Confused With ISO

SydneyBrewster

Hello! I'm so glad I found this website because I want to take photography seriously, but I'm have trouble with using ISO and knowing when I should be changing it. I recently was trying to take a picture and it came out with a bright white light over the image. Any suggestions?

bruto

It's hard to know what the problem with an image is without seeing it. The problem may have more to do with a scene exceeding your camera's dynamic range, or with flare or other problems than just with ISO.

However, it's true that ISO, especially in the D3200, can be a little confusing. It operates differently in the different modes. Sorry it can't be explained in a few words, but I will try to be concise at least to start.

First of all, in Auto mode you cannot control ISO at all. In scene modes, ISO defaults to Automatic, but you can choose a single manual ISO. When it is in Automatic, you have no input at all. It chooses. When you manually override it, the manual setting prevails whether or not the exposure is right. In P, S, A and M modes, Auto ISO is the default, and you must go to the menu to turn it on or off. You'll notice that the "auto" entry is grayed out in the ISO choices. It has a completely different meaning here.

In P, S, A and M modes, "auto" ISO starts with whatever ISO you have manually chosen, and the camera changes it as required to maintain proper exposure. In other words, unlike the scene modes, you should choose a starting ISO. If the shutter speed goes below a certain point in P and A mode, or if the aperture goes below range in S, or if the exposure goes off in M mode, the ISO will change. You get a choice of where to start, but unlike the scene modes, you cannot override auto ISO without turning it off.

You can set a maximum point to which Auto ISO will rise before it quits, and a shutter speed at which it initiates (in the menu). Not made clear in the instructions is that if you are in Auto ISO mode, you cannot manually choose an ISO above the max you've set. It will show in the display, but it won't be used. I generally do not use auto ISO, but as a rule you should experiment with high ISO to determine what level of noise and edge degradation you can tolerate, and set your maximum not to exceed that. If you regularly use a VR lens, you may also find that you can reduce the shutter speed point, since it defaults to 1/30 second. That's a good safe point most of the time, but a wider angle VR lens can go lower.

When you are using Auto ISO, the display will not show what ISO the camera has chosen. The ISO will flash in the display to show that it's being overridden, but the choice is not shown. Auto ISO can choose finer increments than are available in manual. You can find out what it actually was by opening the EXIF information in playback (enable "overview" in the playback menu for a useful display), where it will be shown. The number is in red if auto ISO kicked in.

In any case, whether you use auto or manual ISO you should generally always try to keep it as low as possible, as noise, clarity and dynamic range are best at low ISO. If you're using Auto in the P, S, A and M mode, there is essentially no down side to setting it at 100, as the camera will raise it if needed, but will not lower a higher one if it can get the exposure.

With regard to bright light over an image:

If the light is a bright spot, chances are you've got a blown out spot caused by overexposure. This can happen when a part of the image is much brighter than the rest, and your meter is trying to expose the darker parts correctly. Some of this may be unavoidable. Some can be controlled either by composition or by exposure compensation.

If it's a haze over the whole image, it's likely to be lens flare. Make sure you use a lens shade whenever possible, and watch out for oblique light. The kit zoom lens is actually pretty decent with regard to flare, but you'll get some flare when you shoot into light, and more when bright light comes obliquely into the lens. To eliminate flare, try to keep the light behind you and above you.

SydneyBrewster

Wow! Thank you so much!! That really helped. Is it okay if I ask you a few questions regarding other things?

bruto

You can ask. Quality of answers not guaranteed, but there are others who know stuff I don't, so by all means, ask.

SydneyBrewster

Okay. My ultimate goal is to learn how to take an image of running water with the water looking as if it's foggy, if you know what I mean! I know that has a lot to do with shutter speed, so if anyone is willing to help that would be great!

bruto

OK, that one is pretty simple really. It does indeed have to do with shutter speed, and in normal light you're going to be hard pressed to accomplish it. You need to set your ISO at its lowest point, and your aperture relatively small (higher F number). Above about f/11, you'll begin to lose definition from diffraction (an optical issue about which you can do nothing), but depending on the lens, subject, etc. you can probably get away with going to f/16 or even smaller. You can experiment here.

You will need a tripod, as your shutter speed will probably be slower than the lens's VR can handle.

If you shoot in Aperture priority mode, with Auto ISO turned off, the camera's meter will set the slowest shutter speed available. Chances are you'll get a certain amount of motion blur from the water, but it won't be right up there. At shutter speeds below about 1/4 second, water will lose definition. Waterfalls and the like will smooth out, but slower water, and waves, won't get that creamy look unless you go slower.

