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

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187 views

Is the wide aperture and bokeh of a 50mm prime more important than getting to the 70-90mm range for portraits?

I've a Pentax K-30 with the following lens: Pentax-M 50mm 1.7 manual focus Tamron 17-50mm 2.8 autofocus Pentax 55-300mm 4-5.6 autofocus Considering that : Pentax 50mm has the nicest bokeh and ...
3
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4answers
232 views

Given the same sensor size lens, will a higher megapixel sensor give more “reach” then a lower one?

I've been wondering this for a while now, and I can't seem to find a straight answer about this. If we are talking about the exact same sensor size, (lets say FX) and we are using a 50mm lens. ...
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1answer
132 views

How do lenses focus? (and zoom?) [duplicate]

My understanding of focal length is that it is the distance from the lens to the sensor; in my observations: higher focal lengths make for longer lens. Then I started thinking about how a lens ...
24
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6answers
9k views

How to capture the scene exactly as my eyes can see?

What settings of my DSLR camera will emulate the scene exactly as I can see through my naked eyes? I think it's not possible to get the contrast and colors exactly as my eyes can see, and it may vary ...
55
votes
6answers
19k views

What is “angle of view” in photography?

I read on the Lens Buying Guide @ neocamera: Focal-length determines the angle-of-view seen through a lens for a given sensor-size. With a full-frame sensor a lens gives the same angle-of-view ...
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votes
3answers
22k views

What mm lens for distance shots?

If I am looking to take landscape and wildlife shots and some of those shots being from a decent distance what mm lens would I need? I am not sure what else I should be adding here, I am just looking ...
41
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7answers
172k views

How do I convert lens focal length (mm) to x-times optical zoom?

What is the rule to convert the 'mm' notation to the 'optical zoom' notation? I searched a bit and found this one: optical zoom = maximum focal length / minimum focal length For example a 18-55mm ...
0
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2answers
149 views

What is the relationship between focal length and minimum focus distance?

If I know the focal length of a lens, How can I know the minimum focus distance? I have checked several webpage, but I am still wandering is there a formula? I know there is mark in the lens, but ...
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4answers
66k views

How do I calculate the distance of an object in a photo?

If I took a picture of a windmill on the horizon — given that I know the sensor size and the focal length of the lens and other factors to do with the shot — could I calculate how far away an object ...
0
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1answer
148 views

I have camera specifications but don't know the actual focal length

I'm trying to figure out the focal length of my camera. I'm trying to figure out the distance from my camera to an object using the equation listed here (How do I calculate the distance of an object ...
0
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0answers
32 views

Tamron 18-200mm super wide angle lens [duplicate]

I purchased this lense, it says that it is a wide angle lense also. I would like to know hiw i can tell for sure, is it a wide lense or not?
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6answers
297 views

Why does Sony say that a 35mm lens is “35mm equivalent when used with an APS-C camera?”

I'm thinking of getting a Sony A6000 with a Sony SEL35F18 Lens. I'm a little confused about the actual focal length (and/or field of view) of the lens when attached to an APS-C sized sensor. The ...
0
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1answer
529 views

Camera sensor size vs pixel size and focal length [closed]

I've already seen the answer about the crop factor. I'm writing a small software for motion tracking (from two cameras, videos) in 3D space and research. To do that, I need some information about ...
31
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6answers
10k views

What software can show my most frequently used focal length?

Many people recommend a focal length of 35mm, 50mm, and sometimes even 85mm and upwards for those interested in purchasing a prime lens. I, however, would like to figure out what focal length(s) I use ...
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1answer
76 views

how to calculate “FocalLenIn35mmFilm” with limited metadata

Im creating an app that uses "FocalLenIn35mmFilm" to calculate feild of view(FOV). unfortunately not all photographs contain this property in their meta data, the Motorola Nexus 6 is an example. The ...
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0answers
23 views
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3answers
1k views

Does the size of the front glass mean anything?

Considering the Nikon lenses: Prime lenses: AF Nikkor 14mm f/2.8D ED has a huge front glass (●₃), AF-S Nikkor 50mm f/1.8G has a tiny little front glass, deep inside the body (∙₁), AF-S VR Nikkor ...
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vote
1answer
116 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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3answers
24k views

How do people shoot very large moon views?

I see pictures of the moon that looks like it is very close to the earth; I am wondering whether they are real or is there a trick to show the moon that big? Here is an example: ...
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2answers
5k views

How can I calculate focal length from a photograph?

I posted this question over on Stack Overflow, but someone suggested this site might be of more help to me. I'm doing a college project where I'm trying to calculate the focal length of a camera ...
0
votes
1answer
89 views

Comparing focal length [duplicate]

Hello I want to move from my compact camera to a dslr. I am fan of landscape photos so I want to buy an ultra-zoom lens. My camera supports 14x optical zoom. I know that for compact cameras it's just ...
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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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2answers
10k views

How to calculate the FOV in degrees from focal length or distance?

