To see examples of our photographic work, be sure to visit our web site at:
or vist our Facebook Page at:
To see examples of our photographic work, be sure to visit our web site at:
or vist our Facebook Page at:
Cohoes Photography Club tech tip talk for February 14, 2018.
I was at an event recently and happened to be chatting with a photography club member and asked what she’d like to have for the monthly tech tip. She thought for a moment and replied, “Shooting through glass.”
So … we shoot through glass every time we take a photo. Light strikes our subject, bounces off and is transmitted through the glass (or plastic) of our camera lens to the sensor (or film).
I suspect this is not what our club member was looking for, but it does beg the question, “What is different about the glass of our lens and say a window?”
Not all glass is created equal. We have plain old glass, we have leaded glass crystal, we have low dispersion glass, extra-low dispersion glass, glass coated with an anti-glare or other special optical property material. We have polarizing coatings, we have UV filtering coatings, even window glass called Low E glass which is supposed to allow light to pass through but reduces radiant heat transfer. All of these have some bearing on what happens to the light striking the glass but probably are not the source of our problem with shooting through glass.
In this diagram we see a source of light on the same side of the glass as our camera. When it strikes the window some of the light is transmitted but some also bounces off both surfaces of the glass – camera side and subject side. The diagram does not show it but some of the light reflected off the subject also gets reflected back, away from the camera – again from both glass surfaces. So, the light from our subject is mixed with other light reflecting off the glass when it reaches our camera. That extra light may just appear as an unfocused hot spot in our image or it may reflect an object that part of the original source light.
Let’s consider one other factor that has impact on our image. Here are two photos, shot through the same window, a few moments apart. One was shot from inside looking out, the other from outside looking in. You’ll notice that one shot has a reflection and the other doesn’t. Anybody want to hazard a guess as to what’s happening here? It has to do with the relative light levels on opposite side of the glass. It turns out that when the shooting position is on the side with less light, there is less of a chance of reflection. And this is why, most of the time, you don’t have to think twice about shooting through the glass of your lens. The inside of your camera is really dark. Sure, the lens coating, filters, lens hoods and the flat black surface of the inside of the lens help to control stray non-imaging light. About the only time you have to think about the effects of non-imaging light is when you have a bright light source shining directly into the lens.
Now I think we’re ready to talk about some potential solutions to the problem.
Here is an couple of samples of shooting through a different kind of glass. Because the light is pretty much even on both sides of the crystal globe there are no reflections, but you still have to careful to shade the globe because the sun or a bright sky can still create hot spots on the globe.
In our first two parts of this series we looked at the basics of the components of exposure and in camera adjustments that can be made to get the desired exposure. In this part we have a guest – Charles Mossey – introduce us to things that can be done to choose and/or modify the light source for our exposure.
This series of posts is from tech tips presented at meetings of the Cohoes Photography Club. Chuck wrote and presented this part and has generously sent me a PDF file he used during the presentation. Here is his presentation.
Lets start with a quick review of part 1 from last month.
We discussed the fact that in the opinion of your light meter the world is 18% gray and proper exposure renders it as 18% gray. (Hand modeling by Anne Marie Koschnick)We talked about the difference between incident and reflected light metering.We briefly touched on the idea that you might not agree with your meter’s opinion of the world. So now in part two lets expand on that.
Some times when subjects are deep in shadows, you meter thinks they should be brightened up. In this shot it was late afternoon and the deer was mostly deep in shadows with only a small portion getting lit with direct low angle sun.The shadowy parts were truly lightened up to the point that it looks like mid-day, but the little bit getting sun was over exposed and washed out. I switched to manual exposure and set shutter, ISO, and f stop based on what I thought would be a more realistic representation of the scene.The image is much darker – but then the actual scene was pretty dark with only the small portions of the deer in the sun standing out. Some might argue that this is too dark – and that fine – we all have different tastes, including the engineer that programmed the light meter. Think of this as exposing for the highlights and letting the shadows fall where they may.
Back lit subjects are often grossly under exposed – sometimes rendered as a silhouette. Like this Green Heron in a tree with bright sky behind him.I dialed in two stops of over exposure to get this version.Some might say why not just correct in Photoshop? Photoshop is a wonderful tool and can allow you to create images that your camera just can’t capture but when possible it’s usually a good idea to get as close to what you want in camera. Why? Well look at this Photoshoped version of the original heron image.It’s brighter than my in camera exposure compensation but look at the digital noise. This is a common result when you have to resort to Photoshop to make too big a change to exposure when you and your meter have a disagreement.
