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ContactExtension Tubes for Macro Photography
by boyan on Feb.26, 2010, under Reviews
Let’s briefly look at something that we use fairly often – Extension tubes. If you don’t know what extension tubes are used for, it’s basically a cheap way of converting any lens into a macro lens. So if you plan on doing any kind of close up photography, even just occasionally, you may find this interesting.
Since it’s pretty much impossible to do any kind of macro work without specialized equipment, let me briefly explain what our options are, as well as, the pros and cons of each alternative.
Your first option is to get a macro lens. A macro lens is like any other prime (or fixed focal length) lens with the added bonus of being able to focus much closer than regular lenses. That way you get magnification which you need for photographing things which are really small. To give you an idea of what this means in practical terms, a typical portrait 50mm non-macro lens has a focusing distance is about half a metre. So if I wanted to take a close up of a cell phone for example, I wouldn’t be able to fill my entire frame with it because I wouldn’t be able to get close enough.
Pros are that macro lenses are usually optically among the best lenses you can get, with very little distortions, they are very sharp and fast typically, and obvious advantage would be that you don’t need to fiddle with any additional equipment which would only slow you down. The down side would be that you need to purchase another lens (and we all know that photography isn’t cheap) and also if you want different focal lengths you’d have to get different macro lenses.
Second option would be to buy macro (or close-up) filters. They attach to the lens like any other filter and provide magnification. The down side to this is that they are optically not that great, and you will be losing quality. You’d have to spend a lot of money to ensure that the close up filter is of adequate optical quality to retain the quality of your lens. As a general rule, the more pieces of glass you put in front of your lens, the more you’re degrading final image quality. Also, you need different filters with different levels of magnification if you want variety.
Last option is to get a set of extension tubes. The way tubes work is that they increase the distance between your lens and camera sensor and force the lens to focus closer than it normally would. The bigger the tube, the more magnification. What’s great about the tubes is that they contain no glass, it’s just a hollow tube, so it does not affect or change the quality of whichever lens you’re using. A down side is that you lose infinity focus when you have the tubes attached, although presumably if you’re attaching the tubes in the first place, you’re doing so because you intend to take close up pictures and you don’t care about focusing on some mountain range on the horizon. So while this is a limitation, it is essentially not a problem at all for all intended uses.
Another benefit of extension tubes is the unbeatable price. It is the cheapest alternative by far, and considering that image quality is not compromised like I mentioned earlier, it makes it a no brainer. While it is the cheapest option, it may not be the case if you go with Canon made tubes. Although I love Canon, sometimes they just don’t make sense. If you go with Canon, you’ll easily pay twice as much. And this is one of those situations where you are really not sacrificing anything by going with a third party manufacturer. There are no glass elements inside the tubes, and the electronic connections all work properly so your autofocus will work no problem.
We use tubes made by Kenko, and they retail for about $230 for a set of 3. You get 3 tubes of different lengths which gives you the flexibility so you can get as much magnification as you deem necessary and you can also stack them for maximum effect.
Let`s take a closer look at the structure of the tubes:
They are made of plastic, they are nice and light, and don`t add too much weight to your kit. To detach the tube, press on the lock release and that`s it. You can stack them all you want, although with all 3 tubes in place you`ll notice that you start blocking off a significant portion of ambient light because you are so close to the subject, so you may want additional light sources.
So what do we use Kenko tubes for ? Well when we`re on the job – mostly ring shots. Details are important so we use the tubes to get really close and capture those small details, and the rest of the time, we use them for pretty much anything. Take a look at some samples below, and if you`re interested in doing some close-up work and you`re looking to get most bang for your buck – this is it!
Enjoy!
Good lens / bad lens
by boyan on Feb.19, 2010, under Tutorials
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How does one decide which lens to buy? Why are some lenses more expensive than others, and how can we tell if one lens is better than another? These are some of the common questions which we’ll try to answer here.
The purpose of a camera lens is to focus the light rays into a single point on the imaging plane(sensor). In theory, a single convex lens would suffice for this task, however in practice, such a simple design suffers from various aberrations that need to be corrected by introducing additional lens elements.
