The Role of ISO in Digital Photography?

Hi guys.

 

Hey so I'm trying to get a fix on ISO. With film, ISO relates to film "speed", yes? Slower film (far as I know and I may be wrong) results in finer grained images, yes? Slower speed film needs more light, higher film speeds need or require less light? (please correct me if I'm wrong)

 

SO what role would ISO play in digital photography? I'm asking because I've been fiddling with my digital Olympus micro four thirds camera, shooting in manual and aperture priority, occasionally trying shutter priority- making some effort to learn as I go. Recently, I was shooting some motorcycle races at night. Not too successfully, I might add- the bikes were moving fast, everything was lit by artificial light and we couldn't get very close in to the action. My 12-40mm lens wasn't really cutting it, but that didn't stop me from trying! ha ha.

 

Along the way tho, I found my camera goes all the way up to about 23,000 ISO! I set it up there and made every effort to also adjust the shutter speed to as fast as I could get- which for some reason, didn't seem to be too fast? Now this OMD EM1 camera is pretty complicated, way over my head but in fiddling with it, I'm getting to know its ins and outs... we had fun watching the races and all but in the end my photos were crap!

 

But in all this I got to wondering how important ISO is in digital photography and why in the world a camera's ISO capabilities would go so high as 23,000? How does digital ISO relate to actual film speeds and stuff? Is or was there ever a film with a super high ISO? If not, why then, these (what seem like) crazy levels of ISO in digital?

 

Thanks!

Tom

FIlm often needed flash because the ISO was low. WIth Higher digital ISO's, you could get away with no flash.

Firstly, I really like the Micro 4/3 cameras, and I'm thinking of moving over to that system. My current system (Sony) is great but the Olympus cameras in particular have features which I really like. And IMO, Micro 4/3 is where the fun is.

 

So, to answer some of your questions, the highest ISO that you can take modern colour negative film is about 6400. Back in the '80s some people were getting 3200 out of Fujicolor Pro 400. And the results were pretty damned good, at least for press use. The highest that you can take b&w negative film is probably a stop higher than that, although I couldn't point to any evidence right now. I'd have to look for it.

 

High ISO is quite useful, and you should take it if you can get it. Having said that... cinematographers are often using neutral density filters on their cameras, and those have a native ISO of about 800. The top of the line digital cinema sensor has a native ISO of... get ready for it... 1600. That's insane!

 

Some digital cameras, such as the Leica SL I think, have dual native ISO. So they can have a native ISO 50, and a native ISO 200, or something like that. So, that takes away some of the need to use NDs.

 

Edit: I forgot to mention that even back in the '50s and '60s, photographers were occasionally able to take 1/2 second exposures handheld (with improvised supports) at f/2 with ISO 160 film. Back then, 400 was considered 'high speed' for negatives. 160 was considered high speed for slides. Search for High Speed Ektachrome. ;-)

Film ISO has a very specific definition based on the density a certain amount of exposure generates. That's overly simplified, but ISO is actually a fixed property of a film(folks will talk of pushing and pulling film, where the former is underexposing and overdeveloping, and the latter the contrary-this changes the contrast but not the ISO sensitivity). In any case, you are correct IN GENERAL that slower film is finer grained. As an overly simplified handwaving explanation, film grains are microscopic silver halide crystals, and if they are physically larger they have more area to gather light and thus be "exposed." At least in B&W film, where a developed image is formed by silver in the film(color film has the silver removed and has what you see are dye clouds), there are "tricks" to change the apparent size of grains for a given sensitivity. A lot of common developers soften the edge of the grains, making them less obvious. Some films use differently shaped "tabular" grains that look smaller for a given sensitivity. In the heyday of film, 400 was probably the most common "fast" film, and it would often fall apart at about an 8x10 or so in 35mm. Fuji made a 1600 speed color film, which AFAIK was the highest ISO rated film commonly/commercially available. I used it a few times, and it was terrible(there are two B&W films on the market as 3200 speed, but their true ISO speed is somewhere in the 800-1000 range, and they just respond well to push processing).

