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Focal length is the distance (measured in mm) between the surface of a lens and the focal point. Smaller focal lengths indicate wide-angle lenses, larger focal lengths indicate a telephoto lens.

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368 views

Help me understand effective f-number

If I set a lens to, say, f/2 but my focus is set to its closest point, my effective f-number won't be f/2 any more but it will be higher by a factor that depends on focal length, image magnification ...
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2answers
186 views

What happened to multi-focal lenses?

Apparently multi-focal lenses such as the Tri-Elmar 16-18-21mm went out of fashion but I was wondering if the reasons for that were technical or commercial. Are multi-focal harder to build compared ...
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4answers
1k views

Will a short focal length cut it for indoor event photography? (Context: It's Crowded, Dark, Has Mixed Lighting, and Requires Walking Around.)

Short version: What primes are good walk-around lenses for an indoor, dark, crowded environment where you'll be taking pictures of individuals or small groups ad-hoc, walking around and stopping in ...
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2answers
3k views

DX 35mm vs FX 50mm

Will the picture taken from AF-S DX NIKKOR 35mm f/1.8G and AF-NIKKOR 50mm f/1.8G be one and the same because of the DX and FX format??
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2answers
132 views

What is the importance of the back focal length of a lens?

What is the effect and importance of the back focal length of a lens? For instance, if I look at these two lenses by Ricoh, they have the same focal length and aperture, but their back focal lengths ...
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3answers
156 views

How can I get a 12ft wide field of view at 3ft distance?

Is it possible to get 12ft wide image from a 3ft distance? I am a beginner and have very little knowledge on the field of view of cameras. I calculated that a Go Pro would need a lens with 1.5mm ...
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3answers
346 views

How to shoot/capture the droplets of water being sprayed through a spray bottle

I am trying to capture the droplets of water while being sprayed on a subject through a spray bottle. What I mean here is - when I am spraying the water on my subject, I want to capture the droplets ...
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3answers
3k views

Is the formula for object image size given focal length, etc. independent of sensor size?

I am trying to figure out how big an object of, say, 50cm height at 100m distance and 600mm focal length would appear on a camera's sensor. The ubiquitous formula object size in image = focal length ...
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1answer
826 views

Canon 24-70mm 2.8f - Optimal aperture for sharper pictures

I always have trouble getting sharper images from my 24-70 lens. I have watched numerous YouTube videos to correct this and its improved but not completely corrected. I am going on a trip and don’t ...
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2answers
4k views

How do I choose among the following lens of 55-250 IS, 70-300 IS and VS 75-300?

Sorry by this specific question, but I'm pretty crazy here looking for a difference. I've got to buy a lens tomorrow (I leave my country in 2 days) I could see the difference between 55-250 and ...
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1answer
152 views

Panasonic Lumix FZ1000 - How does it compare to binocular magnification?

I know almost nothing about photography. But I am interested in learning. My dad just purchased a Panasonic Lumix FZ1000. I own a pair of Leica 10x50 binoculars. I asked him how the maximum zoom or ...
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1answer
190 views

How do I calculate the maximum aperture at each focal length on a 35-200mm lens

I am looking for the linear maximum aperture of a 35-200mm 3.5/4.5 Nikon manual focus lens. I already know the max & min of the 35 & 200mm it's the 50, 70,105, & 135 that I am interested ...
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4answers
99 views

Does the crop factor affect the field of view (FOV)? [duplicate]

I'm working on smartphone cameras. I want calculate Field Of View of different smartphone cameras using the formula : FOV = 2 arctan(SensorSize/2f) where: f is the focal length sensor size is the ...
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3answers
2k views

Why image at 400mm is LARGER THAN DOUBLE of image at 200mm? (according to lens formula)

Like most of us, I thought it was yes. Until I really look into the Lens Equation: (1/subject distance) + (1/image distance) = (1/focal length) ...
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1answer
260 views

What is a 50mm focal length good for on an APS-C camera?

This is on a Sony NEX, so the 35-mm equivalent focal length is 75mm. What kind of photography is this focal length good for? I shoot low-light, landscapes / cityscapes, and the typical vacation ...
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2answers
234 views

What does different focal length offer me?

