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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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39 views

Which is better for portraits: 18-55mm or 75-300mm? [duplicate]

Would it be better to use a 18-55 or 75-300 for portraits? I inherited the Canon rebel xti kit and I'm new to photography. Eventually I will expand but for now just trying to get the settings down.
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4answers
147 views

What is the equivalent f/stop for 50mm?

If f/8 And Be There is the rule for 35 mm, what is the best f/stop if I am using 50mm? Context: Street Photography Note: Though one can say that "it depends", this is a very specific question. When ...
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1answer
76 views

How does focal length determine lens quality? [duplicate]

What does an 18 - 50 mm lens mean? Are those numbers the first focal length and second focal length? How do you use this parameter to judge what kind of lens to buy? Does more equal better?
4
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2answers
149 views

How do zoom, magnification, and focal length relate?

Zoom lenses and cameras with superzooms are often sold with an × zoom number — like a 12x zoom or 30x zoom. The question How do I convert lens focal length (mm) to x-times optical zoom? explains how ...
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3answers
113 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 ...
3
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1answer
163 views

Are wide angle adapters bad?

I would like to get wider angle photos than my current setup of min 18mm APS-C allows, but decent wide angle lenses (for Sony with 10-14mm focal length) cost 300+€. I stumbled upon these wide angle ...
4
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2answers
106 views

Understanding Lenses Focal Length with Converters

I read about APS-C sensors EOS DSLRs, that if the focal length is 300mm and as the image ratio is 1.6 then the 300mm x1.6 = 480mm focal length. So if I add a 1.4x teleconverter to 300mm lens so I ...
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1answer
60 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 ...
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0answers
67 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
32 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 ...
1
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1answer
276 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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0answers
41 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, ...
2
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1answer
128 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
191 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 ...
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1answer
56 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 ...
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2answers
98 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 ...
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1answer
102 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 ...
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3answers
400 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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3answers
502 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
393 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 ...
3
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2answers
655 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 ...
2
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3answers
268 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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1answer
49 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
181 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 ...
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4answers
657 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 ...
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3answers
256 views

Phone camera (Samsung S4): is it possible to determine the distance to the object in focus on jpg picture?

I took a picture with Samsung S4 phone. Is it possible to determine the distance to the object on the picture? The object is in focus. I looked at the JPG picture properties but could not find ...
0
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1answer
176 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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1answer
179 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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0answers
88 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
971 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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3answers
297 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
212 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 ...
4
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5answers
276 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 ...
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4answers
1k 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?
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3answers
152 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
671 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
283 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
223 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
491 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
votes
1answer
124 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 ...
1
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1answer
158 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
votes
1answer
87 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
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2answers
261 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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1answer
342 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
248 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 ...
1
vote
5answers
490 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 ...
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6answers
856 views

Why is focal length measured in millimeters?

Why is focal length measured in millimeters?
7
votes
1answer
221 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, ...
9
votes
4answers
839 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 ...
1
vote
3answers
268 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?