 

All of that is probably more detail than you're asking about, though. Essentially, digital ISO settings try to approximate the sensitivity of a film with the same rating. Digital cameras work by having light sensitive sights(called pixels) on a slab of silicon. Photons hit the sensor, and then are amplified into a measurable signal that the camera processes into an image. The sensitivity of a given digital sensor is increased by increasing the amplifier gain, or in other words by amplifying the signal more. Increasing the gain increases the amount of "random" signal, which in any measurement is called noise. In digital images, "noise" appears as random splotches of different colored pixels. For that reason, increasing the ISO, aside from making the image look less "clean", can decrease color fidelity and also decrease dynamic range. For this reason, it's usually desirable to use the lowest ISO that, for the lighting conditions, will allow you to use the needed aperture and a shutter speed fast enough to stop action.

 

I have two cameras that have "native" ISOs up to 12,800. That will allow a hand-holdable shutter speed with a reasonable aperture even under relatively dark lights. Neither looks GREAT at 12,800, but they work. Nikons(and probably others) also generally have "boosted" ISOs, where basically camera basically intentionally underexposes and then increases the exposure in software. They tend to look pretty bad, but can give some sort of image in conditions that might not be possible. Nikon makes these ranges VERY clear by designating them has "Hi-1", "Hi-2", and so on. The Df goes up to Hi-4, or 4 stops over 12,800(204,800). Things have come a long way-it was considered a wonder that the D2h could do 1600, while the D2x looked hairy over 400 or so.

I think what it comes down to is that over time digital sensors have become better at working well in low light than film ever did. Having said that, there are still very real limitations. Even though manufacturers may advertise their cameras as being capable of super high ISOs, often pictures taken at those ISOs look pretty bad.

 

My digital camera has a few ways of handling ISO. You can force it to use a particular ISO. You can also have it also pick one automatically within a specified range. What ever you choose for the low end of the range will be the default.

 

With the ISO on auto, the way my digital camera seems to behave in Aperture priority mode is that it will try to keep the ISO at the default as long as the shutter speed will be fast enough for hand held shooting.

 

In Shutter priority mode, it will open up the aperture all the way before it raises the ISO higher than the default.

Recently, I was shooting some motorcycle races at night. Not too successfully, I might add- the bikes were moving fast, everything was lit by artificial light and we couldn't get very close in to the action. My 12-40mm lens wasn't really cutting it, but that didn't stop me from trying! ha ha.

 

Along the way tho, I found my camera goes all the way up to about 23,000 ISO! I set it up there and made every effort to also adjust the shutter speed to as fast as I could get- which for some reason, didn't seem to be too fast? Now this OMD EM1 camera is pretty complicated, way over my head but in fiddling with it, I'm getting to know its ins and outs... we had fun watching the races and all but in the end my photos were crap!

<snip>

 

Along the way tho, I found my camera goes all the way up to about 23,000 ISO! I set it up there and made every effort to also adjust the shutter speed to as fast as I could get- which for some reason, didn't seem to be too fast? Now this OMD EM1 camera is pretty complicated, way over my head but in fiddling with it, I'm getting to know its ins and outs... we had fun watching the races and all but in the end my photos were crap!

 

<snip>

 

Don't forget that the aperture at which you shoot, no matter what ISO, also has an effect on shutter speed. For a faster shutter speed, you probably need to use a wider aperture (= smaller number) - but then depth of field can become an issue ! Maybe try experimenting in a more 'controlled' environment, until you are familiar with the camera's controls ? Should only take ten years or so LOL :)

Why ISO 23,000 (or even higher) is needed? Try to emulate those detectives in the movies shooting hand held at night with a long lens.

Hi guys.

 

Hey so I'm trying to get a fix on ISO. With film, ISO relates to film "speed", yes? Slower film (far as I know and I may be wrong) results in finer grained images, yes? Slower speed film needs more light, higher film speeds need or require less light? (please correct me if I'm wrong)

 

SO what role would ISO play in digital photography? I'm asking because I've been fiddling with my digital Olympus micro four thirds camera, shooting in manual and aperture priority, occasionally trying shutter priority- making some effort to learn as I go. Recently, I was shooting some motorcycle races at night. Not too successfully, I might add- the bikes were moving fast, everything was lit by artificial light and we couldn't get very close in to the action. My 12-40mm lens wasn't really cutting it, but that didn't stop me from trying! ha ha.

