Questions tagged [focal-length]

Focal length is the distance (measured in mm) between the surface of a lens and the focal point, when the lens is focussed at infinity. Smaller focal lengths indicate wide-angle lenses, larger focal lengths indicate a telephoto lens.

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How to calculate Sensor Pixel Pitch?

I need to compute the “Sensor Pixel Pitch (in mm/px)” for some calculation. I have the following data available from the manufacturer: Resolution: 1920x1200 Sensor Type: 2/3” CMOS Pixel size: 4.8 x ...
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Would adding an external lens allow one area outside the focal plane to be in focus?

I’m doing high speed scientific imaging. I have a camera mounted in a fixed location with a Micro Nikkor 105mm lens. It’s viewing a fixed subject that has a small mirror oriented 45 degrees underneath ...
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Does crop factor affect focal distance for APS-C lenses? [duplicate]

I just found my interest in photography, and am about to buy myself a used DSLR. I did some research on what equipment would suit my preferred motives, and came to the conclusion that 35mm focal ...
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Can Tamron Tap-in Console solve focal length problems in metadata?

I recently found some issues on my Tamron 24-70mm f2.8 G2 (A032) lens for Canon. The first issue is about the focal length in the EXIF data. While the lens works well in autofocusing, I found the ...
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How did they do this beauty setup? What lights and focal length? Help me recreate this

From examination the lighting source appears to be 2 fluorescent panels and a light ring. How many lux/lumens/watts is he using? What's the focal length for the field of view is he using? (35mm ...
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Effect of increasing sensor size or focal length on resolution of target object

Suppose I have a camera of sensor size 8mmx8mm, optical class (2/3)" with a compatible lens of also (2/3)". The focal length of my lens is fixed (say 8mm), and the distance to my target object is also ...
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What lens do I need on a P&S camera for photographing faces?

I'm just someone who enjoys photography, but I'm not a photographer. I don't know a lot, so please try and keep things simple. I've been using a Fujifilm Finepix S9200, a bridge camera with a 24-...
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132 views

How do I calculate how high a camera needs to be to fit an object in the frame based on its field of view?

I'm doing a computer vision application related to snooker for my dissertation. In a section of my report, I’m talking about cameras and it would be good if I’m able to do the calculation stated above....
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Is 35mm on a cropped sensor good for fashion photography?

I am quite amateur with a camera but I want to become good in fashion photography. A top model has agreed for a photo-shoot for free and in return she wants me to make a portfolio. We are planning to ...
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Is there theoretical limit on the minimal focal length for a given sensor size?

There seems to be a limit, around 0.33, on the fastest possible aperture. Is there a theoretical limit on how wide a non-fisheye lens can be? That is, what is the minimal possible focal lens for a ...
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Does amount of background blur change with focal length given equal framing?

Let's assume I have two lenses, 50mm f/1.8 and 85mm f/1.8. I want to fill the frame with the photographed object. Now, if the object is 50cm wide, I need to take the photograph at a distance of 1.112 ...
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58 views

How to calculate the new focal length when usng a lens mount adapter

I'd like to know how to calculate the new focal length when using a lens adapter. Is there any formula? To be more specific: I need to attach my old lens (four third) to new micro four third system ...
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94 views

What focal length to use for full-body photography of a chubby person? [duplicate]

Recently I took pictures of someone that was slightly chubby. Close-ups using a 50mm lens went very well, but trying to get some distance in to get a full body shot were not really that satisfactory. ...
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Does field of view change for different lens model for the same focal length?

I am using two lenses - Tamron 75-250mm F/3.8-4.5 Model 104A and AF-P DX NIKKOR 70-300mm. When shot with lenses set to 250mm of focal length, the field of view for the Tamron lens is greater than the ...
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Would a 50mm lens on a Canon APS-C crop produce the exact same image as an 80mm lens on a full frame camera?

Scenario: I put a 80mm lens on a FF camera and take a picture I put a 50mm lens on a Canon APS-C crop camera (1.6x crop) and take a picture Going by the 1.6x crop, I understand the fields of view of ...
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A projection of a real-image is one fixed perspective, but looking through the lens with my eye, I see many perspectives. Why?