I have a beginner photographer and I have spent a lot of time learning the basics (exposures, lenses, focal lengths, crop factor etc). It's all good except I'm not so sure when I need to buy lenses of ...
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2answers
953 views

What are the technical camera specs for the HTC Wildfire S?

I am trying to do some CGI manipulations on pictures I've taken. In order to fake reality with some 3D object inserted in the picture, I need some information to configure my virtual camera so it can ...
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2answers
89 views

How does “designed for APS-C” affect focal length? [duplicate]

If a lens is designated by manufacturer as "designed for crop sensor" (i.e. DC in Sigma, DX in Nikon, DT in Sony), how would that affect the calculation of practical focal length (equivalent focal ...
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1answer
368 views

How to calculate the focal length for old lenses (m42 or m39) mounted on Sony Nex? [duplicate]

As far as I know, it is necessary to multiply the focal length by the crop factor. My Sony Nex 5 has a crop factor = 1.5 For lens Helios 77M-4 1.8/50 focal length will 50 * 1.5 = 75 Is this true for ...
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1answer
667 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 ...
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2answers
157 views

Will old K-mount lenses have the same field of view on Pentax K01?

Will old K-mount lenses have the same field of view on Pentax K01? Or, will 50mm lens (made for 35mm film) function as a 75mm lens?
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2answers
1k views

How to simulate different focal length and sensor size on an image?

I like to simulate different focal length and sensor size based on an image i have taken. I have a full frame body so I like to know how the picture would look like if I have taken with a cropped ...
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1answer
6k views

What is the focal length on your typical cell phone camera?

Now, let me clarify (or...divulge) a few things. I know cell phone cameras are generally wide angle, which makes sense because hey, people wanna go out to dinner, or a show, or at the park with their ...
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1answer
191 views

How to calculate the focal length of cell phone cameras when none of the required parameters are available?

There are many camera phones for which the focal length, aperture size, and sensor size are not available. Is there a formula to calculate these parameters or a site which provides these details for ...
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2answers
2k views

How do I take good portraits with a bridge camera and superzoom?

I'm an absolute beginner with regards to photography. I did some research on portrait photography today. From what I learned, a long-telephoto lens (70mm-135mm or more focal length (35mm ...
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2answers
458 views

Which is a better focal length for fashion models on the runway: 50mm or 35mm?

Which is a better focal length for fashion photography: 50mm or 35mm? I have Nikon D5100 and Nikon D7000 and I'm interested specifically for ramp walk.
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3answers
340 views

How can I take a picture at 50mm with a Finepix s8200?

I have this camera. How do I take a picture at 50mm with zoom lens? Does this camera support zoom lens at 50mm?
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3answers
447 views

How to get focal length from a camera specification which gives a value like “4.5-22.5”?

I am using a Sony W520 camera. The specifications mention Focal Length (f= mm) 4.5-22.5. What number should I take? The lower value or the higher? And if not both of them, then how to calculate actual ...
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3answers
212 views

What is the difference between shooting with different (but similar in quality) lenses at same focal length?

What are the theoretical and/or practical differences between shooting with different lenses at same focal length? For example, if we are shooting with a 24-70mm f/2.8 lens at 70mm focal length vs ...
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1answer
70 views

Why don't all zoom lenses have variable f-numbers? [duplicate]

As I understand it, the f-number is a ratio between the focal length and the aperture diameter. A zoom lens can change focal length, but shouldn't the maximum aperture be a fixed size? If so, that ...
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2answers
140 views

How can I know the focal length and sensor size of my webcam?

I have this webcam: QHM495LM WEB CAMERA and I need to know its focal length and its sensor size, but in the specs of the webcam, it only gives me this information: • Inbuilt sensitive microphone and ...
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3answers
1k views

How far away can I be and still get a sharp subject with a 100mm lens?

