Exercise 1 – Focal length and angle of view

The following is a direct copy and has been Pasted in for future reference from the Art of Photography coursework PDF Doc. (pasted in Maroon)  

1 – 3 photographs (If you have access to a 35mm film camera, try this but it is unlikely to work with digital cameras)

Point the camera at any scene, and keep both eyes open – one eye looking through the viewfinder, the other looking directly at the scene. If the lens is approximately standard in focal length you should notice that the objects seen through one eye should appear to be about the same size as through your other eye. This is what is meant by standard.

If your camera is fitted with a zoom lens, adjust it by eye until the two views (unaided and through the viewfinder) appear equal. If there is a focal length scale on the body of the lens, make a note of the setting; if the lens does not have focal length markings, as many don’t nowadays, simply note how far the lens protrudes from the body when the zoom is set like this, and remember it.

This section works with both film and digital cameras

Now take a photograph and remember where you stood to take it, as you will need to return to this spot. If you are using a digital camera with a zoom lens and have not been able to do the section above you should set you zoom to a focal length equal to about 50mm divided by the crop factor of your sensor. (this you should be able to find in the handbook or on the manufacturer’s website.) 

Now, if you have a zoom lens, set it to its widest view; if you have interchangeable lenses, fit your wide-angle lens. The size of objects seen through the viewfinder will now appear smaller than they do to your unaided eye. Take one photograph.

Adjust the zoom to its furthest telephoto setting, or fit a telephoto lens. Objects through the viewfinder now appear larger than they do unaided. Take one photograph.

Have all three photographs printed onto A4 or 8×10 inch paper (or just the one photograph if you have a single fixed lens). Stand in front of the same scene at the exact position where you took the photograph and hold the ‘standard’ print in front of you at eye-level. Move it towards or away from you until the printed scene appears to be the same size as your view of the real scene. Make a note of the distance from your eye. What is it? You should notice that this is a comfortable viewing distance. Do the same with the wide-angle print. To make the objects in the scene appear the same as in real life, you will need to hold the print much closer. Note the distance. Do the same for the telephoto print, which you will need to hold much further away.

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Equipment

I used three cameras for this exercise (all cameras used were full frame 35mm):

Nikon D4 with 24/70 lens attached – Main camera.

Nikon D800 with 50mm lens attached – Second camera to provide visual explanation.

Nikon D600 with 28/300 lens attached – Third camera to photograph the scene from another angle and give a full visual understanding of the setup.

Mini tripod – Main Camera. Second Tripod – used for positioning the second camera.

Second Tripod – used for positioning the second camera.

Wireless remote trigger used on second camera.

Method

To show that I fully understood this exercise, I photographed the object three times at differing focal lengths and to further demonstrate, I put together a series of pictures providing a visual explanation. My chosen subject was a jar of coffee centrally positioned on a dining table and to make sure the camera was in an identical position for the combination pictures to follow I used a mini tripod for the camera. The first picture needs the most attention by following the instructions given by the Exercise (details above marked in green highlight), I then adjusted the focal length of the lens to 24mm and then finally 70mm. During this I had a second camera setup to photograph the method, showing the process visually, see pictures below. After printing the three pictures, I placed each individually in an up righted fashion with the bottom folded back to give a more accurate impression. I shot he first picture (taken @50mm) beside the coffee jar, then the second picture (taken @24 mm) in front and finally the third (taken @70mm) behind the coffee jar and by moving each print slightly back & forth along the table whilst comparing the visual scale through the camera viewfinder I was able to create a scale illusion. All the combination pictures of both the coffee jar and each relevant print were taken from the main camera at a focal length of 50mm.

Please see pictures and captions below for visual understanding.

Note – all pictures have been compressed hence there will be a quality reduction when     enlarging.

Picture taken at 50mm Focal Length – By moving the item closer or farther away
the correct distance relationship can be obtained by looking with one eye through the viewfinder whilst using the other eye is used to make the visual scale / size comparison.

Picture taken from second camera showing the coffee jar in the optimum position with regards to the relationship between camera viewfinder and visual scale / distance.

Picture Taken at 24mm Focal Length, coffee jar has not been moved.

Picture Taken at 70mm Focal Length, coffee jar has not been moved.

Picture taken from second camera showing the prints of the three different focal lengths (24mm / 50mm / 70mm).

Picture taken from third camera showing the setup from another angle.

Coffee jar and 50mm focal length print side by side – both at 50mm focal length (see picture below for size / scale comparison)

Picture taken from main camera showing both print and coffee jar at a focal length of 50mm

Coffee jar and 24mm focal length print showing scale illusion – picture taken at 50mm focal length (see picture below for size / scale comparison)

Picture taken from main camera showing the 24mm focal length print and coffee jar both at a focal length of 50mm, from the picture above note that the print has been moved forward but the position of the coffee jar is unchanged.

Coffee jar and 70mm focal length print showing scale illusion – picture taken at 50mm focal length (see picture below for size / scale comparison)

Picture taken from main camera showing the 24mm focal length print and coffee jar both at a focal length of 50mm, from the picture above note that the print has been moved forward but the position of the coffee jar is unchanged.

Final picture taken from second camera showing all three focal length / prints in their relevant positions in relation to the coffee jar.

What have I learnt from this exercise

From this exercise I have learnt, as you increase the focal distance i.e. “zoom in” to the subject it does become closer through the viewfinder but in reality the subject has not physically moved. Also the relationship between the viewfinder and naked human eye, in that the two are not coherent in size and scale once the lens has moved either way from the initial 50mm focal length / eye viewfinder setup.

When increasing the focal length it also narrows the frame size down surrounding the subject, but the reverse happens on frame size when decreasing focal length i.e. “zooming out.”

I have also learnt that as you increase the focal distance the subject and background  become “compressed.” From my experience, this “compression” effect becomes more pronounced when moving up the ladder of lens size (focal distance) i.e. more pronounced over a 24/70 with a 70/200 and even more so with a 200/400.