Greetings, volks. Welcome to Hohenfels Volks, THE place for our place!
Today we’re going to go a little bit into what makes up your exposure numbers and how metering works. It sounds familiar, but we’ll be dealing with more math and other advanced parts of your exposure settings.
Let’s start with your ISO. Back in the old days there were lots of ways to label film sensitivity. There was by DIN number, ASA, Weston, and EV, as well as various others fallen by the wayside. Today we use ISO, which is for the most part ASA. Some folks use DIN, that’s why film still carries the DIN number. Under today’s scheme, 3 degrees DIN are equal to 1 full stop. ISO 100/21 has half the sensitivity of ISO 200/24. The Weston number, another popular standard used to gauge a film’s sensitivity, referencing Weston’s meters, is usually .8 times the ISO. Since we’re shooting today, we’ll use ISO, but there may be times we reference others in our future.
Moving on we come to light and light levels. Without the fancy gadgets we have to meter our exposure built into cameras, folks used external meters. Ansel Adams broke it down in his book The Negative. Meters used to measure light in candles, or candela, per square foot. That was the basis for your shutter speed. This will become important in a couple paragraphs.
Next we have aperture, the size of the opening through which light enters the camera. Each ISO had its native f/stop. To find the native stop for any ISO take its square root. For ISO 100 the native f/stop is f/10, for ISO 125 it’s 11, for 200 it’s about 14, and for 400 the native f/stop is 20. Apertures are measured in f/stop, which is a ratio based on the square root of 2, as each step is doubling or halving the light.
The last part is shutter speed. For a native aperture, the shutter speed should be 1/ the light measured in candles per square foot, or c/ft². If you read 125 c/ft², your shutter speed for a native aperture should be 1/125 second. It sounds easy doesn’t it? Well, don’t give up hope. Things are about to get tricky.
Since most light meters today don’t measure in c/ft², finding that speed may be difficult. Automation has taken away many of the tools used by those who came before us in every arena. You can buy a cheap ambient light meter and use it for your photography. The readings are usually in LUX. LUX can be converted, however, by dividing by 10.764. Just round to 10, and there you have it. 1000 LUX is 100 c/ft². At your native aperture, shoot 1/100 for zone 5 placement of what you just read and you’re cooking with gas. Using you digital camera’s metering, set your aperture to the ISO’s native aperture in AV mode. Then seeing the required shutter speed tells you there are that many c/ft² or 10 times that much in LUX.
It seems like talking about this doesn’t do much for you shooting digital, but knowing it will help you improve your light reading skill without your camera’s meter and make getting your exposure correct a lot easier. Plus, if you decide to go old school and shoot with an old camera or use an old meter it will help you to figure that stuff out. It also comes in handy when working with the zone system. Reading 1/100 at your native aperture, you have the knowledge of how to combine your speeds and apertures to get the right exposure for 100 c/ft². You also have the knowledge that you can move your image up or down a zone without playing guessing games as much. It’s quicker and easier to figure out once you try it a few times. A good example is on a bright, sunny, semi-cloudless day. The sky reads about 300 c/ft² when read usually. So for ISO 125 at f/11 you should be set for 1/300 as a good starting point. Then adjusting your speed inverse to any desired aperture changes, and you should have a decent exposure with the sky at zone 5. You can adjust just your aperture or speed to move the sky and other subjects into different zones and create what you visualized that way.
Ansel Adams described it as the exposure formula. He taught that zone 5 was 1/c/ft² at a film’s key aperture. It still holds true. Some minor adjustments may need to be made, but you should be almost dead on. It helps to spot meter for your highlights and shadows to get the best range in your image, but for quick shooting, try it out! I think you’ll see something very cool!
The new theme for this week is “Flattery (Not everything complimentary is flattery!)” You may have already guessed that this has to do with colors, right? Your shots should be composed with complimentary colors as a major element of your composition. Another aspect of your image must consist of contrast in your subject, as well as the contrasting complimentary colors. Perhaps age and youth, or hot and cold. I hope that you get the creative juices flowing for this one and get working on it soon! I also hope that we will see everyone out there submitting this time!