The goal of these additional lens elements is to direct the light in such a way as to recreate the image as accurately as possible while minimizing aberrations and distortions. Aberrations occur when points of an image do not translate back to single points after passing through the lens, but are instead “smeared” over a larger area. These are the major types of aberrations/distortions and are always used to classify a particular lens as “good” or “bad”:
Blurring / Loss of sharpness / softness
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Technically speaking blurring happens when a single point in a scene is not translated to a single point to the sensor, but rather a circle. It should be immediately obvious that sharpness can therefore be a subjective quality, and certainly dependent on viewing distance. In other words, if you move away from a blurry picture far enough, those circles will appear smaller and smaller, and eventually will look like sharp points. However, no one will look at their monitor from across the room when looking at pictures, therefore we cannot get away with soft pictures. Hence, this is probably the single most important lens characteristic. Soft/blurry images are simply of no use, and are impossible to fix in post production. Therefore this property takes the #1 spot in importance.
Loss of Contrast
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This one is pretty straight forward. Even though contrast can be boosted in post production, it will never look the same as a picture which had proper contrast to begin with.
Chromatic Aberration
CA is a type of distortion that occurs when a lens does not manage to focus all the wavelengths of light to the same point on the imaging plane. The manifestation of this distortion is typically purple (or white) fringing, most easily detected when looking at edges with high contrast. Although this can be reduced in software, it is one of the more difficult things to fix properly. Having a lens with a well controlled CA is essential.
Vignetting
Vignetting is used to describe the “light fall-off” near the edges of the frame. This is arguably the easiest thing to fix in post production and does not cause too much headache. Furthermore, vignetting is typically pronounced only in the wide-angle range and at wide apertures. Another thing to note is that vignetting is not always perceived as undesirable. A vignette is often intentionally added in post production to draw the viewer’s attention to the main subject in the photograph.
Barrel / Pincushion Distortion
Lenses will always have some degree of distortion especially wide-angle lenses. However this is fairly easy to fix in post production and therefore ranks slightly lower on the importance scale. However, this does not mean that we shouldn’t care if our lens produces completely warped pictures. Distortion should be mild on a good wide angle lens, and anything extreme would be deemed unacceptable.
To a certain degree, all lenses suffer from the above mentioned problems. As of this date, there is no such a thing as a perfect lens. However, manufacturers put substantial amount of effort into minimizing these flaws by adding elements, coating the glass with various materials in order to improve its optical quality. Nevertheless, even professional grade lenses will suffer from the above mentioned flaws (to a certain degree).
The complexity of the lens, and the level of success in combating lens aberrations directly affects the price. When one lens is said to “be of lower quality than another lens” we usually mean that it suffers from one or more of the above mentioned artefacts to a greater degree than the lens we are comparing it to. Also note that lens performance is not uniform across the frame. Lenses typically have best optical quality in the middle with some degradation towards the edges of the frame. Professional grade lenses have measures in place to prevent significant degradation in quality near the edges of the frame. While these flaws may remain hidden on a crop sensor camera body, they become very apparent on a full frame body. This is why it is very important to upgrade to professional grade lenses when switching from crop to full frame.
Aside from the technical aspects outlined above, here are a couple of additional distinguishing characteristics that could (and should) be a deciding factor when choosing a lens (more details on both of these coming soon):
Large maximum aperture.
If you can afford a lens with a large maximum aperture, by all means get it, and you will not regret it. The larger the maximum aperture, the more light your lens can take in. This allows you to achieve same level of exposure at a faster shutter speed than a slower lens which has a smaller maximum aperture. Low light photography comes up sooner or later no matter what kind of photographer you are and it is good to be prepared. Generally speaking, the performance of the lens will degrade when shooting at wider apertures, although this degradation is minimized in pro level lenses. More on aperture coming soon.
Versatility in focal range
It is good to have a wide focal range covered whether by purchasing one diverse lens or several different ones. To be properly equipped for most situations you should have lenses in your collection that range from wide-angle (say 18mm) to telephoto (at least 100mm, but preferably more) . It’s important to note that lenses which have variable focal range (i.e. 18-200mm) will almost always be inferior (with respect to the 5 points illustrated above) to prime (or fixed focal length) lenses. When it comes to lenses, what you gain in versatility, you pay for – with quality. More on focal length coming soon.
