84 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. ...
scottbb's user avatar
  • 32.7k
40 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 ...
AthomSfere's user avatar
35 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. ...
scottbb's user avatar
  • 32.7k
29 votes
Accepted

How did this note "19/65 21/90 22/130" help previous owner of this old Zenit 12XP film camera?

Those look like DIN speeds that match values on the GOST meter dial. GOST was the Soviet film speed standard; it was on the same scale as ASA speed, but 90% the value (so GOST 360 was equivalent to ...
Zeiss Ikon's user avatar
  • 7,141
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. ...
laurencemadill's user avatar
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....
Romeo Ninov's user avatar
25 votes

Why do people not use large f-numbers (small apertures) when shooting landscapes, when you want large depth of field?

First people want to have (when making photos of landscape) almost all in focus. But they do not use F22-32 because on such aperture diffraction degradate the quality of images. Second, when shooting ...
Romeo Ninov's user avatar
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.
Olin Lathrop's user avatar
  • 17.4k
21 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 ...
aaaaa says reinstate Monica's user avatar
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 ...
James Snell's user avatar
  • 9,709
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 ...
Ilmari Karonen's user avatar
19 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 ...
Cullub's user avatar
  • 500
19 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 ...
scottbb's user avatar
  • 32.7k
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 ...
whatsisname's user avatar
  • 1,192
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 ...
Michael C's user avatar
  • 175k
18 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 ...
mattdm's user avatar
  • 143k
18 votes
Accepted

What are the benefits of the classic f-number scheme?

What is the purpose ... for the existing convention? Math. It's because in many equations regarding simple optics, the ratio \$N = f/D\$ (where \$N\$ is the f-number, and $D$ is the lens (or more ...
scottbb's user avatar
  • 32.7k
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 ...
Caleb's user avatar
  • 31.7k
17 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 ...
Nayuki's user avatar
  • 745
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 ...
Pete Becker's user avatar
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 ...
Alan Marcus's user avatar
  • 39.2k
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 ...
mattdm's user avatar
  • 143k
14 votes
Accepted

Does aperture affect field of view?

Answer with an image : the guy on the left represents your (vertical) field of view and its image on the sensor is inverted on the right (in other terms, the guy fills your entire image). As you can ...
Olivier's user avatar
  • 4,183
14 votes
Accepted

Under what circumstances does f/22 cause diffraction?

Under what circumstances does f/22 cause diffraction? Pretty much all of them. All apertures cause diffraction due to the interaction of the wave nature of light with the edges of the aperture. But ...
Michael C's user avatar
  • 175k
13 votes

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

A faster lens (= low F-stop) allows easier manual focus and better auto-focus, given the camera has AF sensors which can exploit faster lenses. For landscape however, there is usually enough time that ...
Grebu's user avatar
  • 1,316
13 votes
Accepted

What motivated lens makers to now use 1/3 f-stops rather than say 1/4 or 1/2 stops?

Historically, the unit of exposure was a doubling or halving of the exposing energy. This is the origin of the f/stop. Initially, this adjustment was made by inserting a thin metal plate with a ...
Alan Marcus's user avatar
  • 39.2k
13 votes

Why do we need a DOF preview button?

Why do we need a DOF preview button? So that you can see how much depth of field you'll get when the shot is actually taken. Why not just show the effective depth of field, by default? Because ...
Caleb's user avatar
  • 31.7k
13 votes
Accepted

Is a lense with an aperture larger than f/8 useful with an EOS 80 D?

So I have a EOS 80D and supposedly it has a max aperture of f/8. That's incorrect. The aperture is in the lens, not the body. All Canon EF and EF-S lenses, including the one that came with your ...
Caleb's user avatar
  • 31.7k
13 votes

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

Aperture is only one factor in depth of field. Others are: sensor size and focal length. Large format camera lenses often have max apertures in f/4-f/5 range, yet they yield very shallow DOF - because ...
Agent_L's user avatar
  • 2,090
13 votes

Is there any reason to change the ISO manually?

Is there any reason to change the ISO manually, rather than have it set automatically? The primary reason to set ISO, along with shutter time and aperture, manually would be to totally control ...
Michael C's user avatar
  • 175k

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