# I S O Experiment



## pg tips (May 16, 2003)

I think Stanley is a very clever chappy. I didn't think the ISO rating would have much affect on a digi picture.

Here you can see it clearly does. Both pics adjusted exactly the same the only difference is the ISO setting of the camera. You can see quite clearly the 400 setting is grainier. Tip to be added to my site soon. Thanks Stan.


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## AlexR (May 11, 2003)

Loads better,nice one Paul and Stan


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## Roy (Feb 23, 2003)

Very good Paul, I use ISO 80 on mine but I had no idea what it means.


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## AlexR (May 11, 2003)

International Sausage Orstich,I believe


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## Roy (Feb 23, 2003)

Ah' thanks Alex , I thought it had some hidden meaning.


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## AlexR (May 11, 2003)




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## Silver Hawk (Dec 2, 2003)

Most digital cameras have auto ISO setting.....they will always try and use the lowest possible ISO setting giving maximium quality.

But when lighting conditions get poor, they will raise the ISO speed automaitcally if flash etc is not able to provide adequate light.

Of course, you can often manually set the ISO speed allowing you full control. The effects of ISO speed on digital images are really very similiar to 35mm silver based film....I only wish my camera would allow me to set it to 1600.

Cheers

Paul

BTW: old-timers sometimes still use ASA instead of ISO


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## pg tips (May 16, 2003)

Stan will know the real meaning!









It's all to do with speed. In the old film cameras the film speed was dead slow (ISO 25 was common) and you needed big apatures and slow shuuter speeds to get decent pictures, hence the tripods and 3 minute exposures when you had to stand still if it was your portrait, (all those Edwardian photo's with glum faces? that's why).

Film manufacturers pushed the boundaries and started making faster film. 15 years ago 100 was common, now 200 is the norm and 400 very often used. It means you can take pictures in low light without the need for a tripod and still get crisp results. I've seen pros use film as fast at 6400!

I didn't think it would make a difference on digital but obviously it does increase the graininess, only really noticable on the close up photography that we do the most often.

Tip is always use the tripod and always set the lowest ISO (or ASA if your camera has the old settings) you can.

Learn something new every day!


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## AlexR (May 11, 2003)

International Organization for Standardization


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## Roy (Feb 23, 2003)

AlexR said:


> International Organization for Standardization


 Now your takin' the piss.


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## AlexR (May 11, 2003)

Its the truth honest


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## AlexR (May 11, 2003)

ISO link


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## Stan (Aug 7, 2003)

Much better PG.









Digital cameras have a CCD that has an optimum sensitivity. Manufacturers have equated this to an ISO value to maintain familiarity for existing photographers, this base sensitivity is often quoted as ISO 80 or 100.

To force the camera to use higher shutter speeds and improve handheld camera use manufacturers increase the gain electronically which many apply faster ISO numbers to.

The increase in gain produces an proportional increase in visible noise that manifests itself as "grain" similar to that seen in faster, emulsion based film.

It's possible on many cameras (like PG's Samsung) to set the "ISO" to its base level to eliminate the noise that an auto ISO adjustment will produce but this will lower shutter speeds and with some handheld shots, induce camera shake.

For our purposes, watch photography, I think a longer shutter speed is acceptable to maintain picture quality. A tripod is mandatory when working in this manner.

A long shutter speed on a digital camera can introduce other "noise" known as hot pixels, white or coloured dots become visible. This is normally only evident at shutter speeds of longer than 1/4 of a second, though hot pixels can become evident at higher speeds if the camera has heated up.

It seems much easier to remove one or two hot pixels than to put up with a grainy image when taking pictures of watches.

At least to me.


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## Bjorn (Jun 10, 2004)

I have to admit that I liked Paul's first picture (the one that started the ISO discussion). I thought it was grainy on purpose.









Bjorn


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## Stan (Aug 7, 2003)

I used to take landscapes on black and white infrared film through a diffusion filter.









Same thing using T-Max 3200.









Sad old git.


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## Silver Hawk (Dec 2, 2003)

pg tips said:


> I've seen pros use film as fast at 6400!


 I was no pro

...but I do remember pushing Ilford HP5 and Kodak Tri-X to 32000...

...and with not bad results...but those were girldfriend-less days when I could spend hours each night in the dark room....


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## Stan (Aug 7, 2003)

Paul,

It beats sitting on your arse in front of a computer.


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## pg tips (May 16, 2003)

Bjorn said:


> I thought it was grainy on purpose.


 Bugger why didn't I think of that! Ignor everything, I'll just go and edit the first post to read "how do you like my grainy effect technique using the ISO setting on my camera?"


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## Bjorn (Jun 10, 2004)

pg tips said:


> Bjorn said:
> 
> 
> > I thought it was grainy on purpose.
> ...


Or you could claim that you were trying to prevent us from thieving your special technique by deliberately misleading us.


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## Stan (Aug 7, 2003)

pg tips said:


> Bjorn said:
> 
> 
> > I thought it was grainy on purpose.
> ...


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