Macros with a flash
Posted 09/09/2008 - 08:39
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This is more a flash question, rather than a macro one
The shutter speed of 1/125s is the fastest the shutter can go and still work with a flash gun. The camera automatically sets this speed to avoid embarrassing mistakes
That said, there is no problem with the flash using a slower shutter speed - it will still synchronise just perfectly.
However, you need to be aware of some background info:
1) Slower shutter speeds mean you need a more stable camera support. For macro this may be a killer
2) Slower shutter speeds effectively let more ambient light in - balancing the flash with the available light.
Point (2) is perhaps the most important. Let me give you an example.
You turn off the flash and meter with the camera. Let's say the exposure is f/8 at 1/15s for the ambient lighting. Now you turn your flash on (and assuming that the "A" setting on the flash is also at f/8 for your current film speed), the shutter speed will be at 1/125 - as you stated.
This means that the flash is 3 stops brighter than the ambient lighting (1/15 - 1/30 - 1/60 - 1/125). This could give you quite a harsh result. However, if you change the shutter speed to 1/30, then the ambient light is underexposed by 1 stop, and the flash will fill in the rest and you'll get a much more "natural" looking shot.
The main thing to remember is this: flash exposure is only governed by the aperture (not the shutter speed!!), while ambient exposure is governed by both aperture and shutter speed.
Hope that helps (and doesn't confuse too much!)
Matt
The shutter speed of 1/125s is the fastest the shutter can go and still work with a flash gun. The camera automatically sets this speed to avoid embarrassing mistakes
That said, there is no problem with the flash using a slower shutter speed - it will still synchronise just perfectly.
However, you need to be aware of some background info:
1) Slower shutter speeds mean you need a more stable camera support. For macro this may be a killer
2) Slower shutter speeds effectively let more ambient light in - balancing the flash with the available light.
Point (2) is perhaps the most important. Let me give you an example.
You turn off the flash and meter with the camera. Let's say the exposure is f/8 at 1/15s for the ambient lighting. Now you turn your flash on (and assuming that the "A" setting on the flash is also at f/8 for your current film speed), the shutter speed will be at 1/125 - as you stated.
This means that the flash is 3 stops brighter than the ambient lighting (1/15 - 1/30 - 1/60 - 1/125). This could give you quite a harsh result. However, if you change the shutter speed to 1/30, then the ambient light is underexposed by 1 stop, and the flash will fill in the rest and you'll get a much more "natural" looking shot.
The main thing to remember is this: flash exposure is only governed by the aperture (not the shutter speed!!), while ambient exposure is governed by both aperture and shutter speed.
Hope that helps (and doesn't confuse too much!)
Matt
http://www.mattmatic.co.uk
(For gallery, tips and links)
(For gallery, tips and links)
Posted 09/09/2008 - 22:52
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Thanks Matt,
That makes it all a bit easier to understand
Regards
PaulM
That makes it all a bit easier to understand
Regards
PaulM
All cameras are equal but.....
Some are more equal than others
Some are more equal than others
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491 posts
18 years
Frenchs Forest,
Sydney
When your using a flash, do you have the camera set at the flash sync speed (ie 125 on my ME Super), or do you go slower?
When I put my flash (its a Vivitar 550FD) on either the ME Super of the Super-A it sets its self to 125, should I just use that for both day and night shots?
Sorry if there basic questions but I haven't ever used a flash before other than "holiday" style night snaps.
Regards
PaulM
Some are more equal than others