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ISO is the measurement of the camera's sensor/film sensitivity to light. It is one of the 3 ways to create a well exposed image (The other two being Aperture and Shutter Speed). Typically, a higher ISO for a correctly exposed image will result in the image being more noisy/grainy.

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2
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2answers
1k views

Stopping down in manual mode with automatic ISO?

I am using a Canon 5D MKIII. I take a lot of low-light fotos and want to achieve low DOF while keeping the photos sharp with fast-moving subjects (musicians), using a 5mm 1.4 lens. So far, I always ...
5
votes
1answer
331 views

Why can't I set my Pentax K-5 IIs to ISO 100?

I recently got a K-5 IIs, and found that it can't be adjusted to under ISO 200. Even with expanded ISO mode, 160 is the lowest possible value. Can anyone help me out?
12
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2answers
1k views

What exactly is “base ISO” and how do I find what is base ISO on my camera?

If I understood correctly, base ISO is in full stop steps from the lowest possible ISO setting on my camera. For example if the lowest setting on my camera is ISO 100, than the following table would ...
0
votes
2answers
86 views

Can someone explain film speeds to me? [duplicate]

I know the whole 200 400 800 is based on the speed of the film & say youre in a dark room with dim lighting, 800 would be a better choice to use.. But i have searched through flickr and i see most ...
2
votes
2answers
143 views

Does it make sense to “Expose to the Right” except at base ISO?

I have read in a number of places that exposing to the right (ETTR) only makes sense at your camera's base ISO, with the justification being that if you are boosting the gain in camera (by raising the ...
88
votes
5answers
6k views

What is “ISO” on a digital camera?

What is "ISO" in general, and how is the scale defined? How does the ISO scale for film speed differ from ISO sensitivity as used in digital cameras? Is lower ISO always better?
11
votes
4answers
2k views

Why is it called ISO “speed”?

As I understand it, the ISO value indicates how sensitive the sensor/film is to light. How is this related to speed? Is it something to do with how fast old chemical film developed?
4
votes
3answers
567 views

Digital ISO vs Post-Exposure Correction

As far as I know, a ISO setting on a DSLR camera corresponds to a mixture of both analog and digital settings set before a shot is taken and governs how much amplification the incidence luminosity is ...
0
votes
0answers
54 views

Difference between shutter speed, iso and Aperture [duplicate]

What are the main differences between shutter speed , iso and aperture? 1.How are they interdependent? 2.Because every three of them are controlling the light,it gets very confusing how? ...
7
votes
4answers
248 views

Are the aperture, ISO and shutter speed stops perfectly interchangeable?

Imagine you have an scene with shutter speed 1/60, f/8 and ISO 200. Then you change the configuration to get an equivalent exposure: speed 1/120, f/5.6, ISO 200 (plus one stop in speed, minus one stop ...
3
votes
2answers
87 views

Why does ISO sensitivity affect sequential burst mode duration?

I have an Olympus E-PM2 and while testing a new SD card I learned that the camera's ISO setting affects the number of pictures that I can take using sequential burst mode. When shooting raw at 8 fps ...
1
vote
4answers
108 views

Can exposure parameters be kept high even at high ISO sensitivity, to keep image quality up?

Following is from Film speed Film speed is the measure of a photographic film's sensitivity to light, determined by sensitometry and measured on various numerical scales, the most recent being the ...
16
votes
10answers
3k views

Do DSLRs play games with ISO when used with fast lenses?

This article at Luminous Landscape claims that Nikon, Canon, and Sony silently boost ISO when their cameras are used with very fast lenses (f/1.2 and f/1.4 principally), the implications being that ...
30
votes
6answers
4k views

Why is there an ISO setting when shooting raw?

Raw files are supposed to contain mostly unprocessed data from the sensor. What's the point of having an ISO setting if it doesn't affect the amount of photons counted, but only provides ...
23
votes
12answers
3k views

Why use higher ISO when using a tripod and the object is static?

Sometimes when I see a photo such as this one, I wonder why the photographer chose such a high ISO (640), despite using a tripod with a static subject. As far as I know, a lower ISO means less noise, ...
19
votes
9answers
18k views

Is it better to shoot with a higher ISO, or use lower ISO and raise the exposure in post-processing?

