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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3answers
530 views

Why do images sometimes look “softer” at higher focal lengths (like 300-500mm)?

I get that it has to do with the lens, but what exactly is causing this?
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3answers
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does the focal length change the perspective at a given distance? [duplicate]

Situation A: 25mm lense, subject at 5 meters. Take a shot with the Subject covering half of the sensor. Situation B: 50mm lense, subject at 5 meters, Take a shot with the Subject covering the Whole ...
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4answers
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Does my 18-135mm zoom provide a wider field of view than a 28mm wide angle lens?

I recently purchased my first DSLR and I am interested in purchasing a second lens. My camera came with a 18-135mm zoom lens. I am looking to get a wide angle lens. The one I am interested in is a ...
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2answers
119 views

Looking for an iPad lens that makes it possible to capture a person head to toe from up close

I am filming golfers swinging at the driving range. Due to common video standards I want to film in landscape mode instead of portrait mode. However, to fit a whole person in I need to be quite far ...
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4answers
252 views

Why does lower focal length magnifies objects better comparing to other camera? [duplicate]

I have a newbie question about focal length, what it actually means for lenses and how I can translate this into "how close to the target it's going to practically take me" (I don't want to use the ...
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1answer
224 views

How does focus breathing affect DOF?

Like explained in this question Does focus breathing make a lens slower when close focusing? focus breathing does change the effective F-stop. At the same time, the lens behaves, as if it was a ...
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4answers
3k views

Why is the background bigger and blurrier in one of these images?

On my EM-10 Mk2, I'm testing a Panasonic 25mm f1.8 (top image) against the 20mm f1.7 (bottom image). I tried to make the lamp take up the same space in the frame before focusing, yet the background ...
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4answers
300 views

Why don't cameras ordinarily zoom by moving the whole lens as a unit?

Zoom lenses have a moving group of lenses within the whole unit. It seems to me that any lens could easily be made into a zoom lens by moving the whole lens unit towards/away from the film/sensor. ...
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1answer
394 views

Limits of camera lens capabilities [closed]

I read that the canon 35mm f/2 IS is the lowest aperture lens that also has IS. Is this because a stabilizer at any lower F-stop is not possible, or just because it is just currently outside of our ...
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3answers
3k views

Is a 30mm lens a good general purpose lens on an APS-C sensor?

I'm currently looking for a general purpose lens, and I'm more inclined to opt for a prime lens. There are several reasons for that; I want a fast lens and prime lenses tend to be faster at lower ...
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2answers
948 views

What’s an equivalent focal length of a fullframe lens on a crop sensor? [duplicate]

I have an old SLR film camera lens with a focal length of 58 mm mounted on my Micro 4/3 camera with a crop factor of 2. How does mounting the lens on a different sized sensor change the effective ...
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1answer
42 views

Canon ixus 85is achieve 50mm focal length [duplicate]

Hi can please anyone help me. How can i achieve a 50mm focal length on my camera? On the outside of the lens there is written 6.2-18.6mm thanks a lot
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3answers
722 views

DOF change when keeping subject size same in the frame

What I have heard is you get more background blur (narrow DoF) with lenses with longer focal lengths. And another thing to get narrow DOF is the distance between the subject and the sensor, the lesser ...
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1answer
394 views

What focal length is typical for Wedding Photography? [closed]

I am looking to start a wedding photography business and would like to understand what the best length is for the lenses.
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1answer
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How much zoom is needed for a distance of 600 ft? [duplicate]

How much zoom is needed for a distance of 600ft?
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3answers
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Why does the 55-250mm blur the background nicely and easily while the 18-55 does not? [duplicate]

I have a Canon 700D and I am new to photography (around 1 month). I got two kit lenses with my camera - the 18-55mm and 55-250mm. I usually use the 18-55mm lens as most of photography I have yet done ...
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1answer
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18-55 VRII or 35mm 1.8 for Nikon D3300 [duplicate]

I own a 18-55 kit lens for my Nikon D3300. i plan to sell it and buy a 35mm 1.8 prime lens. will it worth. i think there is no much difference in focal range of the both
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2answers
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How to determine film size from smartphone image exif data?

