What is "Base ISO"?
Jan 25, 2014 06:45:02 #
More than you probably want to know about ISO. The article starts by talking about film but gets down to digital pretty quickly.
http://dpanswers.com/content/tech_iso.php
It boils down to how the apparent sensitivity of the sensor is changed via analog or digital amplification.
The article isn't difficult to follow.
http://dpanswers.com/content/tech_iso.php
It boils down to how the apparent sensitivity of the sensor is changed via analog or digital amplification.
The article isn't difficult to follow.
Jan 25, 2014 07:43:52 #
The base ISO is the native sensitivity of the sensor. In order to achieve a higher ISO the camera will boost the signal but the sensitivity of the sensor is always the same. The point of having ISOs lower than that is when you might want a slower shutter speed possibly for photographing a waterfall or something like that.
Jan 25, 2014 07:48:37 #
Bob Andrews wrote:
Canon believes - as other camera manufacturers believe - that you camera has the "best" quality at base iso. Personally I think he is wrong. Btw someone calling their selves professional doesn't automatically mean is a good photographer. Further reading.
http://www.rawdigger.com/howtouse
http://www.rawdigger.com/howtouse
I would be inclined to think that a professional photographer would be taking photographs, not making videos.
Jan 25, 2014 09:32:15 #
gbh46
Loc: St Ives Cambridge UK
Something not quite right, I live in the UK and I once went on a one day Canon course for the EOS7D and I was told that the base iso for the 7D is 200 iso The trainer said there is no quality advantage in switching to a lower figure...who do you believe?
Jolly Roger wrote:
Yesterday I watched a video tutorial by a professional photographer who explaining that his Canon 7D was set up with ISO 640 for the current shoot.
He went on to explain the 7D has a "Base ISO of 160" so reducing the ISO down to 100 will not improve the image quality. Also he increases his ISO in multiples of 160, hence his setting of 640.
Could anyone explain this "Base ISO" to me. Thanks
He went on to explain the 7D has a "Base ISO of 160" so reducing the ISO down to 100 will not improve the image quality. Also he increases his ISO in multiples of 160, hence his setting of 640.
Could anyone explain this "Base ISO" to me. Thanks
Jan 25, 2014 10:02:13 #
CO wrote:
The base ISO is the native sensitivity of the sensor. In order to achieve a higher ISO the camera will boost the signal but the sensitivity of the sensor is always the same. The point of having ISOs lower than that is when you might want a slower shutter speed possibly for photographing a waterfall or something like that.
:thumbup:
Thank you
Jan 25, 2014 10:06:03 #
Searcher wrote:
The lowest ISO setting to attain the highest image quality (low noise) see http://photographylife.com/what-is-iso-in-photography
Good article covering all you need to know about the trade-offs. There is no mystery, lower ISO = less noise and better quality for that particular camera.
Base ISO is simply the lowest normal ISO setting in the camera. For a D70 it is 200, for a D7000 and many other Nikons it is 100. Some cameras offer extended ranges - not part of the "normal" range.
I have seen other statements regarding ISO that imply that one-third increments are not as accurate as full increments, which is nonsense. The numbers you see are 100, 125, 160, 200, etc., but they actually represent factors of the third root of two, which would be harder to remember: 100, 125.99, 158.74, 200, etc.
The same applies to shutter speeds - 1/8, 1/15, 1/30, 1/60, 1/125. etc., is easier to remember than 1/8, 1/16, 1/32, 1/64, 1/128, etc., unless you are mathematically oriented.
Jan 25, 2014 10:15:24 #
Two questions:
What is base ISO?
What is the base ISO for Canon 7D?
The base ISO is the native ISO of the sensor, and is the first ISO setting after L, (if the camera has it and which is lower than base ISO but with no advantage to image quality - but is nice when doing long exposures). Base ISO yields the best Image Quality. Increasing ISO above base is effectively multiplying the measurement, and hence one sees a reduction of signal to noise and dynamic range of approximately 1 f-stop for each doubling of ISO.
The base ISO for the Canon 7D is ISO 100. (See the graph from DxO Mark.) It shows the effect of increasing the ISO upon the performance.
http://www.dxomark.com/Cameras/Canon/EOS-7D and click on the <Measurements> button and then <SNR 18%>.
What is base ISO?
What is the base ISO for Canon 7D?
The base ISO is the native ISO of the sensor, and is the first ISO setting after L, (if the camera has it and which is lower than base ISO but with no advantage to image quality - but is nice when doing long exposures). Base ISO yields the best Image Quality. Increasing ISO above base is effectively multiplying the measurement, and hence one sees a reduction of signal to noise and dynamic range of approximately 1 f-stop for each doubling of ISO.
The base ISO for the Canon 7D is ISO 100. (See the graph from DxO Mark.) It shows the effect of increasing the ISO upon the performance.
http://www.dxomark.com/Cameras/Canon/EOS-7D and click on the <Measurements> button and then <SNR 18%>.
Jan 25, 2014 10:49:40 #
Jan 25, 2014 11:02:22 #
Searcher wrote:
The lowest ISO setting to attain the highest image quality (low noise) see http://photographylife.com/what-is-iso-in-photography
Some cameras have a reduced ISO that does not represent an improvement in picture quality. It allows larger aperture or slower shutter speed.
