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Understanding the exposure triangle


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I shoot on the Nikon D7200. I have a 35mm sigma art and an 85mm 1.8. I have been shooting for many years and have been doing it wrong. I have watched a complete video to learn my camera inside and out. I have changed my ISO to auto. I have my aperture at 2.8 most times but can never decide the f stop. I know that the more people in the image the more stops I move the aperture if they are not in the same plane of focus. How do I decide the f stop? I know that if my subjects are moving I want to go up to 1/500 and so on. If I'm shooting with say 85mm I want to be at least 1/160. I gave it a try today. It is very cloudy out. I have my auto ISO on, f/stop 1/250 to 1/320 not sure why, and 2.8. My white balance is auto. What am I missing?

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You are missing a lot. :)

With Crop Cameras and that Angle of View change, it is WAY more forgiving when it comes to the Wider (or more open) Aperture Settings. You can practically "f/2.8 All the Things." without much thinking. You can't do that on a Full Frame camera and you will need to know your Aperture Values / Reciprocals. There isn't one rule for everything, it's something that you learn as you go. That said, I can give you some guidelines.

Think of your DoF like two invisible walls. One in front of your subject and one behind. The closer you are to your subject and the wider / more open the Aperture, the shallower the Depth of Field, meaning the fuzzy Wall in Front and Behind your subject are closer together. You can really see this in person with a 50mm 1.8 or your 85 1.8. Set your Aperture to 1.8 and photograph something relatively close. Keep in mind that all lenses have a "Minimum Focus Distance" meaning the closer you get, the more the lens will fight you trying to lock on focus until you take a step or two backwards.

You are on the right path, with subjects on different focal planes. The higher the number, f/4, f/5.6, f/8, f/11, f/16, f/22, the further the two "Fuzzy Walls" are apart. and the more that's in focus, with limitations. I can say this, f/8 is the "I Don't Care" Aperture setting. This is the Photojournalist's Setting; meaning it gets most of your subjects in focus, even if they are on two different focal planes, or could be a "walk-around" Aperture Setting. I've also seen the phrase, "Switch to f/8 and be there..." or something along those lines. f/8 works really well for landscapes, in addition to f/11. I used to use f/8 all the time, but I now use f/11 on my "Big and Wide" Landscapes. f/16...that's where lenses start to develop something called "Diffraction," meaning the Image Quality starts to decline. This issue is more pronounced at f/22, but it really depends on the lens. I have used f/22 on purpose to get those "Starburst" shots. Here is an example of mine:

While the Tram-Car Sleeps

While it's great that I got the "Starburst" from the lamps while using f/22, if you look closely, the image is a tad bit soft. That's the Diffraction messing with things. Some lenses are better, others are worse when it comes to this sort of thing. It goes back to the "Knowing your Gear" phrase that I kept going on-and-on about. You just can't half-ass it and click the button. I don't give a shit if it's a "...really nice camera." It doesn't work that way, as you are finding out. :D  

Granted, that photo was taken years ago, and I my technique has improved greatly; I also have better equipment and better lenses. With the exception of the Tripod. I still have the one that I used for that photo and when I took that photo it was a long-ish exposure and people were walking on the boardwalk, which shook a little. Plus it was a bit Windy. Excuses aside, I might take another crack at that photo and see if I can produce a better shot.

OK, back to your original question. Let's review from FB Ask Damien. Depth of Field consists of 5 main things:

  1. Aperture Value
  2. Focal Length of the Lens
  3. Distance from the Camera Sensor / Film Cell to the Subject
  4. Distance between the Subject and Background
  5. Sensor Size.

