My last post was about F stops, the number associated with the aperture of the lens. The more I use the large F stops, like F1.4 or F 2.8 in my best lenses, the more I understand the value of the more expensive lenses. Understanding these numbers will be important if you decide to buy a lens or a camera with a built in lens.
The case of the dissapearing fence
Here is a photo I borrowed from my wife. I purchased a small point and shoot Nikon for her and she uses it for her blog and everything else. She used that camera to shoot the owl at the Maruyama zoo and a shot of me shooting the same owl with my DSLR below that.
Also it only has auto-focus, so when she tried to photograph the owl, the camera focused on the strong lines of the fence, not the beautiful owl. You can see there were metal bars and a monofilament net on the owl's enclosure.
Cameras do not discern what your mind wants to focus on. It is all based on mechanical and optical input with a sprinkle of programming. Your eyes may ignore the fence and focus on the owl without your thinking about it to see the owl, but the camera basically assumes you want it to focus on the fence or whatever strong lines are in the focus area.
In comparison to the point and shoot, my more expensive DSLR with a quality lens assumes the same thing. So I changed to manual focus, focusing on the eyes of the owl, and opened the lens to the maximum aperture of 2 to get theses shots on my 100mm F-2 Minolta prime lens. The F 2 aperture is pretty darn nice, so this 25 year old used lens now sells on Evilbay for about $800.00. Its a pefect lens for portraits of owls or people. A moderate telephoto with a large (F-2) maximum aperture. I bought the lens from Craigslist in Raleigh as part of a package deal for less than $300 before moving to Japan. I sold most of the rest of the package and basically got the lens for next to nothing. In the photo below, left, you can see an X pattern, its the monofilament net around the cage.
Prime just means its not a zoom, it has one focal length such as 200mm, also called "fixed focal length". Generally primes have better quality and allow more light into the camera during exposure. There are fewer pieces of glass in a prime lens than a zoom in general. Zooms are convenient because you can stand in one place and zoom (change focal lengths). With one zoom lens you can shoot wide angle or telephoto. With prime lense you have to physically move to change the angle of coverage or change lenses to match the perspective you want. For example a 16mm prime is extreme wide angle while a 300mm is a long telephoto. You have to carry around several primes to do the same job as one zoom. Most zoom's maximum aperture is around F3.5 or F 4 and changes to 5.6 or worse when zoomed out. You can probably locate these numbers on the side of your camera or on the end of the lens. When purchasing the lower the number the better when it comes to maximum aperture. The problem is that one F stop, for example rom 3.5 to 2.8 can double or triple the price of the lens. The pro use the more expensive ones, its a tool of the trade and can be a tax expense write off.
I shot the next one on the way out of the zoo through the fence with a 200 mm 2.8 prime lens, from about 10 meters away through the same fence.
The open maximum aperture (F 2.8 in this case), has a shallow depth of field. This means there is a small slice of area that is in focus, the owl here. The background is out of focus which is good, because it was ugly and distracting. If you look closely, you will see the owl looks a little "soft".
The fence, especially the netting reduced the sharpness of the image, like looking thru a foggy window. This softening is a technique often used in people portraits, you can use a filter or do it in post processing with software.
The foreground is out of focus also. The fence was in the foreground and is basically invisible because the slice of focus is on the owl, several meters behind the fence, throwing the fence out of focus. The bad news is the smaller the number of the F stop on a lens, (F 1.4 not 3.5 for example) the more expensive it will be. One F-stop can mean a $1,000. or more in price. The more expensive point and shoot cameras often have a larger maximum aperture.
The expense of the lens based on maxium aperture often separates the pros from the hobbists. The pros use their lenses as tools so they have to have the best available. Hobbists like myself, often settle for the less expensive option unless money is not an issue. I used mainly 20+ year old Minolta lenses that sell for 30% of the cost of a new comparable Sony lens and generally produce images that are just as good and sometimes better. Sony does not make a 100 F-2, that is why its used value is so high now.
I just checked on the Calumet photography website, a new 300mm F 4 Nikon lens costs about $1500.00, while a 300 F 2.8 costs about $5,800.00. If you are shooting for a living, you need those extra f stops to freeze the action of a pro athelete or to shoot in a darker environment. Note the photos of the president in the media, the shallow depth of field usually makes him appear "cut out" almost as if he were photoshopped into the scene. The effect is only possible with fast high end lenses.
This photo of a railroad track shows how shooting at F 9 provides more depth of field to keep most of the scene in focus.
This portrait of Pamela and me for our 2012 Christmas mail was shot at F 2.5, to soften the background and add emphasis to us as the main subject. It was shot on a Minolta 50 F1.4 lens.
Well, that's all for this post, stay tuned for more updates this spring. I was awarded a small prize in a local photo competition recently and will be teaching outdoor photography again at the university, so I am motivated again to explore and share my photography skills. I will post again after attending the award event in Sapporo.