Confused about ISO

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digifruitella

Active member
Hey, I took my T2i for a run on a boat ride today, and the sun was going down, hit twilight etc. I was a bit confused about ISO, so late on I just left it on AUTO and it did good.

However, my main question is, and ultimately something I need and MUST know in the future is when to boost this up.

As with the example of a sunset...

obviously I can't leave the ISO on a 100 all the time when I'm shooting video. Is there a general rule of when to raise it up and to which markings?

I get that in night/low light, it's pretty much an imperative to raise the ISO to, say 6400 or whatever the number is.

But for instance today, I was shooting in low light, and with my eyes - I saw everything dim, but with the ISO really high, and the aperture to 1.8 - with the exposure telling me it's CORRECT...it was significantly brighter than what I saw...

this is something that is bothering me, as I would like to translate what I see with my own eyes into videos I shoot.. what am I doing wrong?

Can anybody help? ask me for more info if this doesn't make sense. I really want an answer to understanding ISO and maybe even proper exposure techniques.
 
Uh, do you have a light meter? Don't guess, get a Sekonic. You will need one eventually.
http://www.sekonic.com/products/#
Woops, saw you are using a DSLR.
You cannot trust your eyes unless you have been doing this your entire life. Do you know about average or spot metering.
Start learning basic photo/cine exposure. TTL metering is great if you know what you are looking at. Try getting a gray card to meter a scene.
 
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Firstly, I do not mean this response to sound harsh in any way. I have a lot of respect for people who are trying to learn this stuff and are willing to ask questions to improve their work.

That said, more than anything else I've noticed about the DSLR revolution, is that it's showed up and exposed shooters who have no background in photography. I would estimate that 90% of the questions we see regarding shooting with the cameras are things that are covered in a first year photography course.

As DadinWinchester has noted, the answer here is a light meter. But that is hiding the point. The point here is that there is a general lack of understanding of exposure and the relationship of Iso, shutter speed, and aperture.

To the original poster I would strongly suggest two courses of action.

A. I would suggest signing up for a photography course at your local community college. Everything you learn there will apply directly to video. It will answer a great many of your questions and give you a wonderful level of confidence behind the lens.

B. I would suggest spending some time on your own taking photographs. Treat the camera as though it had film in it. ISO 100, ISO 400, ISO 800. 100 for outdoor sunny conditions, 400 for outdoors without a lot of sun, or well lit indoors, and 800 for indoor with natural lighting, or outdoor evening. Then go through the apertures and see what you come up with. Take notes, or I guess you don't need to do that now since we have EXIF data. Sorry, I grew up with film!

These exercises will cost you nothing. When I learned, it costs hundreds if not thousands of dollars in film and processing.

And if you continue to shoot on a DSLR, buy a light meter. The Sekonics are excellent as are the SpectraCine units like I have, and that one's a bit cheaper though not as fully featured.

Best of luck to you.
 
digifruitella said:
[...]this is something that is bothering me, as I would like to translate what I see with my own eyes into videos I shoot[...]
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You mean what you think your eyes see?

Or maybe what your eyes would see if they were not part of the interpretative visual process?

Or reality (whatever that is)?

Just having some fun with you. Kudos for being unafraid to ask good questions. Can't expound on what's been stated so well here. Just that what makes photography (stills and moving) an art is the fact that the tool (the camera) can be manipulated into capturing what we want it to see. However, I don't believe there's any prize awaiting someone who can design a camera that can see the way a human being does. Not that it's possible anyway due to the differences in human visual perception.

Or perhaps when you referred to "[your] own eyes" you meant your mind's eye, in which case you can ignore this post.

If you don't have time for a class, check out Bryan Peterson's Understanding Exposure.
 
Thanks a lot for taking the time to answer. Exposure is something I've been struggling to understand. I have read about it and practiced many times before, even checked out Peterson's book as well.. but the relationships sometime, or most of the time confuse me. I actually am contemplating and probably will sign up for basic photography class on exposure as I just understand it on my own, so hopefully an instructor can get it through my head.

ISO is one thing that messes with me. For instance, I get that the higher the aperture number (the lower the hole) the greater the depth of field you'll get, the lower (wider hole) the more light you get in, and depth of field can become shallow..

as for the relationships and WHEN to use certain shutter speeds and ISO combinations and all that. It's confusing. I just really want to understand this, so I can comprehend it and start shooting manually understanding when and how to properly expose, etc.

Thanks for the input.
 
digifruitella said:
as for the relationships and WHEN to use certain shutter speeds and ISO combinations and all that. It's confusing. I just really want to understand this, so I can comprehend it and start shooting manually understanding when and how to properly expose, etc.
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Maybe this could help... one way to think about it:

Shutter speed: for "regular" feeling motion, always keep this at twice the frame rate (i.e. 25 fps = 1/50s.). If you want stuttery, jerky feeling motion effect, use a faster speed. If you want overly smooth, slightly fuzzy motion effect, use slower speed.