If I have a 100mm lens, how far away can I shoot the subject? If I am shooting basketball, how far can I shoot the subject and still get a sharp picture?
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0answers
26 views

Relationship between the focal length and sensor size [duplicate]

What is a relationship between the focal length of the lens and the sensor size to achieve the same image area ?
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0answers
61 views

Where is the focal point of a camera lens? [duplicate]

If the distance between the center of the lens and the film is called Focal length, does that mean the focal point of the camera lens is located on the film?
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0answers
57 views

How to overlay the image scaling based on the user distance & focal length

I'm overlaying images on the cameraView and based on the user input of room width & height. The images are displaying proportionally to width & height ratio. but i need to overlay the images ...
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0answers
52 views

Which lens to use for landscapes? [closed]

I bought my Nikon D5200 camera with a 18-55mm f/3.5-5.6G lens as well as a Nikkor 70-300mm f/4-5.6 G lens. I was just wondering if you would be able to tell which lens to use in what situations. Like, ...
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2answers
10k views

How can I find a compact camera with an ultra-wide lens?

I'm looking to buy a compact camera, and having a very wide angle is important to me. I know that review sites often list the real focal length of the lens, but what I'm looking for is something that ...
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1answer
430 views

Does the X-Pro 1's “Lens Focal Length Setting” do anything with automatic lenses?

In the X-Pro 1's custom menu, one of the options is Focal Length Setting. The manual says: FOCAL LENGTH SETTING (Defaults to 50mm) Enter lens focal length when using a lens that does not ...
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5answers
260 views

Is it worth getting a zoom lens which overlaps with lenses I already have?

I want your experience in choosing a new lens. I already have a couple of lenses with focal lengths as follows: 18-55mm, 70-300mm (MF), and 55-300mm (AF) - regardless the 18-55mm. All my zoom ...
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2answers
11k views

So my iPhone 6 camera lens is as wide as my full frame 35mm DSLR lens?

I am trying to understand what is the deal with "full-frame" and what difference it makes, so did a silly test: I sat at my bed and aligned the iPhone 6 camera with the door of the room and took a ...
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3answers
2k views

50mm vs 35mm cropped [duplicate]

For shooting portraits, why is 50mm preferable? For example with an APS-C sensor, why is it not ok to take photos with 35mm equivalent and simply crop them (to 50mm equivalent)? or take photos closer ...
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1answer
158 views

What focal length and quality of lens do I need to read 15cm high text at 500m away? [duplicate]

I have to photograph 15cm high printed text from 500 meters away. The text has to be human readable in the result. What kind of focal length do I need? Can i compromise, and get a camera with less ...
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2answers
94 views

Actual Focal Length on APS-C cameras [duplicate]

I'm aware that actual focal length of a lens on APS-C cameras is longer than what is written on the lens. My question is, for lenses that are specially designed for APS-C cameras (like a Nikkor DX ...
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2answers
499 views

How does focal length change perspective? [duplicate]

@MichaelClark answered a question I posted about zoom using focal length (emphasis added): You are correct that a focal length twice as long (2X zoom) as the original one will make objects appear ...
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3answers
220 views

Which lens/focal length offers the widest viewing angle without too noticable distorions/fish-eye-effect?

I am looking for a lens for my Sony Alpha 77 (APS-C), which gets me an as wide as possible viewing angle, but I also hate that fisheye effect one gets from using too low of a focal length. About where ...
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3answers
973 views

How do I convert focal length to maximum distance?

I would like to know whether there is any relation between focal length and distance. For example, what is the max distance I can shoot from a 55mm-300mm lens?
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1answer
76 views

Do I get more detail from a shorter focal length by being physically closer?

Let’s say I want to shoot a static scene and have a free hand regarding the focal length. If I ignore the geometric distorion for a while, do I get some image quality advantage by shooting from a ...
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1answer
135 views

What focal length does Lee Jeffries use for his portraits?

I'm astonished by the portraits of an English photographer, Lee Jeffries. Does anybody knows the focal length he shoots with? The link to his flicker.
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1answer
749 views

Relationship between camera sensor size and lens focal length [duplicate]

I am choosing a camera and lens. I want to buy a Canon EOS 650D, as this camera seems to be a good point of entry into the world of SLR. My question is in the following: The EOS 650D has a cropped ...
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1answer
100 views

How to calculate the new field of view from an existent one?

I have a photo having H x W (height x weight) pixels and I know, based on the EXIF, that it was shot at F1 focal length. How many pixels I must crop (or add) in order to see how it would be the photo ...