Assume that I have a camera obscura (with a large lens - something like a magnifying glass) setup projecting an image of some still life. I look at my projection on my projection plane and I see one ...
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Why can my eye focus on the real image of a convex lens at many distances from the lens, but a projection only works at a specific distance?

Say I have a single convex lens. I set it up like a camera obscura, shine a light on my object and project the image onto a projection plane. Given the focal length of my lens, the projection plane, ...
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How can the focal length for shake reduction be determined when the lens is mounted using a reverse lens adapter?

My camera (Sony A7RII) offers image stabilisation (SteadyShoot). I shoot macros using a 50mm and a 28mm Olympus lens reverse mounted with anadapter. What values should I enter in the menu to ...
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35mm for portraits

Ok everybody knows 35mm is not the most flattering focal length for a portrait and by portrait I mean somewhere from chest and above... and of course it gets worse as we get closer to the subject. So ...
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605 views

Why are lenses characterized by focal length and not the effective field of view?

In photography, it's the accepted norm to say that if you know the sensor size of your camera and the focal length of your lens, then you know the field of view of your system. However, in optics, it'...
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Dogs & Portraits: Should I buy the Canon 50mm f/1.4 or the Tamron 35mm f/1.8 for my APS-C DSLR?

I recently purchased a Canon EOS 77D (which offers an APS-C sensor) with a Canon 70-200mm f/4. Now, I am looking to purchase a prime lens. My research suggests a choice between the Canon 50mm f/1.4 ...
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221 views

How to take pixel-for-pixel aligned pictures with a DSLR and iPhone 7?

The Plan So I am trying to take two pictures, one with a DSLR and one with an iPhone 7. Why an iPhone 7? That's just what I own currently I want the photos to be aligned so that they are exactly the ...
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215 views

Pixel diameter of a given field of view calculation equisolid (equal-area) fisheye lens

I have a 180° equisolid (equal-area) fisheye lens with a focal length of 8 mm. I want to crop images to a circle defined by an angular field of view from the zenith angle of the lens (i.e. the middle ...
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What factors affect the detail and clarity of a photo taken by a digital camera?

By clarity, I mean to preserve as much detail as possible when zoomed in. For example, I take a photo of my cat 10 meters away, and I want to zoom in and able to see each single fur as clear as ...
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how many f stops should I allow for a given change in focal length - ISO and shutter speed remaining constant?

There are charts that show me what how many stops in shutter speed or ISO to allow when, for example, using an ND filter but given that a longer focal length reduces light available is there a chart ...
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Measure in photo formula help

Good Day I am trying to measure the width of an object in a photo as accurate as possible using the formula found in a previous question. Distance to object(mm)=f(mm) x real height(mm)x image ...
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3k views

How to find the focal length used by looking at image contents without examining metadata?

By looking at a photo, how can one tell what focal length was used without looking at the photo metadata?
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105 views

How is wide field-of-view possible using a tiny sensor?

From looking at the FOV tables on this page, I can see that FOV is greatly reduced as sensor size decreases. It seems that 1/2.3 sensors would produced fields-of-view that are tiny, even at the ...
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662 views

How can I see the equivalent focal length of the current zoom of my Nikon P900?

I have a P900 that I use for birding. It's great for carrying around and not so great when (as usual) the light is low. I'm considering using an alternate set-up, for example a D500 coupled with a ...
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How to test image quality with a camera that is focused to infinity?

I have to test a camera that is focused to infinity, but I cannot take an image of an object that is more then 1.5 meters away from the camera because I can't get it out of the room itself. (The room ...
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Why doesn't the picture become darker the more you zoom in?

As your lens's focal length gets longer, fewer photons pass through the lens to hit the mirror/sensor. Why don't you see darkening when you look into the viewfinder and zoom in with a zoom lens, and ...
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324 views

Given aperture and focal length, what is the minimum distance for maximum resolution? [closed]

I'm going to describe a physics experiment involving imaging a proton beam using a CCD camera by reflecting it on a aluminium oxide surface, and we need some help about how close the camera should be ...
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401 views

What tiny lens to shorten the focus on a tiny camera?