Don’t forget to post any of your images you’d like to see here at the Hohenfels Volks Facebook page. Of course, commenting on both Facebook and here is always appreciated, too!
Showing posts with label lenses. Show all posts
Showing posts with label lenses. Show all posts
Tuesday, January 17, 2012
Wednesday, January 4, 2012
In the Zone- Zone Focusing
Greetings and welcome to Hohenfels Volks, THE place for our place. I hope you’re ready, Hohenfels, to learn about zone focusing. This is something that can make getting some of those passing moments in the can, as it were, quicker and easier.
First off, let’s explain what zone focusing is. Zone focusing is using a combination of focal length, aperture, and distance to allow for enough depth of field to make a usable print. That’s pretty straight forward, right? Well, there is more to it than that, including knowing your equipment.
Zone focus developed as a way for photographers to focus their equipment, as most older cameras had no viewfinder or way to check your focus. Many of the old time greats used zone focusing to maximize the sharpness and detail in their works. Given the nature of early lenses, high f/stops were often required to get good detail and enough DOF to be worth printing. Remember, sheets of film, and rolls, were costly to purchase, develop, and print, so lots of effort went into taking each shot. Zone focusing grew from the concept and practice of hyperfocal distance, which you use to give you the maximum DOF for each lens focal length. We’ll have more on that in another post.
The technique works best with lenses that have markings on them. A distance scale for focusing opposite an aperture scale with DOF markings as shown in the photo below works best. It’s quicker and easier. Unfortunately, most lenses today are auto-focus, and kit lenses generally don’t have such marking. Higher end lenses do have them, as do pro and manual lenses as a rule.
ISO 200, f/4.5, 1/30, 32mm
Notice the f/stops on the front of the ring. They go out from the diamond marking focal distance, to give you the range, or zone, of acceptable focus.
Referring to the image above, you can see that there is a diamond. That is the distance marker. On the focus ring, there are markers that aren’t shown, that tell you your focal distance. Line up the desired distance, then using the f/stops that radiate out from the diamond, identically on either side, determine your needed aperture and distance. The distance covered will line up with the marks for the desired aperture. It’s that simple, anything in that range will be in sharp enough focus for decent size prints, including 8x10 and 11x14 if your camera has the resolution.
If your lens has a focusing distance scale, much like Canon’s 28-135mm, you can figure out your DOF with a little legwork online. The key when using zone focus, is to turn off your auto-focus. The second factor is to shoot either Aperture Priority or Manual modes only! Any other mode nullifies your efforts!
Know your location, and what’s happening there, and you can figure the ranges you will need. Let’s say for our purposes you’re shooting in a decently lit area at ISO 400 and you need to cover 3 meters and 6 meters, with room to spare. You get you’re framing, that will give you your focal length. You know it’s decently lit and you can get by with f/5.6-f/8. Going with a 55mm focal length, as most kit lenses like to go from 18-55mm, you should be focused at 4 meters for f/5.6 and 3.5 meters for f/8, although 4 meters is adequate, and has the advantage of allowing you to switch over to f/5.6 without losing too much DOF. If your lens doesn’t have a focal distance scale, measure off 4 meters, focus your lens, and mark it. An easy tip for marking your focus, is take 2 fat rubber bands and wrap one around the zoom ring of your lens at the focal length you wish to use, then wrap the other around the focus ring. Mark the one on the zoom ring at the top, focus your camera, then make a mark that lines up with the first mark you made. As time progresses and your lens drifts over the course of events, you always have your focus marked and can return to it in a snap. Then set your aperture and you’re cooking with gas!
A great online DOF calculator that just requires your focal length, camera model, and scale used (feet or meters) is DOF Master's DOF table. They also have some great information on hyperfocal distance and some nifty little software to play with!
If your shooting with a flash, your f/stop will be dictated by the flash when you use manual flash. TTL and E-TTL are great for using flash, but to use it right, you need a sync cable that’s designed for your camera maker or line to get it off camera. You can get a good one that’s about a meter reasonably priced. Add in a Flashbender or Sto-fen to diffuse the light some, and you’re off to the races. This allows you to hand hold your flash off camera and get some directional TTL or E-TTL light in your images that just adds to the quality.
