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Showing posts with label AV. Show all posts
Showing posts with label AV. Show all posts

Thursday, March 6, 2014

The Basic, Aperture AV & Shutter Speeds TV




 Infra Red Canon Rebel XSi, Canon 16-35 at 17mm, f18, .6sec, ISO200, This is a great example of perfect combination of AV and TV, f18 bring details, and  .6sec soft the water falls., Elbow Falls Alberta, the falls change since the great flood of June 20, 2013
 Aperture AV 


       AV “ aperture value or A mode determines whether all the photograph is in focus or part of. For example photographers can choose to have a sharp foreground and background, or they can blur the background. To set your digital camera on aperture priority, turn your mode dial to AV.   Now rotate the main dial until you have aperture your after. The camera will set the shutter speed to suit.
Canon 5D Markiii, Canon 85mm 1.8 prime lens, f1.8, 1/500sec, ISO 200, great example of wide aperture 1.8, focus on only one eye.
       The aperture adjustment opens and closes a diaphragm built into the lens which controls the amount of light reaching the film or sensor. When the aperture is at it’s widest, the maximum amount of light possible passes through. At the smallest aperture, the least amount of light passes through.
Canon 5D Markiii, Canon 24-105 at 105mm, f4, 1/25sec, ISO200, f4 is great for portrait, f2.8 and lower are sometime difficult to get the right focus.
       The aperture controls the depth of field, or how much distance is sharp and clear in the image “the area of sharpness”.
       The greater the f-number the greater the depth of field. That is, f2.8 has a much shallower depth of field than f8, in other word f8 will give a larger area of sharpness both in front and behind the subject being focused on. Most lenses will give a better image at f9 to f11.
 Canon 5D Markii, Canon 24-105 at 105mm, f4, 1/125sec, ISO200
       The closer the camera is to the subject, the less area of sharpness there is for the equivalent AV. That is, for any chosen aperture, if the camera is focused on a subject at 10’ you’ll get better sharpness in front and behind the subject that let say if your subject in only at 3’ from the camera
       The longer the size of the lens, the less area of sharpness. A wide angle lens “16-35 zoom” by example has a greater depth of field that a 100mm telephoto.
       So is it always best to use a high f-number to maximise this area of sharpness? The answer is no. The amount of area of sharpness you decide upon will depend on the subject your are photographing and the effect you are looking for!

Shutter Speeds TV
  
       Shutter priority allows the photographer to choose a shutter speed, then the digital camera automatically sets the aperture to suit.
       To set your digital camera on shutter priority, turn your mode dial to TV . In case your wondering, TV stands for time value. Now rotate the main dial until you have the shutter speed your after.
Calgary Stampede 2013, Panasonic Lumix DMC FZ200  zoom at 453mm, f2.8, 1/500sec, ISO160, as you can see even if the aperture is wide open at f2.8 the distance between the camera and subject is so great that more of the subject is in focus. 1/500 sec. shutter speed is more than enough to freeze the action.
       Shutter speed is measured in seconds and looks like 1/500, 1/250, 1/2 or 1 as in one second etc. It can range anywhere from 1/8000 to B for bulb. Bulb keeps the shutter open for as long as the shutter button is pressed down.
       Slow shutter speed, slows motion to blur running water, with a shutter speed of 1 second or slower, water can blur to a ghostly appearance, with the rest of the scene pin sharp.  The trick for this kind of effect is a dim enough lighting  to slow down the shutter speed, in daylight  use the highest  f-number and lowest ISO setting available on your camera, another option is to use a neutral density filter.

5D Markii, Canon 16-35 at 16mm. f22, 65 sec, ISO200, the narrow AV f22 and the wide lens help in getting more details in focus, the 65sec is enough to capture the light trails.
       When using a slow shutter speed use a tripod and remote shutter release or self timer to avoid camera shake.
       Use slow shutter speeds of at least 10 seconds or more for night shots of cities, buildings and streets etc.
       Fast shutter speed, takes the image almost instantly as in frozen in time, frozen water and action.
       Selecting the actual value is pretty arbitrary, so think of it in sections: 1/4000 to 1/250 is a fast exposure, 1/250 to 1/10 is a medium exposure, and 1/10 of 30” is a long exposure. Each will give you a different effect, and you can only pick one and try it. If it’s not what you are looking for, then try again. And again. You’ll eventually get a pretty good idea of what speeds give what effect.


