Just over a week ago, I posted a general knowledge quiz to rattle your brains. Here are the answers and the background behind some of them. Even if you didn't do the quiz, I hope you find some of this information interesting and the links useful.
Between all of you, you got most of the questions right, including the trick ones. Here are the questions again, with the answers.
If your starting shutter value is 1/125, and you add an ND1000 filter, how long would your resulting shutter value be?
Answer - 8 Seconds
This was an easy one to start with. ND filters reduce the amount of light reaching the lens. An ND2 reduces light by a half, or one stop; an ND4 by a quarter, or two stops; an ND8 by an eighth, or three stops; and so on. An ND1000 reduces the light by one-thousandth, or ten stops.
So, starting at 1/125th second, 1 stop - 1/60; 2 stops - 1/30; 3 stops - 1/15; 4 stops - 1/8; 5 stops - 1/4; 6 stops - 1/2; 7 stops - 1 second; 8 stops - 2 seconds, 9 stops - 4 seconds; 10 stops (ND1000) - 8 seconds. If you are confused by the strange jumping from 1/125 to 60, and from 1/15 to 1/8, then see the answer to question 8.
Where is Ammonium Ferric Citrate commonly used in photography?
Answer - it's a chemical, along with potassium ferricyanide, used in cyanotype photography.
Place these in photographic chronological order. A. Daguerre, B. Wedgwood, C. Schulze, D. Niépce, E. Talbot.
Answer - Schulze, Wedgwood, Niépce, Daquerre and then Tablot.
These are significant figures in the birth of photography, albeit not the only names that could have been listed here. The book, A New History of Photography, edited by Michel Frizot, give fascinating insights into the early days of our art. Alternatively, you can read about it on Wikipedia!
- Johnny Cash at Folsom Prison, who was the photographer?
Answer - Jim Marshall photographed Johnny Cash at Folsom Prison.
Johnny Cash insisted on John Marshall photographing his prison concerts. Those images included the famous image of Cash giving the middle finger to the camera at San Quentin.
- You set your camera to ISO 200, f/8, 1/125. You change the ISO to 100, aperture to f/2, and add an ND8 filter. What would the shutter value be to achieve an equivalent exposure?
Answer - 1/125.
From ISO 200-100 is -1stop. From f/8 to f/2 is + 4 stops. An ND8 is -3 stops. -1 + 4 - 8 = 0. the shutter value remains the same.
- Iwasaki, Maeda, Mitarai Uchida, Yoshida. Which is the odd one out?
Answer - Iwasaki.
Iwasaki was the founder of Nikon, the others were Canon's founders.
- What does the "f" stand for in "f/number"?
Answer - Focal
Someone guessed fraction, and, although not strictly true, I am happy with that as it makes sense. See the answer to question 17.
- To the nearest one million, how many pixels are required to produce a photo-quality A3 print at 300 dpi?
Answer - 8 megapixels
A3 is 11.7 x 16.5 inches. According to this chart from B&H, using a typical photo-quality desktop printer, which would be 300 dpi, will produce photo-quality prints up to 16" x 20". It's worth noting that the human eye can only resolve around 170 dpi at a normal viewing distance. So, although the mathematics would suggest a full resolution image would be higher, we would not be able to discern the difference. Makes you wonder what all that competition for higher and higher pixel counts is about, doesn't it?
- 2, 4, 8, 15, 30, 60, 125, 250th second. Why does the sequence jump to 15, 30, 60 and not 16, 32, 64?
Answer - it's just to make the mathematics easier.
1/60th of a second is so close to 1/62.5 that it makes no discernible difference.
What does this calculate approximately?If you want to discover more about depth of field, then Marc Levoy's excellent series of free lectures cover this and a lot more besides.
Answer: This turned out to be a trick question, because I accidentally posted an error in the formula. (It's human to err!) Did anyone spot the mistake? What I posted was part of the formula that ultimately arrives at the following calculation for depth of field:
- What does the 16 refer to in Sunny 16?
Answer: it refers to the f/number, ie. f/16.
On a sunny day, if you set the ISO and the shutter value both to the same numerical value, e.g. ISO200 and 1/200th Second, or ISO 800 and 1/800th second, then for a correct exposure, the aperture will be f/16. Give it a go.
- In an additive color process, what is the result of red plus blue?
This site has a great explanation of additive and subtractive colors.
