Monday, March 28, 2011

Mandolin Bridge Adjustment - A Note with Imre

For whatever reason, this video was probably the slowest to upload on YouTube! Not a huge file either... must be a lazy Internet connection. Anyway, do check out the video if you're interested in reducing the amount of sharpness or flatness you might be getting while fretting notes on your mandolin. I'm glad I got off my butt, put new strings on her and played with the bridge position until it became essentially perfect. I'll write more in a few days as I should be off to bed now! L8r!

Friday, March 25, 2011

Part 2: The Histogram - Photography with Imre - Episode 34

I managed to produce the histogram episode quite quickly and overall it turned out well. I'm not going to elaborate much here other than to discuss clipping a little more, along with presenting a method you can use to help train yourself in analyzing the histogram on your camera; especially useful for those of you new to this.

A Second Take on Clipping
Now that I look back at my script, the segment on clipping could have been put more simply or at least in a different manner. First of all, if the dynamic range of a scene you are taking a picture of is greater than what the imaging sensor of the camera can handle, then the image can have clipping in the shadows, highlights or both regions. Unlike our eyes that can see a much broader range of tones, for a given exposure the camera can only capture a portion of that and this is why some dark areas of certain scenes turn out pure black on the photo and bright areas turn pure white. What is crucial to understand is that clipped areas are completely void of detail. Taking a standard three channel (red, green, blue) image file, all three channels either have 0 (zero) or 255 as their values (so R0, G0, B0 or R255, G255, B255). As long as one color channel has a different value (like R0, G1, B0), then some image information exists, which means there is a possibility to recover a bit of detail (often though, lightening very dark areas results in noise appearing and bright areas that are darkened can look somewhat unusual and washed out).

Depending on the model of camera you have, you may be able to view a histogram in real-time (e.g. live view) or after the shot has been taken during playback or review mode. Signals (light in this case) below the signal-to-noise ratio of the sensor are clipped to black (in other words, there aren't enough photons filling up the photosite(s) to register above the noise level of the electronics) and if photosites on the sensor are saturated with photons then we see blown highlights (think of a bucket overflowing with water; you might try to put more water in, but the amount of water is "clipped" to whatever the bucket can hold).

Many image editing programs also provide histograms. Clipping in most image editors refers to pixels with all color channels having either no data (all zeros) or being at full intensity (255). There's a really good definition given in the help file for Adobe Camera Raw; I love their use of "overbright" and "overdark"... gives me ideas for some horror story... "the Overdark Lord was greater than evil itself." :P

I'd also like to clarify the use of file formats in this context. For example, if you take a picture and your camera is set to save the image as both an 8 bit JPEG file and a 14 bit Raw file, the tonal range of both file formats will be identical. Now you're probably thinking that's incorrect, but think about it this way. First of all, just because the camera is using a different file format does not mean it's using a different sensor. Unless you have a funky camera, only one sensor is used to capture the image and that sensor has a certain dynamic range (usually around five or six stops). Period. So the darkest and lightest points of either a JPEG or Raw file are essentially the same (I say "essentially" because JPEG files are processed by the camera, so for various reasons, like what the contrast setting is, the tonal range might be a little different).

But why is it then that you can "pull" more image detail from a Raw file? I'll use this analogy. You have two perfectly identical loafs of bread; exactly the same size! One loaf is cut into ten slices, while the other is cut into 50 slices (and no funny business, the cuts don't waste material so your loaf doesn't change in size just because you have more slices). Now if you look at the two loafs of bread, they are still the same size --same tonal range-- but one has more detail because it was sliced into 50 pieces. Taking this back to actual images, an 8 bit file provides you with 256 (0-255) brightness levels to work with, wheres a 12 bit Raw file has 4096 levels and a 14 bit one has a whopping 16,384 levels. Because you have more data to massage, you have the ability to lighten up seemingly black areas or darken seemingly white zones, thus "pulling" out those wonderful previously hidden details. There is more great info on this if you check out the last link in the Web resources section.

Anyway, I hope that clarifies the clipping segment of the video, especially where I said, "an 8 bit per channel image can clip more easily, so-to-speak, than a 16 bit per channel image." Now you can see it means you have more data to play with in a 16 bit image versus an 8 bit one... my bad homies, didn't mean to be shiznitting with the down low.

