prop them up. I have a stick pushed into the ground and pushing back the stem of the flower to lift the blossom up. Don't pull them out of the ground (boy did I catch hell for that once) but feel free to both groom the background and prop and support the flower stems. The background is blurrier in this photo because I have both gotten closer and zoomed the lens to a mid-focal length.
Shade and overcast light is going to be easier and for the most part produce your better photos.
Pay attention to the background. I did not find that background as you see it here. It has been arranged and groomed even though I found the honeysuckle growing wild. An obtrusive, too light, wrong color background can ruin the photo.
Shade and overcast is easier but don't shy away from direct sun. Flowers can work really well in direct sun if you can bring together both transparent flower petals backlit against a shaded background.
Even direct sun on the flower will work sometimes especially if you can control the light on the background. This works because the direct sun is only on the flower.
Joe
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