 

Along the way tho, I found my camera goes all the way up to about 23,000 ISO! I set it up there and made every effort to also adjust the shutter speed to as fast as I could get- which for some reason, didn't seem to be too fast? Now this OMD EM1 camera is pretty complicated, way over my head but in fiddling with it, I'm getting to know its ins and outs... we had fun watching the races and all but in the end my photos were crap!

 

But in all this I got to wondering how important ISO is in digital photography and why in the world a camera's ISO capabilities would go so high as 23,000? How does digital ISO relate to actual film speeds and stuff? Is or was there ever a film with a super high ISO? If not, why then, these (what seem like) crazy levels of ISO in digital?

 

Thanks!

Tom

I wouldn't expect to get decent photos of motor racing with a 12-40 whatever the light, though I have managed a few of cars from the inside of a hairpin around the long end of that. For bike's generally at least 100mm (on MFT) would be wanted.

As @ruslan mentioned panning will generally give the best results. I suspect you'd want speeds at the faster end of the range he quotes till your panning skills have been practiced somewhat.

 

If you try photographing the stars without a fancy tracking mount, you'll find you'll wish for noise free ISO well above 23,000.

 

I think ever digital camera has ISO settings that go above what it can mange to give a good noise free image with, but there are times when noise isn't too much of an issue, so these excessive ISO values can still be very useful.

 

I'm not sure about the latest edition of the ISO12232 standard (it's been updated this year, the previous version dates back to 2006) but only about a year ago many cameras where being produced that went well beyond the levels officially specified (they went up to ISO 10,000, so even your EM1 exceeded those limits). Back in 2016 Nikon launched the D5 that goes up to ISO 3,280,000, over 8 stops more than the maximum defined by ISO12232 at the time.o_O

 

I don't see any reason why digital photography should be limited by what could be achieved by film. I'd like a camera capable of taking a decent handheld shot of the stars that sees them much as I do when my eyes are fully dark adapted. Indeed I'd not object to it being more sensitive, so I can use a telephoto...

Sadly manufacturers have yet to offer one, let alone for anything near what I could afford. :rolleyes:

If image quality were equal, you'd take the most sensitivity you could get (highest ISO) for maximum shutter speed and small aperture (good depth of field). Everything could be hand held. Exceptions:

 

Maybe you want the lens wide open for minimum depth of field to isolate and simplify the subject.

Maybe you want a slow shutter speed to show some motion blur on moving objects.

 

Too high an ISO value makes those things difficult.

 

Since image quality deteriorates with increasing ISO, it's all a compromise. The ISO speed is really designed to answer a simple question- how much light do I need to properly expose a given film or sensor system?

All good answers above. But if you're really into night action shooting, higher ISO, wider aperture lenses, potentially faster shutter speeds, knowing how to pan and position oneself with the direction of the action are all important criteria for success. Careful study of what you consider successful photographs and the technique used to create them can give you good hints of how best to proceed, and/or build your gear collection for success.

Hi guys.

 

Hey so I'm trying to get a fix on ISO. With film, ISO relates to film "speed", yes? Slower film (far as I know and I may be wrong) results in finer grained images, yes? Slower speed film needs more light, higher film speeds need or require less light? (please correct me if I'm wrong)

 

SO what role would ISO play in digital photography? I'm asking because I've been fiddling with my digital Olympus micro four thirds camera, shooting in manual and aperture priority, occasionally trying shutter priority- making some effort to learn as I go. Recently, I was shooting some motorcycle races at night. Not too successfully, I might add- the bikes were moving fast, everything was lit by artificial light and we couldn't get very close in to the action. My 12-40mm lens wasn't really cutting it, but that didn't stop me from trying! ha ha.

 

Along the way tho, I found my camera goes all the way up to about 23,000 ISO! I set it up there and made every effort to also adjust the shutter speed to as fast as I could get- which for some reason, didn't seem to be too fast? Now this OMD EM1 camera is pretty complicated, way over my head but in fiddling with it, I'm getting to know its ins and outs... we had fun watching the races and all but in the end my photos were crap!

