ISO What's this ?

[Eifion Williams]

ISO stands for International Organisation for Standardization.

This is a standard for film speed in film cameras, or Sensitivity to light in digital cameras.

The lower the number ,the less sensitive to light either the film or chip ( in digital ) is,ie iso 100, the higher the iso number the more sensitive it will be.

If you use a high iso number you will get what is called noise ( grain in film ), the lower the number you will have little or no noise. Generally we use the lowest speed possible.

When you double the iso number ( 100 up to 200 ) you only need half the amount of light to get a photograph of the same exposure, and so on, 200 to 400 and up.

Many high end cameras now have the ability to shoot at quite high speeds , without the noise levels associated with older or cheaper cameras.

[Andy Sharp]

Hi I have a Canon 550D and it is capable of shooting up to ISO 6400 and is supposed to have noise suppression built in.

However I am finding that if I take shots at anything above ISO 800 the noise is terrible. Has anyone got any ideas for reducing this noise......apart from, buy a better camera!:please:

[Paul Smith]

you can try noise reduction software in post processing. lightroom 3 is pretty good or you could try something like noise ninja. just be careful not to overdo it and end up throwing all the detail out.

trouble is grain looked quite nice and atmospheric where as noise is just horrible, still the modern cameras are way better than even a few years ago, we're just getting a lot more sensitive to it.

[Andy Sharp]

Thanks Paul,

I will try that if what I have just found doesn't work.

In the menus the 8th one from the left has at the top some custom functions 12 to set.

2 allows me to set the ISO to (H) 12,800. (May be silly but if the noise reduction works it could help with night time hand held stuff.)

4 sets noise reduction for long exposure, it was on 0 for off, 1 is for Auto and 2 is for on.

5 sets noise reduction for high ISO values 0 is standard 1 is low and 2 is strong 3 disables the function, it was on 0.

I still cant work out how to set an ISO of 320 or 250, 1/3 stops between 400 and 200 anyone have any ideas? on this. I think the menus are similar to the 7D with a few bits missing. :please:

I have just upgraded the firmware to version 1.0.8 from 1.0.6, just to stay up to date, no extra ISO functions though.

[Eifion Williams]

Hi Andy,

I have as you know Nikon cameras and can just dial in the ISO, even the in between settings like 250 or 320, I would have thought that you could be able to do the same.

I will look into this.

Do any Canon owners have experience of this to help Andy ?

[Paul Smith]

Don't think you can pick intermediate ISO values, it's full stops only as far as I know on the 550.

The 12,800 ISO figure is done be digitally amplifying the sensor and generally gives poor results. It's the same sort of fudge that allows manufacturers to claim 800% digital zoom!!! when they take a tiny art of the sensor and stretch it.

[Andy Sharp]

Thanks Paul. I will make sure that I don't try it out on anything important, can't see me needing 12800 anyway. Just one thing though, I know that Digital zooms are pretty variable in quality (usually poor) but isn't the sensitivity of the cameras sensor changed by a form of digital amplification any way. It would seem that where digital zooms crop the amount of the sensor in use in order to magnify you loose quality due to the fewer PPI in your image, but I can't see a similar situation with sensitivity boosts, I mean I still have 18 million dots per frame or is there likely to be more variance in the sensitvity of each pixel due to the amplification having less control at this level?

Must try it out now, well after this week anyway, got lots of stuff to get in and Going to Deeside Leisure Bommy on Friday with the kids. Trying to get some shots of Fireworks....ISO 100 long shutter speed and a bit of Black card? Well I will try that first anyway.:thumbsup:

[Paul Smith]

I'm no electrical engineer but from what I understand there are native ISO's (the full stop versions 100,200,400) and emulated ISO's (250,320,12800 etc) the native ones are output of the sensor set to a certain analogue amplification, the emulated ones are using digital amplification on top of this.

Tbh I'd be amazed if you could actually tell by looking at two images taken at 100 and 125 so wouldn't worry about it. Apparently the 550 will do the intermediate ISO's if in auto ISO mode, not mush use to you but interesting to know.

[Andy Sharp]

Thanks Paul, that makes sense. I had a feeling that partial stop ISOs were used in Auto mode. As you say it's not much use but interesting to know.

[Andy Sharp]

A good night for trying stuff out tonight. Firstly High ISO as we went out to a Firework display, it was very dark out, low light from the spot lights so I ventured into using ISO 12800 and yes as Paul suggested it was pretty poor on close view. I actually managed to over expose a shot too. It looked pretty good on the camera screen though.

Eif gave me a bit of instruction on how I should take shots of Fireworks, I got a few good ones too, Bulb mode ISO100 after the first shot at 30s, I noticed that it took about twice the exposure time again to write the info to my memory card, during which time I couldn't shoot again. I should have taken a faster memory card I think, but also resetting some of those custom settings may have had something to do with it. I have unset them all again now (have to get some software plug-ins to do it on my computer, post processing), or hope I win the lottery next year to get a 5D mark III?

What do people think, is it more likely slow firmware running the long exposure noise reduction or a result of only having used a grade 4 SDHC card rather than recommended grade 6. (I have three 8GB grade 10s which I should have tried out)

Trouble with the long exposures is I have a few ghostly looking firemen :D . I have posted a picture from tonight on Facebook. Thanks for the tip about the black card Eifion, I should have used it a bit more on my second shot, I opened the shutter for a minute on that one and burned out a lot of the middle of the picture. Love to see some of the shots from Chester tomorrow. I have the kids, so can't make it.

[Paul Smith]

The delay after the first exposure is the noise reduction doing it's thing. It takes a second "black" exposure of the same length of time as the first one. It then removes the noise from the first shot and replaces it with the lack of noise from the second. No way around it I'm afraid other than turning it off in the custom functions (default setting is auto).

[Andy Sharp]

Yes thanks Paul I set it to off. And I shall try to get a plug in, sure one of the guys at college has one.

[Eifion Williams]

Hi Andy,

Since Paul is a Canon user he is probably more familiar with your camera than i am, but i agree with him about the noise reduction taking another exposure over the original, doubling the exposure time.
This can be a pain, but i use this as i think that it is worth the wait giving a better looking image, plus it is something less to do in Photoshop.
You can of course turn it off if you need to shoot images quickly.

Glad you had success with your attempts at Fireworks.