can anybody help me with OU stuff?

  • Thread starter Thread starter Mai
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Mai

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Mai
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I cant do it.I dont really understand!! :shake: and its doing my head in!! :bang:

Here is the question...
Your automatic exposure setting tells you that the correct exposure for a scene is f/5.6 and 1/60th second. However, you want to avoid camera shake and take it at a shutter speed of 1/125th. If you select 1/125th in shutter speed priority mode, what aperture setting will the camera select (all other things being equal)?Select one option
A – f/2.8
B – f/4
C – f/8
D – f/2.0


Im so confused! Thank you!! x
 
You are decreasing the time the shutter is open from 1/60th of a second to 1/125 of a second therefore to compensate and let the same amount of light in you need to open up the lens using a larger aperture therefore to balance I would expect the aperture to be set to A) or B) or D) all wider than f/5.6

(ps: someone far more techie than me will tell you exactly which one :))

Just tried it practically and I get f4 :)
 
Mai said:
I cant do it.I dont really understand!! :shake: and its doing my head in!! :bang:

Here is the question...
Your automatic exposure setting tells you that the correct exposure for a scene is f/5.6 and 1/60th second. However, you want to avoid camera shake and take it at a shutter speed of 1/125th. If you select 1/125th in shutter speed priority mode, what aperture setting will the camera select (all other things being equal)?Select one option
A – f/2.8
B – f/4
C – f/8
D – f/2.0


Im so confused! Thank you!! x
Click to expand...

OK with out doing it for you if you half the time the shutter is open then you need to open up for twice as much light so one stop.
 
You have halved the shutter speed, you therefore have to open the aperture by one stop.

I'm not going to give you the answer cos that won't help you learn. ;)
 
f/? Youve effectively halfed the amount of light by increasing the shutter speed by 1 stop so youve now got to double the amout of light through the aperture so open up the aperture by 1 stop.

so 125th @ F/? is equal to 60th @ f/5.6
 
If you double the shutter speed there will be '1 stop' less light making it to the sensor so you will ned to compensate by allowing more light in to the camera by opening the apeture up by '1 stop'.

So from f/5.6, 1 stop more will be f/**

http://www.photonhead.com/beginners/shutterandaperture.php
 
^^^ too slow :bonk:
 
Mai,

What course are you taking? I'm finding it very difficult to understand how you could be on a Photographic degree course with such poor technical knowledge.

Surely you have to have acheived a certain level of competance prior to being accepted on the course?
 
EdBray said:
Mai,

What course are you taking? I'm finding it very difficult to understand how you could be on a Photographic degree course with such poor technical knowledge.
?
Click to expand...

I am guessing its
Course code T189
Credit points
10
OU Level
1
SCQF level
7

FHEQ level
4

Summary

Whether you’re new to digital photography or want to improve your existing skills, this ten-week online course will develop your ability to create and share digital images you are proud of. If you’re just starting out, you’ll be able to compare notes with many other people in the same situation. If you’re already a keen amateur digital photographer, being part of an active online community will develop your fluency. Visually focused, with text kept to a minimum, the course will develop your technical, visual and creative skills. A series of weekly hands-on assignments allows you to practise the skills you’ll learn.
 
It's not a degree course, it's more of an introductory course aimed at beginners and as such it's very good.
 
parkmoy said:
It's not a degree course, it's more of an introductory course aimed at beginners and as such it's very good.
Click to expand...

Fair do's! I wrongly assumed that the OU were about degree courses!

Not sure I could agree that it is good though when a student is asking on a photography forum what is a pretty basic question.
 
EdBray said:
Fair do's! I wrongly assumed that the OU were about degree courses!

Not sure I could agree that it is good though when a student is asking on a photography forum what is a pretty basic question.
Click to expand...

The OU do all sort of courses these days!

Without meaning to offend Moi, we don't know what's included (or not) in any course texts... or whether they've been read yet... so it's not necessarily a reflection on the course that the question's being asked.
 
incapete said:
The OU do all sort of courses these days!

Without meaning to offend Moi, we don't know what's included (or not) in any course texts... or whether they've been read yet... so it's not necessarily a reflection on the course that the question's being asked.
Click to expand...

Spelling their name correctly might help ;)
 
This might help.

While the halving/doubling relationship between shutter speeds is clear, ie 1/60sec is approx double the time of 1/125sec, the same relationship between f/numbers is not at all obvious.

The key is 1.41 - the square root of two. And a lower f/number passes more light, not less.

That is to say, f/8 passes half the amount of light compared to f/5.6, which is half f/4, and so on. Eg, 5.6/1.41=4.

The halving/doubling principle applies to all aspect of exposure - it is known as 'one stop' of difference. Applies to ISO too. In this way you can mix and match shutter speed, f/number and ISO to get both the correct exposure, and also control other effects such as depth of field and movement.
 
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