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Aperture is the opening in the diaphragm of a camera lens. For questions relating to Apple's photo management software, please use [apple-aperture] instead.

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60
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11answers
21k views

Is there a noticeable difference between 1.8 and 1.4 prime lenses?

I have been shopping around for a prime lens for my Nikon D50. I noticed that the 1.8 is hundreds of dollars cheaper than the 1.4 AF-S. What will I gain for that cost difference? Is it really ...
51
votes
3answers
31k views

What does f-stop mean?

What does f-stop mean? Is it the same thing when people say "2 stops" for example?
42
votes
7answers
6k views

What is a “diffraction limit”?

I've seen the term used, but what is a "diffraction limit", when should I worry about it, and what undesirable effects are a result of it ?
36
votes
3answers
11k views

What apertures are required to enable autofocus, including cross-type or high-precision focusing, on Canon DSLR cameras?

This is a follow-up to Why does Canon and Nikon limit or disable autofocus beyond certain f-numbers? I'm doing this to separate the AF aperture requirements from the linked question above. My goal ...
35
votes
8answers
26k views

What is aperture, and how does it affect my photographs?

How does aperture affect my photographs? Why should I care about the aperture with which a photo was taken?
32
votes
10answers
2k views

What are some tips for shooting in low light?

I own a Canon 450D with just the standard lens kit that comes with it (poor so won't be buy a new lens for a while) and one thing I tend to struggle with is shotting in lower light conditions, indoors ...
30
votes
5answers
5k views

How do constant aperture lenses work?

Cheaper zoom lenses usually are faster at the wide end and slower at the long end (for example, the $150 Canon EF-S 18-55mm f/3.5-5.6). More expensive constant-aperture zoom lenses have the same ...
28
votes
4answers
2k views

How does aperture work without “cropping” the image hitting the sensor?

I've been teaching myself the various settings in cameras and now have a much fuller understanding of how to use my camera effectively, but one thing is still bugging me. When the aperture size is ...
26
votes
7answers
5k views

When to use shutter priority instead of aperture priority?

Under what circumstances would you use aperture priority vs. shutter priority and vice-versa? I typically don’t use shutter priority (ever) and favor aperture priority to try to get a max aperture ...
24
votes
4answers
3k views

How do you find out the “sweet spot” of a lens?

I've tried googling this, but have never found a satisfactory answer. I've heard the term "sweet spot" thrown around by some photographers to mean the f-stop of a lens which results in the highest ...
23
votes
5answers
2k views

What is special about lenses with f-number < 1?

Talking about fast lenses, Wikipedia mentions Nikon TV-Nikkor 35mm f/0.9-Fastest Nikon lens ever made Why don't, for example, f/0.5 lenses exist? Is there some special construction that comes ...
21
votes
2answers
2k views

Why use a small aperture when trying to see sensor dust?

Here and there I read of people who set their lens to a small aperture while testing their sensor cleanness, supposedly to get the best image of dust speckles. However, the image of the on-sensor dust ...
20
votes
4answers
3k views

Why do compact digital cameras not have the aperture range of DSLRs?

Why is it that on compact digital cameras the aperture never seems to go any smaller than about F8 ? Even on high-end compacts such as the Cannon G10 or Panasonic LX5. Is there some practical or ...
19
votes
9answers
2k views

What's the benefit of a tiny aperture?

In this answer to another question Rob Clement wrote: Think background first. What story do you want to tell? Epic background, big mountains. Looking to deliver a sense of grandeur with your ...
19
votes
4answers
9k views

Why is the aperture ring removed from new Nikon lenses?

Maybe I'm wrong, but I notice that Nikon's newer lenses don't have an aperture ring. For example, an older AF 35 mm f/2D is now replaced by AF-S DX 35 mm f/1.8G, or AF 50 mm f/1.8D is replaced by a ...
19
votes
3answers
2k views

Why do wide angle prime lenses have relatively small apertures?

I've noticed that many of the wide angle prime lenses (at least for Canon) have somewhat smaller apertures than their normal or telephoto counterparts. E.g. the regular Canon 24mm prime is f/2.8 while ...
18
votes
9answers
18k views

What is an easy way to remember the full stop scale?

If you were teaching someone new to photography the full stop scales, is there a better way then flat out memorizing these values? Does anyone have an easy way that they remember the scale? Would it ...
18
votes
5answers
835 views

Why do two lenses with the same F-number give different amount of light?