How about sunrise and sunset images. Here’s a sunrise exposed as the meter felt was correct.It’s a lovely image but the meter’s effort to lighten up the shadows has reduced the intensity of the color in the sky. Here is is 2 stops under exposed.I find that when attempting to capture color in the sky that under exposure increases saturation.
Let’s talk about stitched panoramas for a moment. If you put your camera on a level tripod and take a series of image with the camera moved along a horizontal arc for each image, you can then stitch them together to form one continuous panorama. For example, this view of Cohoes from Peebles Island is such a stitched panorama.When shooting the series of images it is important that the exposure stay constant across all the images. So, what I do is pan the camera across my subject and watch the indicated shutter speed change as I pan. I note the range of shutter speed and select what I think is the best compromise and change to manual and set that shutter speed. Think that’s going overboard? Here’s a stitched image not shot in manual. I was walking with my camera set to capture quick images of wild life. The black top of the bike path was very shiny as a light mist was falling. When the groundhog bolted I panned with him firing off about 7 frames. I did not shoot with the intention to stitch them together but decided to play with them just to see what would happen. The exposure shift from frame to frame is quite evident.Just as an exercise in using Photoshop I tried to get approximately the same exposure across the images and restitched to get this.Better but no where near what you would want in an image worth framing for your wall. A couple of days later, when it was dry, I saw a ground hog near the same location. I switched to manual exposure and moved in, ready for him to run. This time the images stitched together without needing any real manipulation.I call this “Get Along Little Hoggie”
By now it should be evident that there are good reasons to ignore what your meter thinks is the proper exposure. Let’s talk about how to do it. I thought about including images of camera buttons, menus, and displays but decided that there is enough variation on cameras currently available that it might just cause confusion when you go looking for a Nikon button on a Canon camera, etc.
First let’s talk about a camera setting that really isn’t so much as over riding the meter as it is refining what the meter is looking at. As far as your specific camera, my best advice is “Read The **** Manual.”
Most cameras have several metering modes including an average of the whole scene – a center weighted mode – and spot metering. The first two should be pretty clear but spot metering lets you select a small portion of the image, often a 1 degree wide angle of view somewhere in the image. This would let you select what you really want exposed to a standard “correct” exposure. It can be tricky to use as slight drifting off the intended spot can greatly change exposure in undesired ways. As said above, dig into the manual to figure out how to set various metering modes on your camera.
Exposure compensation is a method to tell you camera to change the meter’s recommended exposure by a finite amount in a particular direction. For example, for back lit birds against a bright sky start with about 2 stops over exposure. Experiment and adjust accordingly. On many cameras there is a button and thumb wheel sequence to dial in such compensation. On my Nikon camera bodies I push and hold the button with the +/- symbol and turn the read thumb wheel. On the top display panel this will show a number with a plus or minus in front of it. The number is in f stop equivalents and often is in 1/3 f stop steps. So as I turn the wheel I will see something like 0.0 +0.3 +0.7 +1.0. +1.0 adds one full f stop of exposure. What gets changed as a result of dialing in compensation depends on the selected exposure mode. On Nikon cameras aperture preferred mode is designated by an “A” (I think Canon is “Av”). In this mode the aperture is held at whatever you have selected and the shutter speed is adjusted as you dial in compensation. In shutter preferred mode (“S” on Nikon cameras) the shutter speed you selected is held constant and the f stop is changed by dialing in compensation. So when we talk about stops of compensation we are talking about adjusting exposure by an amount equivalent to f stops but we may not actually be adjusting the f stop. Confused yet? On Nikon cameras when you dial in exposure compensation a scale will appear in the data area of the viewfinder and on the top display. It mimics an old light meter scale with proper exposure in the middle designated by a 0 and little tick marks appearing on one side or the other to indicate 1/3 stops steps away from what the meter thinks is correct. Again read your manual for details.
If you switch to fully manual exposure you have to set both shutter and aperture. The meter scale mentioned above is used in Nikon cameras when in manual mode. So if your shooting in manual and you want to dial in some exposure compensation you don’t have to push the +/- button. You just change shutter or f stop as desired. On a lot of Nikon cameras there 2 thumb wheels. One on the front of the body and one on the back. The front wheel adjusts f stop and the back wheel adjusts shutter so you can dial in compensation with your index finger on the front wheel and your thumb on the back wheel while looking through the view finder.