I took an image from my phone and got its exif data below. It was a samsung note 4, which uses a 35mm film size (24x36) with a 43.27 diagonal. But what I am trying to figure out is the sensor diagonal ...
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4answers
3k views

Calculation for getting dimension of object in image not working

I am trying to calculate the dimensions of an object in an image. This is a sample image I took to get height of blue shirt: I am following the math from this page with sastanin's answer. How do I ...
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3answers
117 views

When should ¹/EFL become ¹/(2 × EFL) to avoid camera shake

Where is the boundary when I should set my shutter speed to ¹ / (2 × EFL) instead of ¹ / EFL to avoid camera shake? (EFL = Equivalent 35mm Focal Length). Let's assume the lens has no image ...
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2answers
490 views

Will stepping back and using an FX lens on a DX body get the same “look” as the same lens on an FX body?

Using 85mm as an example, how can I get the same "85mm look" (shot on a FX camera with an 85mm FX lens) on a DX camera with the same 85mm FX lens?? I know a 58mm FX lens (87mm DX equiv), shot from ...
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4answers
546 views

Does being a Macro lens but on a shorter focal length affect taking a tight portrait photo?

I want to do some beauty portraits. Some of my shots will be from waist up, some of them will be tighter. For example just the face and nothing else in the frame OR a little going back to get the ...
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2answers
184 views

Does focal length affect coordinate estimation?

I am using a webcam mounted on the ceiling to track some markers. I measured the area on the ground that the webcam is able to see, it is roughly 2.61m x 1.46m. The output of the coordinates right in ...
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4answers
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How can I increase the flange focal distance (back focal length) of DSLR lens?

I am working on a custom setup where I am using a DSLR lens (Canon 50mm f/1.8) to project an image onto an image sensor (image plane). For my application, I require a very large distance between the ...
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3answers
1k views

What lens will get the whole body in the picture for street fashion photography?

I'm looking for a lens for fashion street photography which covers all the body in the pic. Do you recommend the Nikon 50mm 1.8d or Nikon 35mm f / 1.8G for my D3300 camera body? (I don't have the ...
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1answer
2k views

Why do DPReview's charts show the G7X II as having an aperture around f/8?

I have a Canon G7X II camera, which has a 24-100mm f/1.8-2.8 lens. Why does DPReview's chart show it having an aperture of around f/8 at a focal length of 100mm?
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1answer
297 views

Will a focal length reducer help me image deep sky objects using an 8" newtonian telescope?

Will a 0.5x focal length reducer help me to reduce the exposure time if I am imaging deep sky objects? I'm using a 1200mm focal length optical tube (f/6), a 32mm super view telephoto extension ...
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2answers
3k views

What is the relationship between field of view and focal length for fisheye?

What is the relationship between the focal length and field of view for an equal-area ("equisolid") projection fisheye lens? Alternatively, what is the relationship between the 180-degree image ...
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1answer
125 views

How far do I need to extend bellows to achieve particular minimum focal length [duplicate]

If I have a 200mm lens, and want to focus at, say, 450mm from the camera, two questions: can I (do I need to) use bellows to achieve this? is there a formula for how to work out how much extension I ...
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2answers
408 views

Why are crop lenses indicated with focal lengths they don't have? [duplicate]

If we will use crop lenses only on crop bodies, why do we call crop lenses for example "10mm" when they are effectively "16mm" (with a crop factor of 1.6 in this case)? I am familiar with the history ...
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2answers
90 views

Focus change after switch off camera?

I am using a zoom lens. The focal length is adjusted to 70 mm with manual focus. I then switch off the camera. Will the focus change after i re-turn on the camera? Noted that focal length and zoom ...
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4answers
1k views

What lens will let me take a photo of a bird high up in a tree?

What lens would work for a canon 6D to take up close photos of birds far away in the trees? My Canon 100mm-400mm lens just doesn't get that close.
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3answers
1k views

Difference between focal point and distance away from object? [duplicate]

I have a macro lens for the camera on my phone. I want to calculate the magnification of the lens because the one i purchased does not state it. I've found this guide which states the mathematical ...
29
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6answers
13k views

Is there a difference between taking a far shot on a 50mm lens and a close shot on a 35mm lens?

I am looking for a prime lens to pick up, and I'm wondering if there is any difference between 35mm and 50mm in terms of the end product if I just stand back more with the 50mm. I use the Sony a6000 ...
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9answers
1k views

How can I explain focal length to someone who isn't into photography?

