A tad bit confused

[mrstravis]

Hi guys, I am reading up on aperture and I am a little confused. So first I will give you what I have interpreted/understood and then elaborate on my confusion. Aperture is basically the size of the opening in the lens that allows light in once the shutter release button is pressed. Larger apertures, where more light gets in, have smaller f-stop numbers and smaller apertures have larger f-stop numbers. So my confusion comes in here: if I wanted to take close up pics say of flowers and such, would I need a lens with a large aperture or a small aperture? I may be completely over analyzing this but the more I think about it the more confusing it becomes.

Thanks, Lisa

 

[480sparky]

Depends on the effect you want. Depth of field, the measurement of how much of the image is in focus (in relationship in the distance from the lens) is a function of aperture. If you want a shallow DOF, you use a small number/larger aperture. If you want a lot of the flower in focus, you would use a large number/small aperture.

Try downloading this freebie, a DOF calculator. You can play around with it on your computer and get an idea how focal length, aperture and DOF are related.

 

[mrstravis]

Depends on the effect you want. Depth of field, the measurement of how much of the image is in focus (in relationship in the distance from the lens) is a function of aperture. If you want a shallow DOF, you use a small number/larger aperture. If you want a lot of the flower in focus, you would use a large number/small aperture.

Try downloading this freebie, a DOF calculator. You can play around with it on your computer and get an idea how focal length, aperture and DOF are related.

Ok thanks. I really think I'm just over analyzing. I'm going to keep reading. Do you use the DOF calculator while you're out shooting or is it something that you just learn with time?

 

[Bitter Jeweler]

f/stops are fractions.

A large aperture is actually a large number, and a small aperture is a smaller number

f/2 is a larger number than f/8.

 

[Aerin328]

"Ok thanks. I really think I'm just over analyzing. I'm going to keep reading. Do you use the DOF calculator while you're out shooting or is it something that you just learn with time?"

You can use a DOF calculator while shooting but realistically you will learn with time. To start experiment taking a picture of a single subject relatively close to the camera and shoot the same subject in a variety of apertures (f-stop numbers- try largest and smallest and in between) to evaluate the difference in depth of field yourself.

 

[mrstravis]

f/stops are fractions.A large aperture is actually a large number, and a small aperture is a smaller numberf/2 is a larger number than f/8.

I think I understand that part although it will be a little difficult to remember. Let's say I have a lens that has a f-stop range of 3.5-4.5. This means that the lens will have a small DOF bc the numbers are small but a large aperture number? Small numbers = small DOF; large numbers = large DOF. But small apertures have larger numbers and large apertures have small numbers. Is this correct?

Is the amount of light entering important to remember when dealing with aperture, bc I think that is part of what is throwing me off. I think I am focusing more on the light than I am the actual DOF.

Please forgive me if I sound like a complete moron, just trying to completely understand before I continue reading.

 

[480sparky]

Ok thanks. I really think I'm just over analyzing. I'm going to keep reading. Do you use the DOF calculator while you're out shooting or is it something that you just learn with time?

I don't drag my desktop with me, so it stays at home.

 

[mrstravis]

"Ok thanks. I really think I'm just over analyzing. I'm going to keep reading. Do you use the DOF calculator while you're out shooting or is it something that you just learn with time?"

You can use a DOF calculator while shooting but realistically you will learn with time. To start experiment taking a picture of a single subject relatively close to the camera and shoot the same subject in a variety of apertures (f-stop numbers- try largest and smallest and in between) to evaluate the difference in depth of field yourself.

I am using a p&s right now so I don't have control over anything but my iso right now. I am hoping to upgrade within the next few weeks so I am doing my reading now so that I may practice when once I get an slr. Once i am comfortable with my knowledge of aperture, I will move to iso and will be able to practice with that. Thank you so much for taking the time to respond.

 

[mrstravis]

I don't drag my desktop with me, so it stays at home.

Lol, I thought maybe it was an app on a cell phone as well. Everything is an app these days.

 

[480sparky]

ol, I thought maybe it was an app on a cell phone as well. Everything is an app these days.

I ain't that fancy. My phone is a phone and nothing else. Never needed any more.

 

[mrstravis]

I ain't that fancy. My phone is a phone and nothing else. Never needed any more.

Understandable, thank you for taking the time to help me.

 

[889Media]

Just one thing... you say a given lens have an F-range of 3.5-4.5! This is most likely not the "range" of your aperture, but the minimum numbers of your lens.