Which of these two methods you use will depend on the type of photography you’re doing and what you’re most comfortable with. They both work just fine. Since I tend to shoot landscapes and wild life where depth of field is important to me, I often have my camera in aperture preferred mode and so I use the +/- button for adjustment in most situations. If I’m shooting birds in trees I typically set my f stop to f/11.0 dial in +1 or +2 exposure compensation depending on how bright the sky looks and set ISO high enough to keep my shutter speed in the 1/500 to 1/1000 second range.
Not sure how much compensation you’ll need? Try bracketing. Again most DSLR cameras have the ability to dial in bracketing. You can select how may frames to use, the f stop equivalents to adjust when stepping through the selected number of frames, weather to make the adjustment on both sides of a correct exposure of just on one side. That is I can say shoot three frames; one normal exposure, one over exposure, and one under exposure. Or I could decide to do three frames; one normal, one one stop under, one two stops under. Or I could make all the steps over exposure. So if you’re not sure how much compensation to dial in you could simply bracket the exposure and select the best resulting image. Bracketing is also useful for scenes where the brightness range is too large for your camera to capture. With the camera locked down on a sturdy tripod you could bracket the exposure and then in an editing tool like Photoshop you could merge the multiple images into one with a technique called HDR (which stands for High Dynamic Range). There are some newer camera on the market that can do HDR in camera.
This completes the discussion of the basic in camera adjustments that affect exposure. Next month in part three we will talk a bit about selecting and/or modifying the light source to get the exposure you want.
The technical goal of photography is to record the light entering the lens of the camera.
Suppose for a moment that photography was filling a five-gallon bucket with water. If you put one drop from an eye dropper in the buck the result would be almost imperceptible. You could keep putting drops in for a long time and eventually you’d have something that resembled a bucket of water. On the other had if you pointed a fire hose at the bucket for a couple of minutes – well there’d be water everywhere and you wouldn’t have a very good result. If you had the ability to turn the fire hose on for a very brief time you might also get a bucket full of water. If you could change the size of the bucket, a very small bucket would be more appropriate for the eye dropper and a very large bucket would be appropriate for the fire hose. In this analogy, you can see three things that work together to get a container of water: a) the size of the container, b) the flow rate of the water supply, c) the duration of the flow.
In your digital camera, the water is replaced by a stream of photons – light – reflected off the subject. The bucket is the image sensor. The aperture of the lens (f stop) is the size of the hose. The shutter speed controls how long the flow lasts.
So, when you hear people talk about “The Exposure Triangle” they are talking about the three things that you can set in your camera to get the desired exposure: a) shutter speed, b) f stop, c) Sensor ISO.
A small digression. The term ISO is probably an unfortunate misnomer that is widely used. ISO stands for International Standards Organization. Among other things, the ISO has established a numerical scale to indicate the sensitivity of an image sensor to light. Calling a number on that scale an “ISO setting” is like saying the numbers on your radio’s volume dial are “UL settings.” The important thing to remember is that the so-called ISO setting is akin to changing the bucket size in our water analogy. The higher the ISO number the less light it takes to get an image – think, higher number smaller buckets.
Within limits, the f stop and shutter speed are a reciprocal relationship. If you close the lens aperture one full f stop and double the shutter speed you will get the same exposure. For example, f/8.0 for 1/60 second is the same as f/11.0 for 1/30 second. Switching from f/8.0 to f/11.0 cuts the flow rate in half so we need to let it flow for twice as long. Now bring in the ISO setting. An exposure of f/8.0 for 1/60 second at ISO 100 if the same as an exposure of f/8.0 for 1/30 second at ISO 50. Dropping from ISO 100 to ISO 50 doubles the size of the buckets so we need to let it flow for twice as long.
Back in the days of film, ISO was fixed by the chemistry of the film, yes there were ways that special processing could alter the ISO by about a stop or two for some films but for the vast majority of photographers the ISO was what the manufacturer said it was. Go back even further and about the only exposure control was how long you took the lens cap off – subjects had to sit very still.
Today we have this triangle of settings at our disposal, but what is the right setting? We could argue what the meaning of right is but we’ll save that for part two. For today let’s just say that your camera is equipped with light measuring systems and it (or the engineer that built it) has an opinion of what right is.