If you want the full effect, you will need to add a neutral density filter to the lens, to darken it more. Check out the internet to see what's available. You can go to about 4x without seriously compromising the camera's ability to function. Much above that, you will probably have to focus with the filter off, switching the lens to manual before you shoot, and then put the filter on, because the camera will not AF well when it's too dark.

Be careful not to move the lens's zoom too much when manipulating the filter, because most zooms these days will alter focus a little when zoomed.

If you're shooting on a tripod, it may be possible to get a square filter rather than a screw in one, and just hold it in front of the camera. Use the self timer to control vibration, but remember that the self timer will operate, or attempt to operate, the AF, so if you're using a filter that's very dark, you should probably turn off AF before you try to shoot.

In the matter of personal taste here (about which one can always argue) I would suggest you don't overdo this. I think motion blur in water has become so common it's overdone. Getting some blur in fast-moving water such as streams and waterfalls often makes a picture look better, and conveys the sense of motion, but I think often people go too far and that creamy smooth surface loses its novelty after a while.

SydneyBrewster

Thanks again this really helped. I agree, but I really want to try anyways just to try new things. Not sure where you live but do you know any places in New York that are great for shooting?

SydneyBrewster

I've been to several sites today to look for a cheap but durable tripods (not monopod), and I'm having the hardest time trying to find one. I'm a beginner if you couldn't tell already, but do you have any suggestions for that? Price is a problem, but I'm willing to pay for something that will lastfor a good time,but doesn't have to be the best. I'm just starting out so I'm not looking for much. If you could narrow it down to two that would be great because all these other places are giving me 19 choices and it's way too many.

bruto

You will find many different opinions on tripods, including the one that you should get the best tripod you think you'll ever need regardless of cost, because you'll end up there anyway, countered by the suggestion that any tripod is better than none. Both arguments have some merit.

One thing I would suggest is that you not stint too much, and that if possible you avoid the abundant cheap ones with square extruded legs, leg braces, "pan and tilt" video heads, of the sort that you can find at chain stores. A pan tilt head does not tilt sideways to level horizons, so to get a level horizon you must level the tripod itself. That's necessary anyway if you're panning video, but if you're shooting single shots it's far more convenient to level the camera.

A good tripod is going to cost you some. These days, there are many Chinese brands that have brought the price for features down, but they're still not really cheap. The main thing I'd be looking for at this point is a head that allows horizontal leveling - either a ball head or a three-way head; legs that are easily adjustable for spread as well as height; a quick release on the head, preferably the now nearly generic "Arca Swiss" type. With this kind of setup, you have a plate that is left on the camera, which attaches quickly to the tripod. It makes use much quicker and more convenient, and when properly done more secure. You'll almost always have this with a ball head. Some cheap video head tripods have quick releases too, but it may be hard to find extra pads later, as they are not standardized. "Arca Swiss," originally introduced by the very expensive Arca brand, has become a kind of standard, and is shared by not only the most expensive makers of ball heads and the like, but by most of the Chinese brands.

Just what you can find will vary with where you are shopping, but one other factor is that it helps to have a tripod you'll actually be willing to take with you and use. I've got a huge, heavy, wonderful old Manfrotto tripod, which I use often, but I also often find myself not using it because it's so darn big. There are some newer designs that are very small and portable while still being sturdy and well built; Sirui, Mefoto, and others. You'll pay some pretty serious coin for the best of these, but if you can, try one out and see how it works, because a well made travel tripod is something you can have handy all the time.

In addition to the big old tripods, I also have a little Sirui travel tripod, and it works very well. It looks small, and the ball head is small, not suitable for big telephoto lenses and the like, but it holds the camera reasonably well, and it's so handy I throw it in the car every time I go anywhere. I got mine at a yard sale, so did not have to pay the stiff price for a new one, but it's really very useful and worth saving up for something similar.

Whether or not you buy from them, I suggest you check out the B&H site for information, because their information is very complete, and they carry a lot of different brands. They also have good service and prices. There are others too, but B&H listings are very informative.

Ideally, I'd decide what size and weight are reasonable first. Don't worry much about capacity, as nearly anything other than the obvious mini stuff for iPhones and the like will be adequate there. Avoid video heads, ball heads are pretty versatile. Three way heads are nice for landscapes, less so for action, and tend to be less portable because of the protruding handles. Independent leg spread is very nice if you are on difficult terrain, or if you like to do macro work with the tripod low. Braced legs seem like a good idea, but except on the bigger tripods they're usually a sign of cheap construction. The best small and medium tripods don't need them.

Cruise the internet a little, too, if you have time, and see if there are any other reviews, opinions, etc. You'll run into a lot of tripod snobs there who are convinced you should run right out and get a $700 tripod, but it's worth looking around.