jitteringjr
Senior Member
I don't have it but I have never found myself craving it either. How many people use it and in what situations. Do you shoot basic or creative modes when you use it?
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Auto ISO. Do you use it.
- Thread starter jitteringjr
- Start date
Hardly ever used it on my 40D & 50D, but I do find it very useful on the 7D when shooting in M mode in changeable conditions. I can pin the aperture and shutter speed, and let the camera square them up with auto iso.
Some say this can lead to more noise (.e.g when the camera picks an "in-between" or "fake" ISO). I've no idea if this is true, but with action shots it doesn't bother me either way.
Some say this can lead to more noise (.e.g when the camera picks an "in-between" or "fake" ISO). I've no idea if this is true, but with action shots it doesn't bother me either way.
No I never had. It may sound odd it it seems like I spent a lot of time learning how to take control of my camera and now I'm giving it back to the camera. There is a thread running on this same topic and it sounds like people like it. Maybe I'll try it.
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The solution is always simple. Getting there is the hard part.
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The solution is always simple. Getting there is the hard part.
Wayndom
Senior Member
I love it, and here's why:
The lower the ISO, the higher the IQ. But when I changed ISO on my XT/350D (which doesn't have auto ISO, and didn't display the ISO in the VF), I would often forget, and miss a shot before realizing the ISO was last night's setting (or whatever).
Auto ISO always selects the lowest possible ISO that doesn't violate the "rule of thumb" that the shutter speed shouldn't be longer than the (35mm equivalent) focal length.
So now, if I'm shooting in low light, the camera increases the ISO, but the next morning, if I shoot in broad daylight, the camera goes back to ISO 100.
I only wish I could select the ISO "floor" (which the new 550D offers), but since I'm sure this can be provided through a firmware update, I'm hoping it will become available soon.
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Loose: the opposite of tight; unrestrained.
Lose: to be defeated; to misplace, to no longer have available.
50D, XT/350D, EF-S 17-55, EF-S 10-22
Equipment Emeritus: First-generation F-1, FD 24 2.8, FD 35 f2, FD 50 1.4, FD 85 1.8
The lower the ISO, the higher the IQ. But when I changed ISO on my XT/350D (which doesn't have auto ISO, and didn't display the ISO in the VF), I would often forget, and miss a shot before realizing the ISO was last night's setting (or whatever).
Auto ISO always selects the lowest possible ISO that doesn't violate the "rule of thumb" that the shutter speed shouldn't be longer than the (35mm equivalent) focal length.
So now, if I'm shooting in low light, the camera increases the ISO, but the next morning, if I shoot in broad daylight, the camera goes back to ISO 100.
I only wish I could select the ISO "floor" (which the new 550D offers), but since I'm sure this can be provided through a firmware update, I'm hoping it will become available soon.
--
Loose: the opposite of tight; unrestrained.
Lose: to be defeated; to misplace, to no longer have available.
50D, XT/350D, EF-S 17-55, EF-S 10-22
Equipment Emeritus: First-generation F-1, FD 24 2.8, FD 35 f2, FD 50 1.4, FD 85 1.8
Wayndom
Senior Member
I've never understood this argument. Unless there's some strange quirk of electronics I'm not aware of, it doesn't make any sense.
An ISO isn't a thing, it's simply a measure of how much light is falling on the sensor, and therefore, how much amplification the camera should apply. There are no fake ISO's, any more than there's a fake speed of your car, or a fake volume setting on your stereo.
--
Loose: the opposite of tight; unrestrained.
Lose: to be defeated; to misplace, to no longer have available.
50D, XT/350D, EF-S 17-55, EF-S 10-22
Equipment Emeritus: First-generation F-1, FD 24 2.8, FD 35 f2, FD 50 1.4, FD 85 1.8
DRG
Veteran Member
There are two different aspects to ISO. One is definitional, related to how long it takes for a given amount of light to fill the well capacity of the sensor.
However, there are also the functional aspects. Here, ISO rears its head in two ways. The first is that it is an input to the metering system, so that the system can correctly recommend shutter and aperture settings for a given ISO setting and metered light level. This aspect is irrelevant when using auto ISO in M mode, as both aperture and shutter speed are pinned by user selection.