There are two commonly used types of light meters. Those that measure reflected light and those that measure incident light. You point a reflective type meter at you subject and measure the light being reflected toward the camera. You hold an incident meter in front of your subject and measure the light striking the subject. (A flash meter is a special version of an incident light meter). Before cameras had built in light meters most serious photographers used hand-held meters and reflected meters were more common than incident meters. Today most hand-held meters are incident or capable of both incident and reflected readings with the few reflected meters are spot meters. The meter built into your camera is a reflected light meter. It’s quite obvious that for many subjects you can’t approach the subject to take incident readings.
To the meter the world is 18% gray. Meters are color blind and want to make everything look like it is reflecting 18% of the light striking it.
(Here’s an article that discusses the advantages and disadvantages of various metering devices. http://www.sekonic.com/united-states/classroom/meteringtechniques/benefitsofincident.aspx)
Often times, a landscape photographer is shooting a still subject with the camera rigidly fixed on a tripod. Camera shake and motion blur are not a problem. In this type of shooting many photographers elect to use an automated mode called “Aperture Preferred”. The photographer sets the aperture (f stop) and the ISO. The camera selects an appropriate shutter speed. A sports photographer is more likely concerned with stopping motion and will set the camera to “Shutter Preferred” and select shutter speed and ISO and let the camera set aperture. Newer cameras have a mode where the photographer sets both aperture and shutter speed and lets the camera select ISO. Then there are many “Program Modes” where the camera will select all the setting based on the type of photography specified by the particular program mode. You will see on a lot of point and shot cameras a set of icons to depict the mode. The modes may include things like, close up, landscape, portrait, night, party, etc. Personally, I find that these program modes go a long way toward insuring bad photography! They make certain assumptions about light levels and shooting conditions that don’t always hold and they often don’t tell you what setting they selected making it difficult to know if you should override or select another mode. In manual mode, the photographer has to set everything.
What is it?
What affects it?
Why do I care / How can I use it?
A Wikipedia definition:
“In optics, particularly as it relates to film and photography, depth of field (DOF), also called focus range or effective focus range, is the distance between the nearest and farthest objects in a scene that appear acceptably sharp in an image. Although a lens can precisely focus at only one distance at a time, the decrease in sharpness is gradual on each side of the focused distance, so that within the DOF, the unsharpness is imperceptible under normal viewing conditions.”
Let me emphasize ” … a lens can precisely focus at only one distance at a time …”
Here’s an image with a foreground and a background clearly out of focus, and a 2 foot deep area that appears to be in focus. I focused on the bird’s eye and at f/11.0 had enough depth of field for the whole bird to appear sharp.
1) Lens Focal Length
2) Lens aperture (f-stop)
3) Camera to focus point distance
Below are three examples showing the impact of focal length. All three were shot at an aperture of f/8.0 and all three were shot from a fixed location. All three had the rock out in the water as the focal point.The first was shot at 16 mm and has apparent sharpness from foreground rocks all the way across the river to the trees on the other shore – more than 100 yards away. The second shot was at 70 mm. The foreground rocks are gone. The focus point rock is sharp for it full depth but the trees on the far shore are getting pretty fuzzy. The third was shot at 300 mm. Both the foreground rocks and the distant shore are gone. The focus point rock is not sharp for it’s full depth. So at 16 mm we had apparent sharpness for over 100 yards. At 70 mm the sharpness was down to less than 10 feet. At 300 mm the apparent sharpness was further reduced to less than 3 feet.
Aperture is stated as the f-stop or f-number. The f stop is the focal length in millimeters divided by the diameter of the diaphragm opening. Here are two images of a lens at different f-stops. You can clearly see the diaphragm blades and the difference in the size of the opening.
The bigger the hole in the diaphragm the lower the f-stop. The smaller the hole the bigger the f-stop. In general the bigger the f-stop number (smaller hole) the more depth of field. But as shown in the previous example the shorter the focal length the greater the depth of field so the effect of changing f-stop is less pronounced at shorter focal lengths. Here are two sets of four images. One was shot at 16 mm and one was shot at 70 mm. The f-stops used at 16 mm were f/3.5 (lens wide open), f/7.1, f/16.0, and f/22.0. If you study the example closely you will see slight differences in depth of field – but only slight. The four shots at 70 mm were shot at f/5.3 (lens wide open), f/8.0, f/16.0. and f/22. In this series you will see a more pronounced change in depth of field as the lens is stopped down. [Note, the 16 mm f/7.1 was supposed to be 16 mm f/8.0 but I accidentally adjusted it as I was struggling to keep balance in a precarious position – chalk it up to operator error! ]
Here’s the 16 mm series.
