83 votes
Accepted

Does this telescope only have a 4 blade aperture?

What you're seeing isn't the result of an iris aperture like in a camera. The 4-point diffraction spikes in the telescope are caused by the four struts holding the reflector in the mirror telescope. ...
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  • 31k
39 votes

How can a smartphone take pictures of a landscape with everything in focus?

It's worth noting that sensor size plays a huge role in depth of field and behavior of the lens. A smartphone has a tiny camera sensor, often around 25 square mm. This gives the camera a crop factor ...
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34 votes
Accepted

What makes the difference on partially and fully visible moon?

What makes the difference on partially and fully visible moon? In a word: shadows. I cannot understand why the IQ is extremely diminished when doing the same with an almost fully visible moon. ...
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  • 31k
27 votes
Accepted

Why are aperture settings visible when previewing photo on camera screen?

Assuming this is only on the LCD screen (it is in this case, I can see part of the viewfinder in the top of the photo), then it may be image burn from using the screen to display shooting settings. ...
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26 votes

Do photographers avoid using zoom?

do most photographers avoid using zoom No. If "most photographers" avoided zoom lenses with variable aperture, there'd be fewer zoom lenses with variable aperture on the market. Furthermore, there ...
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  • 31.2k
25 votes
Accepted

Is it possible to change depth of field in RAW images?

No - the aperture is set by the physical blades in the lens when you take the photo; a RAW "image" contains the readings from the sensor when the photo was taken, so there's no way you can go back and ...
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  • 19.7k
25 votes

How can I avoid this blur during taking indoor party pictures?

The blur is caused by the people moving while you were taking the photograph with a slow shutter. Honestly, I think it improves this particular photo a lot: it shows that the people are dancing, ...
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25 votes
Accepted

Do f-stop and exposure time perfectly cancel?

This is normal behavior, caused by: Imperfections of aperture. Usually there are variations from technology process which cause not to have exact size of the hole. On 50mm lens f4 you should have 12....
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  • 9,253
23 votes
Accepted

In what way does the lens mount limit the maximum possible aperture of a lens?

There are two hard limits on how fast a lens can be: The first is a thermodynamic limit. If you could make a lens arbitrarily fast, then you could point it to the sun and use it to heat your sensor (...
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  • 3,335
22 votes

Why do my photos appear grainy when taken at the widest aperture?

Looking at your samples, the answer seems clear to me: that's not grainy, that is, actually, out of focus. Here's a 1:1 crop of your wide-open image: It seems pretty apparent that the wooden sign is ...
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  • 140k
22 votes

How to focus on long distance with object in front and blur the object?

One way is to simply use manual focus. Since the landscape is very distant, there is only one thing to focus on once, then you frame and shoot multiple pictures as you like.
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21 votes
Accepted

Does using an extender actually change the aperture of the lens?

This is really simple when you think about it. The additional element changes the focal length of the lens, without changing the apparent size of the aperture. That means that the relative size of the ...
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  • 140k
21 votes
Accepted

What is the relationship between ISO, aperture, and shutter speed?

The Factors There is an equation, and by convention, it's set up to be really simple. There are basically five factors to consider together: Aperture — the size of the opening which lets light in, ...
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  • 140k
21 votes

How do zoom lenses restrict their widest aperture at the telephoto end?

The entrance pupil is limited by the diameter of the front element, and that is what usually restricts the maximum aperture of telephoto zoom lenses - not the physical size of the aperture diaphragm. ...
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  • 167k
20 votes
Accepted

How do XMP files encode aperture?

The Exif:ApertureValue is stored as an APEX value as mandated by various EXIF standards. The APEX system is a way to calculate exposure and works using base-2 logarithms. The use of base-2 means a ...
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  • 9,430
20 votes
Accepted

How to focus on long distance with object in front and blur the object?

There are (at least) four ways to do this: Use manual focus: This is (one of the reasons) why good cameras still have that feature. For this specific scene, there are other ways to achieve ...
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20 votes

How can a smartphone take pictures of a landscape with everything in focus?

If by "landscape" you mean something like this: then the answer is simple: at very large distances, depth of field is extremely large even at large apertures. That is, at any aperture if you focus at ...
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19 votes

What is the benefit of a wide-aperture lens if you stop it down?

It's widely believed that a lens with a faster aperture will perform better stopped down compared to a slower lens wide open. Whilst this is often the case it's not a hard and fast rule. With DSLRs ...
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  • 117k
18 votes

Why is the background bigger and blurrier in one of these images?

The easiest way to think of this is with an image. When you use a wider lens, you have to be closer to your subject, which emphasizes the distance between the subject and background by making the ...
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  • 480
18 votes

Why do we need a DOF preview button?

Hitting the DOF preview with a stopped down aperture should make it obvious: what you see can be very dim, dim enough it can be very difficult to compose and focus. That's why cameras have the lens ...
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  • 1,174
18 votes

Nikon D3400 aperture

In order to control the aperture from the D3400 with an older 'D' type lens that has an aperture ring, you need to set the lens' aperture ring to the narrowest (highest f-number) and lock it there. If ...
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  • 167k
18 votes
Accepted

How do apertures which seem too large to physically fit work?

Your observations of the lens leads you to both a correct, and incorrect, conclusion. Correct: the aperture (i.e., mechanical iris) of the lens is substantially smaller than the 10 cm it supposedly ...
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  • 31k
17 votes
Accepted

Landscapes: why *narrow* aperture?

Or am I misunderstanding how aperture works?...I thought the further away something is, the greater the depth of field. So when an object is three and a half miles away, it's going to have a huge ...
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  • 31.2k
17 votes

Why is Nikon 1.4g better when Nikon 1.8g is sharper?

1) Sharpness is complicated. Lens sharpness is just one aspect of the overall resolving power of a camera system. The appearance of crispness is separate from the rendition of detail. And a lens can ...
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  • 140k
17 votes
Accepted

Does a lens with a bigger max. aperture focus faster than a lens with a smaller max. aperture?

During focussing, the lens is left at full aperture. It's only when you take the picture that it closes down to the appropriate f-stop. That's so you can see what's going on and so that the camera has ...
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16 votes
Accepted

What are the practical advantages of fast lenses when shooting landscapes?

When used at the same aperture and focal length, a faster lens will have less vignetting than a slower lens. For example if you choose to shoot at 35mm f/4.0, then a 24-70mm f/4.0 lens will have the ...
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  • 684
16 votes
Accepted

Why does wider aperture make snowflakes look bigger?

The use of a large diameter, f/3.2 aperture allowed you to set the shutter at ½ second. You captured snow as it tumbled down. The shutter speed is insufficient to freeze the falling snow. The flakes ...
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16 votes

Do f-stop and exposure time perfectly cancel?

In theory, yes — stops are interchangeable. In practice, they do not perfectly cancel to complete precision. the standard deviation of the raw counts is ~5% of the mean In photographic terms, this ...
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  • 140k
15 votes

Why are large zoom ratio constant apertures lenses not generally available?

The main reason we don't have "super zooms" with a large constant aperture is size/weight/costs. Roger at LensRentals recently blogged about this in the post: About That 25-300mm f/2.8 You Wanted ...
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15 votes
Accepted

What prevents a f/1.8, 24 mm - 70 mm or similar range zoom lens from being made?

It's most likely a commercial decision based upon cost and performance. Let's take your prime at f/1.2 example. Canon makes a number of 50mm lenses. The EF 50mm f/1.8 II is about $100. It has 6 ...
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