Second, the ISO setting is an input to a voltage gain stage that sits between the sensor and the A/D converter. The role of this amplifier is to present the A/D converter with the same signal range even as the exposure is dropped because ISO is increased and talking to the metering system.
At the same time, this amplification boosts the signal from the sensor before it encounters the addition of further noise later in the signal chain, either at the A/D or a pre-amp stage to the A/D. This actually means that for a given absolute level coming off the sensor, the signal to noise ratio improves with increased ISO as long as this ISO is a so-called "real" value that actually changes the amplifier gain. For non-1-series Canon DSLRs, this means only the whole stop values up to the maximum ISO before the H or high range needs to be invoked (which is up to 1600 on the xxD cameras and, I believe, up to 3200 on the 7D).
The important consequence of this for auto ISO in M mode is that, since exposure and thus shot noise are already fixed, you can only work to improve read noise. This means wanting the highest ISO consistent with the required headroom (that is, the highest ISO before highlights that you care about start to clip).
David
M
Mark B.
Guest
I shoot Av most of the time, and prefer to choose the ISO myself.
Mark
Mark
tko
Forum Pro
For indoor sports, street photography, whatever, it's essential, a very basic part of photography, just wish it was even more flexible.
Indoor sports: pick minimum shutter speed to stop action, set lens wide open (you never stop down for indoor sports), let camera select necessary ISO. Nothing else even comes close to making sense.
With auto iso you are basically saying, I know the minimum shutter speed, I know the maximum aperture, let the camera give me the lowest noise image consistent with these two parameters.
If you always have enough light I guess it's not that important. But I've never gotten through a day's worth of photographing shooting ISO 200 . . .
Indoor sports: pick minimum shutter speed to stop action, set lens wide open (you never stop down for indoor sports), let camera select necessary ISO. Nothing else even comes close to making sense.
With auto iso you are basically saying, I know the minimum shutter speed, I know the maximum aperture, let the camera give me the lowest noise image consistent with these two parameters.
If you always have enough light I guess it's not that important. But I've never gotten through a day's worth of photographing shooting ISO 200 . . .
jitteringjr
Senior Member
That's so ironic it's laughable. Litterally while you were typing that, I was in the kitchen shooting shots of my daughter with my 350D using my speedlight with ISO still at 1600 from yesterday.
The mighty Duke Ellington coined it, "I'm beginning to see the light."
Jovo
Senior Member
Never used it on the 40D and 50D, but with the 7D and the 400mm f/5.6L lens I use it all the time. I have C1, C2 and C3 set to auto ISO and Tv.
The reason? I would rather have a bird photo with noise than a photo that is blurred because the shutter speed was too low!
The reason? I would rather have a bird photo with noise than a photo that is blurred because the shutter speed was too low!
jitteringjr
Senior Member
Sure but if you are just worried about blurred birds, you can shoot TV and manually select ISO. It only takes a second to bump ISO if you are AV limited.
Why didn't you shoot with auto ISO with your 40D and 50D?
Was at my nephew's play, where from scene to scene, there could easily be a 4 stop difference. I spent more time changing the iso (anywhere between 320 and 3200,) than I did shooting. There were several scenes that weren't even worth trying to shoot.
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Primary equipment:
30d, EF-S 10-22, 17-55 f/2.8 IS, EF 50 f/1.4, 70-200 f/4.0L IS, EF 70-200 f/2.8L with broken AF, 580EX, and an HP B9180
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Primary equipment:
30d, EF-S 10-22, 17-55 f/2.8 IS, EF 50 f/1.4, 70-200 f/4.0L IS, EF 70-200 f/2.8L with broken AF, 580EX, and an HP B9180
Jovo
Senior Member
When shooting BiF, the lighting can change quickly. Too often it caught me out, when I was focusing on the shot rather than the settings.
Didn't appeal to me with the xxDs.