Zone focusing is great for street photography, event photography, candids, and may other things. Try it out in your works and see how it can help you! You can also use it for this week's theme, as it will allow you to appear less obtrusive when shooting work getting done!
Enjoy the rest of your day, and remember to cast your vote for next week’s theme. Get yours in to have a say! Don’t forget to get your pics posted at the Hohenfels Volks Facebook page. Of course, commenting on both Facebook and here is always appreciated, too!
First off, let’s explain what zone focusing is. Zone focusing is using a combination of focal length, aperture, and distance to allow for enough depth of field to make a usable print. That’s pretty straight forward, right? Well, there is more to it than that, including knowing your equipment.
Zone focus developed as a way for photographers to focus their equipment, as most older cameras had no viewfinder or way to check your focus. Many of the old time greats used zone focusing to maximize the sharpness and detail in their works. Given the nature of early lenses, high f/stops were often required to get good detail and enough DOF to be worth printing. Remember, sheets of film, and rolls, were costly to purchase, develop, and print, so lots of effort went into taking each shot. Zone focusing grew from the concept and practice of hyperfocal distance, which you use to give you the maximum DOF for each lens focal length. We’ll have more on that in another post.
The technique works best with lenses that have markings on them. A distance scale for focusing opposite an aperture scale with DOF markings as shown in the photo below works best. It’s quicker and easier. Unfortunately, most lenses today are auto-focus, and kit lenses generally don’t have such marking. Higher end lenses do have them, as do pro and manual lenses as a rule.
ISO 200, f/4.5, 1/30, 32mm
Notice the f/stops on the front of the ring. They go out from the diamond marking focal distance, to give you the range, or zone, of acceptable focus.
Referring to the image above, you can see that there is a diamond. That is the distance marker. On the focus ring, there are markers that aren’t shown, that tell you your focal distance. Line up the desired distance, then using the f/stops that radiate out from the diamond, identically on either side, determine your needed aperture and distance. The distance covered will line up with the marks for the desired aperture. It’s that simple, anything in that range will be in sharp enough focus for decent size prints, including 8x10 and 11x14 if your camera has the resolution.
If your lens has a focusing distance scale, much like Canon’s 28-135mm, you can figure out your DOF with a little legwork online. The key when using zone focus, is to turn off your auto-focus. The second factor is to shoot either Aperture Priority or Manual modes only! Any other mode nullifies your efforts!
Know your location, and what’s happening there, and you can figure the ranges you will need. Let’s say for our purposes you’re shooting in a decently lit area at ISO 400 and you need to cover 3 meters and 6 meters, with room to spare. You get you’re framing, that will give you your focal length. You know it’s decently lit and you can get by with f/5.6-f/8. Going with a 55mm focal length, as most kit lenses like to go from 18-55mm, you should be focused at 4 meters for f/5.6 and 3.5 meters for f/8, although 4 meters is adequate, and has the advantage of allowing you to switch over to f/5.6 without losing too much DOF. If your lens doesn’t have a focal distance scale, measure off 4 meters, focus your lens, and mark it. An easy tip for marking your focus, is take 2 fat rubber bands and wrap one around the zoom ring of your lens at the focal length you wish to use, then wrap the other around the focus ring. Mark the one on the zoom ring at the top, focus your camera, then make a mark that lines up with the first mark you made. As time progresses and your lens drifts over the course of events, you always have your focus marked and can return to it in a snap. Then set your aperture and you’re cooking with gas!
A great online DOF calculator that just requires your focal length, camera model, and scale used (feet or meters) is DOF Master's DOF table. They also have some great information on hyperfocal distance and some nifty little software to play with!
If your shooting with a flash, your f/stop will be dictated by the flash when you use manual flash. TTL and E-TTL are great for using flash, but to use it right, you need a sync cable that’s designed for your camera maker or line to get it off camera. You can get a good one that’s about a meter reasonably priced. Add in a Flashbender or Sto-fen to diffuse the light some, and you’re off to the races. This allows you to hand hold your flash off camera and get some directional TTL or E-TTL light in your images that just adds to the quality.
