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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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7k views

What is the relationship of aperture, focal length, and ISO in a SLR?

I was using Nikon digital camera, and recently bought a Canon 550D. I am totally new to SLR. I am not familiar with SLR terms: Aperture, focal length and ISO, and their relation to one another. What ...
3
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3answers
463 views

Why do two zoom lenses set to 200mm on the same camera produce different fields of view?

I've been testing out a Nikon 18-200mm F3.5-5.6 against a Nikon 55-300mm F4.5-5.6 I took two pictures of a door knob from an equal distance of about 3 meters away with the same Nikon d7100 DX camera ...
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2answers
1k views

28mm vs. 24mm (wide angle) for selfies?

I know that selfies are an "evil" of this generation, and you're never going to get a good picture when taking one of yourself, let alone when you are unable to compose it bc you can't see the ...
13
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2answers
4k views

What differences between point and shoot zoom versus DSLR zoom cause the price disparity?

I'm just getting into the world of photography, stepping up from a point-and-shoot. I've just purchased a Nikon D3100 and it should be here in a couple of days. I've done lots of research, but ...
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1answer
59 views

Help to choose lens [duplicate]

I recent got 60d and EF-S 18-55mm Lens and i want to buy 1 more lens specially for product and fashion(portrait) photography... I decided EF50mm f/1.4 USM and EF85mm f/1.8 USM? Which one would be ...
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3answers
442 views

What do the specifications mean on the Canon G15's lens?

I am quite new to photography, but spent some days understanding aperture, timing, zoom and ISO. Now I see the values printed on the Canon Powershot G15´s lenses, and I can´t interpret them. I ...
6
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4answers
711 views

Is f/number more relevant than aperture and/or shutter speed?

I've seen on Flickr that the photographers specify values for four settings about their photos (where exif data is available) - Shutter speed F number ISO Focal Length An example can be found ...
0
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1answer
444 views

What's the practical difference in an image taken at focal length of 200mm vs 300mm? [duplicate]

I'm confused about the 200mm and the 300mm zoom ranges. I am looking for some examples of the same subject, in order to visualize the difference between 200mm and 300mm focal lengths. I want to ...
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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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1answer
367 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
6k views

Why does my aperture setting change as I zoom on my DSLR kit lens?

I am new to the photography field, there are few things which I am not able to understand. I am playing around with my Nikon D90 along with its kit lens (18-105mm). While reading about Depth of ...
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0answers
114 views

What is the basic relationship between aperture and focal length? [duplicate]

How does a photograph vary with a decrease or increase in aperture as well as focal length?
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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 ...
2
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3answers
814 views

Is 50-200mm (APS-C) a good zoom range for a single lens for people, buildings, and distant objects?

Assuming I do want to take pictures of things like people, buildings and things further away, but not too far away. Does it sound reasonable to buy a 50-200 mm lens, when just considering the distance ...
0
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1answer
216 views

Is this attempt to make lens measurements and focal lengths more intuitive correct?

I know next to nothing about cameras (other than how to push the shutter button). Up until a few days ago I thought of zoom as simply a multiple (e.g. my Canon S95 has 3 or 5X optical zoom) and had ...
7
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3answers
318 views

Do crop sensors on SLRs changes the depth and flatness of the objects as well? (in comparison to same focal length on full frame sensors)

1- I know different focal lengths change the depth and flatness of an objects in the picture. For examples longer focal lengths make objects appear flatter so they will be appropriate for portraits. ...
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0answers
82 views

How to calculate the zoom power (X factor) for a lens? [duplicate]

Possible Duplicate: How do I convert lens mm to optical zoom times? How can I obtain the "X factor" for a lens? I thought that to get the "X factor" I had to divide the largest focal ...
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3answers
278 views

At what distance from the lens will the image be in focus given a subject distance and focal length? [closed]

I've been trying to figure this one out for more than an hour now and I have no idea how to calculate this... You capture a picture of a tree which is standing 3m away from the camera. The focal ...
2
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1answer
1k views

Can I build my own focal reducer by reversing a teleconverter?

Would it be feasible to reverse a 1.4x teleconverter's optics into a cross-system lens mount adapter & have it function as a focal reducer? For example, like this: Camera hacked adapter ...
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2answers
456 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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1answer
815 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 ...
0
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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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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 ...
0
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1answer
91 views

Take a photo and print it to show approximate view of a human from a distance?

If I want to take a photo from about 600' away from my front door, and I want it to emulate what a person would see with unmagnified view, what mm would I set my camera lens length AND then what size ...
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2answers
367 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 ...
18
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4answers
533 views

Is there construction-agnostic term for a lens with a long focal length?

