Re[2]: Advantage of small f/number!
Hi, Suppose I have a 300 mm f/5.6 lens. What film speed should I use in order to stop the action as well as attaining good depth of focus (say, 4 m) in an artificially illuminated stadium? If your subject is 2m in height then to fill the frame using a 300mm lens you must be 17m away. To achieve a depth of field of about 4m your aperture must be at f/16. On a bright day you can do this with ISO 400 film at 1/500 second. According to Michael Freeman in his book Light all stadiums that have TV coverage use multi-vapour lamps, because these produce a colour quality close to normal daylight. He suggests that for ISO 400 film at 1/60 or 1/125 you will need an aperture of f/2.8. So to achieve a depth of field of 4m your film needs to be rated at 12,800. However, most of the photographers are probably using digital cameras, so these calculations may not apply. For example, a nominal 300mm lens is effectively longer than that, and the f-stop ratio is changed, so there may be more depth-of-field than I've indicated. These numbers are for 35mm. --- Bob mailto:[EMAIL PROTECTED] - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
Re[2]: Advantage of small f/number!
Hi! It is quite an informative email. I never knew the details of the lighting in a stadium until I recieved your mail. On Mon, 1 Jul 2002, Bob Walkden wrote: Hi, According to Michael Freeman in his book Light all stadiums that have TV coverage use multi-vapour lamps, because these produce a colour quality close to normal daylight. He suggests that for ISO 400 film at 1/60 or 1/125 you will need an aperture of f/2.8. So, it means that 400 ISO film is not enough. One has to use atleast 1600 ISO film provided that the lens in use is 300 mm f/5.6. So to achieve a depth of field of 4m your film needs to be rated at 12,800. I am shattered. However, most of the photographers are probably using digital cameras, so these calculations may not apply. For example, a nominal 300mm lens is effectively longer than that, and the f-stop ratio is changed, so there may be more depth-of-field than I've indicated. These numbers are for 35mm. Aah! those DIGI-guys are always at an advantage but I don't want to go DIGI. Many thanks for your comment. With best regards, Ayash. - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