Zone focusing is great for street photography, event photography, candids, and may other things. Try it out in your works and see how it can help you! You can also use it for this week's theme, as it will allow you to appear less obtrusive when shooting work getting done!
Enjoy the rest of your day, and remember to cast your vote for next week’s theme. Get yours in to have a say! Don’t forget to get your pics posted at the Hohenfels Volks Facebook page. Of course, commenting on both Facebook and here is always appreciated, too!
Wednesday, November 30, 2011
Tools of the Trade- More on Lenses
Greetings, Hohenfels, welcome to Hohenfels Volks, THE place for our place. Here’s hoping today sees you starting on the downhill run of a great week!
Today it’s time to talk a little about lens attributes and traits.
We’ve already talked a little about lenses, so today we’re going to concentrate on some of the quality issues and features of your lenses. It’s a little long, for which I apologize.
One of the first things most folks need to know is that your old film lenses will work on digital cameras. They may have a crop factor, for instance 1.6X for APS-C, but if they can mount on your camera, you can use them. On the other hand, your newer digital lenses are unusable on full frame or film cameras. When you put a film lens on an APS-C sensor, the crop factor comes from the distance from the back of the lens to the sensor. The film lenses cover a larger area than the sensor; this in turn causes an apparent increase in focal length and the crop. Canon’s recent systems, the EOS cameras, use EF lenses, which have a 1.6X crop on your APS-C sensor. Their digital line of lenses for the EOS system is the EF-S line. They require no crop factor and apparent focal length is actual focal length. The reason the digital series of lenses don’t work on full frame or film cameras is due to their smaller projection of the image onto a smaller sensor. They won’t fill the frame or film, and most likely won’t even focus properly even if they could be mounted.
Another concern about your lens on zoom lenses is often the aperture. Less expensive lenses read something like 28-135 f/3.5-5.6. This is because the aperture size doesn’t change during zooming, that is the largest it can go. The area of the aperture remains constant, requiring a change in f-number. If you remember, your f-number is a ratio of focal length and aperture. It represents the focal length divided by that number, that’s why it’s written f/2, f/5.6 etc. The longer a lens is, the less light reaches the sensor. That’s why the f/number changes throughout the range of zooms. If your area doesn’t change, your f-number must. The reason for this is the cost and weight added to vary the aperture size throughout the zoom range. That doesn’t mean a constant aperture means a cheap lens, it doesn’t mean less quality, it just means less light as you zoom in.
A great feature of lenses over the past few years is the addition of IS. The affordability of technology has made it possible to use feature that used to be unavailable to the hobbyist. IS allows slower shutter speeds when enabled. Using it hand held, you can get down to about 3 stops lower that the handheld limits. The systems work by compensating for motion with motion in the opposite direction. When hand holding your shot, using proper shooting styles, with arms tucked in etc, will enable the IS to really slug it out with vibration. The most important thing to remember is turning it on for handheld, and ALWAYS turn it off for tripod shots. When on a tripod, the IS searches for motion in the lens and can cause vibration rather than reducing it. The big drawback to IS is that it uses your camera’s battery for power.
The last thing I’ll bring up for now is a quality issue. The problem is chromatic aberration or CA. This is distortion caused by different colors, or wavelengths, of light focusing at differing areas on your sensor. There are several types and names, but we’re not going into it that deep here. It often causes the purple fringing that you see along borders with bright highlights and dark shadows together. Using a smaller aperture can help mitigate this, as can a longer lens. Low dispersion glass and good coatings can combat this effectively. There seems to be many complexities involved in CA, including the types and calculations. The best practice when purchasing a lens, if possible, is to take a test shot using that lens of a high contrast area, and zoom in looking for fringing. CA can also cause blurriness in Black and White photography, so keep that in mind. You can see examples on Google to get more information and some idea of what to look for. According to the reviews I’ve read, Canon makes the most advanced software correction to mitigate CA and other distortions available. Because Canon’s EF lens system is actually all electronic, and records the information on individual lens models, Digital Photo Pro can compensate for it. Yet another advantage of shooting RAW!
