barneymeyer

Cameras and Lenses Session October 2013

Decrease Font Size Increase Font Size Text Size Print This Page

Our class of 20 students participated actively in a number of exercises and were ably assisted by a large number of helpers.

After doing a short study of theory everyone photographed a few scenes in order to learn how to take control of their cameras:

Scene 1: To learn control of aperture and focus to control depth of field.

OLYMPUS DIGITAL CAMERA OLYMPUS DIGITAL CAMERA

Scene2: A moving object, to show you how to set your focus manually, choose shutter speed, freeze an object or pan with it. This is going to be invaluable when you go to the motor races and that Ferrari comes screaming down the track at 300kmh.

Scene3: A wedding, so that you can make sure the bride is in focus and not the father in law, and her dress is white and not grey.

Scene4: Set focus and exposure, Lock, Compose, Shoot. Pulling it all together.

•SETTINGS DIAL

We are going to use M and AV modes

•VIEWFINDER – Optical correction for your eyesight

•EXPOSURE

Aperture  – find out how to set the f number

Shutter speed – find out how to set the speed, like 1/100s

ISO ~ film speed in old terms – where do you set that?

Subject brightness – a little bit of theory and the “Sunny f/16 rule”

•METERING

Measure light from subject – metering preview in the viewfinder

Histogram to review image brightness –read the histogram display, find out how to activate it

•FOCUS

Focal length – zoom in or out with your lens

Aperture

Focal point & distance

Depth of Field (DOF)

DOF preview – find this button or function, usually on the camera body or lens

DOF calculations

•WHITE BALANCE – find this function setting, we will mainly use AWB

•COMPOSITION Focus & Exposure, Lock, Compose, Shoot

This very nice image was sent by a group participant for evaluation and comment, the metadata shows me

I can see that you used aperture to reduce the light and low ISO to get a low sensitivity in order to get a slow shutter speed to turn the flow of water into silk.

Very nice result it is and you have created the look that you wanted using the available tools.

Your exposure is as good as it gets. If you look at the histogram you will see that the brightest spot in the water is not overexposed

The eye finds the shadows to look normal and we don’t expect to see into the black shadow on the LHS.

Improvements that I can suggest:

1. To the right of the waterfall are some bald patches under the ferns which attract the eye, the brown pool is not so interesting and there’s a branch distracting attention.

2. I would crop the image like you see here

This puts the main attraction into the “thirds” position on the RHS and the water flows nicely into the corner forming a diagonal as if it’s flowing out of the frame. The muddy pool has also gone out of the frame as it didn’t add anything.

And I used the clone tool to patch up the bald patch on the RHS and remove the branch.

Technically, you have taken the correct approach to exposure by controlling ISO, aperture and shutter speed like this.

One negative is that the need to stop down to f/22 means that you lose some sharpness due to diffraction.

The only way to overcome this however, is to use a neutral density filter on the lens to reduce the amount of light.

A good quality Variable ND filter is expensive however. I use a German made Heliopan Variable ND 0.3 – ND 1.8

http://www.digitalcameraworld.com/2012/07/05/how-and-when-to-use-nd-filters-and-what-the-numbers-mean/

Uses:

  • Blurring water motion (e.g. waterfalls, rivers, oceans).
  • Reducing depth of field in very bright light (e.g. daylight).
  • When using a flash on a camera with a focal-plane shutter, exposure time is limited to the maximum speed—often 1/250th of a second, at best—at which the entire film or sensor is exposed to light at one instant. Without an ND filter this can result in the need to use f8 or higher.
  • Using a wider aperture to stay below the diffraction limit.
  • Reduce the visibility of moving objects
  • Add motion blur to subjects
  • Extended time exposures

ND0.3 means 1 stop light reduction = 50% let through

ND1.8means 6 stop light reduction = 1.56% let through

This filter can reduce daylight to an almost black transmission.

But they’re very expensive, about $450 for a 77mm adjustable filter.

Here’s how to make your own for $10

http://www.alexwisephotography.net/blog/2013/07/07/create-yourself-a-neutral-density-filter-for-under-10/

QUESTION:

Thanks for a most instructive evening last week.

I have attached a couple of my images, one showing DOF, the other motion freezing.

Can you answer some queries?

  1. I am trying to find the best settings for my 12mm prime micro 4/3 lens (equivalent to 24mm) to get the maximum depth of field.  I took a series of shots with apertures ranging from f/2 to f/22 with the focus on the focus ring set to 1 metre and ISO 200.  At f/22 there was substantial loss of detail at 3 m compared to f/4 which was the sharpest.  Is this the effect of diffraction?  I will do another series outside with objects at 1 m out to infinity and take images at all the f numbers and focus distances.  What am I likely to find and what are typical settings for maximum depth of field AND sharpness?
  2. I am having a go at HDR and have a few sets of images to play with.  Can you recommend any particular software to do the processing?

ANSWER:

  1. According to my DOF Calc app, for an Olympus DSLR with 12mm lens:

For f/8 12mm hyperfocal distance is 1.212m which means Nearfocus = 0.627m and farfocus = Infinity if focused to 1.3m

For f/16 12mm hyperfocal distance is 0.612m which means Nearfocus = 0.326m and farfocus = Infinity if focused to 0.7m

You can calculate this from the Depth Of Field equations in the course slides or just download a DOF app.

For f/22 12mm hyperfocal distance is 0.436m which means Nearfocus = 0.300m and farfocus = Infinity if focused to 1m

But the danger is that you lose sharpness due to diffraction, which then defeats the object of having such a big DOF.

  1. HDR, dearly beloved HDR: Most of my images are HDR due to extreme lighting conditions, some with 9-11 brackets and they are captured in RAW. I have tried every HDR converter and still use and recommend Photomatix Pro 4 because of:
  • Batch processing capability – essential if you have a whole folder of bracketed images to process
  • Best automatic ghost reduction
  • Great tonemapper works best with RAW and badly with jpeg (which you shouldn’t be shooting if you want good HDR.