f/1.2 - f/1.8 - This is the Bokeh shots that are all the rage. You want the Mom with the preggo belly and the greenery behind her blurred out, these are your Apertures. They take practice and time to really nail down. You buy a f/1.2 lens to be "sharp" at f/1.8. f/1.8 lenses are MUCH better at f/2.2. Why? Because the DoF is so Shallow. These are single subject Aperture Settings for the most part, otherwise you need to stand farther away from your subject if you want to get multiple people in focus. For example, say there is a couple posing for Engagement Photos. You want a Fuzzy Background where the trees / plants are, but want the two people to be in focus. To accomplish this, you need to pay attention to #1, #3 AND #4. Hell, #2 shouldn't be discounted either as something called Compression makes people / faces look better. A person's Portrait will be much better at 85mm than at 35mm. To get that f/1.2, 1.8, etc. Setting, you need to be far enough away from your subject, AND the subject needs to be far enough away from the background. See how everything is interconnected? Lots of thinking is involved, this is the Theory that one must know; the other side of things is "Craft," that's where your instinct or "feel" comes into play. That comes from knowing your theory inside-and-out AND knowing your gear. Very similar to a Musician playing on a stage. They aren't thinking, "I'm about to play a A-Flat Minor Pentatonic Scale for this Solo," or "I wonder if I should play a Major Seventh add9 here?" No, they are live on stage, it's about "Feel" and what sounds "Cool."

f/2.0 - f/2.2. Still in the area of f/1.8, but more forgiving. f/1.8 lenses will be a tad bit sharper at f/2.2. DoF is easier to manage. Still takes practice.

f/2.8 - I typically use f/2.8 if I want shallow DoF, but if I'm standing a bit close, I might stop down to f/3.2 to give me a little more "wiggle room." The closer you are to your subject, the shallower the DoF and the more you will notice that's out-of focus. You could take a 50mm 1.8 lens, set it to 1.8 and get really close for a head-shot type of photo, but their head is turned ever so slightly. Which will make one eye in focus and the other one not. So unless you take a step or two backwards, or stop down your Aperture, you aren't going to get both eyes in focus. To further illustrate, one eye is in focus, one is not, BUT the Cheek in front of the eye that's in focus will be blurry. That's the Fuzzy Wall in front of your subject that I'm talking about.

f/4 - I use this Aperture ALL THE TIME with my Weddings. Since I'm shooting with a Full Frame Camera, I don't have the "Forgiveness" with f/2.8 like you do. f/4 for me is like f/2.8 for you; it's about a stop difference. Getting Ready shots, really tight / zoomed in photos of the Groom with an ugly-cry face, I will be at f/4. BUT! At f/4, the Groom will be in focus, but the Best Man behind him will be blurry since they are on two different focal planes. So I will have to stop down to f/5.6 or maybe go to f/8 or EVEN F/11, depending on where I'm standing and what focal length that I'm at. It varies A LOT and it takes practice and experience.

f/5.6 - This is the "Grab-and-Grin" Aperture Setting. Great for the table shots at receptions. Wedding Cake / Details Shots. The photos were you get a few people huddled together and get them to say cheese. f/5.6 is more forgiving for people that are front to back, and works well for the majority of these shots. Have someone looking to photo-bomb from the rear? Then you stop down to f/6.3, f/7.1 or even f/8. That moves the two DoF Field walls further apart, front-to-back, so you get more in focus.

f/8 - I covered this above. The "I don't care..." Aperture Setting. Easiest Aperture to learn. Great for Landscapes and all sorts of things. Perfect for learning to use a Macro Lens (that's a whole other subject,) works for group photos as well. Swiss-Army Tool as far as Aperture Settings go.

f/11 - An extension of f/8. I find that lenses are sharpest at f/8, but have the best contrast at f/11. Meaning the overall look of the photo is better, especially with Landscapes. More is included and I use f/11 a lot. f/11 also works really well for group shots 3-4 rows deep. I'm aware of a saying from a Mom-Tog Group, "Eleven sets of eyeballs, use f/11." While that won't work if they are standing in a single row, you could be at f/5.6 and get a great shot, I will admit it does get you thinking. "Hmmm....large group. Family Tree Type of Photo. Better stop down to f/11 to cover my ass. Might try a few at f/8 as well. 