Here are two image shot with the same lens at 300 mm. In the first the camera to subject distance is less than a foot and the apparent depth of field is only a few inches. The upper twig in the image is less than 2 inches behind the lower twig on the Aspen tree. The second image was used earlier and shows a rock where the depth of field is at best 3 feet. The rock is a good 10 to 15 feet away from the camera. So in this example an increase of camera to subject distance on the order of 10 to 12 times has resulted in an increase of apparent sharpness on the order of 10 to 12 times. I’m not sure that you can expect such a linear correlation of depth of field to subject distance to hold.
Here are two more examples. The same bird as used in the opening image shot at a distance of less than 50 feet resulting in a depth of field of about two feet. The second, shot with the same 500 mm lens has a subject distance of about 8/10ths of a mile and has a depth of field of more than a mile.
So where do you focus? When Carl Heilman is trying to maximize depth of field for an image he is making, he says to manually move your focus back and forth until the foreground and background are equally out of focus. I find that easier said than done. Other sources advise you to focus 1/3rd of the way into your image. That’s also easier said than done in a lot of situations – like where you have a shore bound rock with featureless water behind it for quite a distance. Most modern DSLR cameras have something called a “Depth of Field Preview Button.” This button stops the lens down so that in theory you can see the actual depth of field when looking through the view finder. In practice this is also sketchy at best as stopping down usually darken the viewfinder to the point that is difficult to see much detail in the viewfinder. I usually pick some object past where I want the near edge of the acceptably sharp area to be and then review the image by using a magnifying loop that will block stray light from hitting the display. (See https://www.bhphotovideo.com/c/product/899482-REG/Hoodman_ch32_Compact_Hoodloupe_3_2_Viewing.html for an example product made by Hoodman.) For wildlife the choice is easy – focus on the eyes.
When discussing this topic you might hear the term “Hyperfocal Distance.” Hyperfocal distance is the distance between a camera lens and the closest object that is in focus when the lens is focused at infinity. Alas, back when cameras were mostly manual and there were no connections for sending lens information to body computers, most lenses had marking to facilitate focusing at the hyperfocal distance. Here are three images of lenses with and without such markings.
The first lens is a 50 mm prime lens. There are a series of short colored lines on the lens barrel between the f stop ring and the focus ring. The colors correspond to the colors on the numbers on the f stop ring. So if the f stop ring is set for f/16.0 (blue colored number), you would line up the infinity mark on the focus ring with the left blue line and you are at the hyperfocal distance. You can then read the focus ring value lined up with the right blue line and see what the distance to the near end of the depth of field area is.
The second lens is a zoom lens and the lines are all white but are curved. This lens is a push/pull zoom. You zoom by sliding the end of the lens barrel back and forth. You basically read the focus ring numbers the same as on the prime lens but the curved lines clearly show the decreasing depth of field as you zoom to longer focal lengths.
The last lens is a modern zoom with no hyperfocal distance indicators and no f stop ring. You set f stop with a dial on the lens body. The computer in the body tells the lens what f stop to use. So you are back to having to figure out on your own where to focus.
Bokeh? (pronounced bōˈkā )
It’s not exactly part of depth of field but it can be a consideration when deliberately going for a shallow depth of field. You’ve seen it on Christmas cards. The kid standing in front of the tree. The kid is sharp but the tree isn’t and the lights on the tree are rendered as soft globs of bright color. What we’re talking about is how a lens renders out of focus highlights. This is pretty much a product of the number and shape of blades in the lens diaphragm. It is not unheard of for a photographer to make a lens purchase decision based on how it renders bokeh. Here are two versions of the same subject. In the first I focused sharply to show where the shiny spot on the rocks was. In the second I switched to manual focus and deliberately racked the lens out of focus to to generate the nine sided spot in the second image.
Well, for sure you probably want enough depth to capture all of your subject. On the other hand you might want to reduce depth to reduce the distraction of extraneous items in your frame. Here’s an image where I wanted some foreground rocks and the far shore to both be in focus. The sheer expanse of the subject dictated a wide lens and I then made sure to stop down enough to get the desired depth.
Here are a couple of bird shots where the distance to the subject dictated a fairly long focal length. I then had to pick an f stop that would give me enough depth to get the whole bird in focus. Once those two decisions were made I then selected an ISO high enough to get the shutter speed high enough to eliminate blur resulting from camera movement as I was shooting without a tripod.
