Open

by damned truths

submit your photo


Hall of Fame
View past winners from this year

Please participate in Meta
and help us grow.

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.

learn more… | top users | synonyms

35
votes
8answers
35k 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?
44
votes
7answers
7k 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 ?
17
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 ...
51
votes
4answers
37k views

What does f-stop mean?

What does f-stop mean? Is it the same thing when people say "2 stops" for example?
25
votes
4answers
4k 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 ...
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 ...
16
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?
9
votes
6answers
4k views

Technically, why is the out of focus area blurred more when using a bigger aperture?

I'm wondering, technically, why and how does the out of focus areas blur more when using a bigger aperture. I think it'd help a lot if I presented a problem that's been driving me nuts for a long ...
19
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 ...
37
votes
4answers
13k 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 ...
14
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?
60
votes
11answers
24k 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 ...
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 ...
17
votes
2answers
7k 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 ...
20
votes
4answers
4k 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 ...
14
votes
3answers
2k 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 ...
7
votes
7answers
19k views

Why is my Nikon 50mm f/1.8 giving me an fEE error?

I have a AF Nikkor 50mm f/1.8. When I have the aperture setting on the lens to 22 I can take photos. But when I change the dial to anything other than 22(lowest f/stop) then I get a flashing fEE ...
32
votes
10answers
2k views

What are some tips for shooting in low light?

I own a Canon 450D with just the standard kit lens that comes with it (I don't plan buying a new lens for a while) and one thing I tend to struggle with is shooting in lower light conditions, indoors ...
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 ...
31
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 ...
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 ...
19
votes
9answers
22k 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 ...
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 ...
7
votes
5answers
2k views

What are the benefits and costs of an image stabilized, slower lens vs a non-IS faster lens?

I am going thru a trade off decision between a 24-70 f2.8 lens and a 24-105 f4 IS lens from Canon. My dilemma is that the 24-105 focal length better matches my needs, but the f2.8 would occasionally ...
6
votes
6answers
4k views

What aperture should I use to photograph people and why?

What f/# do you use to photograph people, and why? I know this varies from shot to shot. Let's suppose that you are photographing either a single person or a couple, that it it outside on a somewhat ...
4
votes
2answers
413 views

What are the theoretical minimum and maximum apertures?

Is there such a thing as a maximum aperture that a lens can be open to? What about a minimum aperture that it can be closed to? Do these concepts even make any sense? Is there a lens with the ...
19
votes
3answers
3k 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 ...
7
votes
3answers
3k views

What are the advantages of a lens having a fixed maximum aperture?

What are the advantages of a lens having a Fixed Maximum Aperture? Previous answers have indicated that "pros tend to want constant apertures in zoom lenses". While in general lenses with a fixed ...
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 ...
3
votes
2answers
593 views

What's the difference between real and effective aperture?

I understand that the simple idea that f-stop is focal length divided by aperture really applies to a simple single-glass lens, not the compound lens systems used to provide good image quality in ...
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 ...
11
votes
2answers
6k 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 ...
13
votes
5answers
712 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 ...
8
votes
5answers
2k views

How do different aperture and shutter settings affect a photo with the same overall exposure?

Ok, here's my doubt. Suppose I want to get a certain exposure for an image. Keeping the ISO constant, there are two tentative possibilities here: Put the camera at f 1.4 (say) and at 1/1600 shutter ...
6
votes
4answers
710 views

Is depth of field and bokeh influenced by distance to the subject?

I know that the aperture size has a direct effect on the depth of field. However, what about distance to the subject? Let's say I took two pictures, one at 24mm and one at 70mm, using the same lens ...
15
votes
8answers
948 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 ...
9
votes
2answers
4k views

Why don't comparisons of aperture take sensor size into account?

When one compares focal length, many times we use the 35mm equivalent length. A 50mm lens on an APS-C sensor camera(1.6x) would be a 80mm equiv. length on a full frame camera. But when we state the ...
8
votes
3answers
460 views

What is the limiting factor in lens construction when it comes to f-stop values?

This widely praised Nikon 105mm macro lens has a maximum f-stop value of 2.8. I've held it in my hands, it's a big lens. Meanwhile, this 50mm Nikon lens can go up to f/1.2, despite being 25% cheaper ...
6
votes
2answers
848 views

How are neutral density filters in compact cameras implemented?

I've read here on this very site that some compact cameras don't use aperture blades to stop down the lens and limit the amount of light hitting the sensor. Stopping down increases diffraction. ...
5
votes
2answers
826 views

What's the base f-stop when counting an ideal f-stop for lens?

I've read a lot around this site that an ideal quality of the lens is achieved when using f-stop roughly 2 stops slower than the fastest value of the lens. Firstly, I'm not exactly sure what "2 ...
2
votes
1answer
273 views

What is the largest aperture on a commercially available lens? [duplicate]

Out of pure curiosity, what is the largest aperture, or lowest f-stop, a commercially available lens has. I have seen the 50mm prime lens from canon with 1.2, but not lower than that. What are the ...
1
vote
1answer
408 views

Size of the entrance pupil vs size of the aperture

I understand that the entrance pupil is the image of the aperture as seen from the front of the lens. However, is the size of the entrance pupil the same as the size of the effective aperture? In ...
18
votes
5answers
916 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.
7
votes
4answers
1k views

Why are my photos taken at f/11 less sharp than those taken at a wider aperture?

I am new to photography. I have Fujifilm FinePix HS10 camera. Lately I was trying my hands on landscape photography. I learnt from different tutorials that setting high aperture value gets most of ...
20
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 ...
13
votes
3answers
335 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 ...
13
votes
6answers
576 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 ...
9
votes
2answers
544 views

When using an Extender, does it actually change the Aperture of the lens?

I just bought a Canon 2X Extender and I always believed that It would only result in 2 Stops loss of light and not change the aperture. When I tested this extender on a Canon 135mm F/2 lens, the ...
8
votes
1answer
2k views

Why does the maximum aperture change with focal length? [duplicate]

Possible Duplicate: Why do zoom lenses and compact cameras have varied maximum aperture across the zoom range? It is rather common with zooms that the maximum aperture changes (in fact, ...