Aperture: Set this to get the depth of field properties you want. Shallower depth of field = smaller f-stop number. Use this to isolate your subject from the background, or just to get that trendy blurry look. Deeper depth of field = bigger f-stop number. Use this to keep more things in focus. Like your subject for instance (shallow DOF is kind of pretty, sure, but it makes proper focusing much, much harder).

ISO: use this to adjust the sensitivity of the camera. If the desired shutter speed / aperture combo results in too dark images, increase ISO (or vice versa). If you can't get the image to look dark enough this way, consider using neutral density (ND) filters.

When you're in the right ballpark, tweak shutter speed and / or aperture to fine tune. Now, some may say that this is an upside down way to look at things, as you mainly use the ISO (or Gain in video camera terms) to control the exposure. They are right, technically speaking gain (ISO) should be kept at a minimum for best results - but with today's low noise sensors, this isn't too big a deal unless you go to very high ISO numbers and this way you get the kind of motion and DOF characteristics you want.

As far as the relations go:

Darken: Doubling the shutter speed = cutting ISO to half = turning the aperture down by one stop.

Brighten: Halving the shutter speed = doubling the ISO = opening aperture by one stop.

To keep the exposure constant you need to compensate one with another, i.e. if you double the shutter speed (Darken), you need to double the ISO (Lighten).
 
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I highly recommend practice shooting without ever looking at your LCD monitor, ever. I came into the photography/cinematography scene just as the transition from analog to digital was going on, but I decided I'd be better served learning how to shoot without a monitor to guide me.

Probably one of the best choices I've ever made.
 
cardmaverick said:
I highly recommend practice shooting without ever looking at your LCD monitor, ever. I came into the photography/cinematography scene just as the transition from analog to digital was going on, but I decided I'd be better served learning how to shoot without a monitor to guide me.

Probably one of the best choices I've ever made.
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Care to elaborate? Why so?
 
It's not the BEST thing to do when the money is on the table and the shot counts... but as far as learning, it demands more discipline and exacting knowledge to understand lighting and ratios without looking at a monitor.

But the downside, however, is that being this familiar with lighting is always a non-exact science, unless you work with the same camera all the time. DIfferent cameras have different ways of reproducing light via dynamic range, latitude, and color reproduction... therefore not only do you need very good knowledge of lighting but you need to have a very good knowledge of the camera you are using and how to light for it.
 
Google Ansel Adams zone system. It is one of the most fundamental and important approaches to correct exposure ever developed for any kind of photography. Learn to use the zone system and an incident light meter that measures the actual light falling on a scene instead of the light reflected back off of it and you will have the tools to experiment with your camera to find the best settings.
Digital photographers tend to treat ISO rather casually as just another variable to dial in. But digital imaging systems will have a sweet spot, a very narrow ISO range, where you get the greatest dynamic range between white clip and the noise floor black level just like film stocks do. When you move outside this range you will lose dynamic range at the top of the scale with lower ISO settings ( greater tendency to clip highlights) and at the bottom of the scale with higher ISO(more noise/grain in the shadows). For cameras like the Canons and many video cameras that add electronic gain for high ISO, you can lose dynamic range at both ends of the scale simultaneously.
 
Yes, a light meter is a valued tool but you must understand the relationship between ISO, FPS and aperture. Changes to any one of these settings directly effects the other settings. You must know the look you are going for and how to manipulate these parameters to achieve your goal.

Read, read, read and shoot, shoot, shoot and make notes about your settings.
 
Razz16mm said:
Google Ansel Adams zone system. It is one of the most fundamental and important approaches to correct exposure ever developed for any kind of photography. Learn to use the zone system and an incident light meter that measures the actual light falling on a scene instead of the light reflected back off of it and you will have the tools to experiment with your camera to find the best settings.
Digital photographers tend to treat ISO rather casually as just another variable to dial in. But digital imaging systems will have a sweet spot, a very narrow ISO range, where you get the greatest dynamic range between white clip and the noise floor black level just like film stocks do. When you move outside this range you will lose dynamic range at the top of the scale with lower ISO settings ( greater tendency to clip highlights) and at the bottom of the scale with higher ISO(more noise/grain in the shadows). For cameras like the Canons and many video cameras that add electronic gain for high ISO, you can lose dynamic range at both ends of the scale simultaneously.
Click to expand...

The zone system is based on using a reflective light meter. If I remember right, the Ansel Adams book I learned it in was quite critical of incident metering. I can somewhat agree, though incident metering does have its uses for more advanced light meter users.
 
Halsu said:
Care to elaborate? Why so?
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It's like learning how to think critically. Once you learn how to do it, it's application can be used in numerous situations.

