I have 2 basic questions about photography.

[DannyRodriguez]

I don't see any other forum for questions, so I'm posting here. Hope that's ok.

I got my camera today (FINALLY) and I've been playing around with it all day. I think I've figured something out but I need to know if I'm right about it before asking the first question.

Am I right if I say that exposure is controlled by the aperture and the shutter speed and nothing more?

Question 1. If so, then only in a very low light scenario, when it's ABSOLUTELY NECCESARY, are you to use your ISO, right?

I've had my ISO on 100 all day because it's my understanding that the ISO is nothing but a digital tool built in order to enhance the light digitally in order to take pictures in very low light.

So the question, the actual question is then: I am to adjust exposure using my shutter speed and aperture only, and ONLY if it's neccesary do I go over 100 ISO?

Question 2. The point of exposure.

I noticed that I could adjust my shutter speed and aperture to many different combinations and still be able to fine tune it into a perfectly exposed shot. So that got me thinking... is that the point in all pictures? Fine tune your shutter and aperture to get a perfect exposure for the picture? Or do you use too high or too low exposure in some pictures to get some sort of effect?

 

[willis_927]

1- Sometimes you need a fast shutter speed in low light conditions in order to prevent (for example) camera shake. But lets say that your lens will only allow you to open up to a max aperature of F4, and you need atleast (for example) 1/60 to prevent camera shake, or motion blur. So, say you need to be ar atleast 1/60, and you shoot at F4, but its too dark to properly expose the picture with these settings, and at ISO 100, your camera says you are under exposed at 1/60th. This is a good time to bump up the ISO, to allow (hopefully) to get that 1/60 shutter speed.

2- Yes and no. shutter speed and aperature do adjust your exposure, yes, but they are also used for other things. Ex - aperature - controlling depth of field
Shutter speed- getting motion blur etc.

 

[tygr1]

ISO does not enhance the light digitally and may be used at your discretion to achieve the proper exposure. Aperture, shutter speed and ISO are to be used for sooo much more than just getting the right exposure.

You should use the search function to learn more and to find references to good books concerning light, exposure etc. There is more to it than one lesson here could cover, though the learning curve isn't too steep to pick up quickly.

 

[Compaq]

The exposure triangle: Aperture (size of "hole" that the light goes through), shutter speed and ISO (sensor's sensitivity to light).

With dslrs, you should not be afraid to use iso 800, or even 1600 (though 1600 on my 40D is quite noisy). Newer cameras handle noise better. Use the ISO necessary to get that shot, the only photo you regret is the one you didn't take!

As a general rule, try and keep your iso as low as practically possible, don't compromise the shot by fearing high iso - the important thing is to get your shot. Sometimes, though, you may want a high ISO to generate a noisy picture: artistic effect.

Read up on depth of field and how that relates to aperture. Also read up on what artistic effects the shutter speed is responsible for. Tips: YouTube!

Then come back and ask more

-Anders

 

[analog.universe]

About high ISO's... your shot will come out better, and have less noise, if properly exposed with a high ISO, than if it was underexposed because you were being conservative with ISO.

About low ISO's... 100 may have the least noise, but often 200 is where the most dynamic range is captured (difference between light and dark in the scene), this varies from camera to camera, but it's worth knowing about if you've got a scene where you're really having to choose between black shadows or blown highlights. The actual number that yields the widest range varies from sensor to sensor...

 

[DannyRodriguez]

About low ISO's... 100 may have the least noise, but often 200 is where the most dynamic range is captured (difference between light and dark in the scene), this varies from camera to camera, but it's worth knowing about if you've got a scene where you're really having to choose between black shadows or blown highlights. The actual number that yields the widest range varies from sensor to sensor...

That sounds like something I should know more about. could you tell me how to figure that out on my camera, or some web page that explains that better? My camera is a canon 60d.


A lot of awesome answers here, researching I found out that I could achieve the Saving Private Ryan "war" effect by upping the shutter speed to 1000. Awesome!

 

[Derrel]

I don't see any other forum for questions, so I'm posting here. Hope that's ok.

I got my camera today (FINALLY) and I've been playing around with it all day. I think I've figured something out but I need to know if I'm right about it before asking the first question.

Am I right if I say that exposure is controlled by the aperture and the shutter speed and nothing more?

Question 1. If so, then only in a very low light scenario, when it's ABSOLUTELY NECCESARY, are you to use your ISO, right?