Why do I need to buy a hot shoe flash when my camera has a built-in one?
by boyan on Feb.08, 2010, under Tutorials
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A flash is a device used to provide an instantaneous burst of light at about the same color temperature as daylight (5500K). A flash is typically used in situations when there is not enough ambient light to properly expose a scene. These days most cameras have a built-in flash unit, and for the most part, users absolutely hate the results that it produces. Subjects tend to take on a very typical “deer in headlights” look, with very flat looking faces, and a dark background. As a result, there is a very common misconception that flash is something that should be avoided altogether. In fact, some people believe that buying a more expensive camera will eliminate the need for flash. However, every professional photographer will tell you that a flash is an absolutely essential part of the photographic kit, and it’s not going away any time soon. In fact, it is often used by professionals to enhance the results, even in seemingly well lit situations (i.e. outdoors with plenty of sunlight).
However, the majority of users are right about one thing – built-in flash does indeed tend to produce horrid results. There are two reasons for this:
1. Flash head is a small source of light and, as a result, it produces harsher shadows. As a rule of thumb, the larger the light source, the gentler the shadows and more pleasing the result. One valid question here would be:
“But if size of the light source determines the “harshness”, then why is the sun considered a harsh source of light?”
Size of the source is meaningless unless we take into account its relative distance. We are very far from the sun, so the sheer distance effectively turns it into a small light source.
2. The angle at which the built-in flash fires (straight-on) washes away all the shadows and creates a very flat looking image. Shadows are essential for creating the perception of depth in the photographs, and the built-in flash simply cannot do anything to fix this problem because it is mounted on the camera itself.
Luckily, both of these problems can be solved with an external hot shoe flash unit. External flash units are mounted on the camera’s hot shoe and provide far greater flexibility than the built-in flash. The head of the mounted flash has a unique ability to rotate 180 degrees, and tilt up and down. This feature alone solves both problems by allowing the operator to “bounce” the flash off of walls and ceilings.
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“But how does bouncing solve the 2 problems listed above?”
By bouncing the flash off a ceiling, we are converting a small source of light into a very large source of light (a large portion of the ceiling becomes the source of light) Therefore, shadows become many times softer and as a result, flashed pictures can look as if they were not “flashed” at all.
It is for this same reason that photographers like cloudy skies when photographing people outdoors. Sun’s harsh light is diffused by converting clouds into a large and even source of light:
The “bounce” also solves the second problem; now the flash does not fire directly from the camera to the subject, but instead fires from above the subject (in case of a ceiling bounce) and hence allows shadows to form on the face of the subject, creating a much more realistic, three dimensional look.
Take a good look at the 2 samples below and notice how the pattern on the sweater is much more visible on the picture with the bounce flash. This just goes to show you how important shadows are. In the first picture, we fired the flash directly and washed away the shadows causing the pattern to be barely visible.
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Other advantages of hot shoe flash units:
- Because bouncing disperses the light much more, even some of the surroundings reflect the light from the flash and become better lit, and also act as reflectors, bouncing additional light around the room. This can (although it may not depending on shooting circumstances) reduce the “black void” behind the subject that is often created when there is little to no ambient light, and built-in flash is the main source of light.
- External flashes have much higher power outputs than built-in flashes, so you can reach your subject from much further away.
- The short burst of flash helps “freeze” subject motion. To understand this better, think of a strobe light in a night club – the strobe makes people who are dancing appear “choppy” and “robotic” because the short bursts of flash dominate the low ambient light, and our eyes start noticing only the intervals when the strobe fires. This can be taken advantage of in photography to freeze motion of really fast subjects and achieve maximum sharpness. This effect is also attainable with built-in flash as well, but results will be less appealing due to already mentioned limitations.
- Remote firing. Mounted flash can be mounted on a stand and fired without even being physically on the camera. This is achieved using either a sync cable, or a wireless flash trigger. This allows you to move the flash away from the camera lens axis in order to eliminate the flat look that built-in flash produces. The effect you can achieve is kind of like bouncing mounted flash off a wall, except that the light will not spread nearly as much and you can create a “spotlight” look.
- Daisy chaining. Several mounted flash units can be set up to fire together, and thus allow for more creativity and control over the lighting of a scene.
