15 July 2010

Exposure tutorial

Hi all. .
Thanks for all the lovely comments over the last few days! you are all so lovely. From stopping by on a few blogs, I think a lot of people are confused about exposure when taking pictures on full manual mode. I am honestly no expert but this is something we had to learn for photography AS, so I thought I would share...
This is the exposure triangle and if all of these seprate parts work together you have a nicely exposed picture.
Shutter speed: I think everyone knows that if you have a long shutter speed you get that nice motion blur and a fast one you can freeze stuff like water droplets? Shutter speed also contributes to exposure. Fairly straightforward.
The slower the shutter speed the more time the light has to go in so... the lighter the photo
The faster the shutter speed the less time the light has to go in so...the darker the photo.
. .
Aperture: Here is a little diagram I found on the internet:
I think you all know that a large Aperture (F/2 for example) gives a nice shallow depth of field and vice versa for a small aperture. Aperture also works for exposure. Look at the large aperture diagram and the lens is wide open. More light can therefore get in and...guess what.. a lighter picture. Same with a small aperture.. hardly any light comes in so darker picture.
ISO: This is basically how sensitive the camera is to light. A good rule of thumb is the higher the ISO number, the lighter the picture becomes. Beware of this though because the higher the number, the granier the picture is as well.
So...basically. Here is an overexposed picture:
To get it at the right exposure I have three options..Shutter speed, Aperture or ISO.
I personally, always use shutter speed first. With this picture it is clear the shutter speed was too slow because the lens has been opened for too long, allowing too much light in. Therefore I need to make the shutter speed faster, meaning less light can come in.
Here is another option:
This picture is quite underexposed. The first thing I would do would be to adjust the shutter speed. The picture is too dark because the shutter speed is too fast (the lens hasn't been opened long enough for enough light to come in) I would make the shutter speed slower.
Because its quite a dark room though, the shutter speed would need to be quite slow for it to be correctly exposed, that means more chance of camera shake and a blurred photo.
So...I have two other options. first ISO. I can push that up to say 800 and the picture will get lighter but there will be quite a lot of grain.
Or.. I can adjust the aperture and rather than it be on F5 I could make it F1.6.
Most pictures you will need to fiddle with all three aspects to get a correct photo. It really is just experimenting! Again, I am no expert and I'm sure others could explain this in a much easier way but I just wanted to share how I make a picture exposed on manual mode!
And..later this afternoon I'll share a new layout! woo hoo!
Thanks for stopping by
Loves xxxx


JO SOWERBY said...

can u explain how to do these things on a point and shoot ;-))
Jo xxxx

Maria Ontiveros said...

Wow- Abi, this is sooo helpful! I think I'll print it out and stick it in my camera bag.
Thanks for taking the time to explain it.

debs14 said...

I think that AS photography grade is going to be a good one! You explained this really well.

Amy said...

Abi I was coming by today to say how much I've loved your contributions in class and to ask if you had any simple ways to explain a few technicalities and up pops this great tutorial! Thankyou so very much for taking the time to explain exposure, I'm a bit afraid of the shutter - it confuses me! I tend to fiddle with apperture and ISO before the shutter - I know I need to practice a lot more to fully grasp the concepts and to feel confident using manual mode.

Lizzie said...

Abi, this is wonderful! Thank you very much. I did photography for a while at art college, also had a bf that was a photographer and who bought me my first SLR (manual!) camera. But I never really understood all the technical waffle about ISO, Shutter speed, aperture... I think it was because it was "men-speak" and it didn't register properly with the way my brain works (or something).
But this was so clear and easy to understand... makes me wonder why I found it so hard!
Thank you for a very straightforward and easy little tutorial. You are a star!