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Old Mar 3, 2006, 7:28 AM   #1
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Everyone I see posting wishlists for new CanonSLRs always ask for a greater number (eg 6400). I would like to see theoppisite, a really low number, like 25 even lower maybe.

The reason why is to use low ISO values to simulate ND filters in bright light. Is this a difficult thing to put into cameras?
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Old Mar 3, 2006, 9:29 AM   #2
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I'd like to think that it wouldn't be... but I don't know. You're just reducing the sensitivity of the sensor.

This is the best reason I've heard for doing it, though. I've read of people wanting it for less noise, but there is so little at 100ISO that that doesn't seem like a good reason to me. But not having to carry an ND filter makes perfect sense.

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Old Mar 6, 2006, 8:28 PM   #3
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I believe the 5D already does this to achieve 50ISO.
Technically I doubt this is easy at all. These chips have been designed over a few generations to grab as much light as they can get. Raising ISO is simply a matter of boosting the signal they get which is also where the noise is generated, but lowering ISO would require either including a way to screen out some light or redesigning the receptors so that they can become less efficient. The other solution would be to have a lower ISO level as the chip's base performance level but I suspect that this would involve a lot of development for effectively no image quality improvement for virtually all users as 100ISO is virtually noise free. I bet the solution Canon has used in the 5D is a bit of a hash-up that gives the appearance of 50ISO without a lot of the benefit. This could be done perhaps by manipulating the data of a 100ISO shot to look underexposed rather than by actually having a longer, less sensitive exposure.
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Old Mar 7, 2006, 12:12 AM   #4
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I was just thinking, for landscape photographers, how often does any ISO value over 400 ever get used. It would be awesome in the future if a camera came out with an ISO range from 25 to 800. Imagine alsohaving the abilityto split the sensitivity of the chip to simulate agraduated ND filter(this is really just dreaming now)

Maybe in the future, we are going to see bodies specifically designed for a certain type of shooting (landscape, sports, portrait, ect.) What do you think?
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Old Mar 7, 2006, 10:29 AM   #5
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Certainly, in the age of film, ISO 800 would not produce the clean detail that a landscape photographer typically wanted, so it would not be used. Landscape photography frequently calls for a high depth of field to capture both near and far detail. This requires a small aperture which, in turn, results in a slow shutter speed. If a landscape photographer can successfully use a high ISO setting when they need a wide depth of field, they reduce the risk of wind-induced motion blur in foliage. A low ISO number is only desirable for such pictures to the extent that it reduces visible noise.

Beyond reducing noise, a low ISO number is usually needed only in cases where you want both a shallow depth of field and a slow shutter speed. For example, when you want to capture some motion blur while bluring a stationary background.

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Old Mar 8, 2006, 12:10 AM   #6
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I agree with what you had to say Ken, but most people doing landscape photography would be using a tripod, so essentially shutterspeed is irrelevant unless it comes to shooting in really low light. Even though Canon chips produce useable pictures at ISO800, the quality of the capture cannot really be compared to ISO100. Even with todays noise reduction software, there is still a significant loss of detail.

There are often times when I'm shooting waterfalls or coastal scenery when I've wished I could get a slower shutter speed, possible with ISO25.
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