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Daz9681

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I just don't get it, i read some stuff about it but it's just not sinking in, maybe i'm not understanding it properly, does ISO effect shutter speed or apature. I know it changes how sensitive the sensor becomes, but i dont get when to change it or what setting to use.

Outdoors in bright sunlight would be 50/100 so would i never use 800 in daylight on indoors in a dim lit room?

Help haha
 
I am doing a course and learning about shutter speed, aperture and ISO. Seems quite confusing at first, but all makes sense after putting into practice.
 
Daz9681 said:
does ISO effect shutter speed or apature. I know it changes how sensitive the sensor becomes, but i dont get when to change it or what setting to use.
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It just depends on what mode you're in. If you're in Tv (shutter priority) then changing ISO will affect the aperture, in Av (aperture priority) it will affect the shutter speed.

For me the vast majority of my shooting is done in Av and I use ISO essentially to give me enough shutter speed for the situation I'm shooting in. If it's dark and my shutter speed is a bit on the slow side then I'll increase ISO until my shutter speed is quick enough, but I generally try keep ISO as low as I can get away with. :)
 
Thanks for the reply.

So it's just a case of playing about with settings to find what works, remember it for the conditions and tweeking them for the perfect picture (or at least what i'm happy with)
 
As above really in that ISO, shutter speed and aperture are intrinsically linked and all form part of the 'exposure triangle'.

When I was learning the ropes, what made selecting ISO sink in for me was when somebody said that the ISO should always be as low as you are able to get it for your chosen aperture and shutter speeds. That's the crux of the matter.

Basically higher iso values will deteriorate your image by introducing noise or grain. Some cameras handle this better than others but it is still always a factor, so you use the lowest ISO you can for the conditions.

Here are a few example scenarios so you can see my own thought process.

Shooting a moving car in fading sunlight. In this scenario, you're unlikely to need much depth of field so your lens aperture will probably be wide open, let's say F/4. But because the car is moving and I want it to appear sharp, I'm going to need a fast shutter speed, say 1/1000. Because the light is fading and I want such a fast shutter speed if I were to shoot at base iso of 100, the shot would be badly underexposed. To get a well exposed image, I'm going to have increase the ISO which will effectively amplify what little light the camera is going to see. In fading light, maybe this would be something like iso 800 or 1600, whatever it takes to get the image to look how you want it. Inevitably this will introduce some element of grain to the picture but most people would agree that a little grain is better than a blurred or under exposed image.

Another scenario. I'm up in the hills with the camera. I want to take a landscape shot and I'd like a big depth of field so I'm going to close the aperture up to maybe f/11. This is going to limit the amount of light reaching the sensor but is crucial to me as I want everything to be in focus whether near to the camera or in the far distance. I've left my tripod at home so I'm going to have to hand hold the camera. It's cold so my hands are a bit shaky so I think I'm going to need at least 1/100 for my shutter speed. Because the aperture is quite narrow, again light reaching the sensor is going to be diminished so unless it's in blazing sunshine, I'd likely have to up my ISO again.

One last scenario that's a little different. Let's say I want to photograph a night scene in the local city centre. This time I have my tripod with me. What I'm photographing requires a large depth of field so again I've selected F/11. This time the camera is on a tripod and I'm not looking to freeze movement so my shutter speed can be anything I want, maybe even over 30 seconds. Because I'm not worried about shutter speed, I'm going to set the iso at it's lowest value as that will give me the least noise in the final image. This will then dictate how long the shutter needs to stay open.
 
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Think of them as a triangle, each point, shutter, aperture and ISO. If you change one setting then you need to change one of the others to maintain the same exposure. For example say a scene is 1/250 f8 ISO 400, you increase shutter speed to 1/500 as it's a moving subject you can either increase the aperture to f5.6 to let more light in or increase the ISO to 800.

If you wanted more Depth of Field (more of the shot to be in focus from front to back) then change the aperture to f11 say, then to compensate you use a slower shutter speed of 1/125 or again increase the ISO to 800. Each one is linked.
 
You know that increasing the ISO will make the sensor more sensitive, well if you have taken a picture that is correctly exposed and then you take the same picture again but this time increase the ISO, it will be over exposed...ie too much light ...the way you can adjust this is to either make the aperture smaller ( larger f number) or reduce the time that the shutter is open (faster shutter speed). Either one will work but each will have a different overall effect.