 Combining Shutter Speeds with Apertures

       With shutter speeds and apertures we found that each numbered value was called a stop.  If we changed the value up or down by one value, we reduced or increased the exposure by one stop of  a difference.
           To recap.
       If we changed our shutter speed from 1/60 to 1/125 we decrease the amount of time the shutter was opened and consequently halved the amount of light reaching the sensor.
       If we changed our aperture from f8 to f5.6 we increased the size of the aperture and doubled the amount of light reaching the sensor.
          
With this in mind we are also able to alter both the aperture and shutter, and still have the same amount of light getting to the sensor.  For example, say we have composed our shot and have taken a meter reading of 1/60 at f8 giving us the correct exposure. If we changed the shutter speed to 1/125 we would under expose the image by one stop.  Now what happens if we really need to set the shutter speed to 1/125, say to prevent camera shake?
          
We must counteract the underexposure by changing the aperture by one stop giving the correct exposure again.  That is, we select f5.6 increasing the amount of light reaching the capture area.

       Example if the proper exposure is 1/125 at f8, the following combinations of shutter speed and apertures could also be used. 
          1/1000 - f2.8
          1/500 - f4
          1/250 - f5.6
          1/125 - f8
          1/60 - f11
          1/30 – f16
          1/15 – f22


Monday, March 3, 2014

Bird view, Shooting from an airplane


City of Vancouver, 5D Markii, 50mm prime lens, f11, 1/320sec, ISO 320  AV Aperture Priority
This happens to all of us, being in an airplane passing over beautiful country side, approaching a city, sitting in our  window seat waiting for the opportunity, missing it, because the pilot decided to change course, or the light change or that big cloud just moved in, a lot of frustration. 
 
Even if we are not in command of that big bird, the light and weather, the opportunity of a great shot is there, and to be able to seize it we have to be ready.

  • Make sure your battery is full, and if you have a spare one bring it
  •  Used the biggest storage card you have, I use 32G
  • Prepared your camera before hand, what kind file to shoot, I always shoot Raw,
  • Check all your settings, ISO, I put mine at 200, if needed I boost it but I don't exceed 800, shooting mode,  I suggest  AV Aperture Priority, f8 to f11, don't let your camera take over,  it may boost the ISO to get the shot, read your book or search the web and make sure that the shooting mode you are choosing will not boost  ISO, put your white balance to auto, put your metering to evaluative, depending on the camera you own, you can use single or continuous  shooting  it all come to how fast  your camera is, I put my Canon 5D Markii at single shooting, it's a very fast camera, if your is slow use continuous, AF auto focus, I use one shot AF, I am in a plane I am not following any action, but again read your book and find out what work best for your camera and do some testing.
  • What kind of lens will work better, I tried different lenses, my zoom  24-105,  my small 50mm 1.4 prime lens,  a zoom is more flexible, but it takes a lot more space, space is a problem in plane, I tried both lenses, I found that the 50mm was perfect for the job, wide enough and very small.
  • Bring 2 cloths one to clean the plane window and the other to clean your lens.
  •  Now you are ready to shoot,  you can use your view finder, or live view,  I tried both,  and live view works better for me, cause you have to put your lens against the window to prevent the glare if you are using your view finder, it may be difficult to avoid  knocking your lens against the glass, it happened to me quite a bite, learn from your errors, another thing I learned is to take off your lens filter, it can add a lot of glare, just be careful not to knock your lens.
Canadian Rockies, Canon 5D Markii, 50mm Prime Lens, f9, 1/400sec, ISO 200 AV Aperture Priority
  • Start shooting, and shoot till you're plane touches the ground, I had no problem doing it traveling with Westjet

    Canadian Rockies, Canon 5D Markii, 50mm prime lens f9, 1/320sec, ISO200 AV Aperture Priority

  • Don't get too excited, many of the shots won't be in focus, but you'll get some great ones, that can be improved in Light Room,  Photoshop, Corel etc... 

City of Calgary, Canon 5D Markii, 50mm prime lens f8, 1/250sec ISO 200, AV Aperture Priority