Suppose there are two photos taken in the following scenario: Scenario 1 - Photo taken using ISO of 3200. Scenario 2 - Photo taken using ISO of 100. Both photos are taken in a medium light ...
-5
votes
3answers
132 views

Optimum ISO? How can I tell? [closed]

I Own a Canon 60D what is the optimum ISO can reach without getting much Noise?
28
votes
9answers
1k views

Should higher ISOs really be preferred (all other things being equal)?

My understanding of the ISO setting on digital cameras is that, unlike film-cameras, changing the ISO does not evoke any physical change in the camera. Rather, it simply tells the camera to multiply ...
0
votes
2answers
147 views

How does a camera in an automatic mode choose what exposure, aperture and ISO to use? [duplicate]

For example: Does the camera detect if the scene contains fast-moving objects and if so use a shorter shutter speed? Does it detect if the entire scene is beyond the hyperfocal distance, and there's ...
-1
votes
2answers
410 views

Why doesn't an f/1.8 lens result in a lower ISO than an f/2.8 lens?

When I bought my Sony NEX-5R, I had a choice of an f/1.8 or an f/2.8 lens (both are prime, normal lenses). I was told the 1.8 will work better for low-light photography since it will let in lot more ...
41
votes
8answers
19k views

What does “expanded ISO” mean?

The ISO specification for the Canon EOS 7D reads as follows: High ISO For handheld shooting in low light, the EOS 7D offers ISO speeds of up to 6400. Expandable to ISO 12800, for low light ...
0
votes
2answers
405 views

Exposure compensation or ISO sensitivity? [duplicate]

If ambient light isn't enough and I don't have a tripod with me for long exposure, which one should I prefer to increase the brightness of my photo? I know high ISO comes with noise. Is there any ...
2
votes
3answers
6k views

What is the relationship of aperture, focal length, and ISO in a SLR?

I was using Nikon digital camera, and recently bought a Canon 550D. I am totally new to SLR. I am not familiar with SLR terms: Aperture, focal length and ISO, and their relation to one another. What ...
1
vote
1answer
3k views

What is the Base ISO of a Canon 5D MK III?

Can anyone tell me what the base ISO is of a Canon 5D MK III? I was reading this great piece on ETTR (1) and (2) and it repeatedly mentions how important shooting at Base ISO is when using ETTR. I ...
14
votes
6answers
3k views

What megapixel value is equivalent to which ISO film?

Is there some kind of equivalency table or formula that expresses what kind of pixels you need in a digital camera to have roughly the same quality as a particular ISO graded film? What other ...
-1
votes
7answers
414 views

Are these photos ruined because of ISO? [closed]

I took a lot of photos during a family get-together and I really liked many of them. My girlfriend then edited the photos to make them look better. The photos looked GREAT on her iMac monitor but when ...
17
votes
2answers
833 views

Why do I see this yellow color shift at high ISOs and fast shutter speeds? [duplicate]

I recently purchased a full-frame DSLR with a reported highest ISO of 204,800. I’m intrigued by the possibilities of the high ISO range and how far Lightroom and Aperture (I use each of them) can ...
0
votes
1answer
223 views

I have acquired an old Minolta Freedom Dual point-and-shoot. What ISO does it shoot at?

I have acquired an old Minolta Freedom Dual point-and-shoot camera. It's a straightforward enough device, and pretty automatic: no user set aperture or shutter-speed settings. But obviously it's ...
2
votes
1answer
168 views

What does fast/normal/slow mean for Pentax auto-iso?

I'm very confused about the Pentax auto-iso implementation. What does "fast/normal/slow" mean for the Auto-iso in the menu settings? The camera in question is a K-3, but I think it applies pretty ...
6
votes
1answer
505 views

Fuji X100s: Why are high ISO settings (>6400) only available in JPEG and not in RAW?

Reading an article about the Fuji X100s, I came across this quote: [...] the high ISO setting is only available when shooting in Jpeg Fine format. When shooting in Raw the highest ISO setting is ...
7
votes
2answers
245 views

Do low ISO photographs need Long Exposure Noise Reduction?

I usually took long exposure photo with ISO 100, so do I really need to turn on Long Exposure NR on? It really take time for processing.
1
vote
3answers
4k views

What is the highest acceptable ISO to use for weddings with Canon 7D?

