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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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36 views

Is there an “optimal” background distance when striving for a minimally distracting background?

Let's assume a thin lens and an object O in focus at a distance of dO from the lens. Further, let's assume there's a large out-of-focus background object B at a distance of dB. Now, we know ...
0
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0answers
42 views

How to get width and height of an image based on distance

I have an app to overlay the images on the camera overlay. But I need to set the width and height of the image based on the user distance. If the distance is, say 8 feet, how can I calculate the width ...
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0answers
26 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 ...
20
votes
2answers
29k 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 ...
1
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1answer
117 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 ...
1
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0answers
36 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, ...
4
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5answers
260 views

Unable to get sharp landscape picture

I'm facing often the same kind of trouble when taking landscape pictures... I end up with a picture that could be great but that is totally not sharp ! Example : I set up the maximal focal ...
45
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5answers
10k 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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1answer
111 views

Is 85-135mm really the best for every single kind of face?

They say that focal length around 85-135mm is the best for the head and shoulder kind portraits. I've done some tests myself, I can definitely see the differences. The face is more natural looking ...
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3answers
317 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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3answers
109 views

Which is better: a smaller f-number lens or a bigger sensor size?

When choosing a camera, which of the following options would be the best in taking photo in low light situation and cropping photo situation? A smaller f-number lens with a bigger sensor size A ...
29
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5answers
73k 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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1answer
44 views

How to obtain a subject's measurement from image [duplicate]

I am trying measure real object height from an image. I'm using the below formula real height = (object px height * pixel size * distance)/(focal length) my camera is Canon_EOS_550D, my values are ...
2
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2answers
85 views

What is the real focal length of the Lytro Illum

According to Lytro, the Illum Light-field camera will have a 30-250mm equivalent focal length with a constant f/2.0 aperture. What is the actual focal length of the camera? Or, What is the sensor ...
0
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3answers
229 views

35mm vs 40mm: Does it matter?

I want to buy the lens Voigtlander Nokton 40mm F1.4, $449 Voigtlander Nokton 35mm F1.4, $629 I am asking, why the slightly difference in focal length, the price difference in so much as $180? ...
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1answer
73 views

Does manual focus carry over to a different aperture, lens or focal length?

This is in the manual focus mode. If I focus my lens so that a certain object is clear and crisp, and then do one of the following, will I have to focus again? Change the aperture Switch to a ...
0
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3answers
174 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 ...
2
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3answers
5k 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 ...
2
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3answers
216 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 ...
3
votes
2answers
402 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 ...
5
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2answers
2k views

Calculating focal length from 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 ...
12
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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 ...
0
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1answer
46 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 ...
2
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3answers
130 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
634 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
123 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 ...
1
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3answers
249 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?
1
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1answer
130 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 ...
5
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1answer
4k 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 ...
0
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0answers
78 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?
29
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4answers
6k 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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3answers
484 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
262 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
209 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
votes
3answers
249 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. ...
3
votes
4answers
682 views

What is relationship between focal length and shutter speed?

I am very new to photography and am trying to grasp the basics of it these days. Can someone please help me understand the relationship between focal length of a lens and shutter speed of camera?
0
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0answers
81 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
115 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 ...
16
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2answers
6k 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: ...
2
votes
1answer
485 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 ...
0
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2answers
245 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.
1
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1answer
199 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
votes
2answers
376 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
116 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 ...
32
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10answers
8k views

Which focal-length lens is usually used for portrait photography, and why?

What focal length or range of focal lengths are usually used for portraits? What is used by professionals? Why would one select a certain focal length? What are the advantages and disadvantages of ...
1
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1answer
139 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 ...
4
votes
5answers
2k views

Why do Canon EF and EF-S lenses exhibit the same crop factor?

I have a Canon 7D, which has a crop factor of 1.6x. When using a Canon EF-S lens I get the focal length stated on the lens, when using a Canon EF lens I get the focal length times 1.6 when used on ...
0
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1answer
86 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 ...
1
vote
2answers
240 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
votes
4answers
492 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 ...