When shooting at extremely close distances, depth of field becomes very shallow. There are a couple of techniques that can help. One is to make sure as much of your subject as possible is in one plane. Here are two flies. By shooting side on I only needed enough depth to capture the width of the flies. If I shot head on I would have needed twice as much depth.
Here’s a tiny lilac blossom that does not have enough depth to capture the whole blossom.
After taking it I read up on a technique called “Focus Stacking.” The camera need to be locked down and the subject need to be motionless. So this isn’t something you do hand held on a windy day! I have tried it exactly once and clearly need to refine my process. Here’s the camera and subject that I used for my test of the technique.
I had an extension tube between the camera body and the lens. This allows closer focus than with the lens alone. It also reduces depth of field. The items to the left of the camera are a radio frequency remote release that allows triggering the shutter without touching the camera thus reducing the likelihood of camera movement during exposure. The other item is my Hoodman loupe. Looking through the viewfinder in this position was difficult and also increased the risk of moving the camera during focusing. So using live view with the loupe on the screen allowed a more delicate focusing process. I took three shots, each focused on a different mushroom. I combined the three shot in Photoshop resulting in more depth of field than I could get in a single frame. Here are the original three shots.
And finally, I highly recommend checking out a free application called DOF Master available for multiple platforms. The web version has a series of boxes that are either filled from drop down menus or filled with numerical data about you settings. When the form is filled you will be presented with a report showing the near limit, far limit and total depth. Check it out at http://www.dofmaster.com/dofjs.html
Water, water, every where,
And all the boards did shrink;
Water, water, every where,
Nor any drop to drink.
The Rime of the Ancient Mariner
Samuel Taylor Coleridge
But we’re not here to talk about parables or ancient mariners.
It’s summer, it’s hot, a vacation some place with a cool breeze – some place near water.
There are quite a few articles, tutorials, and blog posts with tips about shooting water, shooting near water, even shooting in water.
Here are a few links:
If you read through all the links you will find that they are heavily weighted toward subject selection and composition with a smattering of technical how-to bits. They are certainly worth the read. We will briefly look at a couple of technical items. Specifically, the use of polarizers and neutral density filters.
“A polarizing / polarising filter is often placed in front of the camera lens in photography in order to darken skies, manage reflections, or suppress glare from the surface of lakes or the sea.”
We can dive deep into the weeds of the physics of light and what we mean by polarized light but let’s see if we can perhaps over simplify it to an understandable level. Pretty much everything you see is because light reflects off of it – except for things like your tv, light bulbs, the sun and stars all of which directly emit light. We can think of light as travelling in waves. Unlike the waves on the ocean or a lake moving along on a horizontal plane, light waves can travel on almost any plane. When those waves strike something and reflect off – they reflect in multiple planes. When a strongly directional light source strikes a shiny surface causing glare – much of the glare are waved in one plane. If we can block the waves in the plane of the glare without blocking light in other planes we can reduce the glare. That’s what polarizers do – they block light in one particular plane. To use one you rotate it until the glare is minimized.
What does this mean in practical terms for photographers. Here are a series of images that I shot to demonstrate the difference between shooting with and without a polarizer.
The first pair do not involve water but clearly show the elimination of unwanted glare and reflections. In the without shot the glare and reflections on the car windshield make it pretty much opaque. With the polarizer, you can see the steering wheel, seat backs, and the back window – through the windshield.
Without polarizer.The second pair is of a frog. Without the polarizer, you can see the portion under the water but degraded by a blue cast of the sky reflecting on the surface. If the light from the sky had been brighter you might not be able to see the portion below the surface at all. With the polarizer, you can more clearly see below the surface of the water.
Without polarizer.Next, we have a partially cloudy sky. The difference here is not as pronounced but the polarizer darkens the sky creating more contrast to the clouds.
Without polarizer. Finally, we have a long shot showing summertime atmospheric haze. A polarizer can help reduce haze.
Without polarizer.Here’s a link to a post with sample images that show a greater difference between shooting with and without a polarizer. My examples suffer from shooting on a day where light conditions reduced the need for a polarizer. http://www.bobatkins.com/photography/technical/polarizers.html
There are quite a few other similar articles.
Next up on our tour of shooting water deals with moving water. A popular aesthetic is to capture sylvan cascades a milky white blur flowing through an otherwise sharp image. Thus creating something of a sense of quiet serenity. Like this image of a small stream burbling over moss covered rocks.