Why do the following two lenses provide different amount of light? In both images we have fixed focusing distance, distance to the object, ISO, shutter speed and F-number.
18
votes
3answers
1k views

Do smaller apertures provide more depth of field past the diffraction limit, even if peak sharpness suffers?

In Understanding Exposure (3rd edition, on page 48), Bryan Peterson has what might be called a rant against modern on-line conventional wisdom about diffraction limits. Answers on this web site are ...
18
votes
4answers
3k views

Why is the depth-of-field preview in the optical viewfinder of my Canon 500D inaccurate?

I have noticed that in my Canon 500D, the depth-of-field preview in the optical viewfinder is inaccurate with large aperture settings. If I press the DoF preview button, there is very little ...
17
votes
2answers
5k views

What is T-number / T-stop?

Usually, when discussing aperture of a lens, F-stop and F-number are used for quantifying. But some photographers, and especially videographers, also mention T-stop. The concept and numbering used ...
17
votes
0answers
2k views

Why does a larger aperture cause more blur of the background? [duplicate]

Possible Duplicate: Technically, why is the out of focus area blurred more when using a bigger aperture? Why is it that a larger lens aperture produces a shorter depth of field, causing the ...
16
votes
5answers
2k views

How can aperture be f/11 on a lens with an aperture range designation of 3.5-5.6?

I made a series of outdoor shots with Nikon D5000, with the 18-55mm 1:3.5-5.6G VR kit lens. On some shots, I see in the EXIF info f/11, and in another shot, f/9. How can that be, that the f-number ...
16
votes
7answers
1k views

Why isn't my variable-aperture photo more interesting?

I took a photo where I changed the aperture of the lens during the exposure. I was hoping to get a cool or unusual effect, but I didn't. Why not, and is there any really interesting effect that I ...
16
votes
6answers
2k views

Can a smaller sensor's “crop factor” be used to calculate the exact increase in depth of field?

If APS-C and similar crop-sensor digital cameras have a focal length multiplying effect such that a 50mm lens has an apparent focal length closer to the field of view of an 80mm on a full frame ...
16
votes
2answers
786 views

Do rounded edges on aperture blades improve image sharpness, and how?

In the description for the XF lenses for its new X-Pro system, Fujifilm crows: The [XF lenses] all offer precise control over depth-of-field and deliver excellent out-of-focus bokeh thanks to the ...
15
votes
4answers
3k views

What is a “fast” lens?

I've been reading lots of camera reviews lately and have ran across several references to "fast" lenses. What exactly is a fast lens and what are its advantages compared to other lenses?
15
votes
8answers
873 views

Would a prime be redundant with a fast zoom?

Now that I am finally getting a fast zoom (Tamron 17-50mm 2.8) I've been considering a fast prime to go with it, specifically a Sigma 50mm 1.4. Despite its shortcomings, it still does really nice ...
15
votes
2answers
789 views

Does a specific f number across all lenses denote same amount of light?

When we say a light source emits 1500 lumens of light, it does not really matter if the light source is incandescent, CFL, diode etc. Similarly, when I say f/1.8 can I assume that all lenses pass the ...
15
votes
5answers
960 views

How do I find the aperture that produces the highest-quality images for a given lens?

I'm not talking about large aperture (f/1.8, f/2.8...), rather, about small apertures (f/18, f/20, f/23...). I read somewhere (actually I think it was on this site, but I don't exactly remember which ...
14
votes
3answers
3k views

Does a bigger aperture create better photos?

I have observed that the wider the aperture, the more expensive the lenses are. However, I would like to know whether it really makes a difference in your photos or not?
14
votes
2answers
2k views

How do DSLRs figure out what aperture to select in P mode?

In program mode, DSLRs adjust not only the ISO and the shutter speed, but also the aperture. The aperture has a huge impact in some situations. For example, when shooting a close subject in front of ...
14
votes
2answers
868 views

DSLRs with separate controls for aperture and shutter?

I just bought a Nikon D3200 DSLR and I'm going to return it. It's fine if you always want to use in fully automatic mode, but in Manual mode, it's much less convenient. You have to set the shutter ...
14
votes
3answers
1k views

Do the same camera settings lead to the same exposure across different sensor sizes?

