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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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291 views

Is lens focal length specified considering the effect of barrel distortion on field of view?

Given a NIKON 14mm f/2.8D ED AF Ultra Wide-Angle Nikkor Lens on a full-frame sensor, in theory the field of view is HFOV: 104° x VFOV: 81°. However this lens exhibits noticeable barrel distortion ...
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1answer
213 views

Why 5-50x focal length for autofocus micro-adjustment?

When we do an AutoFocus Micro Adjustment session, the general opinion is to set the focusing target at 25 x focal length (or somewhere in the range of 5-50 x focal length). Why is so? What happens if ...
2
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3answers
656 views

EF-S lens focal length [duplicate]

Possible Duplicate: Does my crop sensor camera actually turn my lenses into a longer focal length? If I have an EF-S lens with a focal length of 10mm on an APS-C camera (i.e. with sensor ...
2
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3answers
81 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 ...
2
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3answers
270 views

Does lens metadata from crop-sensor cameras factor in the crop?

I use a Canon 60D, which is a crop-sensor DSLR. Does the metadata found in Lightroom or Bridge report the actual focal length or the crop-sensor equivalent? For example, if the metadata says the ...
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3answers
210 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 ...
2
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4answers
277 views

At what focal range does it make sense to have Image Stabilization turned on when using a Tripod?

I was always under the impression that one should turn off the Image stabilization when using a tripod but when I see lenses with long focal length (300mm, 600mm etc...) comes with IS on them. ...
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3answers
376 views

Should I upgrade my camera or lens to shoot pro hockey games?

I've gotten the opportunity to shoot pro hockey games. My current gear doesn't cut it: Nikon D70 Nikon 18-70mm F/3.5-4.5 Kit lens Nikon 70-300mm F/4-5.6 D Nikon 50mm 1.8D Monopod From where i'm ...
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2answers
1k 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 ...
2
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2answers
340 views

Why are the area of aperture, focal length, and amount of light specified in these terms?

So I'm looking at the wikipedia article on Aperture, and I'm a bit confused. I understand aperture to be the diameter of the hole that lets light in. In the article, someone states that The ...
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3answers
345 views

Are there specific use-cases in mind that make the 70-200 F2.8 worth its weight/size?

I've been looking to upgrade my Mark iii's kit lens, and am comparing lens strategies. The 70-200mm canon F2.8 seems like an enduring and very popular lens. After holding one, i am left wondering why? ...
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2answers
818 views

Zoom Lens and Prime Lens Photo Comparison

Are there any examples comparing the picture quality of prime lenses and zoom lenses with the same scene and shot at the same focal length? I have not seen anything that shows me why a prime is better ...
2
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1answer
292 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 ...
2
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2answers
802 views

How to calculate the size of the image circle at infinity focus?

How can I determine the diameter of the image circle (i.e. the diagonal size of CCD required to fully utilise a telescope's optics) at near-infinity focus? I have looked around online and found this ...
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3answers
676 views

How to compare the focal length of a 50mm prime lens with the default lens of a point and shoot camera?

To imagine the 50mm focal length of a prime lens 1.4F, can I simply zoom the lens of my point and shoot camera up to 50mm? Will both the focal lengths be same? Any other way to imagine the focal ...
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2answers
603 views

What is the benefit of a dedicated wide angle zoom vs a superzoom?

I am considering buying a Sigma 10-20 mm F3.5 wide angle lens for my canon 550D, but not sure what the benefit would be compared to using the wide angle end of my existing Sigma F3.5-6.3 18-250 mm ...
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5answers
267 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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3answers
1k views

50mm lens=75mm on DX camera? [duplicate]

I'm looking for a 50mm lens for my nikon d3100 and I just came across an AF-S 50mm f/1.8G lens and it says in the description that if it's used on a DX camera, the angle of view is going to be 75mm. I ...
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4answers
441 views

What exactly is focal length when there is also flange focal distance?

If focal length is the measure between the rear element and the sensor then how can you have different flange focal distances? Is the focal length not literally the measure between the rear element ...
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3answers
323 views

Is it possible to calculate focal length if you know the aperture?

I need focal length (for my IA homework), but I didn't know that in real world I would only get the aperture. Ok, my camera is an Olympus X-21, and manual says: -----Olympus lens: 6.3 to 18.9 mm, ...
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2answers
220 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
156 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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1answer
174 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
546 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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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 ...
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2answers
2k 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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1answer
125 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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3answers
505 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
216 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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3answers
1k 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 ...
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2answers
806 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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1answer
62 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
219 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
118 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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1answer
2k 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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3answers
199 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
3k 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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3answers
308 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
198 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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2answers
867 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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1answer
346 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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1answer
103 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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3answers
108 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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2answers
285 views

How does focal length chage 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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2answers
248 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
413 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
92 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 ...
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2answers
201 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
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 ...
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2answers
62 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 ...