If you have a correct exposure at a given app and then change the app up four stops am I correct in thinking that the shutter speed has to change four stops as well to keep the exposure levels?

And am I right in thinking that a stop in shutter speed is double the previous time.

eg change from f2.8 – f6.3 (3 stops I think) would need a shutter speed change from 30 secs to 240 sec?

I think I have this right but just wanted to clarify in my mind.
App change up brings in half the amount of light so you need to double the shutter time to get the same light….

In essence, yes. You could also bump the ISO up rather than changing the shutter speed

Took this last night. Was happy with the exposure at 2.8 but wanted to increase the app to get the full picture in focus. I think I was on the right path but took 4 different exposures of 150, 180, 210 and 240 just to make sure.
If I was sure in my mind it would have saved me a fair bit of time stood about in the dark and cold!

54.1 ~ Fall Into The Goyt by Enotsnad, on Flickr

Put camera on aperture priority and see what it sets shutter at?

wysiwyg – Was shooting a water blur in pitch black so shooting bulb.

Yes, you are right.

It’s cleverly set up so that a whole f-stop halves or doubles the amount of light. So doubling the shutter speed also doubles the amount of light, and doubling the ISO doubles the sensitivity. Each doubling or halving is known as 1 EV. So the next f-stop means you have to double or halve the shutter speed or the ISO.

Quite neat really. Of course don’t forget that the next setting on your camera might not be a whole EV – most do 1/3 EV increments.

I don’t think f2.8 to f6.3 is three whole stops though.. but your camera should show you in manual mode if your settings are under or over what it thinks is normal, so if you are shooting at say -1.3EV you should be able to adjust the settings to keep it saying -1.3EV

Yep that fits with my understanding.

I’ve always found the explanation here very useful:
A Tedious Explanation of the f/stop

f6.3 isn’t a full stop by the way.

The full stops are: f1, f1.4, f2.0, f2.8, f4, f5.6, f8, f11, f16, f22

(an easier to remember sequence than it looks: each f number is double the one before last)

f6.3 is actually stopped down two and 1 third stops from f2.8.

but wanted to increase the app to get the full picture in focus.

decrease the aperture = increase the f stop

The full stops are: f1, f1.4, f2.0, f2.8, f4, f5.6, f8, f11, f16, f22

Cheers fella I never knew that.

Ok cheers guys so I was righ in principle just need to try ot remember the specifics.

decrease the aperture = increase the f stop

Yeh got that, I knew what I meant 🙂

Still very much in the experimenting stage of things but starting to get my head round it all now.