Say you have a 18-85 mm lens with F: 3.5-4.5. This do not mean your lens can only use values between 3.5 and 4.5. What these numbers mean are that when you zoom all the way out on your lens widest angles, you can stop your aperture down to 3.5 - and as you already know (from reading earlier posts) will let in more light through your lens, and produce a shallower DOF. If you zoom in to your maximum zoom, the lowest F-stop you can use will go up 4.5.

BUT... as mentioned, these numbers are the minimum values you can use! Your lens will most likely give you a much higher number as your maximum. E.g: my newest lens, the Canon 70-200mm 2.8 can not only be used at 2.8 - but can range from 2.8 to about 22!

 

[mrstravis]

Just one thing... you say a given lens have an F-range of 3.5-4.5! This is most likely not the "range" of your aperture, but the minimum numbers of your lens.

Say you have a 18-85 mm lens with F: 3.5-4.5. This do not mean your lens can only use values between 3.5 and 4.5. What these numbers mean are that when you zoom all the way out on your lens widest angles, you can stop your aperture down to 3.5 - and as you already know (from reading earlier posts) will let in more light through your lens, and produce a shallower DOF. If you zoom in to your maximum zoom, the lowest F-stop you can use will go up 4.5.

BUT... as mentioned, these numbers are the minimum values you can use! Your lens will most likely give you a much higher number as your maximum. E.g: my newest lens, the Canon 70-200mm 2.8 can not only be used at 2.8 - but can range from 2.8 to about 22!

Ahhhh, that clarifies some things also. That makes a lot more sense. I decided to do my research so that when I go to buy a slr I know what I want, especially in a lens. That just made things easier. I assumed that f/3.5-4.5 was the range and thought it insane that the numbers would be so low. Thanks for clarifying that. Glad I used that example now. Lol

 

[KmH]

When that 18-55 mm lens is set to 18 mm and f/3.5, as it is zoomed towards 55 mm the aperture will automatically change until it is at f/4.5 just before it reaches 55 mm.

In other words the maximum aperture the lens can have at focal lengths between 18 mm and 55 mm changes, such that at 35mm the maximum aperture is about f/4.

That type of zoom lens is known as a 'variable aperture' zoom lens.

The other type of zoom lens is a 'constant aperture' zoom lens. A constant aperture zoom only has one f-number, like a 24-70 f/2.8, which means the maximum aperture does not change as the lens is zoomed from 24 mm to 70 mm, it stays at f/2.8, or which ever aperture it can be set to at any focal length between 24 mm and 70 mm.

Constant aperture zoom lenses usually cost a fair bit more more than an equivelent variable aperture lens.

 

[mrstravis]

Just one thing... you say a given lens have an F-range of 3.5-4.5! This is most likely not the "range" of your aperture, but the minimum numbers of your lens.

Say you have a 18-85 mm lens with F: 3.5-4.5. This do not mean your lens can only use values between 3.5 and 4.5. What these numbers mean are that when you zoom all the way out on your lens widest angles, you can stop your aperture down to 3.5 - and as you already know (from reading earlier posts) will let in more light through your lens, and produce a shallower DOF. If you zoom in to your maximum zoom, the lowest F-stop you can use will go up 4.5.

BUT... as mentioned, these numbers are the minimum values you can use! Your lens will most likely give you a much higher number as your maximum. E.g: my newest lens, the Canon 70-200mm 2.8 can not only be used at 2.8 - but can range from 2.8 to about 22!

Ahhhh, that clarifies some things also. That makes a lot more sense. I decided to do my research so that when I go to buy a slr I know what I want, especially in a lens. That just made things easier. I assumed that f/3.5-4.5 was the range and thought it insane that the numbers would be so low. Thanks for clarifying that. Glad I used that example now. Lol

Thank you for your help KmH. I feel important when you respond to my threads. LOL. Seriously, thank you for your help. I am trying to understand all of this. A lot goes into making a great photo. Things that up until joining this forum I didn't know about. I have been looking at slr cameras and trying to decide which one will be the best for me. That is why I started with aperture in my quest of photo knowledge. I needed to know which lenses to look at. I find myself being drawn to landscapes, flowers, and wildlife so I think that macro lenses would be my best bet. What do you think? They seem to be the most expensive. Are there any lenses that will yield the same or close to the same results? Once I have grasped the concept of aperture, where should I go from there in my reading?