Let's say I have a micro-4/3rd camera and a full frame camera, both set to 1/60 at f/2.8, taking a picture of the same scene in the same lighting. Will the exposure be the same across both cameras ...
13
votes
2answers
4k views

How iPhone 5S can have such a big aperture? f/2.2?

I thought that in order to have a big aperture such as f/2.2 a big amount of light should be able to enter to the sensor and in order to do it, a big lens was needed. How is it possible that in the ...
13
votes
5answers
668 views

Why are only certain shutter speeds or apertures available?

For the exposure control function DSLRs there are specific shutter speeds available. For example there are 1/4, 1/100, 1/500. Why, even in high end DSLRs, is there no option to use a custom shutter ...
13
votes
5answers
3k views

What is the meaning of “stopped down”?

Was reading this answer (emphasis mine): It also tells us that the lens was stopped down, as if it were wide open there would be no corners to cause diffraction, regardless of the number of ...
13
votes
2answers
2k views

Why do zoom lenses and compact cameras have varied maximum aperture across the zoom range?

Why does a camera's maximum (allowed) aperture get smaller when you increase its zoom?
13
votes
3answers
331 views

How to test what aperture is actually used?

It seems odd to me that Canon EF 100-400mm f/4.5-5.6L does away with a front element of only about 63 mm, as reported by @jrista - which would be enough for only f/6.3 at 400mm, missing the spec by ...
12
votes
8answers
3k views

Will using a lens at max aperture (“wide open”) result in poor images?

I’m looking to add a second lens to my kit lens I got with my Nikon d7000. I have read several reviews on both the 35 and 50 mm lenses made by Nikon in particular that said using either lens at the ...
12
votes
6answers
561 views

Does lens speed still increase meaningfully when the physical aperture is larger than the sensor size?

This question came to me this morning, thinking about 50mm lenses. I have the Pentax 50mm f/1.7 (manual) and it's a very nice lens, but would be considered (relatively) slow on 35mm film, and many ...
12
votes
4answers
700 views

Is there a noticable difference in sharpness between a 1.8 lens and a 2.8 of similar design?

I recently bought a second-hand Carl Zeiss Jena PANCOLAR MC 1.8/50mm Lens off eBay (still waiting for it to arrive though) and am going to mount it to my Canon 7D via a M42 adaptor. I primarily shoot ...
11
votes
2answers
5k views

Why does Canon and Nikon limit or disable autofocus beyond certain f-numbers?

One thing that I've noticed with Canon DSLR camera is they will disable or limit autofocus when the lens is below certain aperture values, which are specified in my answer to What are the aperture ...
11
votes
4answers
590 views

Why aren't lenses designed with extra large apertures for autofocus beyond what's used for imaging?

Historically, designing large-aperture lenses has been difficult because correcting the optical aberrations that arise from large apertures requires complex designs and very large amounts of glass. ...
11
votes
3answers
3k views

What settings should I use to photograph aurora borealis with a wide angle f/4 lens?

I've tried my first night photography of the stars last week. Most articles I've seen were recommending a fast lens, fully opened, @ ISO 800 and about 20 - 30s exposure, etc. Unfortunately, my only ...
11
votes
1answer
272 views

What are the limits of extension tubes?

Given lighting is not a problem, can you hit a limit where you have too much extension tubes (a very long tube) and the quality of the image will suffer? For example a diffraction limit will be hit ...
11
votes
4answers
2k views

Is overall light gathering of a lens only dependant on aperture?

My impression is that the aperture value of a lens determines its light gathering ability, but I'm not sure I understand how it works... When considering light gathering in telescopes, it is ...
10
votes
4answers
482 views

Focusing on moving target with large aperature?

I have read about difficulties getting focusing right when using a large aperature (because of depth-of-field issues). If I am using a fast prime wide open (say F1.4 or F1.8) to shoot a target in ...
10
votes
2answers
944 views

How to stop a high F number from appearing blurry?

I have been out taking some evening photos (just after sunset) and I have noticed that in a number of instances the higher f numbers ( 14+ ) are appearing more blurred than the lower f numbers ( < ...
10
votes
3answers
403 views

ND filter vs stopping down for long exposures?

To achieve long exposures in daylight, one might need to stop down, or use an ND filter. By stopping down, the depth of field increases, but at some point the image quality/sharpness will suffer, due ...