Other than point and shoot plastic cameras from my childhood, I've never shot film. However, because I know how to use a light meter, and on top of that, the zone system, I wouldn't feel entirely uncomfortable DPing a shoot using a film camera, so long as I had a crew who know how to physically operate it (this also applies to other digital cameras I've never operated). I'm a DP, I direct photography, it's my job to understand exposure, lighting and post processing. It's not my job to know every menu item on every digital camera ever made. There's a reason why professional camera operators exist.
 
cardmaverick said:
It's like learning how to think critically. Once you learn how to do it, it's application can be used in numerous situations.
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Okay - though i still don't fully understand how using a monitor (in other words, checking how the theory works in practice) would slow that learning process down. But cool if that worked well for you.

I'm personally from the opposite school of thought - i light by/for eye/camera, and usually only check the 100% zebra for highlight prevention / ETTR exposure.

I'm personally not a DSLR user (other than for stills) so i don't use the ISO exposure technique i described earlier - i do use reasonable amounts of gain and/or ND though, to get close to the shutter speed / stop combo i'm after.
 
Halsu said:
Okay - though i still don't fully understand how using a monitor (in other words, checking how the theory works in practice) would slow that learning process down. But cool if that worked well for you.

I'm personally from the opposite school of thought - i light by/for eye/camera, and usually only check the 100% zebra for highlight prevention / ETTR exposure.

I'm personally not a DSLR user (other than for stills) so i don't use the ISO exposure technique i described earlier - i do use reasonable amounts of gain and/or ND though, to get close to the shutter speed / stop combo i'm after.
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To clarify, I would check my results, just after I was finished shooting ;) I wanted to get used to doing things blind essentially.

BTW - There is NO right or wrong way to use a light meter. There are endless ways to use them. I personally prefer spot metering highlights (I have my meter setup to compensate for it).

Once upon a time I used to actually use a system that would let me spot meter a location while scouting, and I would be able to calculate how many extra foot candles I would need to physically have fall on the set in order to shoot at the camera settings I wanted to use. I would then use mole/arri photo metric data tables to choose the appropriate fixtures.... Extremely useful for big shoots you can't afford to screw up.
 
I'm not a total noob towards exposure. I mean, I understand "creative exposure". I just am not sure when to boost up ISO, but one person here already gave a general outline.

So getting a light meter looks like is the next step for me it seems. Will this do? http://www.bhphotovideo.com/c/product/200224-REG/Sekonic_401_208.html

The next question I have is my dilemma on how to expose the shots anyway.

Here's a scenario from last night.

I'm on a boat, on a lake. It's twilight. What do I point the camera at? Sky? Water? Horizon? and THEN expose? For this type of scenario... going low in the F-Stop seems to be logical...which is what I was doing. And boosting the ISO seems to be the logical thing to do if you don't want underexposure.

These are type of things I'm having problems understanding.

I shot this two days ago, and I was having the same kind of dilemma

http://www.youtube.com/watch?v=ac3KbmiLEho

as you can see in the first shot, the sky is underexposed - I take it I needed a gradual density filter here... however the other shots of the player's face worked out better as the sky was exposed and the sunlight worked as a fill light.

Either way, can somebody take a look at the video and tell me whats wrong with the exposure there?
 
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digifruitella said:
I'm not a total noob towards exposure. I mean, I understand "creative exposure". I just am not sure when to boost up ISO, but one person here already gave a general outline.

So getting a light meter looks like is the next step for me it seems. Will this do? http://www.bhphotovideo.com/c/product/200224-REG/Sekonic_401_208.html
Click to expand...

That meter is not very useful if you want to learn spot metering. That type of meter simply averages all the tones values it sees when used in reflective mode, so its rather clumsy. This is what I use, but its not a meter for beginners one bit, but just so you know what direction to move in...

http://www.filmtools.com/l758c.html

The white ball is for incident metering, and the little tube shaped viewfinder is for spot metering. This is the type of light meter you work you way up too, to say the least. You can find dedicated spot meters for less money, about $200 if your really serious but on a budget.

Keep in mind that pro (and even amateur) DSLR's already have spot meters built into them.
 
Ok..so for instance what is the limit to how low you should go during sunsets/twilight scenarios.

Another thing. I'm serious, AND on a budget, what is the 200 dollar meter you speak of.
 
This meter has 5 degree spot metering, as well as incident. 5 degrees isn't the best, but its much better than the other non scope meters. You'll find more choices in the $500+ range. Again, if you have a DSLR, don't buy anything, just use that to get your feet wet.

http://www.buy.com/prod/polaris-dua...r/q/listingid/12448280/loc/111/203463188.html

Disclaimer - I've never used the meter above, but it's specs are a closer match to what your interested in.
 
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