A Little Self Training
Ok. In the video I said I'd write about a method you can use to help train yourself in understanding what the histogram on your camera is trying to tell you. On my own cameras, I've consistently noticed that if the image seemingly appears properly exposed on the camera's display, they are actually underexposed when I view them on my computer monitor. Those images appearing a bit overexposed on the cam's screen are generally exposed properly. This is why using the histogram can be helpful, but for novice shooters it might be hard to relate what a well exposed histogram looks like. In addition, since virtually every photograph has a unique histogram, it takes a little bit of experience to gain that intuition about which one looks about right. So if you think you need a little help in this area, then feel free to follow the simple steps below:

  1. Get out there and take some photos, but be methodical. First, if possible use a tripod as you'll need identical shots. Second, use the bracketing feature of your camera to take three shots varying the exposure by 0.7 (so you'll have one shot at -0.7, 0.0 and +0.7). If your camera only does half-stops, then use that and if by chance your cam does not have a bracketing feature, then adjust manually via EV compensation. At this point, ignore the histogram; all we want are three photos of a scene. Take a bunch of shots of various locations, some darker, some lighter... whatever.
  2. Download the shots into your computer, but DO NOT delete the photos off the memory card.
  3. Now open up a file on the computer and also display the same photo on your camera with the histogram feature.
  4. And you're probably getting the idea now, but keep doing the same thing for each shot, each time comparing what the image on the computer monitor looks like in comparison with the one on the camera with it's histogram.
By comparing what the photos looks like on the two devices, you'll start to get a feel for what histograms look like for well-exposed shots, along with those that didn't turn out.

As a final note I want to add that it appears I've placed a great deal of emphasis on histograms, but keep in mind that you don't always need to use them and depending on what you're shooting they might not be that useful. In addition, it's not like the exposure has to be absolutely perfect or else the photo is junk. I personally don't necessarily believe there is such a thing as a perfect exposure to begin with, as our personal tastes or creativity will alter that definition and there's a fair amount of leverage to correct some issues in editors. Nonetheless, with some time and practice, I'm sure most of you budding photogs will start to see the benefits to histograms and when they're worthy of employing.

If all goes to plan, stay tuned for the next episode on time lapse photography. Happy shooting! L8r!

Web Resources

Tuesday, March 22, 2011

The Histogram - Photography with Imre - Episode 34

Well I managed to get this episode done fairly quickly in about 15 hours start to finish. Plus, I think it turned out to be a great primer for those who are not familiar with histograms. Supplemental post to follow in the next few days as usual!

Um... yea I know I said I'd do time lapse photography next, but well... ok I have no excuse! I'll try to make that the next show! L8r!

Monday, March 14, 2011

Shooting Birds in Flight

I got a message from a subscriber of my YouTube channel today about taking photos of birds in flight. This individual expressed problems of getting a fast enough shutter speed, especially due to how cloud cover often blankets the location this person is from and reduces light intensity, which has resulted in some blurry shots. Hopefully my advice to follow will be of some assistance and those blurry shots will turn into some detailed and stunning captures of those featured creatures gliding gracefully through the air. To make this a more complete post about this topic, I've added more detail about shooting birds in general. Please keep in mind too that these suggestions and techniques are what I tend to use and as such they may not work for everyone in every case. So always feel free to experiment.

One of the first steps to ensuring a nice sharp image is to get the scene/subject in focus. Birds swooshing through the air can make this somewhat more challenging, so here are a few suggestions I'll offer based on what the background is like.

Bird Against Clear Sky or Even Cloud Cover: The clear sky bit makes sense here; simply imagine a nice blue sky without any clouds. But by even cloud cover I mean a sky that is cloudy, but fairly evenly throughout; in other words there are no puffy or wispy clouds contrasting against a blue sky, but rather that dull light grey tone up everywhere you look.

In cases like this there are a couple of modes you can try to get a sharp lock on your feathered subject. The first mode is to employ the center focusing dot on your camera, aim at the bird and start clicking the shutter button. Overall this method has worked fairly well for me, but I've noticed some issues. It's hard enough as it is to track a flying creature, so I've often ended up with the center focus dot on the sky next to the critter. Since there's nothing much the camera can focus on, the lens starts hunting unsuccessfully and by that time the bird is long out of focus and out of frame.

