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Old Jun 22, 2005, 12:13 AM   #1
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Hi,

I have a general question: Why do different digital cameras have different lowest ISO settings. I cant see why cameras cant go as low as they want, why not ISO 25. If you could actually do this then the images would be soooo smooth.
As I see it the ISO setting is just a set point where the camera decides a set number of photons hitting the sensor (and hence activating the sensor) is actual signal and not noise. So if this is true why cant you set the sensor to be even less sensitive to light? I know this would require longer exposure times but on nice sunny days it wouldn't be an issue.

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Treemonkey
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Old Jun 22, 2005, 1:10 AM   #2
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Treemonkey wrote:
I think it comes back to speed the higher ISO is an advantage to the shooter, with the in camera proccessing the FZ20 @ ISO80 is as good as the FZ10 @ ISO50
Pana made a choice and I think the lower the ISO beyond a certain lower point gives no improvement, the sensors are very small.

Quote:
Hi,

I have a general question: Why do different digital cameras have different lowest ISO settings. I cant see why cameras cant go as low as they want, why not ISO 25. If you could actually do this then the images would be soooo smooth.
As I see it the ISO setting is just a set point where the camera decides a set number of photons hitting the sensor (and hence activating the sensor) is actual signal and not noise. So if this is true why cant you set the sensor to be even less sensitive to light? I know this would require longer exposure times but on nice sunny days it wouldn't be an issue.

Cheers

Treemonkey
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Old Jun 22, 2005, 6:27 PM   #3
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I can understand your point boyzo but then why does the Nikon D70 only have iso 100 and the canon 350 have iso 50? I have seen many people complain about the Nikons images not being as smooth as the canons because of the iso difference. To me one of the major issues of the FZ line is the lack of a long exposure mode (8 sec is pretty short) and surely having a lower iso setting would be a way of getting around the noise issue at longer exposure times?

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Simon
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Old Jun 22, 2005, 6:39 PM   #4
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Treemonkey, Nikon D70 starts from ISO 200.

Probably as low as ISO 50, it would have been impossible to grant the F2,8 larger aperture over the whole zoom range.

I consider that FZ20 has many good points over the other, but each model, from FZ1 to FZ5 also has some better features over FZ20.

Maybe this is the way they improve the products.
Personally I think that many of the FZ20 users will not upgrade to FZ30, because some of the former cam's issues could have been fixed via firmware update, which has never come. This is not a good way to behave with clients. And this is also offtopic....

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Old Jun 22, 2005, 8:14 PM   #5
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Maybe this will help you more than it did me.

http://www.kodak.com/global/plugins/...asurements.pdf
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Old Jun 23, 2005, 9:31 AM   #6
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Good question... Probably it's due to there being little - if any, difference in noise between 50 and 80 ISO. It's kinda like film. There are low speed films out there a few 25 iso and 50 isos... One is tempted to use these films in the daylight because you would reason that they have less grain. But from what I've read, advances in film stock over the years means that ISO 100 films have as fine a grain as the lower 25 and 50 speeds, so you're not really gaining anything.

That said, I think it's different for digicams and DSLRs. They "should" include lower ISOs... not for noise reduction (if it's not an issue from an optical engeering standpoint as Narmer points out) but as an alternate means to control light sensitivity in bright daylight, since it's so easy to blow out highlights.

For example, almost everyone who owns an FZ reduces the EV boy 1-1/3 outdoors in the sun. I use a ND filter. Why not just provide a lower iso setting?
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Old Jun 25, 2005, 4:10 AM   #7
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I have no proof of this..but I have suspected for a while now that when you shove more megapixels onto the same size chip as the previous lower megapixel camera, the individual light sensors are gonna be smaller and absorb less light. As such, a slightly higher ISO may be necessary to make up for that lost light.

Personally, I like the power of choice..and would prefer that they kept the ISO 50 on there...and then just stated the camera would work better at 80. I am a firm believer in trying to go my own way..and if I can get images that are acceptible to ME at iso 50 on an FZ20..then thats my choice.

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Old Jun 30, 2005, 6:32 PM   #8
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Treemonkey wrote:
Quote:
Hi,

I have a general question: Why do different digital cameras have different lowest ISO settings. I cant see why cameras cant go as low as they want, why not ISO 25. If you could actually do this then the images would be soooo smooth.
As I see it the ISO setting is just a set point where the camera decides a set number of photons hitting the sensor (and hence activating the sensor) is actual signal and not noise. So if this is true why cant you set the sensor to be even less sensitive to light? I know this would require longer exposure times but on nice sunny days it wouldn't be an issue.

Cheers

Treemonkey
Extract from www.luminous-landcape.com

link http://www.luminous-landscape.com/es...odak-iss.shtml

Base ISO [align=left]Everyone knows that digital cameras have a "base level ISO" setting, the lowest sensitivity setting, at which noise is also lowest. But what we've seen is that sometimes different cameras which use the same chip have different base level ratings. Sometimes 50, 64 or 100. Why is this?[/align] [align=left]The answer partially lies in the fact that sensor makers like Kodak don't publish an ISO spec. Rather, the talk about Quantum Efficiency (QE) . This is a measure of how efficient the chip is in converting photons into electrons. It's then up to the camera maker to apply their own electronics, which often includes both amplification and noise reduction circuitry, to achieve a desired ISO sensitivity.[/align]

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Old Jun 30, 2005, 7:52 PM   #9
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John

Thanks for helping to explain the question that Tree's asked.

Harj


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Old Jun 30, 2005, 9:43 PM   #10
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Thanks boyzo,

That does explain the FZ20/FZ10 difference but I would still like to know why we cant have ISO 10. I guess it is just a feature that not enough people would want.

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Treemonkey
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