 

But in all this I got to wondering how important ISO is in digital photography and why in the world a camera's ISO capabilities would go so high as 23,000? How does digital ISO relate to actual film speeds and stuff? Is or was there ever a film with a super high ISO? If not, why then, these (what seem like) crazy levels of ISO in digital?

 

Thanks!

Tom

 

I am not so sure that you're asking the question or trying to make a statement.

Another issue in low light situations can be autofocus performance. Some body-lens combinations offer excellent autofocus performance even in very low light situations. Others not so much. If a camera is struggling to obtain focus before allowing the shutter to release it can severely impact the outcome in the exposed image. For these situations it is best to go manual focus and pre-focus on the selected spot so the shutter release is not delayed by a struggling autofocus system. Likewise, pre-metering and setting manual exposure values can offset some of the issues associated with difficult conditions, though technical capacity of the equipment will still establish the outer limits possible in any given situation.

ISO (International Organization for Standardization of Geneva, Switzerland) assigns numerical values to the sensitivity of photographic film. Heretofore, this authority was undertaken by various country-based Standard Agencies.

 

As you know, the CMOS (complementary metal–oxide–semiconductor) imagining chip has a surface covered by millions of photosites. Each contains a photodiode that converts photon hits to electron charges. The greater the number of hits received during an exposure, the greater the charge. This charge is then converted, in place, to a weak voltage. The voltage is then amplified, also in site.

 

Any time you amplify, you induce static into the signal. As an example, turning up the volume of the TV makes the sound louder but this act induces static. In the jargon of digital photography, this static is called “noise”.

 

We can reduce noise by lowering the amount of amplification needed. This can be accomplished by somehow more brightly lighting the scene or using a lens and shutter setting that causes more light energy to play on the sensor as the exposure ensues. These methods are not always available.

 

We can also reduce the need for greater amplification by enlarging the photosites. This presents a larger photon capture area thus reducing the amplification needed. Modern digital cameras employ clever software routines that mitigate noise.

 

Nevertheless, noise is with us always. When we up the sensitivity by tuning up the ISO, we induce more noise.

 

A big problem: In a perfect world, all of the in-place amplifiers in the photosites would operate with the same efficiency. Sorry to report that each is independent with different operating curves. The result is fixed-pattern-noise. To see for yourself, set the ISO high and shoot a frame or two with the lens cap on. The pattern you see is fixed-pattern-noise.

 

We also get blooming: The photosites are close to each other. Some of the charge and or voltage is always leaking out to adjacent sites. The higher the amplification, the more likely their will be blooming.

 

All of these noise things are worsened by heat. The CMOS consumes electric energy and this induces heat. The hotter the chip the more the noise. In astronomy where hours long exposure is often practiced, the imaging chip is cooled by a refrigeration system.

 

Future cameras, as the digital technology evolves will find many ways to mitigate noise.

Thanks, everyone. All of your answers and responses are helpful and also very informative.

 

I am not necessary making shooting fast moving things at night my end goal; it happened that I was dialing my camera up and down and all around with its various functions during a night racing event- and in doing so made some discoveries.

 

There is still so much I don’t know, but I’m still having fun!

 

Some of this information I had heard before in the context of other questions. Hearing it again helps me to do a bit of triangulation- tying the info together from a couple different directions. Which, perhaps unbelievably, is helpful to my way of learning!

 

Thanks again!

Tom

ISO in a digital camera, dictates how much 'gain' or amplification is applied to the signal stored on the sensor. It defines how sensitive to light the camera is.

 

Compared to a modern digital camera, film is pathetically insensitive to light. The maximum real speed of film only reaches to just over1000 ISO, and is horribly grainy at that speed in the 35mm format. Digital, OTOH, is very useable at the equivalent of 1600 ISO with even a cheap compact camera, and at much higher speeds with a more sophisticated DSLR or MILC.

 

I think it's fair to say that digital technology has made handheld photography possible, nay easy, in low lighting conditions that would have taken exposure times of seconds or even minutes to get any sort of image on film.