Whenever you look to purchase a lens, make sure you read a variety of reviews, and look at loads of test photos taken with that lens, it could save you some headaches! If you have a lens that you favor and would like to write it up here, let me know, and I’ll get it posted for you!
Now on to other things, remember to get your votes in for next week’s theme. This week our theme is “Morning Moments.” Dazzle me with your work! Get shooting and start posting at the Hohenfels Volks Facebook page. Of course, commenting here is always welcome, too!
Today it’s time to talk a little about lens attributes and traits.
We’ve already talked a little about lenses, so today we’re going to concentrate on some of the quality issues and features of your lenses. It’s a little long, for which I apologize.
One of the first things most folks need to know is that your old film lenses will work on digital cameras. They may have a crop factor, for instance 1.6X for APS-C, but if they can mount on your camera, you can use them. On the other hand, your newer digital lenses are unusable on full frame or film cameras. When you put a film lens on an APS-C sensor, the crop factor comes from the distance from the back of the lens to the sensor. The film lenses cover a larger area than the sensor; this in turn causes an apparent increase in focal length and the crop. Canon’s recent systems, the EOS cameras, use EF lenses, which have a 1.6X crop on your APS-C sensor. Their digital line of lenses for the EOS system is the EF-S line. They require no crop factor and apparent focal length is actual focal length. The reason the digital series of lenses don’t work on full frame or film cameras is due to their smaller projection of the image onto a smaller sensor. They won’t fill the frame or film, and most likely won’t even focus properly even if they could be mounted.
Another concern about your lens on zoom lenses is often the aperture. Less expensive lenses read something like 28-135 f/3.5-5.6. This is because the aperture size doesn’t change during zooming, that is the largest it can go. The area of the aperture remains constant, requiring a change in f-number. If you remember, your f-number is a ratio of focal length and aperture. It represents the focal length divided by that number, that’s why it’s written f/2, f/5.6 etc. The longer a lens is, the less light reaches the sensor. That’s why the f/number changes throughout the range of zooms. If your area doesn’t change, your f-number must. The reason for this is the cost and weight added to vary the aperture size throughout the zoom range. That doesn’t mean a constant aperture means a cheap lens, it doesn’t mean less quality, it just means less light as you zoom in.
A great feature of lenses over the past few years is the addition of IS. The affordability of technology has made it possible to use feature that used to be unavailable to the hobbyist. IS allows slower shutter speeds when enabled. Using it hand held, you can get down to about 3 stops lower that the handheld limits. The systems work by compensating for motion with motion in the opposite direction. When hand holding your shot, using proper shooting styles, with arms tucked in etc, will enable the IS to really slug it out with vibration. The most important thing to remember is turning it on for handheld, and ALWAYS turn it off for tripod shots. When on a tripod, the IS searches for motion in the lens and can cause vibration rather than reducing it. The big drawback to IS is that it uses your camera’s battery for power.
The last thing I’ll bring up for now is a quality issue. The problem is chromatic aberration or CA. This is distortion caused by different colors, or wavelengths, of light focusing at differing areas on your sensor. There are several types and names, but we’re not going into it that deep here. It often causes the purple fringing that you see along borders with bright highlights and dark shadows together. Using a smaller aperture can help mitigate this, as can a longer lens. Low dispersion glass and good coatings can combat this effectively. There seems to be many complexities involved in CA, including the types and calculations. The best practice when purchasing a lens, if possible, is to take a test shot using that lens of a high contrast area, and zoom in looking for fringing. CA can also cause blurriness in Black and White photography, so keep that in mind. You can see examples on Google to get more information and some idea of what to look for. According to the reviews I’ve read, Canon makes the most advanced software correction to mitigate CA and other distortions available. Because Canon’s EF lens system is actually all electronic, and records the information on individual lens models, Digital Photo Pro can compensate for it. Yet another advantage of shooting RAW!
Whenever you look to purchase a lens, make sure you read a variety of reviews, and look at loads of test photos taken with that lens, it could save you some headaches! If you have a lens that you favor and would like to write it up here, let me know, and I’ll get it posted for you!
Now on to other things, remember to get your votes in for next week’s theme. This week our theme is “Morning Moments.” Dazzle me with your work! Get shooting and start posting at the Hohenfels Volks Facebook page. Of course, commenting here is always welcome, too!