Instead of using just that single dot, I've instead found myself selecting all targets (or area focusing mode) more often for birding. Since the background is simple and lacks contrast, the bird wonderfully stands out against the evenly toned sky. So even if its off center, one of the those many focus points will register the bird and the focus should lock. Some sources say this mode is somewhat slower than just using a single dot, but in my experience --specifically in this case-- I've found that point fairly moot (in cases where the subject and background are more complex, then indeed the system needs more time to focus... keeping in mind that time is generally very small, around one or two tenths of a second).

Busier Backgrounds: Things get more interesting when the background is busier. Take for example a bird flying against a scenic landscape (e.g. a forest, mountains) or city skyscrapers. In this case, area focusing mode may not be a great choice as the focus could very well be hit and miss... mostly miss. In such situations, I've either gone back to using the single center dot for focusing and tried my best to follow the subject or have used manual focusing. Manual focusing is tricky on the fly but if a bird is at rest, like on a street light post, it's a cinch to perform. So when the fellow takes flight, you are already have perfect focus. Now this is not with its downside though, because if the bird flies towards or away from you, it may go out of focus. Therefore, one has to hope the bird flies more or less parallel to your position. I recommend trying out a few of these techniques and I'm pretty certain you'll find one that you favor and works quite well.

Lens, Camera Mode and Settings
Shooting birds can essentially be called a sub-category of action photography, so many of the considerations you find there can be applied here.

Lens: It pretty much goes without saying, but with most photographs of this nature a long lens is required (unless you want tiny dark specks as birds). Thus, we're likely looking at a range of at least 300mm to 600mm or even larger if you have access to such equipment. A fast lens can be beneficial too, as less light loss will allow you to use faster shutter speeds in situations where, for example, cloud cover is blocking sunlight. On the other hand, shooting stopped-down a little, like around f/5.6, might yield slightly sharper images and a bit more depth of field (DOF), although that's not as critical; the distance most birds would be at means the DOF will be fairly large anyway. Even an aperture around f/8 will very likely provide a sufficiently blurred background, but as usual, take a few shots and adjust to your liking.

Shutter Speed and Mode: Not only would the person who asked the birding question like to get sharp photos, but so would most of us when shooting these airborne lifeforms. Therefore, to ensure a quick enough shutter speed, I strongly recommend shutter priority or manual mode. With shutter priority, you can force the camera to use a specific shutter speed and the machine will adjust the aperture and sensitivity (if set to auto) accordingly in order to get a good exposure. For focal lengths of around 300mm, 1/500 of a second should freeze the action, but of course use 1/1000 or even 1/2000 if you're noticing that blur is still occurring or if you're using a lens with a longer focal length (... err, just because you're using a longer focal length lens doesn't mean you have to use a faster shutter speed, but if you're hand holding, it can help prevent hand-shake effects for some photographers).

Now I also mentioned the use of manual mode, where you can force the camera to use whatever shutter speed and aperture you want. The advantage with this mode is that if you want the aperture to be something specific (e.g. you want f/5.6 because the lens is sharper in that range, or you want f/2.8 to ensure the lens stays wide open), then you can force the camera to entirely do your bidding.

Whichever of these two modes you choose, you'll likely have to play with the numbers to get the right exposure on the bird; not too dark (details lost or too noisy when processed to be lighter) nor to light (loss of contrast and details washed out). In addition, don't be afraid of pushing the sensitivity higher up if needed if you're finding the exposure is too dark. Many cameras, even some models a few years old, still produce good quality images up to 1,600 ISO and if you shoot in RAW, you'll have a fair amount of control at your fingertips to eliminate much of that noise (or you might already have software/plug-ins dedicated to noise reduction). Of course if you want to keep noise at a minimum, then try either a larger aperture or slower shutter speed setting first.

And before moving on, remember to use the high speed sequential shooting feature on your camera. Pressing the shutter button repeatedly while panning will make things more difficult than they need to be. This is also where traditional mirrored DSLRs still have a major advantage over the electronic viewfinder (EVF) types. Although the mirror slapping up momentarily blacks out the picture, you can still see the subject moving along quite clearly, whereas EVF cams generally show you the last photo taken for a split second.

