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11-07-2014, 08:58 AM   #1
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Iso 80

I hear folks bemoaning the lack of ISO 80 on the K3.

Do you really notice a difference in image quality over ISO 100?

Thanks

11-07-2014, 09:07 AM   #2
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No, but you are talking different sensors completely. I would think there are many factors involved so that isolating the small ISO difference would be difficult.

I do miss ISO 80 though, it just allowed a little more flexibility in some situations. I would love to have ISO 64 on a digital camera.
11-07-2014, 09:30 AM   #3
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How about between ISO 80 and 100 on the K5 itself, so the only real variable is the ISO selection?
11-07-2014, 11:21 AM   #4
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Iso 80 is also useful for strobe shooters. It makes up for the 1/ 180 sync speed

11-07-2014, 01:21 PM   #5
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I have the K5IIs with ISO80 available, so far I didn't really notice any practical difference as compared to ISO100, did not tested though. I don't even know how ISO80 works, is it real or just a some marketing trick?
11-07-2014, 02:19 PM   #6
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Iso 50
11-07-2014, 02:32 PM   #7
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The way I understand it, ISO100 is the basic iso of the camera, meaning the digital noise of the camera itself when it's turned on. Increasing ISO more than 100 scales up the signal (also scaling up the noise in the process). If ISO100 is the base iso, how is ISO80 achieved then? scaling down maybe?
11-07-2014, 06:06 PM   #8
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ISO

QuoteOriginally posted by Hattifnatt Quote
The way I understand it, ISO100 is the basic iso of the camera, meaning the digital noise of the camera itself when it's turned on. Increasing ISO more than 100 scales up the signal (also scaling up the noise in the process). If ISO100 is the base iso, how is ISO80 achieved then? scaling down maybe?

ISO used to be film speed ! ( sensitivity to light )
The higher the ISO the more sensitive the film was to light allowing for higher shutter speed , thus called faster film ..


So when we got digital , they had to call the sensors sensitivity to light something , so they gave us something familiar ( ISO )
Now whether Digital ISO 100 matches the film speed ISO 100 ???????????????


But , being digital and all , there is no reason they could not have gone , ISO 127 or ISO 96 or what ever .. But why confuse people ... SO we have 100 200 400 800 and so forth ...
But I see no reason , they could not do 100 150 200 300 400 600 800 1200 1600 or something custom defined by the user ...
Say you have a really bright day , like today , having an ISO 50 would be quite useful ... Especially if you are shooting aerial . ( Balloons / Aircraft ) , even an ISO 25 might not go astray ...


As for noise .. All that sensitivity has side effects ...
The higher quality cameras can handle more ISO ( also newer cameras ) .. You will find early digital SLR's such as the istD got noisy very quickly ... ( also because of the lower pixel count which contributed greatly )
ISO is not about noise , that's a side effect of sensitivity to light ..

11-07-2014, 11:50 PM   #9
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I have no idea how film ISO works, I was only talking about digital ISO, which in signal processing is basically a scaling up.
11-08-2014, 04:09 AM - 1 Like   #10
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QuoteOriginally posted by Hattifnatt Quote
The way I understand it, ISO100 is the basic iso of the camera, meaning the digital noise of the camera itself when it's turned on. Increasing ISO more than 100 scales up the signal (also scaling up the noise in the process). If ISO100 is the base iso, how is ISO80 achieved then? scaling down maybe?
DXO Mark measures the base iso of different sensors and they measure the base iso of the K5/K5 II to be between 75 and 80, while the base iso of the K3 is 100. Having a lower base iso hopefully will give you a little more dynamic range and allow for faster aperture shooting in bright sunlight (without ND filters).
11-08-2014, 06:38 AM   #11
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QuoteOriginally posted by y0chang Quote
Iso 80 is also useful for strobe shooters. It makes up for the 1/ 180 sync speed
Thanks for pointing this out. I have used ISO 80 on K5 and k5iis but have not seen any clear difference but sync speed does make sense. I rarely use flash.
11-08-2014, 08:35 AM   #12
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On a k5, from an IQ standpoint alone you won't see much of a difference between iso80 and iso100 unless you're really critical or severely punishing your image in PP. Nor would you see a big difference between iso100 and iso125 for that matter. Everything is so darn clean and the dynamic range is already so high that the differences in 1/3 stops is pretty small to my eyes at least.

In terms of exposure, the extra low iso is handy enough outside in bright light (flash or not) that I'd complain bitterly if someone tried to take it away from me. If it never went down to iso 80 in the first place, I'd probably be blissfully happy with iso100.
11-08-2014, 05:29 PM   #13
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I use to make photographs of archaeological sites. Whenever possible i use the ISO 80 because I have the impression that it gives me more dynamic range than ISO 100. In a situation with some parts in the sun ligth and some parts in the shadow, i make sure that the sunny parts are exposed correctly (or only a bit to bright). Later, in post processing, I make the shadows ligther. I have the impression that with ISO 80 that gives a less noisy image than with ISO 100. It's not a huge difference but it is there.
11-11-2014, 10:30 PM   #14
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ISO80 lets you use wide f stops in bright light that you may not be able to use otherwise without underexposing. 1/8000 is pretty fast, but on a bright day at f/1.8, you can hit the limit. ISO80 gives you that extra little bit to keep the shutter speed under the maximum of 1/8000.
11-13-2014, 05:12 AM   #15
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QuoteOriginally posted by Hattifnatt Quote
I have the K5IIs with ISO80 available, so far I didn't really notice any practical difference as compared to ISO100, did not tested though. I don't even know how ISO80 works, is it real or just a some marketing trick?
According to dxomark the improvments in iso 80 compared to iso 100 is very real. Dynaimc range, signal to noise ratio, tonal range and color range are all "much" better in iso 80.

see
Tests and reviews for the camera Pentax K-5 Measurements - DxOMark
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