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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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3answers
4k views

What settings should I use to photograph aurora borealis with a wide angle f/4 lens?

I've tried my first night photography of the stars last week. Most articles I've seen were recommending a fast lens, fully opened, @ ISO 800 and about 20 - 30s exposure, etc. Unfortunately, my only ...
4
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4answers
890 views

Is higher ISO noise evenly distributed, or does it affect colors differently?

It's obvious that higher ISO affects the photograph by adding noise or grains. But will that grain or noise be distributed equally over all parts of the photograph, or will it specifically affect ...
6
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1answer
1k views

Why does the camera default to ISO 400 in auto ISO mode with flash?

I've observed this behaviour on my Canon 550D, and I was wondering why it didn't use a lower or even variable ISO. I'm not sure if this is a camera/brand specific setting. Is there any particular ...
5
votes
1answer
561 views

Bracketing with ISO or exposure time?

With old cameras, you had film with fixed ISO and you could bracket your shots by either adjusting the f-stop or exposure time. Normally, if I have enough light, I prefer to keep the f-stop constant ...
12
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9answers
7k 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 ...
7
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4answers
1k views

Should I prefer raising ISO or lowering the shutter speed in a low light condition?

Example: 1. A "still" object/scene. 2. Night time. 3. The only light source you have is: a tubelight on a wall. Provided, you want sharpness all around so you won't maximize the aperture. Flash ...
8
votes
4answers
4k views

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

I found that formula on the Internet: Guide Number = (Shooting Distance * Aperture) รท ISO Sensitivity Is it correct? If it is could someone please explain why ISO is related to guide number in this ...
9
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1answer
2k views

What film should I use for black and white outdoor 'formal' shots?

I'm wondering what type of black and white film is best to shoot good-quality outdoor photos that capture the quality of the trees, etc., and still show detail in people's faces. Is there a ...
4
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4answers
389 views

Are there any situations in which it makes sense to raise the ISO in bright daylight?

Are there any situations in which it makes sense to raise the ISO in bright day light? For example, this pic has been taken in bright day light with ISO 3200, f18, 1/1250: ...
4
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1answer
166 views

What makes a good sample image for ISO comparison?

To be more specific this image is always used by Digital Photography School for ISO comparison. What are those features that make this image suitable for ISO comparison.
3
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2answers
571 views

Assuming a perfect sensor, what is the physical limit of ISO/pixel area?

Assuming that camera manufacturers can eventually make the perfect sensor that introduces no electrical noise to the signal, at what point (measured in ISO/area of a pixel) will shot noise be so ...
3
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0answers
284 views

Why does Nikon (e.g. D5100) use Hi1 and Hi2 instead of numeric ISO settings? [duplicate]

Possible Duplicate: What does “expanded ISO” mean? Are these settings real sensitivity options when reading the CMOS sensor or just after-processing what can be done outside the ...
11
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3answers
2k views

Does shooting at lower RAW resolution using crop sensor camera mimics qualities of full frame cameras?

I'm not talking about changes to the focal length. I've read many post that say in full frame camera the pixel density is lower compared to crop sensor camera's and so it captures more light and has ...
2
votes
3answers
145 views

Is an artificial external source of light required even with a low-noise high ISO range?

Is an artificial external source of light required even if you have a camera with a high range of effectively noiseless ISO? Are there some special cases which "need" external lights, at all costs?
1
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1answer
8k 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 ...
6
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3answers
733 views

Does Av mode on my Canon DSLR take IS into account when deciding shutter speed and ISO?

Most of the time when I'm out I'm shooting, my camera is in Av mode. I've selected the aperture size I want and I'm letting the camera decide on the correct shutter speed and ISO that are required to ...
11
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3answers
1k views

Why can't I set a partial ISO stop?

On my Canon 500D, I can set aperture and shutter speed in 1/3 stops, however with ISO I appear to be limited to whole stops (100, 200, 400, 800 etc...) Why is this? It would appear the camera is ...
2
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2answers
22k views

In Canon EOS 1100D how do you manually set shutter speed and ISO in M mode?

Can someone explain how to set the shutter speed and ISO in M(manual) mode in a canon EOS 1100D.?
1
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1answer
401 views

Why doesn't the Nikon D90 record ISO in EXIF?

Why is there no ISO data in EXIF of images taken with Nikon D90? I'm using exiftool.
3
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2answers
2k views

How do I configure a Nikon D90 with minimum shutter speed and aperture?

How can I configure my Nikon D-90 with minimum shutter speed of 1/60th of a second and aperture of f1.4 and have it adjust the ISO and speed as needed? I currently have it working with 1/60th fixed ...
5
votes
5answers
2k views

How do I go about choosing film for an old LOMO camera?

I have a old LOMO analog film camera with four closures. How should I choose film for my camera? What ISO should I select? Is there anything else I have to be aware of when choosing film for this ...
10
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4answers
551 views

How does flexible ISO make shooting digital different from film?

I was thinking at the differences between SLR and DLSR (in Manual mode). In both cases you can change aperture and shutter speed as it suits you. But with SLR you are stuck with the ISO of the film ...
20
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7answers
3k views

Is high ISO useful for photography?

I started photography sometime back, and always wondered when is high ISO handy in photography? Also can it be used to get any special effect in pictures? My camera has Max ISO of 800 but I see some ...
8
votes
3answers
847 views

Why do two different cameras using the same settings produce photos with different exposure levels?

Please refer to this photo: The image on the left was taken with a Panasonic GH2, a micro-4/3rds camera with a crop factor of 2, and the right one was taken with a Nikon D700, a full-frame camera. ...
7
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5answers
2k views

Does noise in images depend upon “Megapixels” or “ISO”?