 

In the mindset of film, an ISO number of 256,000 or even 512,000 seems ludicrously high, but that's what can be achieved with modern digital sensor technology. Albeit with roughly the same amount of noise as the grain of the highest speed film you can buy.

 

Except of course you can expose the digital camera at an action-stopping 1/125th of a second instead of the 2 or more seconds you'd need for 1000 ISO film.

 

Any bets on digital cameras exceeding one million ISO before the end of next year? Not exceeding that number would probably get far longer odds.

Edited September 25, 2019 by rodeo_joe|1

I’ve struggled with iso settings so much that until recently I thought a billboard poster that quoted, say, ISO 9000-1 was shot at ISO 9000 and the “-1” meant it was shot using medium format.

 

Nowadays , I use auto ISO.

 

As a rule of thumb, I try to match focal length, ISO and shutter speed, using shutter priority and checking general exposure on the screen. I also set EV at either -0.3 or -0.7, depending on brightness and reflectivity of subject. This works for many, possibly even most, of my shots - YMMV.

Just some specific Olympus M43 advise. I generally cap the maximum ISO that can be set by the auto ISO function at 3200 on my EM-5 Mk I, in order to retain reasonably acceptable (to me) image quality. I would guess that M43 cameras using the newer 20mp sensor may allow higher max ISO settings, while I would probably stick with 3200 for most 16mp sensor cameras, but your assessment may be different. While Olympus m43 meters seem to work quite well in outdoor night shooting, it is possible that with the 12-40mm lens, there was a lot of dark areas around the subject, which may have resulted in some overexposure and that excessively high ISO you were shooting at. Can't tell this without seeing the files . No current m43 camera will provide decent image quality at 23,000 ISO, though I would expect that with the current generation of FF cameras, such high ISO settings may be OK.

I'm going to try to reassemble a few of the pieces of this thread because I think it might lead you to misunderstand a key point.

 

This may sound like nitpicking, but it isn't: increasing ISO does not increase the camera's sensitivity to light. Given any exposure to light, the signal recorded by your sensor is fixed. Increasing ISO only increases the degree to which that signal is amplified. It's a way of compensating for having less light. It is NOT analogous to putting a faster film into a film camera. It's more like pushing a film above its native ISO in developing, although actual process of boosting, the the impact it has on the image, are different.

 

Increasing ISO has its costs. Many modern sensors can handle increases in ISO much better than sensor did in the past, so the costs are smaller, but they are there. One is that increasing ISO will give you more noise than a similar exposure at a lower ISO (that is, an exposure that produces an image of the same brightness), for the simple reason that it amplifies everything, signal as well as noise. This extra noise can be inconsequential, particularly if you don't go to high and if you don't have much in the way of very dark shadows, but it can be severe. The second effect, which is really another expression of the first, is that increasing ISO decreases dynamic range--that is, the range from the darkest to the lightest tones the camera can record.

 

There are reasons to accept these costs. You may need to because of low light. You may do it to allow you to use a faster shutter speed or narrower aperture. If you are using TTL flash, you may do this to increase the brightness of the background relative to the target. However, many people, including me, keep the ISO as low as we can.

 

How big the costs are depend on the camera's sensor and the type of image. For example, I shoot with both a 5D III and a 7D I, and the noise caused by increasing ISO is substantially less with the 5D III. The brighter an image is, the less the impact because the signal:noise ratio is higher in bright areas.

I'm going to try to reassemble a few of the pieces of this thread because I think it might lead you to misunderstand a key point.

 

This may sound like nitpicking, but it isn't: increasing ISO does not increase the camera's sensitivity to light. Given any exposure to light, the signal recorded by your sensor is fixed. Increasing ISO only increases the degree to which that signal is amplified. It's a way of compensating for having less light. It is NOT analogous to putting a faster film into a film camera. It's more like pushing a film above its native ISO in developing, although actual process of boosting, the the impact it has on the image, are different.

 

Increasing ISO has its costs. Many modern sensors can handle increases in ISO much better than sensor did in the past, so the costs are smaller, but they are there. One is that increasing ISO will give you more noise than a similar exposure at a lower ISO (that is, an exposure that produces an image of the same brightness), for the simple reason that it amplifies everything, signal as well as noise. This extra noise can be inconsequential, particularly if you don't go to high and if you don't have much in the way of very dark shadows, but it can be severe. The second effect, which is really another expression of the first, is that increasing ISO decreases dynamic range--that is, the range from the darkest to the lightest tones the camera can record.

