Understanding ISO

DannyFilming

So far I've only ever used an ISO of 100 on my camera because I find that the ISO really doesn't do anything but brighten up the photo and decrease image quality. I've heard about certain "sweet spots" with the ISO and I think this is something I should know about.

1. What are the ISO sweet spots on the Canon 60D?
2. What kind of situations should I use a low ISO (say if the sweet spot is 100)
3. What kind of situations should I use a high ISO (say if the sweet spot is 800)
4. What is your experience and opinion on ISO? Right now I am highly uneducated on the matter and my opinion on it is that ISO is cheating and inhibits creativity.

Thank you for your answers.

PBked

Hi again @DannyFilming - I have never heard of sweet spots regarding ISO. On a sunny day outside 100 ISO will give you the best quality pictures, but you could also use ISO 200 because the difference in quality is negligible.

ISO doesn't just function to give you a brighter picture, it also helps to raise your shutter speed so that you can still get a shot in low light for example.

Aperture, shutter speed and ISO all work together to give you a proper exposure. One function on your camera which is highly useful is the Auto ISO function.

In basic Auto mode this is what is used for choosing ISO. However, in creative modes P, A, S and M you can set your ISO to Auto.

I usually limit my auto ISO to 800, but even 1600 is useable. Anything from 1600 and up tends to produce a lot of noise and soften picture detail considerably.

Below I have put a little scale if you wish to set your ISO manually, it is only a general guide.

Bright sunny day - 100 or 200 ISO
Dull or overcast - 400 ISO
Very overcast or low light - 800 ISO upwards

Hope this is of some use. Regards, PBked

P.S. ISO is a standard from the days of film and was a measure of the amount of grain (speed) of a roll of film. Many photographers who developed their own film stock would often 'push the speed' of the film in processing to be more creative. So it's not cheating at all. Fiddling with ISO can be in fact quite creative.

Moose

@DannyFilming - It sounds like you might be getting the "sweet spot" term confused. That term is generally used when talking about lenses. Most lenses have an aperture range that produces the sharpest results, hence the term "sweet spot".

ISO is the image sensors sensitivity to light. In situations where you have plenty of light, an ISO of 100 is the ideal choice. However in low light situations, it's critical to use higher ISO's in order to freeze subject movement and/or to reduce the effects of camera shake.

Here's a general guideline...

Moving subjects (people, animals, etc...):
100 to 200 - Bright daylight
200 to 800 - Overcast, dawn, dusk
800 to 3200 - Indoors, low-light

Still subjects/scenes (hand-held)
100 to 200 - Bright daylight
200 to 800 - Overcast, dawn, dusk
800 to 3200 - Indoors, low-light

Still subjects/scenes (using a tripod)
100 - Bright daylight, overcast, dawn, dusk, indoors and low-light

Happy shooting! :)

DannyFilming

Are you telling me that the ISO sweet spots depends on my lens and not my camera?

Because if that's what you're saying then are you also telling me that this video is incorrect? I just set my ISO to 160 and planned to keep it there.

PBked

Hi Danny,
As far as I am concerned this video is a complete and utter waste of time. For starters video mode is being used on the 60D but at what resolution? Secondly, the author mentions using 'levels' which as anybody will know has a great effect on the quality of a picture. Thirdly, how often are you going to be taking pictures of a black cat in a coal cellar at night?
As I tried to explain in my post above, ISO was a standard measure of a film's emulsion (the chemicals on the film) sensitivity to light. In this digital age, we can increase or decrease the sensor's sensitivity to light by using the ISO. With this video, I pose the question "How can you possibly measure the sensor's sensitivity to light by filming the inside of your lens cap?" I rest my case!
Look at Moose's guidelines if you want useful information about ISO.
Regards,
PBked

DannyFilming

I stand ISO corrected. Thank you both

Vinylspider

If you increase the ISO you'll get your image faster so you can make your shutter speed higher for a crisp image of a moving scene. Conversely you may actually want a little motion blur but for artistic reasons you've got a wide open aperture and you want a slower speed. Altering the ISO gives you a third factor to play with to get the exposure you want if the aperture and shutter speed are fixed.

The other effect you'll see when you up the ISO is image grain, which again you way want for artistic reasons.

Finally, if you set the ISO too high, especially on lower quality cameras, you'll get more noise in the image. I've not had my 60D long, but from the specs I don't expect noise to get problematic until I hit ISO 1600 or higher.

poshpixel

I've seen this sweet spot video a thousand times and while it initially looks like it is something, it is not. Unless you plan to make a hobby or turn professional by lens cap videography then ignore it completely.

I am an old guy who used to take pictures using film! In addition I actually went to college to become an x-ray technologist. Although x-rays and photography seem different, they are very similar, including ISO, which measured film speed on all film. As stated above, ISO used to mean the size of silver halide crystals in the emulsion attached to the film base. But digital images no longer need film, so the term ISO was simply switched to measure image sensor capability. As a side note, I think ISO sensors on cameras in a few years will be eliminated because the auto functions take care of it and manually setting ISO adds to the confusion.

With that being said, you have your three basic functions on a camera. First is the amount of light getting to the sensor which is controlled two ways (size of aperture opening and length of exposure and ISO setting).

As far as light getting in you balance the size of the hole f-stop/A (aperture opening) with the amount of time the hole is open, time/T. If you do the math there are lots of combinations to get the same amount of light to the sensor. Big hole plus short time equals little hole plus long time. Obviously, there are issues of motion and artistic issues.

The other issue is the ISO setting. As stated by almost everyone, the basic rule of thumb is the same as when film was used; the lower the ISO the better the quality exposure. Honestly, unless you plan to re-print your pictures at huge scale for sale there is very little difference between 100 to 400. After that, a whole range of issues can kick in, both artistically and photographically (including contrast, image sharpness etc). If you are taking pictures of the family to post in Facebook then think more about composing a good picture than the technical settings.

Back to the video. If you check out the post you'll see it is some kind of start up foreign videography company with a website that is still under construction. Heck, my website is under construction too and I'm not telling anyone about how their gear works. Well technically I am, but you know what I mean.

Most people think too much about megapixels in their camera and not about proper lens use or taking a second to make pictures look nicer by employing a little thought. Modern techno-phobes get hung up on technical specifications so they can talk about vignetting at high ISO when they never print their work and only look at photos on their laptops. What about the quality of their laptop monitors (LCD, LED, which brand, how old, what size, do they wear glasses)?

Digital photography has made a lot of older people like me completely nuts. Better to spend $10 on a book (a real paper book) to learn how to pose subjects than to spend $2,000 to upgrade to a canon L series lens. A proper photographer can get a better picture with a decent camera phone than any wannabe can with $10,000 worth of equipment. Think back to the wild west when photographers had one shot, literally, to get it right. Are those pictures any less awesome today because they are a little grainy?

Forget the hard stuff and concentrate on the easy stuff; people, places and things. Happy Shooting!

And I know I haven't updated my own website in a year because I still haven't found studio space that's right and I have been shooting on locations with other fun ideas that have nothing to do with ISO settings. Go look at interesting people and interesting places and make good pictures. Read a few books too!