f/16 - This is where I tend to stop with my photos. Deep DoF with my Landscapes, more-so than f/11. Image Quality starts to decline. If I'm using really high-powered lights / flash, I might use f/16, but that's even a little extreme if I have my lights that high.

f/22 - This Aperture is used when I have a purpose to use it. Like if I want starburst lights. This Aperture setting is the easiest to use to get those type of shots. If I'm in a really-REALLY bright situation and have no choice, I will use f/22. Basically, this is the last Aperture Value you learn how to use. Master all the other ones first. THEN play with this one. Same thing with f/16, but that's easier to play around with. Again, f/22 is even worse Image Quality-Wise than using f/16.

Now, if your eyes haven't glazed over by now, I have some additional reading for you. I want you to purchase this book from Amazon:

Understanding Exposure by Bryan Peterson

This book by far covers everything that I've written and goes into more detail. Not only with Aperture, but ISO and Shutter Speed. This book is the one that most Photographers own and where they start. I realize you are a Video Person, but there is something about a book, you can stop and re-read things to get it in your head. With a video, you are constantly pausing and going back trying to keep up. This shit takes time. You are not going to get this stuff in a Video or two.

On 4/4/2023 at 3:45 PM, snelson said:

It is very cloudy out. I have my auto ISO on, f/stop 1/250 to 1/320 not sure why, and 2.8. My white balance is auto.

This is that part of "Learning to See the Light" that I was talking about. You aren't necessarily in "Cloudy" conditions, but depending on the light, you are inside a big "Softbox" and don't have a lot of contrast or shadows to work with. Cloudy Conditions mean very even light. With Digital Cameras, you need to be double what your focal length is. So if you are using your 85mm, you want to be around 1/160th or preferably faster, like 1/250th or 1/320th. This cuts down on camera shake which can result in blurry photos. That said, the higher the Mega-Pixels on your Camera's Sensor, the faster you need to be, usually 1:4 Ratio instead of the standard 1:2. Why? Because so much detail is recorded by high MP Cameras, you need to be faster Shutter Speed-wise to compensate. Or use lenses that have Vibration Reduction Technology to compensate. VR Tech is awesome. Here is a hand-held shot of mine I joking call, 

Not Bad for Hand-held.

That shot was a single exposure, hand-held at 1/10th SS | f/11 | ISO 100 @ 32mm. Vibration Reduction Technology is amazing in certain situations. :)

Why f/11? Because I wanted 1/10th to make the Waterfall "Silky" and I needed to cut the light hitting the sensor. If I was mounted to my tripod, I might have been at ISO 64 | 2 Second Exposure | f/16 or f/22.

Now, you have to remember, the "Middle' Mark in your viewfinder is what your camera considers 18% Gray. It's the "Most Even" Exposure the camera's software thinks is correct. Often, middle can be the most boring and your exposure really depends on WHAT you are shooting and WHEN. (Along with the Lighting Conditions.) So don't always think your camera knows best. If you are looking for more dramatic and eye-catching shots, you need to be in all sorts of different places on your meter, combined with certain editing techniques in ACR / Photoshop to really put a shine on things. Same thing with Auto WB. That's what your camera thinks is correct, but often it is not. Unfortunately, I can't go much into this subject, because it's covered in the Raw Class. Same thing with the "Learning to Shoot in Manual" courses, where Kim goes way into more detail that I do.

Hopefully this at least put you to a Starting Point. Get out there and fiddle and take notes. THINK before you click. Look at the entire scene, pay attention to what the shadows are doing, what the quality of light is. Meaning is it Hard or Soft? Is there a bit of Glow or is it just icky? Then take a photo. Do not shoot 200 photos and get frustrated. One at a time. Again, THINK BEFORE YOU CLICK. Then do it again. And again. And again. Take notes if you have to with a pad and paper. Remember, this is digital, you can afford to experiment. Back when I started, we didn't have a LCD, hell...we only had one focus point and only 36 tries to get it right. If you blew it, you didn't know right away.

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