Spring 2012

Spring 2012
by ani

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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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2answers
77 views

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 ...
0
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3answers
165 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 ...
2
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1answer
112 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
52 views

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

Will a 0.5x focal reducer help me if i am imaging deep sky objects using a 1200mm focal length optical tube(f/6), 32mm super view telephoto extension eyepiece and a nikon d5500 with a sensor size of ...
4
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2answers
96 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 ...
0
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1answer
32 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 ...
0
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3answers
211 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 all crop lenses for example "10mm" when they are actually "16mm" (with a crop factor of 1.6 in this case)? Edit: I am familiar with the ...
0
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2answers
53 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 ...
0
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4answers
144 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.
0
votes
3answers
86 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 ...
23
votes
6answers
3k 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 ...
2
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5answers
784 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 ...
0
votes
1answer
39 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 ...
0
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4answers
237 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 ...
0
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2answers
135 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 ...
0
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2answers
142 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
42 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?
21
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5answers
1k views

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 ...
1
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2answers
390 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 ...
1
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3answers
430 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 ...
1
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2answers
89 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?
9
votes
4answers
365 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 ...
12
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3answers
1k 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 ...
4
votes
5answers
486 views

What focal length is used in photos that both model is zoomed in and the background is open

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 ...
0
votes
2answers
130 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 ...
6
votes
4answers
496 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 ...
5
votes
6answers
457 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 ...
0
votes
6answers
164 views

What is the shortest focal length before a black ring appears?

I know it depends on brand to brand and model to model, but in general terms, what is the shortest focal length I can have before the black zone (A) starts to form, or it is barely noticeable? (B) ...
4
votes
4answers
188 views

Which focal length lens generally has the sharpest lens? 24, 35, 50 or 85?

Context I realize that the above four focal lengths lend to having a different perspective that make them all unique. It might be possible to use one as the other but that isn't always true with the ...
3
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1answer
94 views

General rules when compression in the background looks good (like with longer focal lengths)?

Is there any general set of rules or guidelines on when would the background compression generated by a long focal length look good in a picture? Example : in a headshot, I really like the background ...
2
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1answer
146 views

Possible to lock focal length on zoom lens? (SELP1650)

(This could turn out to be a bone, practical, product-specific query, but this is the internet so the worst that could happen is a 0 rather than a 1.) Anyhoo: is it possible to lock a zoomable lens ...
2
votes
2answers
125 views

Do I need the 18-55mm lens that comes with the camera, or should I instead get a 55-250mm lens?

I'm a novice so don't know whether I need the 18-55mm lens that comes standard with the Canon EOS Rebel T6i or should I instead get the 55-250 mm lens - or both? I'll be using the camera primarily ...
0
votes
2answers
629 views

Effective focal length of kit 16-50mm lens on A6000 (APS-C 1.5x crop factor) [duplicate]

This is likely a tedious question for you guys but, as a camera noob, I'm miffed, so please bear with me. I have a: Sony A6000 (APS-C 1.5x crop sensor). With kit lens: SELP1650 lens (16-50mm) So, ...
3
votes
1answer
95 views

Which lens size will generate more detail for equivalent field-of-views in an image snapshot?

We are getting ready to purchase a 3 megapixel IP camera. It comes with either a 4mm or 6mm lens. We will only be using the camera for still image snapshots on a specified interval. Basically, it's an ...
2
votes
4answers
365 views

Are wide angle lenses suitable for portraiture of children?

Wide angle lens tend to make faces more "chubby" than they appear otherwise, and are therefore not used often for portraits, unless the landscape is an important part of the frame. I'm curious as to ...
1
vote
3answers
203 views

What focal length is recommended for photography for social media, like groups of people in weddings?

I want to get a lens for social photography (groups of people in weddings, or a close up for a bride). What focal length range would be recommendable? Also would it be good to get a wide angle lens ...
2
votes
2answers
261 views

How do you calculate the focal multiplier of a non-full frame camera?

I'm currently using a Sony RX100 Mark 3 camera and want to buy a Canon 6D + 24-105 F4 L lens from an online retailer, which is not in my country. (before continuing I'd like to state that there are ...
4
votes
3answers
625 views

Does focal length change when I adjust the focus? [duplicate]

When I adjust the focus of my camera, in general, does this affect the focal length? I have heard that it does.
2
votes
3answers
432 views

Is the Canon 70-200mm or 24-70mm better for convention photos? [closed]

I've decided I want to upgrade to a better lens, but I'm really torn between the Canon EF 70-200mm f/2.8L IS II USM and the EF 24-70mm f/2.8L II USM. I like to take convention photos, where space is ...
2
votes
3answers
230 views

Why isn't my computation of the actual size of an object in a photograph matching the expected value?

Let's say I have a full frame camera (Sony A7) with a 50 mm lens (Canon FDn 50mm f/1.4) mounted on it. At a given object (a plane) distance I should be able to compute the size of the image in real ...
3
votes
2answers
145 views

55mm on an 18-55 lens versus 55mm on a 55-250mm lens

I have two canon kit lenses which came with my 1100D. While experimenting casually with my lenses, I came across something that I find peculiar. When I am focused at an object at a certain distance on ...
4
votes
1answer
362 views

What are the advantages and disadvantages of zoom lenses with a wide range of focal lengths? [duplicate]

Are there some disadvantages of a zoom-lens with wide range focal length compare to a lens with narrow range both having the same max. aperture? For example, if we have two lenses: Sigma 18-55mm f4 ...
0
votes
1answer
40 views

Focal length of the sony DSC-H20 [closed]

I am working in finding the distance of the objects in a video taken using a Sony Camera model DSC-H20 and suppose that any lens or zoom distortions were applied. In order to know the position I need ...
0
votes
1answer
129 views

What's the ranges of ratios of Focal Length to Sensor Height to approximate a human eye's view? [duplicate]

Given this formula for calculating the distance to an object as long as you have a picture of the object and know the actual height of the object... distance to object (mm) = focal length (mm) * real ...
3
votes
4answers
259 views

Given the same sensor size lens, will a higher megapixel sensor give more “reach” then a lower one?

I've been wondering this for a while now, and I can't seem to find a straight answer about this. If we are talking about the exact same sensor size, (lets say FX) and we are using a 50mm lens. ...
0
votes
6answers
194 views

Is the wide aperture and bokeh of a 50mm prime more important than getting to the 70-90mm range for portraits?

I've a Pentax K-30 with the following lens: Pentax-M 50mm 1.7 manual focus Tamron 17-50mm 2.8 autofocus Pentax 55-300mm 4-5.6 autofocus Considering that : Pentax 50mm has the nicest bokeh and ...
0
votes
1answer
186 views

How do lenses focus? (and zoom?) [duplicate]

My understanding of focal length is that it is the distance from the lens to the sensor; in my observations: higher focal lengths make for longer lens. Then I started thinking about how a lens ...
0
votes
2answers
209 views

What is the relationship between focal length and minimum focus distance?

If I know the focal length of a lens, How can I know the minimum focus distance? I have checked several webpage, but I am still wandering is there a formula? I know there is mark in the lens, but ...
0
votes
1answer
183 views

I have camera specifications but don't know the actual focal length

I'm trying to figure out the focal length of my camera. I'm trying to figure out the distance from my camera to an object using the equation listed here (How do I calculate the distance of an object ...
0
votes
1answer
242 views

How can I tell what focal length a zoom lens was set to for a photo of the moon?

It appears that neither the Sony 55-210 mm f/4.5-6.3 nor the Canon EF-S 55–250mm f/4–5.6 reports the actual focal length to the camera: both cameras' metadata show the lens but report the focal length ...