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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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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? ...
4
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1answer
172 views

What factor determines the largest usable sensor size with a certain lens?

Reading this excellent answer about field of view, focal length and sensor size a new question came to mind. From the drawn diagrams it is clearly visible that for the same focal length an increase ...
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4answers
11k views

What lens focal length most closely resembles the human eye perspective?

For example, if I have a lens that is 16mm-50mm, which focal length would be the closest to the human eye view? (I don't have a camera yet, so I'm just curious). Would 50mm be more zoomed in than ...
14
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2answers
5k 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: ...
3
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2answers
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 ...
5
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2answers
546 views

Is there a difference between using a telephoto or wide-angle lens for portraits? [duplicate]

Possible Duplicate: Which focal-length lens is usually used for portrait photography, and why? Assuming a similar aperture, what difference would you see using a 50mm, 85mm, or telephoto ...
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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
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 ...
3
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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 ...
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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, ...
7
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3answers
550 views

How much distance should one move so that a shot that can be framed at xx mm be framed at yy mm?

Is there a website / app that will tell you approximately how much distance a person should move so that they are able to frame the same shot at different focal lengths? Say for example, I'm ...
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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
433 views

Must I allow for crop factor in the viewfinder when shooting with a Nikon DX format camera?

Will a Nikon D5100 (dx format) viewfinder show me what the captured image will be, or do I need to allow for "crop" factor? Will that depend on/alter with using a DX lens or an FX lens? I don't have ...
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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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11answers
4k 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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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
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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5answers
657 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, ...
4
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2answers
593 views

Why does calculated distance of an object in an image vary when zooming?

I would like to calculate the distance of an object from my camera, so i used the formula given in this question and I got a very good answer, but I've found that when I zoom and take the picture and ...
3
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1answer
2k views

How do I find a camera's focal length in pixels?

I am working on camera pose estimation. For this, I need the focal length of my smartphone camera in pixels. (My phone is HTC Wildfire S, with Android 2.3).
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0answers
78 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 ...
3
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1answer
194 views

EOS M focal length conversion to cropped frame and full frame camera

I am thinking about EOS M .. it looks appealing to me ... especially for Hiking .. the thing i want to know is if I use my 18-55mm Canon lens (that normally come with 550D, 600D series) on EOS M with ...
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1answer
158 views

Where exactly would the focal length of a lens in the ray diagram fall?

If a lens is specified as (EF 50mm f/1.8), where exactly is the 50mm distance if I were to show it in a ray diagram? Considering that a lens is made up of multiple elements, I could not find a ...
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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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1answer
1k views

Why does a 50mm lens appear to give a human perspective, rather than a normal lens?

I grew accustomed to the notion that what one sees through a normal lens equates (or is close to) what can be seen with the naked eye (although that is not the "pure" definition of a normal lens, ...
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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 ...
3
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2answers
2k views

What is the conversion between focal length and times zoom? [duplicate]

Possible Duplicate: How do I convert lens mm to optical zoom times? What is the conversion between focal length in mm (e.g. 50mm) and x zoom (e.g. 20x) commonly used in compact cameras? Is ...
3
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1answer
616 views

Taking pictures with fixed/full focus camera

I have got a fixed focus, 5 MP camera with 3.3mm focal length (not sure what it means) on my phone. I want to know what's the best way to take pictures with since it's missing auto-focus feature. Is ...
5
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1answer
842 views

Should my flash zoom match my lens focal length or its 35mm equivalent?

I have a camera with an APS-C sized sensor. Should my flash zoom match my lens's actual focal length or its 35mm equivalent? I am hoping that someone can shed some scientific light to this matter.
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5answers
483 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 ...
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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 ...
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1answer
779 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 ). ...
6
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2answers
323 views

Can I get better image quality with a higher focal length or by cropping an image from a sharper lens?

Two well known ways to get better image quality are to use a sharper lens, and to zoom in to fill the frame (as opposed to zooming out and cropping in post). Sometimes there is a give and take between ...
7
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3answers
1k views

Does the shutter speed and focal length rule of thumb apply to cropped sensor cameras?

So, the rule of thumb for shutter speed is that it shouldn't be less than 1 / focal length. Well, that's straight forward on full frame cameras, but what about cropped sensor cameras? Is it going to ...
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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
856 views

What is the actual distance for taking a photograph with a 4.3-180mm Super Zoom camera lens vs. a 55-200mm DSLR lens? [closed]

What will be the true actual distance for both lens in terms of actual meters?
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3answers
960 views

How does using a lens with some focal length on a full frame camera differ from using a lens with “equivalent” focal lens on a crop camera?

As an example, a 35mm lens on a crop body (such as Nikon DX) is said to be "equivalent" to a 50mm lens on a full frame body. Equivalent here means that they will have the same field of view, but what ...
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
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 ...
11
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4answers
2k views

What is the reference point that the focal length of a lens is calculated from?

I understand the idea of a focal length for a single lens, i e the distance from the lens to the point at which parallel rays of light converge. However, in the case of a photographic lens with ...
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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 ...
7
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4answers
842 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 ...
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2answers
805 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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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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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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5answers
8k views

If I have an 85mm lens for portraits, is a 50mm useful as well?

I recently got my Canon EF 85mm f1.8, after lot of thought over if I should buy Canon EF 85mm f1.8 or Canon EF 50mm f1.4, I decided on 85mm so that I can shoot portraits of people even from a ...
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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??
12
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4answers
2k views

What is a normal lens?

I've heard people call 50mm lenses "normal lenses". For a lens to be considered normal, does it have to be exactly 50mm or is there some leeway? Does the normal focal length depend on crop factor of ...
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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 ...
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2answers
2k views

Why doesn't the background become blurred when I change the aperture on my Fujifilm S4000?

I am sorry if my question is too naive, but I am a complete beginner in photography, and I think I still need to understand well what aperture is. I have a Fujifilm S4000 camera, and I know I can't do ...