I'm trying to set up a tiny camera for a tiny science experiment. The camera is an OmniVision OVM6211: It's pretty much a 3mm cube, containing the image sensor and all the lenses. It has a 90º FOV ...
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526 views

Does changing the focal length change the depth of field for the same magnification?

When taking pictures with lenses with the same f-stop and different focal lengths, and magnifying the same subject to the same size (by changing the distance), how does the depth of field vary? I am ...
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51 views

Retrofitting of an old image documentation system with a new camera

I am trying to retrofit an old laboratory gel documentation system (Kodak 2000r) with a new camera (the original is dead). I connected to system lens a Basler acA1300-200um but the image I got is from ...
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42.8mm on Nikon COOLPIX P7700 > 55mm on Canon EOS 77D? [duplicate]

I have a Nikon COOLPIX P7700 and because it has been losing function due to wear and tear after 6 years, and I wanted a better zoom range for wildlife, I decided to get a Canon 77D DSLR so I could get ...
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510 views

Can you use a focal reducer with a teleconverter?

I don't believe it would be possible to do it but, is it? If I was to use say a full frame 50mm lens on a 2x teleconverter with a 0.71x focal reducer on APS-C would it work? Would you also get the ...
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1k views

How do I obtain sharp images on full body portraits?

I currently have a 50mm 1.8 and 85mm 1.8 and would want to know if the bokeh or sharpness would be any different at all. Many seem to say that the 85mm woud work best, but wouldn’t I have to bump up ...
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151 views

How does sensor size affect minimum front element size for a given f-stop and focal length?

Does the sensor size affect the needed size of the front element given a focal length and f-stop? My intuition tells me that a bigger image circle would require a bigger front element to maintain the ...
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605 views

What is so special about the 18mm focal length in kit lenses?

Looking at this Wikipedia article, a huge portion of kit lenses start with 18mm For example: 18-55 18-70 18-135 18-200 Why?
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Is this “tack sharp with blurred background” look done with Photoshop?

I’m relatively new to photography and although I feel like each photographer has their own style when capturing an image it seems that sometimes I just don’t have the right equipment. The pictures ...
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2answers
207 views

Which lens focal length to match binoculars' magnification: An alternative approach

The question of how lens focal length and binocular magnification appears to have been asked over 3.86 quinzillion times. Regardless, it's still hard to get an answer the layman can understand. I'd ...
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How is focal length facial distortion different on an APS-C sensor compared to a full frame? [duplicate]

From my understanding (and research) focal length affects how a face will end up looking on a photograph. Here's an example of focal length distortion on a full-frame sensor: My question is: will a ...
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255 views

Why would lens be much longer than its focal length?

I accidentally saw Nikon 17-35mm f/2.8 lens and noted that it is rather large for its focal length. Here's the first review of this lens search offered - looks like it's 107 millimeters long. Given ...
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290 views

Focal length measurement and definition in DSLR cameras [duplicate]

So i am a bit confused when it comes to focal length in DSLR cameras. According to multiple sources online i found and as per NIKON "It is a calculation of an optical distance from the point where ...
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168 views

At which focal lengths is it ‘safe’ to have the sun in frame?

I've seen both beautiful wide angle pictures that include the sun as well as camera damage from pointing long lenses at the sun. At which focal lengths is it safe to have the sun in frame? assuming ...
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134 views

Best focal length for Micro 4/3 camera for a shoot of gardens and garden features?

I am mainly a web developer but now have become also a sort of a semi-pro photographer as well - shooting only portraits on my micro 4/3 system with only one lens - a beautiful Leica 25mm. I have a ...
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3answers
2k views

APS-C crop factor 1.5x or 1.53x

I'm having issues wrapping my head around how to get crop factor based on 35mm. I understand what crop factor is but my math is confusing me. For example, everyone knows that aps-c is a 1.5x crop ...
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How does crop factor affect perspective?

I have a question about crop factor and how it affects the perspective. Suppose you have one Super 35 camera and one APS-C camera. As far as I understand, to photograph the same image on the APS-C ...
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704 views

What is the typical FOV / focal length for house interior shots?

I don't do interior shots, but I do see a lot of them these days because I am house hunting. If you look at high end houses on Redfin.com, you can see typical examples done by professional ...