Increasing the shutter speed will affect the cameras ability to freeze the action/reduce the effects ofcamera shake.

Increasing the f number will increase the death of field (DoF) ie it will widen the distance in front of and behind the subject that is in focus.

Sorry if this was teaching you to suck eggs.
 
Again thanks guys, only been using a dSLR for a week, but due to the weather only had it out twice, so nerding up until i can get out again hammer my batteries and cards and learn 'on the job' but you have all help a great amount.

Gad-westy, your situation was perfect with the moving cars as i plan on using the camera at anglesey raceway in Feb for a drift car event with some mates. But also i want to use it for friends and family for some portrait stuff. My main interest though is macro/cars so both are static so i have more time to play with settings and take as many shots as i need without the worry of the subject moving.
 
Daz9681 said:
I just don't get it, i read some stuff about it but it's just not sinking in, maybe i'm not understanding it properly, does ISO effect shutter speed or apature. I know it changes how sensitive the sensor becomes, but i dont get when to change it or what setting to use.
Click to expand...


It's all covered in here.

http://www.talkphotography.co.uk/forums/showthread.php?t=440126

Post up any questions in here after reading it. There are loads of people on here who are willing to help, but there's nothing better than reading up on a subject and hearing teh penny drop. I used to love those eureka moments :)
 
ISO - the volume of your bucket
Aperture - how much you can open the tap/how much water can come at once
Shutter - how long you leave the tap running for


Your tap is limited by how much it can be open, but you can turn it down for creative effect - you may want to turn it down because when fully open it's not as steady a pour as when closed down a bit.

Sometimes you can only use the tap for a limited time or you might want to have it on for longer so you can also have a chat to your neighbour whilst waiting.

Some people use their bucket size creatively, most go for the biggest bucket they can given their tap and time constraints
 
It's ISO that makes me feel sorry for new photographers with digital.

When I was learning I went to the shop and bought film, 100 ISO was what they had most of, so it's what I used. When there wasn't enough light for that I used flash.

Then I discovered I could shoot more in the winter with 400 or 800 ISO film, but I only used it when I had to, because the grain ruined my pictures:(.

Of course eventually I used all kinds of speeds, but I was steeped in the principle that ISO was fixed and I chose it to suit the shooting conditions:thumbs:.

Nowadays, with the great ISO handling of modern cameras I can see why people think of it as 'just a variable we get to choose', but often it leads to confusion about what it's for and some people just bitch and moan that their 3200 ISO shots aren't as clean as their 400ISO ones :gag:
 
Phil V said:
It's ISO that makes me feel sorry for new photographers with digital.

When I was learning I went to the shop and bought film, 100 ISO was what they had most of, so it's what I used. When there wasn't enough light for that I used flash.

Then I discovered I could shoot more in the winter with 400 or 800 ISO film, but I only used it when I had to, because the grain ruined my pictures:(.

Of course eventually I used all kinds of speeds, but I was steeped in the principle that ISO was fixed and I chose it to suit the shooting conditions:thumbs:.

Nowadays, with the great ISO handling of modern cameras I can see why people think of it as 'just a variable we get to choose', but often it leads to confusion about what it's for and some people just bitch and moan that their 3200 ISO shots aren't as clean as their 400ISO ones :gag:
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Indeed. I'm shooting more and more film now and I'm a bit lost without my iso button. Shot a 135mm shot at 1/30 at the weekend. I know it's going to be crap but I wanted the shot and din't have any other options as I stuck with my 125 film! I'm getting some 400 next time round :)

I suppose things aren't so different in some regards though. I think when anybody approaches a scene ISO is still the last thing on your mind. It's a tool rather than a creative option. Aperture and shutter speed are your creative variables, ISO is just adjusted to the minimum value that will allow you to use the aperture and shutter that you want.
 
gad-westy said:
Indeed. I'm shooting more and more film now and I'm a bit lost without my iso button. Shot a 135mm shot at 1/30 at the weekend. I know it's going to be crap but I wanted the shot and din't have any other options as I stuck with my 125 film! I'm getting some 400 next time round :)

I suppose things aren't so different in some regards though. I think when anybody approaches a scene ISO is still the last thing on your mind. It's a tool rather than a creative option. Aperture and shutter speed are your creative variables, ISO is just adjusted to the minimum value that will allow you to use the aperture and shutter that you want.
Click to expand...

But that is different, when you shoot film it's the first consideration, usually without much thought!
 
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