Funny how manufacturers haven't caught onto the idea that if you're in sequential shooting mode on an EVF type camera, why the heck not just keep showing the image as normal to the photographer? I mean think about... seeing the last image taken for a split second is basically useless, as it's not enough time to give the photos a good examination for anything in particular and it's of little to no help in keeping up with the subject in motion (especially for more unpredictable movement). Personally, and I have a feeling most photographers would agree with me, as long as I can trust that the machine is capturing images while I'm pushing down the button (ok, show me a bloody red blinking dot in a non-intrusive spot), I don't need to see the screen blacking out or the last pic displayed momentarily; I'm more than happy to review the results afterwards. And if any of you manufacturers out there implement my idea, I'll gladly let you know where you can make my royalty payments to! :)

Tripod/Monopod vs. Hand Holding: Whether you choose to use a tripod/monopod or hand hold your camera plus lens is mostly up to you and is generally a personal choice. However, if you have a fairly long lens, it can become tiring to hold the thing for an hour or two, and panning along with the subject can be smoother (but perhaps not as flexible as hand holding).

Almost any type of tripod can be used but certain types might have better results. For example, less expensive tripods with the head build-in might not allow fine control over tension and might not have a quick release plate, thus making removal of the camera more cumbersome and slow (e.g. maybe a quick change in position is needed to capture another subject or a bird in an usual location). On the other hand, more flexible tripods that can be fitted with various types of heads may be more to your liking. Perhaps a ball head can give you the freedom you need to quickly pan around with a single tension control, or a three-axis (aka three-way) head is more to your fancy as you can constrain the panning to a single plane (e.g. horizontal, thus keeping bobbing to a minimum; could help keep a certain composition too, as you wouldn't pan to high or low).

A monopod may offer a more compact and lighter weight solution to help with panning and I've certainly found them great to use, especially for horizontal movement as you can simply rotate the thing left or right. But adjusting the camera's gaze vertically is a bit unusual, as it can place one in an uncomfortable position.

So that concludes my quick post on shooting birds in flight. There's certainly more information out there that could be applied, but I believe this is a good starting point for those interested in this subject matter. Good luck and happy shooting! L8r!

Thursday, March 10, 2011

Check out the new look of my website!

Web design has never come that easily to me. It's unusual because I can certainly tell if a website looks professional and is well developed, but drawing something up that looks like some of those awesome sites out there... eeek!

Nonetheless, I think I did fairly well with the redesign of my personal website; feel free to comment and let me know (be nice! LOL):

The "old" version of the site was a little simpler looking and concentrated more on my IT skills (programming, Web application development, etc.), and although I'm not quitting that work I'd rather emphasize my "Photography with Imre" series and other creative projects. As time goes on I'll be adding more resources to the site (i.e. more links and more useful content of my own creation), so at some point the website will become a virtual entertainment and educational hub. Considering it took me two (very full) days to do this, I actually have high hopes on this venture!

Please feel free to make suggestions; anything can help! L8r!

Tuesday, March 8, 2011

Part 2: Intro to Action Photography - Photography with Imre - Episode 33

I already said it, but man did I have fun creating the action photography episode! Gigantic topic though but hopefully the show gave people a good idea of what it's about. Speaking of which...

The Subject is Key
... it is indeed all about the subject and I don't just mean you have to get the thing you're shooting in the frame. Since I hit up this subtopic quite thoroughly in the video I won't spend much time on it here, but I can't help emphasize it a little. Virtually everything such as the camera equipment you'll need for the shoot, the location you select, perhaps the time of day and camera settings will depend largely on the subject. In addition, some research might also improve the composition of the photographs. It's like the examples I provided in the video. Skateboarders doing tricks might look better with a wide angle lens, flash and a large depth of field (DOF) to capture cool moves, while certain motocross shots will be more impressive with the background motion blurred and a smaller DOF.

Preparation also fits into this realm. Since action photography can encompass many different types of subjects, consider creating a checklist so important details don't slip the mind (especially if you're shooting for money). Be mindful if shooting at various events where a permit or permission might be required to photograph. Although laws differ from place to place and I'm no legal expert so I recommend you ask someone qualified, generally speaking if you're on private property then you usually need some sort of permission. In some cases it's clearly allowed and nothing written is required, whereas I've read some articles stating that certain sporting stadiums only allow focal lengths below a certain value (e.g. 200mm or less) and in some cases you need to be a VIP with an ID tag dangling around your neck.