I recently had my first wedding shoot(yippie!). For a person like me who usually shoot still life and landscape, weddings is a whole new world. I am used to shooting at low ISO's (800 or less) but the ...
1
vote
0answers
100 views

What is happening in the sensor when you change the ISO? [duplicate]

I understand the relationship between ISO, aperture and shutter speed. What I'd like to know is what actually happens in the sensor when you raise or lower the ISO number? In other words, what is ...
3
votes
3answers
234 views

Shooting objects under glass with pop-up flash

I sometimes need to take photos of new devices kept behind glass at trade shows. Currently I have to depend on my camera's in-camera flash. Often the picture is spoilt because of the flash's reflected ...
6
votes
7answers
10k views

What are some common ISO, aperture, and shutter speed settings for street photography?

I recently purchased a Panasonic GF1 with the 20mm pancake lens. It's by far the nicest camera I've ever owned and I'm really excited to learn the basics of digital photography (primarily street ...
0
votes
3answers
254 views

Why does the live view switch off for a long time and my photo is of low quality when I take a picture in low light?

I have Nikon D3200. I am trying to take picture in A mode. I have set Aperture f/3 and ISO to 200. I am taking a picture in very low light. The problem I am facing is that when I press the shutter ...
6
votes
4answers
463 views

What “influences” the ISO sensitivity of the camera?

In comparing, let's say Canon's 600D and 100D (which are by explanation from my store guy, practically the same camera) I noticed that they have different ISO sensitivity declarations. Since, they ...
4
votes
1answer
273 views

How to denoise a dark photo with extremely high ISO?

There are situations where I would reluctantly have to turn the ISO to the larger extreme. Nevertheless I can get some photos that I pretty much like under these circumstances. Here is an example. ...
0
votes
2answers
106 views

How do i select right exposure? [duplicate]

I have canon EOS 600D and also I have following lenses: 18-55mm 55-250mm 40mm f/2.8 How do I select correct exposure. what is the sequence of priory. currently I first changing the iso, ...
22
votes
5answers
8k views

What is the difference between digital high ISO noise and film grain?

What is the difference between digital high ISO noise and film grain? Why does one "eat detail" and the other does not?
1
vote
1answer
7k views

How do I enable auto-ISO in non-scene modes in a Nikon D5100?

I'm trying to enable auto-ISO on my dad's Nikon D5100. There is an "Auto" option for "ISO sensitivity" in the menu, logically-enough under "ISO sensitivity settings"). This works fine in the Scene ...
13
votes
1answer
763 views

Is it really better to shoot at full-stop ISOs?

The second half of this answer says Notice that I only shot full-stop ISO which is important with Canon DSLRs because the gain to obtain the 1/3 stops in between is applied in software by the ...
3
votes
1answer
166 views

What is the fastest film (highest ISO) made commercially?

On wikipedia there is a reference to Polaroid 612 which is ISO 20000. Was there faster film? Was there faster film made for specialized purposes (say military, astronomy etc)?
0
votes
2answers
202 views

How about high ISO (low light) performance testing of sensor with camera's auto-ISO option?

I'm in the market for a camera with better high-ISO capability than my current ones. There are more than enough reviews on the internet that measure cameras' high ISO performance. They usually pit one ...
8
votes
4answers
3k views

What is the quantative relation between flash guide number and ISO?

I found that formula on the Internet: Guide Number = (Shooting Distance * Aperture) ÷ ISO Sensitivity Is it correct? If it is could someone please explain why ISO is related to guide number in this ...
10
votes
5answers
385 views

For night photography with lots of unexposed areas, should I go with high iso and low exposure, or low iso and high exposure?

I have been doing so much research on iso, and for awhile I've been going with the theory that low iso= less noise, so I've been shooting at iso 100 and then adjusting my flashlights and increasing ...
12
votes
9answers
6k views

Why aren't my night shots sharp even when I shot at ISO 100 on a tripod?

I recently purchased a tripod because I really want to do some night photography. I have tried practicing with street lamps, moon shots etc with my Canon 550D and 70-200 f/4L and most of them are shot ...
1
vote
3answers
222 views

Can we always talk about noise difference between crop and full frame?

Let's say we have two systems: 1) full-frame camera, 80 mm lens at f/2.2 2) APS-C camera, 50 mm lens at f/1.4 The subject is the same, as well as the camera position, focus distance, shutter speed ...
17
votes
4answers
752 views

What is ISO and how does it affect my photos

What is the ISO setting on my camera? What does it represent? What should I be aware of with regards to ISO when taking photographs
0
votes
2answers
121 views

How to take a moving object(far distance) in outdoor low light situation?

It's always been tricky to me how to take a far distance picture(moving) in a low light situation. I don't think flashlight would help in this case since it can't reach to the moving object. For ...