Turns out that telephoto refers to a specific construction of a long-focal-length lens, i.e., one where the lens is physically shorter than the focal length. Is there a generic term for referring to ...
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1answer
666 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 ...
3
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2answers
506 views

Image size of the Sun / Moon from a telephoto lens

I'm interested in taking a picture of the Sun / Moon using a telephoto lens. For example like this. It would be very helpful for me to know what the approximate image size of the sun / moon would ...
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5answers
1k views

Keeping two subjects in focus (depth of field)

What is the best way to get two subjects in focus in a portrait (sometimes not at the same distance from the lens)? Obviously, this is a question of depth of field, but I am curious what some of the ...
7
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6answers
1k views
7
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1answer
319 views

Why do certain lenses increase angle of view upon close focus?

I recently picked up a superzoom lens, the Nikon 28-300mm. Although I got it primarily for its versatility, my intuition was that a lens that can do 300mm focal length at 50 cm, as indeed it can, ...
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4answers
1k views

How much does 1 mm get you in a wide-angle lens?

I'm looking at a Canon 17-40 mm wide angle lens, and I don't understand why anyone would buy it. EFS18-55mm II is the standard Canon 18-55 mm lens that DSLRs come with, and it seems almost as ...
14
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4answers
5k views

How does changing focal length affect depth of field?

I'm curious about how my "area of acceptable focus" changes when the focal length of the lens I'm using changes as I zoom (or switch lenses). In particular, I'd like to know how the front & back ...
0
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1answer
141 views

What does “focal length multiplier” mean? [duplicate]

I have heard of something called a focal length multiplier, particularly in connection with the size of the image sensor in a camera. What I don't understand is what this is and why ans how it is ...
36
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10answers
5k views

What is crop factor and how does it relate to focal length?

I'm reading that a 50mm lens is recommended as a first prime lens for DSLR owners as it's supposed to give a 'natural' perspective, but when used on (most) DSLRs, the view is cropped, as if you were ...
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2answers
77 views

Finding the point corresponding to a known height in an image

I have an image of a wall taken from a phone camera from a known height h from the ground. Assume that the camera was held perfectly parallel to the wall and that the bottom of the image is perfectly ...
8
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5answers
846 views

Does crop factor still apply to a vintage film SLR lens?

My friend has a Tamron 24mm lens on his Nikon D5000 and he says that because of its age and the fact it is manual focus, it is still actually a 24mm on his crop sensored camera. Is this right? If so, ...
9
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4answers
956 views

Is it the same if you take a picture by setting 50mm in a 18-55mm lens and by using a 50mm prime lens?

Is it the same if you take a picture setting 50mm with a 18-55mm lens and a 50mm f/1.8 prime lens? Assuming that ISO, aperture, and shutter speed are the same, will both the lens give same results? I ...
8
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2answers
950 views

Do lenses with the same f-stop but different focal length gather the same amount of light? [duplicate]

I'm taking images of a light source in a scientific labratory, and I thought I had a good grasp on all these things, but now i'm second guessing myself after some results. The most important thing is ...
1
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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?
3
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2answers
346 views

Why is there no apparent relation between focal length and physical lens size?

Why is there no apparent relation between focal length and physical lens size? For example, the Nikkor 20mm lens has a physical length of 42.5mm! That's more than twice the focal length! And if you ...
3
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2answers
291 views

How much versatility does a 85 mm lens have?

Can it be effectively used for landscapes as I am not a portrait shooter? This may be first "prime" lens so I need to understand what it's usable for. How far of a "range" does it have as far as ...
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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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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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5answers
755 views

What are the different focal lengths of macro lenses and their advantages?

I am interested in macro-photography. I see there are macro telephoto (zoom?) lenses (e.g. 200mm), or smaller macro lenses (e.g. 40mm) ... What are the different types of macro lenses and their ...
4
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3answers
330 views

How do they come up with focal lengths for lenses?

There are a lots of lenses for each camera and I understand that each lens caters to a different use case but my question is on how they arrive at these numbers. For eg: there are prime lenses which ...
14
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11answers
8k views

Will a 50mm f/1.8 work for general outdoor photography?

I want to know if it's advisable to use 50mm lens for general outdoor photography. I'm torn between 35mm and 50mm primes, and have read all the pros and cons. I understand that 50mm could be tight in ...
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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 ...
5
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3answers
589 views

What does it mean that a lens is x millimeters?

Every lens has different focal length in terms of millimeter so if I have a 100mm lens, what does that refer to? Does it mean the length of the lens itself is going to be 4 inches long, or does this ...
4
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2answers
360 views

How can lenses with different focal lengths have the same angle of view?

I always assumed that there was a fixed relation between focal length and angle of view. But compare the technical data for the following lenses, all from the same manufacturer: Canon EF-S 15-85mm ...