I've had my ISO on 100 all day because it's my understanding that the ISO is nothing but a digital tool built in order to enhance the light digitally in order to take pictures in very low light.

So the question, the actual question is then: I am to adjust exposure using my shutter speed and aperture only, and ONLY if it's neccesary do I go over 100 ISO?

Answer from Derrel: NO, this is not correct. Absolutely, 100 percent NOT correct. Unless you have a d-slr that was made Before the Flood, feel free to move up, and away from the camera's base ISO by one, or two full values, ie, from 100 to 200 or 400, with very little in the way of actual, visible noise penalty. What **is** imperative, is to get an exposure that "works" for the situation. Many,many,many,many times the ISO 100 shooter will be stuck making perfectly exposed, low-noise, full dynamic range, perfect smears. If ISO 100 causes your shutter speed to be stuck at 1/60 second, and the lens wide open, then ISO 100 is going to be robbing you of motion-stopping ability, robbing you of optimal optical quality due to a wide-open lens, and also limiting the depth of field available to cover any focusing errors. In other words, using ISO 100 because it has "the lowest noise" or "offers the best technical image quality", is in many real-world situations a huge,huge mistake. ISO 100 also drains flash batteries more quickly, limits how far a flash is effective, and tends to make the background of flash photos "inky" and dark. ISO 100 carries with it many,many limitations for the photographer and the equipment. In boating photography for example, ISO 100 is often an absolute disaster waiting to happen, and ISO 400,500,or 640 can be much better.

Question 2.

The point of exposure.

I noticed that I could adjust my shutter speed and aperture to many different combinations and still be able to fine tune it into a perfectly exposed shot. So that got me thinking... is that the point in all pictures? Fine tune your shutter and aperture to get a perfect exposure for the picture? Or do you use too high or too low exposure in some pictures to get some sort of effect?

Yes, there are MANY equivalent exposures. Let's say we are at ISO 100; f/2.8 at 1/500 is equal to f/4 at 1/250 or f/5.6 at 1/125 or f/8 at 1/60 or f/11 at 1/30 or f/16 at 1/15. In this real-world case, let's say I am aboard a charter fishing boat, salmon fishing in the Pacific Ocean with a 2-foot wind chop, with the wind out of the Northwest, gusting to 12 knots, on 9 foot swells, spaced 20 seconds apart. Okay...we want to get some "action" shots of the anglers bringing in salmon, with at least some hint of the fish in the water at 10-20 feet behind the boat, where they typically will come up and jump, roll, or slash. Well, f/16 at 1/15 second is gonna be a PERFECTLY EXPOSED SMEAR with the chop, and the swells,the wind gusts, and the speed of the fish slashing around...but by the same token, using f/2.8 at 1/500 second kills the depth of field, which becomes very shallow, and 1/500 second is the bare minimum speed that works on a boat in rough seas. So....what do we do...we BOOST THE ISO VALUE!!!!

So starting at a slightly faster exposure of ISO 100 at f/11 and 1/30 second, because f/16 at 1/15 is just simply a ridiculously slow speed to start at, we notch the ISO value up, from 100 to 800. That way, we get f/11 at 1/250 second. Or f/8 at 1/500. Or f/5.6 at 1/1000 second.
Using a shorter lens, like a 28mm on FF, f/5.6 at 1/1000 second will stop motion, and give amply deep depth of field to capture both an angler at the rail, and his catch below at the water's surface, all with stop-motion capability, and with the ability to stop the movement of the boat in the chop, the wind, and the ocean swells. You will NOT see much noise at elevated ISO settings using a modern d-slr **unless** the exposure is under. On a good, generous, properly-exposed and well-lighted marine scene where there is plenty of water to refelct light as fill-in, there are almost NO SHADOWS close to the side of a 40-foot boat...and so there is almost no chance of dark,underexposed areas showing noise.

 

[Kerbouchard]

There is something called an exposure triangle. There are three parts to it. Shutter Speed, Aperture, and amount of Light. That is exposure.

ISO is a means of amplifying the signal that the sensor records while it is still in an analog state prior to it becoming digital data. Like any circuit, there is noise or electrical interference. Like any amplifier, it doesn't know or care what it is amplifying. Therefore, when you amplify the signal, the digital noise becomes more pronounced.