- With an 8-bit camera, how many shades of gray per channel (including black and white) are recorded by the sensor?
You will usually see Red, Green, and Blue having values of 0 to 255, with 0 being black, 255 being white, and all the numbers in between being the shades of brightness from black to white. Those shades of gray are mixed with each of those colors to produce very dark reds through to very bright reds, dark greens to bright greens, and dark blues to bright blues. Various combinations of these various shades and these three colors give the full gamut of colors we see in our photos.
- Develop, Stop, Fix… what comes next?
Answer: In film photography, the negatives and prints are washed after fixing and before drying.
- Which Hollywood director was famed for his innovative use of a Carl Zeiss Planar 50mm f/0.7?
Answer: Stanley Kubrick
Kubrick used the superfast lens, first developed for NASA, in his film "Barry Lyndon". It allowed him to shoot using very low natural light, such as candlelight.
- Who wrote the photographically titled song that famously had to include a ™ symbol?
Answer: Paul Simon, who was required to include it in the title of his song "Kodachrome™"
- How is the f/number calculated?
Answer: Focal length divided by aperture.
- What’s photographically special about a place in France that translates into English as “The Fat”?
Answer: View from a Window in Le Gras (The Fat) was the location of the first photographic print by Joseph Nicéphore Niépce in 1826
- Who was famously photographed on 8th December 1980, and by whom?
Answer: The photo was of John Lennon by Annie Leibovitz, taken a few hours before he was murdered.
- If you put a 50mm f/1.4 lens FROM A 35mm SLR onto an APS-C camera, what effect does it have on the focal length and aperture?
Answer: This was the planned trick question. There is no change at all to the focal length or the aperture.
There is a lot of hogwash written about crop frame sensors. If the pixel density of the sensor is the same, the only thing that changes is the crop of the image when you change sensor size. If you crop down a full frame image to the same size as an APS-C or Micro Four Thirds in post-processing, the images will be identical, with the same depth of field, as if shot with those cameras.
- Replace one of the following to make the list correct. Bailey, Capa, Eisner, Rodger, Seymour, Vandivert, Vandivert.
Answer: David Bailey wasn't a founder of Magnum. Henri Cartier-Bresson was.
- What do 暈け and ボ both say?
Answer: Boke, more commonly spelled bokeh.
- What word commonly used in photography is derived from a Latin word for hearth?
- What prehistoric artifacts have been suggested were inspired by what photographic phenomenon?
Answer: Cave Paintings and the camera obscura effect.
Matt Gatton, wrote "The Camera Obscura and the Origin of Art: the Case for Image Projection in the Paleolithic." about this subject.
- In black and white photography, what color filter would show up facial blemishes the most? Which color filter would darken the sky the most?
Answer: Green and Orange.
I must add a caveat to the first answer to this question, as it very much depends on the color and tone of the skin. On a Caucasian face, blemishes tend to be red, and so a green filter would make them appear darker and stand out more. Clearly, the topic requires a whole article different skin colors are likely to respond differently to different color filters.
Orange filters darken a blue sky. See the photo of the fishing boat coming into the harbor above.
- You are photographing a bride in a white dress in a snow-covered landscape. Using TTL metering, would you compensate for that whiteness by adding or subtracting exposure? Why?
Answer: You would add exposure compensation.
It may seem counter-intuitive, but you would usually add exposure compensation. Camera metering systems expect the world to be mid-gray. Consequently, if the scene is predominantly white, the suggested exposure will be darker, thus making those whites gray. You, therefore, need to brighten up the image by increasing the exposure. Saying that, it seems cameras are getting better all the time at recognizing scenes such as this, and the inbuilt software automatically compensates.
- Which form of photography involves firing electrons in a vacuum tube from a cathode to a tungsten anode.
- The Hubble Space Telescope WFC3 camera’s sensor is how many megapixels?
- The years 1957 and 1975 were important for two related photographic firsts. What were they?
Answer: 1957 was the first digital image conversion. 1975 was the first digital photograph.
In 1957, Russell Kirsch produced a digital file from a photograph of his three-month-old son.
Twenty years later, Steven Sasson invented the first digital camera for Kodak-Eastman.
- Why is the Bayer filter in a camera designed with as many green sensors as red and blue added together?
Answer: The Bayer Pattern has, approximately, the same ratio of the three color light receptors as do the cone cells on the human retina: 2 parts green, 1 part red, 1 part blue.