Didn't appeal to me with the xxDs.
tko
Forum Pro
ISO really has nothing to do with the light falling on the sensor. It's the sensitivity of the sensor to that light. In film that was determined by the, well, film. But a digital sensor only has one sensitivity. The sensitivity is actually increased by electronic gain after the sensor, like turning up the volume on a stereo (the microphone always has the same sensitivity)
Trouble is, there are two ways to increase the gain (amplification.) One is basically analog, that's the good way. The other is digital (bit shifting) which is bad (kind of, but that's what generates the argument). Major steps in ISO are handled by changing the analog gain, minor in-between steps are handled digitally.
When you set auto-ISO it uses both analog and digital methods, hence the controversy. The disadvantages are somewhat minor in my opinion. That is, if the light changes suddenly and the ISO automatically decreases from 1600 to 400 you will always be better off than if you didn't have auto-iso and didn't have time to adjust the ISO.
Of course, if you have all day to tweak the settings you may get better results, but that's true for any camera setting . . .
http://ktophoto.blogspot.com/
http://la-photos.blogspot.com/
Trouble is, there are two ways to increase the gain (amplification.) One is basically analog, that's the good way. The other is digital (bit shifting) which is bad (kind of, but that's what generates the argument). Major steps in ISO are handled by changing the analog gain, minor in-between steps are handled digitally.
When you set auto-ISO it uses both analog and digital methods, hence the controversy. The disadvantages are somewhat minor in my opinion. That is, if the light changes suddenly and the ISO automatically decreases from 1600 to 400 you will always be better off than if you didn't have auto-iso and didn't have time to adjust the ISO.
Of course, if you have all day to tweak the settings you may get better results, but that's true for any camera setting . . .
--I've never understood this argument. Unless there's some strange quirk of electronics I'm not aware of, it doesn't make any sense.
An ISO isn't a thing, it's simply a measure of how much light is falling on the sensor, and therefore, how much amplification the camera should apply. There are no fake ISO's, any more than there's a fake speed of your car, or a fake volume setting on your stereo.
--
Loose: the opposite of tight; unrestrained.
Lose: to be defeated; to misplace, to no longer have available.
50D, XT/350D, EF-S 17-55, EF-S 10-22
Equipment Emeritus: First-generation F-1, FD 24 2.8, FD 35 f2, FD 50 1.4, FD 85 1.8
http://ktophoto.blogspot.com/
http://la-photos.blogspot.com/
I would use autoISO and manual mode all the time but I am missing exposure compensation. It seems that Canon is missing one wheel more.
Now if I use manual optics with aperture ring I have Tv, autoISO with exposure compensation. But the function is like manual mode, autoISO with EV correction.
Now if I use manual optics with aperture ring I have Tv, autoISO with exposure compensation. But the function is like manual mode, autoISO with EV correction.
Yep that would great. That and custom modes that don't forget changes every time the camera goes to sleep.I would use autoISO and manual mode all the time but I am missing exposure compensation. It seems that Canon is missing one wheel more.
garykohs
Veteran Member
I was shooting a baseball scrimmage under cloudy conditions with variable light. I set Tv at 1/1,000. I was very pleased with the results. When the sun started setting and the lights came on it was pretty dramatic - ISO 1000 in the infield and 3200 in center field. It worked well though!
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Gary
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Gary
KariP
Veteran Member
I can imagine that auto ISO could be great in serious action photography - reporters in warzones or something like that - things you can not ask people to do again. In a place where you really want the photo and some extra noise or lower resolutions means nothing.
Traveling , nature , some macro, landscapes etc are my basic subjects - auto ISO could ruin my shots ! I want to know exactly what the image quality will be.
http://web.me.com/karipenkkila/Minun_kuvani/World_seen_%28home%29.html
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Kari
SLR photography started in 1968, 40D since 2007
60.21 N 24.86 E
Traveling , nature , some macro, landscapes etc are my basic subjects - auto ISO could ruin my shots ! I want to know exactly what the image quality will be.
http://web.me.com/karipenkkila/Minun_kuvani/World_seen_%28home%29.html
--
Kari
SLR photography started in 1968, 40D since 2007
60.21 N 24.86 E
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