Friday, September 23, 2011
FOCAL LENGTH
Welcome to another post!
Our topic this time is FOCAL LENGTH, and covers more than just lens sizes.
Let’s start out with the basics; FOCAL LENGTH refers to the length of your lens, usually in millimeters. A 300mm lens is 300 millimeters, but crop factor can change the apparent FOCAL LENGTH of the lens. Crop Factor refers to sensor size on a digital camera. Most of us use cameras with an APS-C sensor, which provides a 1.6x crop factor, or 1.6 times the magnification of the lens’s FOCAL LENGTH. Unless a lens is made for the specific crop factor, for instance Canon’s EF-S lenses, crop factor must be counted to provide the correct focal length. Therefore, a 300mm lens at 1.6x crop factor has an apparent FOCAL LENGTH of 480mm. Since most of us now use the digital lenses that either came with our camera, or we purchased later, I’m not going to make too much of crop factor, that’s for another post.
A large number of folks believe that the perceived change between two FOCAL LENGTHS is caused entirely by magnification. This is actually not entirely true. When you zoom in closer, your lens covers a smaller area of the scene. It doesn’t really magnify it, just shows less in the same amount of space, although there is some magnification from the optics. If you look through a toilet paper tube and take note of what you see, then look through a paper towel tube of about the same diameter, you’ll notice this effect.
Another effect of FOCAL LENGTH, is longer FOCAL LENGTHS, compress the distance between objects in your scene, making them appear closer together. This is great for a portrait with a shallow DOF, as it can blur out and compress the background for a nice effect. It’s something to pay attention to, as the effect can make a great picture look somewhat flat and plain.
For more the rest of this article about FOCAL LENGTH, check out our Intro to Photography page, which contains our full intro series posts so far. And for a great article about the effects of FOCAL LENGTH, check out Photo Tuts+. You can also get into the maths of it at Wikipedia!
I hope this article will be useful on your photographic journey. The knowledge really helped me! Enjoy the weekend folks, and keep your eyes open for more articles, tips, and Hohenfels Volks photo goodness!
Our topic this time is FOCAL LENGTH, and covers more than just lens sizes.
Let’s start out with the basics; FOCAL LENGTH refers to the length of your lens, usually in millimeters. A 300mm lens is 300 millimeters, but crop factor can change the apparent FOCAL LENGTH of the lens. Crop Factor refers to sensor size on a digital camera. Most of us use cameras with an APS-C sensor, which provides a 1.6x crop factor, or 1.6 times the magnification of the lens’s FOCAL LENGTH. Unless a lens is made for the specific crop factor, for instance Canon’s EF-S lenses, crop factor must be counted to provide the correct focal length. Therefore, a 300mm lens at 1.6x crop factor has an apparent FOCAL LENGTH of 480mm. Since most of us now use the digital lenses that either came with our camera, or we purchased later, I’m not going to make too much of crop factor, that’s for another post.
A large number of folks believe that the perceived change between two FOCAL LENGTHS is caused entirely by magnification. This is actually not entirely true. When you zoom in closer, your lens covers a smaller area of the scene. It doesn’t really magnify it, just shows less in the same amount of space, although there is some magnification from the optics. If you look through a toilet paper tube and take note of what you see, then look through a paper towel tube of about the same diameter, you’ll notice this effect.
Another effect of FOCAL LENGTH, is longer FOCAL LENGTHS, compress the distance between objects in your scene, making them appear closer together. This is great for a portrait with a shallow DOF, as it can blur out and compress the background for a nice effect. It’s something to pay attention to, as the effect can make a great picture look somewhat flat and plain.
For more the rest of this article about FOCAL LENGTH, check out our Intro to Photography page, which contains our full intro series posts so far. And for a great article about the effects of FOCAL LENGTH, check out Photo Tuts+. You can also get into the maths of it at Wikipedia!
I hope this article will be useful on your photographic journey. The knowledge really helped me! Enjoy the weekend folks, and keep your eyes open for more articles, tips, and Hohenfels Volks photo goodness!
Subscribe to:
Comments (Atom)