Now, all that being said, cameras and software have very sophisticated noise reduction algorithms, and it is often advisable to boost your ISO in order to use a faster shutter speed or a larger depth of field, even knowing that some noise will be introduced. A noisy photo is better than a blurry or out of focus photo.

On the flip side, some high end DSLR's have so little electronic noise that there is almost no difference between upping the exposure in post processing or increasing the ISO prior to the shot. The primary difference being when you are shooting, you don't have a reviewable picture to be able to see the final result.

I often shoot at ISO 2000 to get the shots I need to get. There is nothing wrong with boosting your ISO from base when you have moving subjects or you can't stabilize your camera to have a long shutter speed. But, and it's a big but, before I move to ISO's above 800, I do my best to add light via flash and add stabilization via a tripod.

The most important thing to remember when shooting at higher ISO's is to make sure you have a strong signal for the sensor to work with. This is often referred to as a signal to noise ratio. I can easily take a shot at ISO 2000 that has less noise than a shot at ISO 200. It all depends on how much good data the sensor and electronics have to work with vs the bad data that is the electrical interference. There is a technique referred to as 'ETTR', or expose to the right. That basically means to come just on the brink of overexposing every photo you take, and then pull it back in post processing. This allows you to use your sensor to the best of it's capabilities, minimizing noise and extending dynamic range.

Not saying you should adapt it, as it is more work, but again, the trend is there. Make sure your sensor has the most amount of data possible so that it can generate a good signal. It will make you a lot less afraid to shoot at ISO 1600 or higher.

There is a reason why most noise appears in the shadow regions of photographs...there wasn't much of a signal there to work with in the first place.

 

[Fleetwood271]

I suggest you go to the Adorama Learning Center at:

Adorama TV from Adorama Learning Center

Scroll down and look on the left side for videos on subject that you are interested in. Most are only 6 to 10 minutes long and they are FREE!

For example, this one on Exposure is very good:
Exposure
It covers the Exposure Triangle that someone mentioned above.

Here is one on Understanding Stops:
Understanding Stops: Adorama TV from Adorama Learning Center

Enjoy!

 

[KmH]

There is something called an exposure triangle. There are three parts to it. Shutter Speed, Aperture, and amount of Light. That is exposure.

ISO is a means of amplifying the signal that the sensor records while it is still in an analog state prior to it becoming digital data. Like any circuit, there is noise or electrical interference. Like any amplifier, it doesn't know or care what it is amplifying. Therefore, when you amplify the signal, the digital noise becomes more pronounced.

Now, all that being said, cameras and software have very sophisticated noise reduction algorithms, and it is often advisable to boost your ISO in order to use a faster shutter speed or a larger depth of field, even knowing that some noise will be introduced. A noisy photo is better than a blurry or out of focus photo.

On the flip side, some high end DSLR's have so little electronic noise that there is almost no difference between upping the exposure in post processing or increasing the ISO prior to the shot. The primary difference being when you are shooting, you don't have a reviewable picture to be able to see the final result.

I often shoot at ISO 2000 to get the shots I need to get. There is nothing wrong with boosting your ISO from base when you have moving subjects or you can't stabilize your camera to have a long shutter speed. But, and it's a big but, before I move to ISO's above 800, I do my best to add light via flash and add stabilization via a tripod.

The most important thing to remember when shooting at higher ISO's is to make sure you have a strong signal for the sensor to work with. This is often referred to as a signal to noise ratio. I can easily take a shot at ISO 2000 that has less noise than a shot at ISO 200. It all depends on how much good data the sensor and electronics have to work with vs the bad data that is the electrical interference. There is a technique referred to as 'ETTR', or expose to the right. That basically means to come just on the brink of overexposing every photo you take, and then pull it back in post processing. This allows you to use your sensor to the best of it's capabilities, minimizing noise and extending dynamic range.

Not saying you should adapt it, as it is more work, but again, the trend is there. Make sure your sensor has the most amount of data possible so that it can generate a good signal. It will make you a lot less afraid to shoot at ISO 1600 or higher.

There is a reason why most noise appears in the shadow regions of photographs...there wasn't much of a signal there to work with in the first place.

What he said....↑ ↑ ↑ ↑

Pertinent to his last sentence you may want to read: http://www.adobe.com/digitalimag/pdfs/linear_gamma.pdf

 

[Kerbouchard]

Keith and I seem to agree on something...OMG, that pastor was right! The world is coming to an end.