I have a question about image quality. Does noise in an image is depends upon "Megapixels" or on "ISO"?
9
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3answers
4k views

How do I manually set the aperture and shutter speed, while auto selecting ISO with the Nikon D90?

I have a Nikon D90 and would like to set the aperture to f/1.4 and the shutter speed to around 1/60, all while having the camera compute what ISO is required for the current light conditions. I am ...
24
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5answers
7k views

Are there general rules for selecting the correct shutter speed and ISO in manual mode?

I have purchased my first DSLR (a Canon 500D) and have been playing around quite a lot within the aperture priority mode, with auto shutter speed and ISO. Anyways as I would like to become a better ...
10
votes
4answers
2k views

Should I use low-end expanded ISO?

My Pentax K-5 comes with a "regular" low ISO setting of 100, but if you enable "expanded ISO" you can set it as low as 80 (plus go up to an absurd 51200!). I know that in general to reduce noise, ...
13
votes
1answer
1k views

Is in-camera high-ISO noise reduction worthwhile?

I shoot in RAW and post-process in Aperture where needed. Does the in-camera noise-reduction do anything that I can't do in Aperture or other post-processing software? It seems to add a bit of time ...
4
votes
3answers
614 views

What is preventing sensor ISOs from going lower than 100? [duplicate]

Possible Duplicate: Why can't the ISO level on most digital cameras be set below 80 So, take your typical DSLR sensor. It probably tops out at anywhere between 1600 - 6400 ISO. The ...
13
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6answers
7k views

Is ISO 200 still considered to be a bad choice, on digital cameras?

In times of film photography there was a rule to either use ISO 100 film (or even great Velvia 50) which usually had considerably less grain noise than ISO 400 film. So 100 for outside or well lit ...
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2answers
776 views

What is the quantitative relation between f/# of the lens (aperture), exposure, and ISO?

Let's say we shoot with a DSLR camera and we have two interchangeable lenses. Lens #1 has aperture f/X, X between 1 and 2 (see below). Lens #2 is f/4.5. Same focal length and other characteristics as ...
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3answers
3k views

Why can't the ISO level on most digital cameras be set below 80?

Why is it that the ISO level on most digital cameras doesn't seem to go lower than ISO 80? I understand (vaguely) that the sensors adjust the gain in order to achieve the equivalent of a high ISO ...
13
votes
3answers
800 views

Where do ISO numbers come from?

I understand how an ISO number affects the film sensitivity or a digital image, but I'm curious where did the numbers come from? How come we talk about ISO 100, 200, 400, and so on instead of ISO 1, ...
9
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0answers
375 views

What does expanded ISO mean?

Especially with regards to image quality. I am particularly interested in when you expand to a lower ISO, say 50 rather than 100. Generally the standard high ISO is too noisy, with the expanded ISO ...
3
votes
3answers
580 views

ISO when shooting at night

Why does the signal to noise ratio decrease when using high ISO speeds (e.g 3200) when shooting at night with a digital camera?
13
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2answers
1k views

Capturing vapour or faint steam

I was trying to capture a scene that was in a dark area with a bright background. There was faint steam that I wanted to be the focus of the picture. I tried first by having a very large aperture and ...
94
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?
8
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3answers
1k views

Is 125 or 400 ISO film better for black and white studio shots?

ISO 125 or ISO 400 film: which should I use for studio shots? By the way, I am planning to shoot in black and white.
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5answers
3k views

What is exposure compensation?

What does exposure compensation do? If I take a photo with a given shutter speed, aperature, and ISO, and then take the same shot with +1EV or -1EV, what is actually happening? Is this just a gain ...
17
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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 ...
10
votes
4answers
1k views

How important is ISO speed?

My wifes Canon EOS 450D has various speed settings and an auto mode. The quickest one is 1600. She photographs mainly birds, both stationary and in flight and mainly still insects. What are the ...
13
votes
3answers
5k views

What are the pros/cons of the high-ISO noise reduction feature on D90?

So my D90 offers "High-ISO Noise Reduction". Sounds like a good thing, but obviously there must be a cost of some kind. The settings are "Off", "Low", "Normal", and "High", and the default is ...
10
votes
3answers
686 views

Is it possible to use a lower ISO instead of ND filters?

I've seen in the CHDK page, that you can change the ISO values, and put lower ones. Now lets suppouse I want to shoot a waterfall in day, and also I want a long exposure time (10 sec. i.e.). I know I ...
43
votes
8answers
23k 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 ...
13
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1answer
315 views

What factors determine the lowest ISO for a camera?

With the introduction of the Nikon D7000, one of its advantages over the D90 is that its lowest "true" ISO is 100 instead of 200. What does this mean though, what had to change in the the ...
43
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6answers
4k views

How is ISO implemented in digital cameras?

If I change the ISO settings on my camera, obviously the gain of the system is increased, amplifying the signal from the sensor. What's not clear to me is where the amplification takes place. I see ...
10
votes
1answer
795 views

Why the smallest ISO in Nikon D40 is 200, rather than 100?

I have a Nikon D40. The ISO ranges from 200 to 1600. Why isn't ISO 100 (or smaller) available? Is this common in other cameras? I understand that there are technical limitations to provide higher ISO ...
4
votes
1answer
326 views

Why is Adaptive Dynamic Range incompatible with ISO Expansion?

[EDIT: The original main question here was "What is Highlight Tone Priority?" It turns out that Highlight Tone Priority, Active D-Lighting, D+, and Adaptive Dynamic Range all mean the same thing, so ...
16
votes
4answers
3k views

What are general rules for ISO settings?

Being a novice in photography and reading about preferable settings of my camera I'm a little bit confused about ISO settings. Sometimes I'm advised to set as little ISO as possible to have higher ...