Context So my friends and family are curious about how far my lens can reach. I usually explain with focal length and show them a few pictures. Question Is there any easier way to explain what ...
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1answer
974 views

focal length 300mm on dx camera + 2X TC [duplicate]

I saw nikon Nikon AF 70-300mm f/4.0-5.6G which works on both DX and FX sensor camera. I have Nikon D3300 which have DX sensor. As lens works on FX sensor if we use this lense on DX camera what would ...
2
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4answers
9k views

Does an APS-C lens label itself with effective or true focal length? [duplicate]

I'm not sure if I've phrased this correctly, but I've just purchased two prime lenses: Nikkor 50mm f1.8/G (FX) Nikkor 35mm f1.8/G (DX) I know that the effective focal length of the 50mm FX lens is ...
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2answers
831 views

Shouldn't the diameter of the moon with a 600mm lens be double what it is with a 300mm lens?

I used a 300 mm lens and recently bought a 600 mm lens, thinking that the area in the frame with the 600 mm lens will be exactly half of the area covered by the 300 mm lens. Practically I am not ...
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2answers
2k views

35mm DX prime lense on dx crop sensor(nikon d3300) [duplicate]

I have Nikon D3300 DSLR. I'm confused with 35mm and 50mm prime lenses on FX and DX cameras. Somewhere I read that if a 35mm prime lens is used on a FX camera the focal length is equivalent to around ...
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1answer
178 views

Which one is better for outdoor portraits Nikon DX NIKKOR 55-200MM F/4-5.6G VRII or 35mm f1.8? [duplicate]

Which one will give me more intense background blur with sharp foreground subject?
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5answers
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What is the shape of the focal plane?

This is something I just realised I don't entirely know the answer to, so I'm going to ask it here as I think it's interesting. In most non-scientific writing on depth of field, diagrams generally ...
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2answers
5k views

How to achieve full-frame look/view on a crop-sensor - without changing the lens?

I have a Canon 600D, which is crop-sensor camera. If you're shooting with a Canon EF 50mm, it'll be (50x1.6) = 80mm on a normal full-frame body right? I'm also a street-photography-kinda guy, which I ...
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3answers
5k views

What is the sweet spot of the Canon's 18-55mm IS STM lens?

I'm plannning to photograph negative film like this. And I would like to know what would be the sweet spot of my lens to achieve best sharpness possible, what f stop and at what mm I should be ...
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2answers
170 views

Does 4.0-72mm on the lens when equivalent focal length is 24-432mm mean crop factor of 6×?

The Samsung WB250F has 4.0mm-72.0mm printed on its lens, and its 35mm equivalent focal length range is 24mm-432mm. Does that mean it has a 6x crop factor?
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5answers
1k views

Circular polarizer works great at shorter focal lengths, but significantly degrades the image at longer lengths. Why?

I bought a cheap CP recently to play around with, and noticed an interesting phenomenon: Using it with my 24mm lens on full-frame, images turn out tack-sharp - there is hardly any difference in ...
13
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3answers
2k views

How do zoom lenses restrict their widest aperture at the telephoto end?

Does the aperture ring lock the apertures beyond, say 5.6 at length lens's telephoto end? Does the lens introduce an obstacle to the aperture ring so the lens can't be opened anymore beyond the ...
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6answers
1k views

What focal length is used in photos where the model is zoomed in but the background appears open and wide?

It is easier to explain my question just by a sample photo from Lyndsey Adler: See the models are so big in the photo — and still that big RV is also in the image. What focal length do I need for a ...
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2answers
2k views

Where is the image sensor located in a camera with a fixed-focus lens?

I am working on some research on the Kinect for XBOX One. I am looking into the depth measurements of the device. I have read that the depth values are calculated from the devices focal plane. So i ...
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4answers
1k views

How is actual focal length greater than focal range of lens?

This image (not shot by me) is shot using 70-300mm f/4.5-5.6 lens, but the EXIF shows the focal length to be 302 mm. How is it possible to be shot at a focal length (302 mm) greater than the ...
6
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6answers
15k views

What do the mm numbers on lenses mean?

I'm confused about lenses and numbers. Why are some lenses ex. 50mm-300mm Different sizes? Some lenses with the same mm numbers are huge and some are small... What's the difference? Also the prices ...

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