How does one to calculate the field of view (or angle of view) in degrees from the following details: sensor size (for example, 1") distance to target (for example, 7 feet) focal length (for ...
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2answers
737 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 ...
2
votes
3answers
152 views

If the zoom number doesn't tell me magnification, what does? [duplicate]

I've read How do I convert lens focal length (mm) to x-times optical zoom?, and learned that the times-zoom number doesn't tell you much. So, how do you determine the magnification — the amount a lens ...
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3answers
226 views

Will a macro extension tube eliminate the cropping of an APS-C lens on a full-frame sensor?

I understand using an A-mount lens intended for APS-C sensors on a full-frame camera results in cropping of the image. According to a tech at Sony, you lose 1/3 of pixels (APS-C is a 2/3 sensor so it ...
0
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3answers
1k 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?
0
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1answer
82 views

How do I measure the distance from an object to fit it in the screen? [duplicate]

I'm curious if there is any math formula for this. Let's take a close-up of a human face for instance, given the human face is about 20cm/8 inches, how do I choose the right focal length and from ...
0
votes
1answer
91 views

I want to know about the relationship between focal length and aperture [duplicate]

I have Nikon D7000 and I know the basic relation of shutter speed, aperture, and iso. All I want to know is focal length and aperture relation. As I zoom in the camera the f/stop increases (e.g. it ...
1
vote
1answer
411 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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votes
5answers
2k views

Does sensor size affect lens distortion?

There was recently a video posted about how different focal lengths affect portrait photography, specifically how distortion at smaller focal lengths have more distortion and are less flattering. So ...
7
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5answers
2k views

Do bigger focal lengths capture more light?

I never understood what the f really stands for in the f-stop values, like f/1.8. Wikipedia explains it in various articles, but I still find it very confusing. What I understand, though, is that it ...
2
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2answers
202 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 ...
0
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1answer
150 views

How do I find the focal length that will fit a poster in the frame from across the room?

If suppose I want to take a photograph of a poster on the wall of the room, so I can't back away any farther than 5.0m to take the shot(max dist of the room). The poster is 0.80m wide and 1.2m tall, ...
15
votes
4answers
2k views

What is a parfocal lens and how beneficial is it to photography?

I heard someone say that after using a parfocal lens for the first time, they would never switch back. What is a parfocal lens, how is it different from any other lens, and what are the advantages and ...
0
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5answers
303 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 ...
1
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3answers
170 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 ...
1
vote
2answers
132 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 ...
0
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1answer
68 views

What's the full frame equvialance of this phone lens?

I took a photo with my phone, and here is the EXIF: F/2 4mm 1/14s ISO-1250 I searched on the Internet and found that the sensor is Sony IMX134, 1/4 inch. Then how to calculate the equivalent focal ...
3
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4answers
440 views

What kind of lens is typically used for these type of night street shots?

I've been trying to duplicate the depth of field like in these photos on snowy nights and I'm not getting comparable results. I'm using a 35mm prime lens at f/1.8 on a D3100. So my question is: Are ...
1
vote
1answer
14k 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 ...
0
votes
1answer
156 views

How do prime lens allow variance of focal length when focusing? [duplicate]

If the definition of prime lens says that their focal length is fixed, then how come you can still alter the focal length when focusing? (either MF or AF)
1
vote
1answer
379 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 ...
1
vote
4answers
168 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 ...
2
votes
2answers
596 views

How does physical aperture size relate to f/stop?

There are two lenses on the market I am comparing AF Micro-Nikkor 60mm f/2.8D AF-S VR Micro-Nikkor 105mm f/2.8G IF-ED If I use the formula for calculating apertures of both the lenses I will use ...
0
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2answers
251 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 ...
4
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2answers
1k views

Is it worth to buy old Sigma lens instead of Nikkor?

I'm amateur and I want to try something new. I have Nikon D3100 with Nikkor AF-S DX VR 55-200/4,0-5,6 G ED and I'm shooting everything - animals, landscape, people, sport, ... (like real amateur :D ). ...
0
votes
3answers
270 views

Is an 18-200mm lens sufficient for an Alaska trip? [closed]

I am an amateur photography enthusiast, mostly for vacation shots. I have a Nikon D80 body and the 18-200mm lens which I use as my "walking around" lens. I have a trip to Alaska coming up this ...
5
votes
4answers
356 views

Can a telephoto lens have a wide field of view?

85mm-135mm lenses are great for portraits because of compression perspective distortion, meaning they flatten facial features. However at those focal lengths, you have to step back a few meters from ...
0
votes
2answers
575 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 ...