To do this you need to mount the camera on a sturdy tripod to keep it motionless and use a long exposure to allow the moving water to blur. How long does it have to be? Well that depends on how you want the image to look. Obviously the longer the exposure the smoother the water will be. I’ve seen images of the ocean with 5-minute exposures that result in an ocean with no waves! Just a smooth glassy surface! For falling water to create a milky effect you need shutter speeds longer than 1/8 of a second. Of course, there may be times when you don’t want to smooth the motion out. Freezing the motion with a fast shutter speed can convey more of a sense of power and tumult.
Here’s an image of a wave breaking just off shore. I think that freezing the spindrift blowing off the top of the wave more accurately captures the sense of the wave pounding down despite a stiff wind trying to blow it back out to sea.
Let’s say you wanted to duplicate the smoother shot of water flowing under the ice on the Mohawk River. Set you’re ISO to 50 … wait your camera only goes down to ISO 100 – Dang! Now stop down to f/36.0 … wait your lens only stops down to f/16 – More Dang! You see where this is going. So what is the solution. Enter the neutral density filter. Wikipedia defines it as: “In photography and optics, a neutral–density filter, or ND filter, is a filter that reduces or modifies the intensity of all wavelengths, or colors, of light equally, giving no changes in hue of color rendition. It can be a colorless (clear) or grey filter.” That’s sun glasses for your camera that don’t affect the color you see.
There are a couple of neutral density filter types. Solid fixed value ND filters reduce light by some fixed number of f stops. Graduated, and/or split neutral density filters reduce light in part of the image but not in others – Handy for darkening sky without affecting the foreground objects. Variable neutral density filters affect the full image but have an adjustable amount of darkening. In a pinch, the polarizer discussed earlier can be used to reduce scene brightness about a stop and a half. Both neutral density and polarizers come in a couple of different mounting systems. Most lenses have threads at the front to let you use screw on filters. Some very large, very long lenses have a slot at the back for drop in filters. I’m not sure how you adjust the position of a drop-in polarizer. Then there are systems like Cokin that have filter holders that mount to the front of the lens and have slots for filters. The Cokin system makes it much easier to adjust the position of things like split neutral density filters. Before you run out and buy, do your homework. Not all filters are created equal. I have heard a fair number of complaints particularly with variable neutral density filters.
The last thing I want to cover is one of my favorite types of water shots – reflections. When I was thinking about this tip session I thought I’d look back through some of my reflection images to see if I could demonstrate some general rules about shooting reflections. Things like look for reflections in shaded water, keep the sun behind you, etc. but in the end, it is just a matter of seeing the reflection. Any size body of water can reflect. Any type of light can lead to a reflection. Reflections in calmer water can be easier to see but even rippled water can reflect. The only tip I can give is remember “The angle of incidence equals the angle of reflection.” Huh?? The angle of what is reflected in the water must be the same angle of the camera to the water to be able to see the reflection. Move up or down to match the angles. Here are a few samples.
September has a week to go and the New York Tourism Fall Foliage map says that portions of the high peaks of the Adirondack Mountains are at the midpoint of change while Long Island has not yet begun to change. The rest of the state is said to be just starting to change.
The towers of the former headquarters of the Delaware & Hudson Railroad (now the central offices of the State University of New York) seemingly rise out of the band of trees that buffer the waterfront from an expressway and a bustling downtown.
The dock at Jennings Landing, with a solitary figure relaxing at the end, floats in what Native Americans called “The River That Flows Both Ways” as it would rise and fall twice each day with the ocean tides. These days the tide ends at the Dam in Troy – 8 to 10 miles upstream of Albany.
The calendar says it is fall but just as Albany is betwixt ocean and mountain – it is also betwixt summer and fall. The oppressive heat and humidity of summer are gone but green still dominates the trees and one does not need a sweater or jacket to stroll along the waterfront.
The photographer with a low budget may look at a macro lens and say “Woa! That’s a bit steep.” There are cheaper alternatives for taking macro or macro like images without the expense of a specialized macro lens. One such option is a set of extension tubes. These tubes fit between your lens and your camera body and make it possible to focus on objects much closer to the lens.
I hear a lot of people trying extension tubes for the first time complain that they can’t get anything in focus. Often this is due to not knowing just how close their lens has to be to the object they want to photograph.
This post outlines a procedure for getting you to a point where you know what the focal range is for any given tube and lens combination. All of the examples shown are with one particular lens and tube set up and should not be taken as the final answer for your lenses, camera, and tubes. You will want to do something similar to this procedure with all of the combinations you want to use in the field.