Setting the Shutter Speed and Camera Modes
In most action photography scenarios, the shutter speed is key to making the shot work. For example, if you need a very high shutter speed to completely freeze the action, then you'll likely be looking at something around 1/1000 of a second (I have visions of a speed boat race in my head with rooster tails flying out the back). If your camera is set to auto mode, the results will likely be unpredictable; simply said the camera will decide what shutter speed and aperture to use (I'll discuss sensitivity/ISO in a moment). So in some cases the action might be nicely frozen, but in others (perhaps due to lighting conditions) the detail might be blurred as the cam decides to slow the shutter in order to get the right exposure. Aperture priority may not be much help either (although it's worth mentioning that this mode might very well work for many cases, except in places where a very particular shutter speed is required or desired). Sure, you could open the lens as wide as it'll go, which would deliver more light to the sensor and help increase the shutter speed, but your DOF may be too small to your liking.

So this is where shutter priority and full manual mode come into play. Let's examine some of the pros and cons to these modes:

Shutter Priority - Pros
  • You can set the shutter speed to almost anywhere you want
  • Camera will decide on using the appropriate aperture to get the right exposure
Shutter Priority - Cons
  • Depending on the shutter speed set, the camera may not be able to produce a good exposure (e.g. aperture may not be adjustable to where needed; a shutter speed of 1/8000 may need the lens opened wider than it can go, thus underexposure results)
  • DOF might not be what you would like it to be as the camera manipulates the aperture
Manual Mode - Pros
  • You are the master; you can basically adjust any setting to wherever you want on the camera
  • Excellent for specialized cases such as fireworks
Manual Mode - Cons
  • To confirm exposure, either test shots must be taken or a light meter has to be used; one is a bit slow to setup and not everyone has a light meter
  • If sudden changes in lighting conditions occur, then the exposure settings need to be adjusted. Think of a cloudy sky and shooting that boat race. Everything might be ok when the sun is out, but when clouds obscure the sun, the drop in light intensity will likely result in an underexposed photo.
  • Might be tricky to setup if a novice
The choice between shutter priority and manual mode must be made by you. As much as I'd love to suggest something, the problem is that everything from the type of subject you're shooting, to lighting conditions and even personal preferences must be considered; there are simply too many factors. But with what I've presented and some further research and experimentation on your own, I have a feeling you'll start to get a feel for it (seriously, experiment lots!).

Now I'd like to discuss sensitivity as it plays a significant part in getting the correct exposure. As with some other settings on your camera, you can leave ISO at automatic or set it yourself. Leaving it at auto means that the camera will decide when the sensitivity needs changing. There are some trains of thought on this as with anything, so I'd recommend that you again experiment and discover how your camera behaves. Personally, I tend to set it myself, as I usually go for keeping the noise as low as possible. On the other hand, leaving it at auto may give you some extra flexibility. For example, if you're shooting in shutter priority mode, then the camera could set both the aperture and ISO to get the right exposure; this may overcome certain cases where an adjustment to aperture alone isn't enough (Think back to the example in the cons section of shutter priority. If the lens cannot be opened any wider then the ISO could be increased, perhaps making the sensor sensitive enough to light to get a good exposure at 1/8000 of a second).

It's in the Skills
Having the right equipment and being able to push some buttons on the camera are only small parts to being an effective action photographer. In my opinion, the ability to "feel" the shot is another significant issue. In other words, the skill of the photographer to nail the composition of the shot and be able to anticipate what would work in regard to factors such as lighting, background and time (i.e. getting the right moment(s) to capture the images), amongst other things is key. I'm the type of person to believe that some people have a natural ability to do this, while others can learn and hone their skills by practicing often. To at least provide something useful in this regard, I've created a list below with a few things that might help you get started:

  • Practice panning the camera so you can follow subjects in motion. And don't just pan, take shots during the motion to get used to pressing the shutter button while doing this.
  • Sometimes it's convenient to shoot handheld versus using a tripod or monopod. Practice holding and taking shots with a large lens to get the feel for it, but keep in mind the focal length reciprocal rule, which works as follows. Let's take a 600mm lens, which in fractional terms is 600/1 (600 "over" 1). So the reciprocal would be 1/600... so to get a potentially blur free shot, use a shutter speed of at least 1/600 of a second. Of course you might need a faster or slower shutter speed in some cases, but it's a quick guideline to go by.
  • Try unusual angles and not just those from a high or low perspective, but consider banking or tilting the camera. Often you can better fill a frame with the subject and create more interesting shots with the horizon off-kilter.
  • If the possibility exists, experiment using a flash; either on your camera or remotely triggered in various locations.
There would be so much more to write about, but I think I'll stop here and if anyone has questions or if I think of something useful, then I'll zero-in on that matter and create a new post.

The next episode will be on time lapse photography as that topic had quite a few requests. L8r!

Web Resources