17 questions linked to/from How do I set exposure with a manual flash?
6k views

### What is the relationship between ISO, aperture, and shutter speed?

I know digital cameras have ISO options, and that ISO is the camera's sensitivity to light, but if you set higher ISO then you can get a noisy image. I also know there are two other camera options, ...
7k views

### What is the quantative relation between flash guide number and ISO?

I found that formula on the Internet: Guide Number = (Shooting Distance * Aperture) ÷ ISO Sensitivity Is it correct? If it is could someone please explain why ISO is related to guide number in this ...
739 views

### Do flash guide numbers assume some amount of ambient light built-in?

My flash shows its potential range in meters, but is that indoors or outdoors? The question came up the other day when I was trying to work out whether fitting a diffusion dome would be suitable for ...
2k views

### How do TTL flash metering systems calculate how much power is needed?

Does anyone know how TTL calculates the amount of power to put in after the preflash is done? I understand that the value is somewhat brand specific, but what is the general logic? Because if you ...
177 views

### How to use the exposure guide table on the back of Vivitar 1900 flash?

I have an old Vivitar 1900 flash. New flashes have a lot of controls, but this one has two buttons and two lights. One button is on and off. The other one says test. One light is when flash is ready. ...
1k views

### What is the inverse-square law, and how does it apply to lighting for photography?

I hear photographers talk about the inverse-square law, particularly with reference to lighting. What is this law about, and most importantly, how is it applied to lighting for photography?
1k views

### What is the power output from two speedlites combined?

When you have two speedlites in a softbox firing at the same time, let's say at 1/64 power, what is the total power output?
2k views

### How to understand flash distance scale when used with a wireless transmitter?

I am reading Bryan Peterson’s book, Understanding Flash Photography. In this book, Bryan mostly talks about using the flash in manual mode and not in ETTL mode. I own a Yongnuo 600-Ex-RT speedlight ...
460 views

### Why does the Guide Number have a distance given with it? [duplicate]

I am learning photography and looking to buy a flash. I learned the basics of the flash, and as far as I saw everywhere, the Guide Number had a feet unit with the ISO number; e.g. 160' at 100 ISO. I ...
372 views

### Sony rx10 with generic flash makes overexposed pics?

Are there special settings to use a "regular" external flash? I have a Canon Speedlite 430ex II flash from a previous camera, and when I try to shoot with it, it fires fine (so, it is in the shoe far ...
955 views

### how to determine how much power to use in manual mode for external flash? [duplicate]

i recently added an sb700 to my d3200 and am unsure how to determine proper amount of power to use in photos. in another thread here on stack exchange, it was suggested that the ttl metering makes a ...
487 views

### What are these green numbers on my Canonet’s aperture scale?

There are three green numbers on my Canonet QL19’s aperture scale: The numbers are 28, 20, and 14. What are those?
422 views

### Does the Canon DS6041 support TTL flash?

I've got that Canon model, and I'm using it with a Promaster 7500DX flash. The flash appears to support TTL light metering, but I can't find any way to make the camera recognize this. Consequently, ...