To start this test I am using a Nikon D300s camera body with a 36mm Vello extension tube and an old Nikon manual lens – specifically a Nikkor 50mm f/2.0 prime lens. Here’s the lens and tube.
For a target I used a ruler with 1/32 inch markings. I placed the ruler on a diagonal to my camera position. I carefully placed the zero end of the ruler on the line that would be the front of my camera lens, and placed the other end of the 16 inch ruler 8 inches from the front of the lens. With this set up I can simply divide any reading I get by 2 to get the actual camera to subject distance.
Here’s the target set up.
Here’s the camera and lens set up to shoot the target.
A word about the front of the lens position. In the first image above you might have noticed that no filter was attached to the lens and that the actual front glass element is recessed some distance into the lens barrel. It is possible to get a small subject into that space but it may be difficult to light it once there and you may have a filter attached. Therefore, for ease of measurement and consistency with what I might encounter in the field, I did all my distance tests relative to the front edge of the lens.
For each lens/tube combination I did four test shots. Two with the lens diaphragm wide open (f/2.0 on this lens) and two with the lens stopped all the way down (f/16.0 with this lens.) Each set of two shots included one with the focus set at infinity and one with the lens focus set as close as it will go.
Starting at f/2.0 and infinity I moved the camera left and right along the base line until I found a ruler mark in focus in the center of the field of view. Without shifting the camera position I changed the f stop to f/16.0. After the infinity set of shots I refocused at the near limit and again moved the camera to find a line in focus and then did the f/2.0 and f/16.0 images.
Here are the resulting images:
f/2.0 at infinity
f/16.0 at infinity
f/2.0 at near focus limit
f/16.0 at near focus limit
Remember that because of the ruler angle all of its readings should be halved. So f/2.0 at infinity for this lens and tube focuses about 3.25 inches away and the depth of field is all of about 1/8 inch. Switching to f/16.0 doesn’t change the focus distance but increases depth of filed to about 1/2 inch. Meanwhile f/2.0 at the near focus limit focuses at about 2.75 inches and has a depth of field only marginally more than f/2.0 at infinity. At this point the astute reader might notice that in the near focus limit examples the focus point is not centered in the field of view and that at f/16.0 the near limit of the depth of field is out of the frame! There are two solutions to this error in shooting. Reshoot with the focus point centered or change the ruler angle to get more of it’s length in the image. If you do the latter be sure to use an angle that will make the math easy!
If you do this test, and find that no matter where you slide the camera, you can’t find anything in focus, you may be using a tube that is too long for the lens. The shorter the focal length of the lens the shorter the tube length that will work. A 36mm tube on an 18mm lens will move the focus point inside of the lens! I would bet that you don’t want to try and position your subject inside the lens |:-)>
This lens, camera, and tube combination has a focus distance from 2.75 inches to 3.25 inches. Yes that all of 1/2 inch! If I put my subject outside of that range and I will never find focus. Depth of filed ranges from 1/8 to 1/2 inch. If my subject is over half an inch long I won’t be able to get all of it in focus. Knowing these limitations makes me better prepared to pick subjects to shoot.
One last example. You might think that if you put your ruler running straight away from the lens that the math is eliminated. Well that presents its own problems.
Something like the above you say.
There is one little stretch of the yard stick in focus – but as you can see, you can’t see the readings! Of course you could always reach out while looking through the viewfinder and put your finger down on the spot in focus. This will work but will not be anywhere near as accurate.
A biting wind, freezing temperatures, and a light – barely perceptible snow forms a haze on the horizon. And winter gives breath to Dylan Thomas –
“Do not go gentle into that good night,
Old age should burn and rave at close of day;
Rage, rage against the dying of the light.”
Spring will come to the registration desk tonight and find that her room is still occupied.
O.K. the March photo contest theme is “Transition.” I hope you understand my confusion.
Ah Spring! The season of things ephemeral like the pot holes that mark the highway department’s transition from winter plowing to summer repaving. While drivers face the confusion of selecting a safe non-damaging path along the road.
Imagine the confusion of the outdoor person’s closet floor. What footwear can be stored away, what can still be used for awhile longer, what needs to be dug out of winter hiding places. O.K. the skates can go away but I might get another backcountry ski in. The packboots can get stowed unless it snows tomorrow. The bike shoes can come out ….
Now if I could get a person undergoing “Gender Reassignment” to pose – that would be a transition that could provoke discussion.
Nope – I got nothing for this month! What’s up for April?