Jan 25, 2014 12:24:45 #
Jolly Roger wrote:
Yesterday I watched a video tutorial by a professional photographer who explaining that his Canon 7D was set up with ISO 640 for the current shoot.
He went on to explain the 7D has a "Base ISO of 160" so reducing the ISO down to 100 will not improve the image quality. Also he increases his ISO in multiples of 160, hence his setting of 640.
Could anyone explain this "Base ISO" to me. Thanks
He went on to explain the 7D has a "Base ISO of 160" so reducing the ISO down to 100 will not improve the image quality. Also he increases his ISO in multiples of 160, hence his setting of 640.
Could anyone explain this "Base ISO" to me. Thanks
Lots of interesting answers. Searcher is right about "The lowest ISO setting to attain the highest image quality (low noise)". You can't depend on the camera manufactures to tell you the truth. Read noise is measurable. To see why your tutorial said to use iso 160 go to http://home.comcast.net/~NikonD70/Charts/RN_ADU.htm . Select the 7d from the camera choices on the right. You will see that iso 160 has the lowest read noise.
Jan 25, 2014 13:14:10 #
Jolly Roger wrote:
Yesterday I watched a video tutorial by a professional photographer who explaining that his Canon 7D was set up with ISO 640 for the current shoot.
He went on to explain the 7D has a "Base ISO of 160" so reducing the ISO down to 100 will not improve the image quality. Also he increases his ISO in multiples of 160, hence his setting of 640.
Could anyone explain this "Base ISO" to me. Thanks
He went on to explain the 7D has a "Base ISO of 160" so reducing the ISO down to 100 will not improve the image quality. Also he increases his ISO in multiples of 160, hence his setting of 640.
Could anyone explain this "Base ISO" to me. Thanks
Your question has generated some really good info here. Psergel showed a link that was really informative and will change the way I do some shots in the future. For long exposures I usually set the camera at it's lowest setting by going below the native ISO setting. The article indicates this can cause loss of dynamic range. For longer exposures in the future I will use Neutral Density filters.
Jan 25, 2014 13:46:38 #
Jolly Roger wrote:
Yesterday I watched a video tutorial by a professional photographer who explaining that his Canon 7D was set up with ISO 640 for the current shoot.
He went on to explain the 7D has a "Base ISO of 160" so reducing the ISO down to 100 will not improve the image quality. Also he increases his ISO in multiples of 160, hence his setting of 640.
Could anyone explain this "Base ISO" to me. Thanks
He went on to explain the 7D has a "Base ISO of 160" so reducing the ISO down to 100 will not improve the image quality. Also he increases his ISO in multiples of 160, hence his setting of 640.
Could anyone explain this "Base ISO" to me. Thanks
That is also true of the Canon 5D MK II which I own.
Jan 25, 2014 15:49:29 #
sirlensalot
Loc: Arizona
Pentax recommended a 200 as the "default" ISO, but had options to reduce below and above the recommended settings.
You may be asking "what were they thinking"?
Probably best to ask the manufacturers for their logic and rationale for any particular setting?
You may be asking "what were they thinking"?
Probably best to ask the manufacturers for their logic and rationale for any particular setting?
Jan 26, 2014 04:11:48 #
Thanks everyone for your inputs.
Unfortunately going through the replies it seems we now have three figures for the 7D Base ISO: 100, 160 & 200.
I will be going through the various links provided. I hope it doesn't scramble my brain too much. :roll:
Unfortunately going through the replies it seems we now have three figures for the 7D Base ISO: 100, 160 & 200.
I will be going through the various links provided. I hope it doesn't scramble my brain too much. :roll:
Jan 26, 2014 06:35:14 #
JR, I don't think your original question has really been answered and the article links given only serve to muddy the waters by talking about different ISOs changing the sensitivity.
The truth is that any camera Sensor has only one sensitivity which is determined by the technology at the time of manufacture and comes down to (Q)uantum (E)fficiency. QE is the efficiency with which the Sensor is able to convert photons into electrical energy and in the case of the 7D it stands at 41% meaning that 59% of the photons fail to register. The Nikon D7100 does better with a QE of 52% and the latest Sony Sensors are better still although I have no figures for the A7r as yet.
Going above BaseISO on a digital camera only serves to increase the analogue gain of the signal from the Sensor which necessarily means that noise is amplified as well as useful signal. Given that the DR of the 7D maxes out at iso200, I would guess that is the BaseISO of the camera; iso100 shows the same DR so is probably an extended ISO.
The truth is that any camera Sensor has only one sensitivity which is determined by the technology at the time of manufacture and comes down to (Q)uantum (E)fficiency. QE is the efficiency with which the Sensor is able to convert photons into electrical energy and in the case of the 7D it stands at 41% meaning that 59% of the photons fail to register. The Nikon D7100 does better with a QE of 52% and the latest Sony Sensors are better still although I have no figures for the A7r as yet.
Going above BaseISO on a digital camera only serves to increase the analogue gain of the signal from the Sensor which necessarily means that noise is amplified as well as useful signal. Given that the DR of the 7D maxes out at iso200, I would guess that is the BaseISO of the camera; iso100 shows the same DR so is probably an extended ISO.
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