YN560iii flash advice

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stevebuk

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Steve
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Hi all,

I've decided it would be good to try my hand with flash and I have bought a cheap 560iii and wireless trigger for my X-T1. To get me up to speed, I've read "Understanding Flash Photography: How to Shoot Great Photographs Using Electronic Flash" from Bryan Peterson and I think I've got the basic understanding of manual flash. All good, or so it seemed!

My problem is that he talks about the flash to subject distance scale a lot and also setting the flash to the aperture. The 560iii doesn't seem to have a scale or option to set aperture. I see I can adjust the power on the flash but how do I know what setting? I believe I can calculate the distance from the gn per focal length etc but this seems a lot of work :). Am I missing something for manual flash, or do I need to just use trial and error with regard to locating the flash and setting the power?

Any advice for how to determine the power would be much appreciated.

Thanks
Steve
 
I'll be following this with interest.

I currently use trial and error. You soon get to know how much power to use and, on digital, it costs nowt to take a couple of frames to get it right.
 
Trial and error Steve. Start with a ball park figure and adjust to suit.

I usually go with 1/200 and f4 with flash at around 1/16 then take a test shot and see what the outcome. If it's over exposed then close the aperture down a little. If it's under exposed then open the aperture, increase the flash power or bump the iso.

If you want to drag in more ambient then drop the shutter speed.

Remember that the closer the light source the softer the light will be. And also the bigger the light the softer it will be too along with being able to cover a bigger subject.
 
Thanks guys. Just wanted to make sure I wasn't missing something obvious. May seem a daft question, but surely including a distance scale would be helpful? Why did this practice die?
 
You can manually calculate

The guide number of this flash is 58, not sure if it zooms but if it does it will be when at narrowest angle (max focal length zoom) - guide numbers are given at ISO 100 normally.

So with the flash at maximum power and a distance of 10 feet we get an aperture of f5.8

GN / distance (in feet) = aperture

If we go to half power the GN goes to 58/1.414 = 41 and to 1/4 power the GN halves i.e. 29

Conversely if we up the ISO by a stop the power goes up by a factor of 1.414 so at 200 ISO the flash has a guide number of 81 and at an ISO of 400 a guide number of 116

The practice did not die but became less needed with TTL flash - remember this assumes the flash in direct mode, use a brolly etc. and it all changes.

There are plenty of guide number apps that you can get

Mike
 
Thanks Mike. that's what I was looking for :)

It does zoom, and the 58 gn is for 105mm. Your equation above states gn / distance in feet = aperture. I think the 58 gn is metric, so would be 190 gn in feet?

So for your example I think I should calculate 190gn / 10feet = f19 aperture at iso 100, 10 feet and 105mm focal length? My Fuji base ISO is 200, so I think that for the same exposure at the same distance I would use aperture f27? (190*1.414=268.66), 269 / 10 = 27?

If this is correct, and I want to move to a wider aperture, am I correct that I can reduce the power of flash to 1/4, so half my gn at ISO 200 that would be 134.33gn, so divide by 10 gives me f13 ish?

I hope the above makes sense and I'd appreciate it you can correct me if wrong!

Assuming I am correct, this is all great at 105mm. How do I know what to do for 35mm or 50mm etc?

Thank you!
Steve
 
stevebuk said:
Thanks Mike. that's what I was looking for :)

It does zoom, and the 58 gn is for 105mm. Your equation above states gn / distance in feet = aperture. I think the 58 gn is metric, so would be 190 gn in feet?
Click to expand...

Yes, that sounds right (1metre =3.28 feet) so 58 x 3.28 = 190

ISO 200 would be 1.414 x 190 = 269 so at 10 feet we do have f27 and 1/4 power would be a half so f13.5

at the 35mm setting the Gn will probably be about half or just above, hence why they quote the 105mm :)

Mike
 
There are plenty of guide number apps that you can get
Could you advise Mike please
 
The problem with the distance calculations (and the reason we use Auto flash on camera) is that they're based on a bare flash pointing directly at the subject. So Mikes calculations are absolutely spot on if that's what you're doing. But as soon as you add a modifier, or bounce the flash, or both - the calculation needs propping up with trial and error.

And lets face it, most of us, most of the time will be either bouncing the light or using some kind of modifier.

If you start with David's idea of a ballpark figure, you'll soon be able to adjust with accuracy, it's just one of those things that you 'just learn', and one of those things that freaks out people who insist life needs some kind of instruction book.

Let's assume you'll start with a 3/4 portrait shot through an umbrella about 4' away. Once you have the correct exposure, it'll always be the same for that setup, if you move the flash out for a full length shot, open up the lens or increase the flash power, if you go in close for a soft head and shoulders, turn down the flash (it's unlikely you'll want more DoF)
 
Jango said:
There are plenty of guide number apps that you can get
Could you advise Mike please
Click to expand...

Jan,

to be honest I do not use that type of app but this is an example https://itunes.apple.com/us/app/photocalc/id287811118?mt=8 and the reason I do not use one is two fold, basic calculations I can do in my head, my background is electronic engineering and when measuring a voltage, waveform etc. the instruments I learnt on had manually set ranges so you would do the calculation to work out which range to start on and as Phil says
Phil V said:
The problem with the distance calculations (and the reason we use Auto flash on camera) is that they're based on a bare flash pointing directly at the subject. So Mikes calculations are absolutely spot on if that's what you're doing. But as soon as you add a modifier, or bounce the flash, or both - the calculation needs propping up with trial and error.

And lets face it, most of us, most of the time will be either bouncing the light or using some kind of modifier.
Click to expand...

which means the power will always be lower

Mike
 
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