Determining flash settings in manual mode?

12 years 5 months ago - 12 years 5 months ago #152787 by MLKstudios
It is a power rating for the flash at full power. It also includes an ISO number (100 was standard but some use ISO 200 now to boost their GN rating) and is measured in feet or meters. New GN's include the head zoom setting.

A medium powered flash has a GN of around 100 feet (at ISO 100). The SB-900 and 580EX-II are closer to 150. A low powered flash is rated around 50-70.

Note that zooming the flash head changes the GN too. So it gets really complicated when using modern equipment.

Ex. for the SB-700. Guide Number rated at 28 (in meters), or 92 (in feet), at ISO 100 at normal 35mm FX setting.

In practice that would be the flash head at full power pointed straight on, and for example you are 16 feet away, and using ISO 100 (and the 35mm FX zoom setting), you'd divide 92 by 16 to get the f/stop (5.75). Any tilt, other ISO, modifier and etc. means you would need to recalculate some impossible factors.

Studio strobes are rated in watts per second. The modifiers used (including reflectors, umbrellas, softboxes, snoots and etc.) have a great affect on their power. A flash meter helps.

:)

Lighting is about learning to SEE and find good light. If you have to work in bad light (ex. a wedding) then you need to know what to add (or subtract) to make the available light look good. That's when flash is a necessity, and not an option.

Matthew L Kees
MLK Studios Photography School
www.MLKstudios.com
[email protected]
"Every artist, was once an amateur"

,
12 years 5 months ago #152825 by Imagegourmet
If you are shooting digital setting up an off camera flash is relatively easy without a "Seconic" meter, just check the image on your screen, check the histogram, or highlights and change the distance or power of your flash reshoot and check again.

Or read this article, www.vividlight.com/articles/1214.htm
,
12 years 5 months ago #152907 by MLKstudios
I just breezed over that out of date article, but with digital he should choose f/11 rather than f/8 when the GN gave him a f/9.8 result. Negative films benefit from additional exposure but chrome films (and digital) get washed out easily.

Would save you from a flashy looking blowout. :)

Matthew L Kees
MLK Studios Photography School
www.MLKstudios.com
[email protected]
"Every artist, was once an amateur"

,
12 years 5 months ago #153235 by Moe
I don't shoot with manual flash settings to much these days but will say this thread was very good reading. :thumbsup:


Photo Comments
,
12 years 5 months ago - 12 years 5 months ago #153236 by MLKstudios
One of my better ones, right David? ;)

Matthew L Kees
MLK Studios Photography School
www.MLKstudios.com
[email protected]
"Every artist, was once an amateur"

,
12 years 5 months ago - 12 years 5 months ago #153385 by Henry Peach

MLKstudios wrote: ...impossible factors.


Once again I'm glad I learned all this before the internet so I never had anyone to tell me this stuff was impossible. ;)

I encourage everyone to practice a bit. You will find that flash power is adjusted in plain old stops, 1/2 stops, or 1/3rd stops, just like everything else. It's quite easy to calculate if you understand what a stop is. You will find that a particular light mod, if used in a consistent manner, tends to reduce the flash power by the same amount every time. As does adjusting the focal length zoom head on the flash. With some experience you will even become fairly accurate at estimating the effects of bounce distance, and bounce surface tone and texture. You may not be able to get it perfect on the first try every time, but with practice you will learn to make a close estimate. At first it will seem complicated, but the more often you do it the sooner it will seem like old hat. Just practice. No expensive DVDs or online courses necessary.
,
12 years 5 months ago - 12 years 5 months ago #153389 by MLKstudios
What's the exposure factor for an umbrella? Or a soft box? Or from wide to telephoto?

No, these are not calculable. Even with an HP calculator.

Straight on, zoomed in -- maybe.

Nikon's i-TTL makes that all go away. You might have to adjust the EV now and then, but more often you get good exposures the first time.

Matthew L Kees
MLK Studios Photography School
www.MLKstudios.com
[email protected]
"Every artist, was once an amateur"

,
12 years 5 months ago #153611 by Jim Photo

Henry Peach wrote:

MLKstudios wrote: ...impossible factors.


Once again I'm glad I learned all this before the internet so I never had anyone to tell me this stuff was impossible. ;)

I encourage everyone to practice a bit. You will find that flash power is adjusted in plain old stops, 1/2 stops, or 1/3rd stops, just like everything else. It's quite easy to calculate if you understand what a stop is. You will find that a particular light mod, if used in a consistent manner, tends to reduce the flash power by the same amount every time. As does adjusting the focal length zoom head on the flash. With some experience you will even become fairly accurate at estimating the effects of bounce distance, and bounce surface tone and texture. You may not be able to get it perfect on the first try every time, but with practice you will learn to make a close estimate. At first it will seem complicated, but the more often you do it the sooner it will seem like old hat. Just practice. No expensive DVDs or online courses necessary.


:agree: :goodpost:


Photo Comments
,

817.3K

241K

  • Facebook

    817,251 / Likes

  • Twitter

    241,000 / Followers

  • Google+

    1,620,816 / Followers

Latest Reviews

The Leica SL2-S is an attractive, premium mirrorless camera with photo and video specs that are sure to impress. And with the legendary Leica name, you know this camera exudes quality!

Mar 26, 2024

The Sigma fp L is a compact full-frame camera with a 61-megapixel sensor, 4K video capabilities, in-body image stabilization, and weather-sealed construction. What’s not to like?!

Mar 19, 2024

The Canon 1DX Mark III is a big, burly professional camera packed with top-end features. Is it worth the investment in 2024? Find out in this detailed review!

Mar 04, 2024

In the OM-1 vs OM-5 debate, which camera comes out on top? Though they’re different cameras for different purposes, comparing them head to head clarifies which is best for your needs.

Mar 01, 2024

Forum Top Posters

Latest Articles

Time management is a critical skill to master when you’re a photographer. But how do you get the most out of the limited time you have? Check out this guide to learn a few tricks!

Mar 27, 2024

The Leica SL2-S is an attractive, premium mirrorless camera with photo and video specs that are sure to impress. And with the legendary Leica name, you know this camera exudes quality!

Mar 26, 2024

Opening a photography business means undertaking various photography marketing strategies to promote your work. But you don’t want to do the same old thing - try these unique ideas!

Mar 22, 2024

The Canon EOS 80D might be a few years old, but it’s nevertheless a quality camera to invest in as a beginner or enthusiast looking for a mid-range DSLR with tons of lens options.

Mar 22, 2024

Wedding consultations are a critical part of a wedding photography gig. It’s when you learn about the couple and their wants, and present them with how you will meet those desires.

Mar 22, 2024

If you're looking for the best metal print of 2023, you'll find it from Artbeat Studios. After months of testing, Artbeat Studios beat out the competition!

Mar 21, 2024

Getting the best video shots on your camera or smartphone requires you to understand the fundamentals of composition and video editing. It helps to have the appropriate gear, too!

Mar 20, 2024

It’s easy to lose your inspiration behind the lens, especially as a beginner. These creative photography projects can help inspire you to try new techniques and improve your photos.

Mar 20, 2024