 

There are reasons to accept these costs. You may need to because of low light. You may do it to allow you to use a faster shutter speed or narrower aperture. If you are using TTL flash, you may do this to increase the brightness of the background relative to the target. However, many people, including me, keep the ISO as low as we can.

 

How big the costs are depend on the camera's sensor and the type of image. For example, I shoot with both a 5D III and a 7D I, and the noise caused by increasing ISO is substantially less with the 5D III. The brighter an image is, the less the impact because the signal:noise ratio is higher in bright areas.

 

Although you can have film of different sensitivity the penalty for using high sensitivity is much greater than setting a higher ISO on the digital camera. I have no problem with ISO 1600 on my digital camera yet when I use ISO 1600 color film the grain is terrible to the point that when I use film I don't use anything higher than 160.

I've learned a lot on this thread about high ISO values amplifying light in digital cameras. My (amateur) take is that the the ISO (and aperture and shutter values you set depends very much on the situation/shot. With my (old) Canon 6D, I can dial in up to ISO 256000. There will be a lot of grain and a lot of noise so I really need to think about whether a shot at 256000 is going to be in any way 'salvageable' in PP. It's usually not. I've gone up to 128000 and used noise reduction for some shots (in the dark). I regularly use ISO 1600 - 6400 (and sometimes much higher) for indoor work. Depending on the format of the print, I might reduce the noise or not. Fast movement (fast shutter speeds) in low light is the worst scenario. I usually shoot in AV and set the ISO to give me the shutter speed that I need with a reasonable aperture.

It is NOT analogous to putting a faster film into a film camera. It's more like pushing a film above its native ISO in developing,

No, it's nothing like 'pushing' film. Pushing film simply increases the contrast of the image, whereas increasing the ISO or gain in a digital camera genuinely raises the level of shadow detail that can be seen. Whether this done through altering the ISO setting of the camera, or by post-processing a RAW file doesn't really matter. What's important is that with digital there is a genuine increase in the visibility of dimly-lit subject details. The same is definitely not true for 'pushed' - AKA overdeveloped - film.

 

A comparison between Ilford Delta 3200 (right) exposed at 1600 EI and an 'ancient' Nikon D700 (left) using the same exposure settings, and with the same lens.

The D700 has several stops more ISO increase in hand. The Delta 3200 image quality is bad enough already!

 

So. I would agree that raising a digital camera's ISO isn't like using a faster film; it's far superior.

Edited September 25, 2019 by rodeo_joe|1

I generally find that high ISO shooting yields a good bit of noise. Of course, it's entirely possible and expected that what's acceptable to one person in a given photographic situation may be unacceptable in another photographic situation or to another person. Our eyes may see the very same thing and yet we may feel very differently from another photographer about what we're seeing. And noise may bother us in one photo that winds up adding something in another photo. That's where you come in and the particular shot comes in. What you see and how it makes you feel and in what context is important.

 

Low light shooting at a high ISO is often a trade-off, as is so much of photography, as has already been mentioned. You make choices and no choice is perfect. If I choose to shoot hand held in very low light, I am not only willing to accept the noise, I might even try to embrace it as a known result of such shooting, rather than trying to mask it with mostly ineffective filters and rather than simply trying to pretend it's not there. Just as grain had a defining characteristic, so can noise. Neither can fully be run away from if there, so I find it best to figure out how to most effectively use it when I either want to or must.

 

Denial, on the other hand, is often very obvious and can undermine genuine expression.

Hearing it again helps me to do a bit of triangulation- tying the info together from a couple different directions. Which, perhaps unbelievably, is helpful to my way of learning!

The best way to learn things like photography. Nobody can teach you photography - you have to discover it! For maths and science, maybe not so much. ;-)

The best way to learn things like photography. Nobody can teach you photography - you have to discover it! For maths and science, maybe not so much. ;-)

If I can see further than other men, it's because I stand on the shoulders of giants. Sir Isaac Newton