Guide number
Indicates the output, or power, of an electronic flash. You can use the guide number to work out the aperture or flash to subject distance by dividing either into the guide number.
Guide Number
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Guide number
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The Guide Number (GN) defines the amount of flash light which is necessary for a correct exposure of a a subject dependent on its distance from the flash and the chosen aperture: ...
Techniques Glossary Guide number
Indicates the output, or power, of an electronic flash. You can use the guide number to work out the aperture or flash to subject distance by dividing either into the guide number.
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Guide number
The number which indicates the effective power of a flash unit. For a given film speed, the guide number divided by the distance between the flash and the subject gives the appropriate f stop to use.
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Guide Number
A number used to represent the illuminating power of a photographic flash for comparison of efficiency with other flash units.
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GUIDE NUMBER - A number which serves as a guide to proper exposure when using flash. Also known as "Flash factor." The number is based on a flash unit's light output and the film speed.
Guide Number
Most flashguns for a camera list a rating referred to as a Guide Number, or GN. This number is used for manual settings to determine the proper aperture based on the distance from the subject.
Guide number. A rating of a flash’s power.
Hot shoe. A clip on the top of the camera that attaches a flash unit and provides an electrical link to synchronize the flash with the camera shutter.
Guide Number: A rating of a flash unit's power. Can be divided as the proper exposure setting for a photo taken with the flash ten feet from the subject, multiplied by ten.
Guide Number - GN
Guide Number is a measure of how much light a flash emits. It can be used to manually set the correct aperture for proper exposure based on the distance between the flash and the subject.
Guide number. A number rating for a flash unit that can be used to calculate the correct exposure for a particular film speed and flash-to-subject distance.
Guide Number. The power output rating of a speedlight flash unit.
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Guide Number - The output power rating of a electronic flash unit.
HAD CCD - Sony's latest CCD imager, HAD = Hole Accumulation Diode ...
Guide number.
The maximum distance range of a flash unit is indicated by its guide number.
Guide number (flash factor). Figure denoting the relative power of a flash source. The GN is the light-to-subject distance (usually in meters) multiplied by the f-number for correct exposure, e.g. GN of 16 = 2 m at f8 or 1 m at f16.
Guide Number
Value for the maximum power of a camera flash based on a film with an ISO of 100. Built-in camera flashes have a guide number (GN) of approx.
Guide Number (Flash)
Guide numbers proclaim the light output of Electronic Flash units more realistically than Watt/seconds do, but still ignore such essentials as reflector design.
GN (Guide number)
Used to express the power output of the flash nit. It indicates the power of a flash in relation to ISO film speed. Guide numbers are quoted in either meters or feet.
Guide number
Term sometimes used to describe a flash factor, which provides a guide to correct exposure when using flash. Also used to describe the output power of a given flash focal length.
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Guide number: 9/30 (at ISO 100 m/ft) Flash control: sensor flash system, Flash modes: Auto, Flash Cancel, Anytime Flash, Slow Sync, Red-Eye reduction (illuminates for 0.8 seconds before main flash)
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Guide Number
The Guide Number for a flash unit is calculated by the formula:
GN = f-stop x flash to subject distance. Most GNs are taken at ISO100, but some makes can cheat! Be aware also some flash spec sheets are in Feet, some in Metres.
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Guide number in feet formula multiplies the f/stop used times the Flash to subject distance to calculate the guide number at an ISO of 100. Since the guide number increases by 1.
The guide number is most frequently quoted in metres, although feet are used. Many manufacturers quote a land guide number as opposed to an underwater guide number, although many give both.
With a guide number of 80 and power levels in 1/7 stop increments, you can make fine adjustments to the StarFire™ that precisely match your setups.
However, guide numbers are difficult to use in the real world, and it's unlikely both strobes will aim at exactly the same spot, or be exactly equal in power.
The 283 has a guide number of 120(ft) at 100 ISO and features both manual (full power) and auto modes.
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The power of a flash in relation to ISO film speed. Guide numbers are quoted in either meters or feet. (To convert from meters to feet, multiply the metric number by 3.3).
Information packaged with film may also provide guide numbers appropriate to their speed in regard to the various powers of electronic flash units. Manufacturers tend to overrate the power of their electronic flash units.
Power of an underwater flash is usually given by a guide number. The higher the guide number, the stronger the strobe. The precise formula for guide number = distance * F-stop.
Some essential features you need in a flash, are TTL-metering, bounce capability, and its Guide Number. With TTL flash, exposure is calculated automatically.
Metz 76 MZ-5TTL, with a guide number of 250 at ISO 100, is one of the most powerful wireless flash units available.
Plus points of the Metz system include: TTL operation and user-friendly setup and controls.
Light intensity is determined by Guide Numbers. The value of these numbers represents the aperture times the maximum distance the camera flash will be applied to (in feet).
From what used to require tape measures and calculators to decipher guide numbers and placement distance of the flash to the subject can now be accomplished by turning the command wheel or hitting a few buttons.
After experimenting with my Vivitar 2600 flash, I discovered that manufacturer's guide numbers are not to be trusted even though they are printed on the flash. The quoted guide numbers are usually almost double (!!) the real guide number of the flash.
The Nikon SB-M dedicated flash is designed specifically for the FM10, but it will also accept any other nondedicated hot shoe mounted flash for guide number manual or flash mounted sensor automatic exposure control - the venerable Vivitar 283 (guide ...
GN Mode on Nikon Speedlights With distance-priority manual flash operation the guide number is automatically determined by the Speedlight according to the distance value and aperture set.
This gives me a working guide number in the mid 300s and allows me to reach f35 at 10ft.
This guide opens with in-camera flash basics, then moves to topics such as exposure flash readings, detachable units, flash guide numbers, bounce flash, and fill flash, then covers advanced methods for using off-camera flash, flash brackets, ...
Obviously no rule was broken in the tests, that is, shooting outside of the flash range dictated by the Guide Number (GN). If you don't break it, your images should always look well lit. If they don't, ask your photo lab to redo your prints.
Then we have studio flash which is usually only available to professional photographers. These are big flash units with very high guide numbers for use in the studio.
Advanced features & high performance with a powerful guide number of 61
Click here to read more
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This one is great article for beginner like me and even for professional photographers. I am much more appreciate if you can update this article with "WHAT IS GUIDE NUMBER FOR FLASH?" and many thanks for publishing this great article.
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However, under the circumstances described above only, the guide number is reduced from that of full flash output level by approximately 0.6 EV.
 See also: Flash, Camera, Light, Photograph, Image
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