ISO advice

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kopite

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Mark
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Hey guys,

After my recent Visit to Blackpool Zoo I have been advised that I need to change the ISO I`m using.

I had gotten myself into mindset that I should be using iso100 for everything as there would be noise in photos other wise.

I realise this is the wrong way of thinking but Its ingrained in me.

are there any rules for ISO or a guide to how to get the most using higher ISO values.

In a situation like the zoo where I was advised i should be trying to freeze the animals So Shutter speed is more important should I be setting the ISO first or the shutter ?
 
The rule of thumb is to shoot at as low an ISO as you can, unless you specifically want to add noise / grain for effect.

I would advise increasing your ISO to give you the shutter speed you need to get the shot right. Certainly if you are trying to freeze the animals in your shot then you will need a high shutter speed and consequently, unless you have very good light, a higher ISO. You are right that the higher the ISO the more noise you will introduce but it is a trade off between that and shutter speed. Better to get the shot with a bit of noise than no shot at all :)

Edit: Most modern DSLR's can cope with moderately high ISO surprisingly well nowadays :)
 
You could experiment with using auto iso and see how you get on, rather than trying to guess at the correct setting,until you get more of a feel for the camera.
 
It really depends on light levels and the shutter speed your after. I'm sure a more experianced member will come along and explain better than I can so Ill just give you this link to save confusing you.

Have a play with that link, it helps you understand the relationships between iso, f stop and shutter speeds.

Edit, I see two members got there before me, still worth trying the link above though!
 
Also, the book understanding exposure could help you out.....
 
I set iso first then see if it works for me. Depending on your camera I would say an overcast day at the zoo could require an iso of around 400.

If I were you I would see how slow you could go with 100 iso. Obviously if you cant use a fast enough shutter to freeze the movement I would step it up to maybe 200 or 400 like I say.

Each time you increase the iso you should be able to use a faster shutter. Its all relative too. For example If you took a picture at 100 iso and a shutter speed of 1/30th of a second you would get the same exposure as a shot at 200 iso, shutter speed of 1/60th. 400iso would be 125th and so on.....


The only difference would be noise, and movement in the picture.

HTH
Corrected
 
So long as you get the exposure spot on then noise is less of a problem. if you underexpose then noise is a big problem... A lot of people over expose slightly if they know there will be noise.. but to be honest thats on quite high iso.

Also dont judge your picture by looking at it 100% on your computer screen.. there arn't many cameras that can survive that sort of quality control :)
 
Mike V said:
For example If you took a picture at 100 iso and a shutter speed of 1/30th of a second you would get the same exposure as a shot at 200 iso, shutter speed of 1/15th. 400iso would be 1/8th and so on.....
Click to expand...

Arnt you going totally the wrong way with that?
 
Mike V said:
Each time you increase the iso you should be able to use a faster shutter. Its all relative too. For example If you took a picture at 100 iso and a shutter speed of 1/30th of a second you would get the same exposure as a shot at 200 iso, shutter speed of 1/15th. 400iso would be 1/8th and so on.....
Click to expand...


Err I think that's the wrong way round :shrug: The higher the ISO the faster the shutter speed :)
 
Mike V said:
For example If you took a picture at 100 iso and a shutter speed of 1/30th of a second you would get the same exposure as a shot at 200 iso, shutter speed of 1/15th. 400iso would be 1/8th and so on.....
Click to expand...

KIPAX said:
Arnt you going totally the wrong way with that?
Click to expand...

Was thinking exactly the same. :thinking:
 
KIPAX said:
Arnt you going totally the wrong way with that?
Click to expand...
I agree.

Here is how I would do it.

I generally know what aperture I want to shoot at for beasts large & small - so I put myself in AV mode. The shutter speed required is mainly to stop camera shake and also th freeze movement if the animals are quite active. Zoo beasts are generally not overly active so I can go for a shutter speed as low as 1/30th but I'd rather not. I'd rather be 1/125th if on a monopod @ 300mm or 1/500 if handheld (OK i can do lower, talking ideal world here).
So in AV mode I have set my aperture, and I see the shutter speed is 1/125 @ ISO 100.
Since I want 1/500 (2 more stops) due to me handholding then I up the ISO to 400. The noise does not go up much and my image is definitly sharp.

Do some tests in good light, find the highest ISO where the noise is acceptable and don't go above it. A noisey shot is better than a blurry shot.
 
Isn't the native iso of most dslr's 200? i thought using the lo settings didn't improve the noise handling just had the effect of requiring a longer exposure
 
cannockwolf said:
Isn't the native iso of most dslr's 200? i thought using the lo settings didn't improve the noise handling just had the effect of requiring a longer exposure
Click to expand...

It's 100 on Canon's and lo is 50 :D

:canon:
 
ahh ok
 
:lol: :thumbs:
 
Not familiar with the Sony A200 but certainly, as long as the exposure was correct, then you can easily get away with 800 ISO on a 50D
 
As KIPAX mentioned earlier, the key to shooting at higher ISO is to not under expose the shot :)
 
The native ISO on the Sony is very likely to be close to 200 as it has a CCD sensor and not CMOS. With this in mind, there's little or no benefit noisewise by dropping to 100. The signal to noise ratio will be pretty much identical but you're sacrificing a some dynamic range with the drop.
Going the other way and increasing the ISO will increase the noise relative to the output from the sensor and noise starts to show. The base output from the sensor is not a variable and the amplification is applied after the photo-sensor's output has been converted to an analogue voltage...hence the noise increase.

Bob
 
you need to ask a sony user as i could get away with up to 4000 and if it got desperate 6400, but like has been said dont underexpose the shot as the noise really kicks in
 
As a general rule, ISO choice is similar to offroading - as slow as possible and as fast as necessary.

How fast am I happy using? Well, it depends on the shot and the final use. Up to 1600 with very few reservations and even faster if a smaller print will do (or for web use) but there again, I'm using a D700 :happydance: which handles high ISOs rather well!!! On the D70 and D200, 800 was pretty much as fast as was useable without some noise reduction work.
 
Nod said:
As a general rule, ISO choice is similar to offroading - as slow as possible and as fast as necessary.
Click to expand...

Great analogy :thumbs:
 
You could always use a good filter program if the shots are too grainy. maybe some thing like noiseware standard edition, should you not have one already.
 
Thanks for all the advice guys.

As a bit of a summary then.

with the A200 camera iso100 is a bit redundant as the sensor works best at 200.

Shutter should be the priority as much as possible when taking pictures to freeze action and increase the ISO accordingly.

ISO up to 1600 should be ok on pics especially if they are going to be used for web or small prints.

And ISO is like offroading :D

I feel a bit more confident now about this and more comfortable with changing the ISO to get the best Picture possible
 
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