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Focus is the mechanism of converging light from a point light source onto an imaging plane by a lens.

learn more… | top users | synonyms

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1answer
844 views

Nikon D3000 Blurry Pictures. Focus Issue?

Here are two examples: Both pictures are in NEF format here. The pictures have not been modified in any way except except for being resized and converted to PNG. Just for kicks (and to prove I'm ...
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2answers
190 views

How to focus manually with a Nikkor AF-S DX VR 50-200mm f/4-5.6G zoom lens?

I have a Nikon D3100, for which I just bought a Nikkor AF-S DX VR 50-200mm f/4-5.6G zoom lens. This is a CPU lens and works very nicely in auto-mode, i.e. when you let the camera set the focus. ...
9
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1answer
619 views

Why is the Canon MP-E 65mm F/2.8 Macro Lens not called a zoom?

The Canon MP-E 65mm works differently than my other macro lenses. Compare: With a standard 35mm macro, I can frame first and then adjust focus which only changes framing very slightly with. With the ...
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1answer
113 views

Why do my photos appear more in focus when I use a long exposure? [duplicate]

Why does an unfocused lens still give a focused view with a longer exposure? For example, I took an out-of-focus photo with a ¹⁄₁₀th second exposure (at f/7.1), but when I change to 10 seconds (at ...
3
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1answer
162 views

Do lenses have focal planes or focal spheres/ellipsoids?

The title says it pretty much all. I'm asking this because I find myself always using the focus point in the center, and after I focused, I rotate my camera to make the framing right. However, if ...
3
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1answer
3k views

Nikon D5100 Focusing Issue

The issue I have had is where the camera tries to focus and cannot focus. It just zooms in and out constantly and no matter what I do it will not focus and fire. The only way I have found around this ...
0
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1answer
110 views

Why does the focus light come on in manual focus mode?

When I'm in the manual focus mode, I find that the focus light (the red blinking light) sometimes still comes on before it takes a photo. Why is this? I thought the purpose of the light is to ...
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2answers
262 views

How can I increase the amount of 'keepers' from my Nikkor 50mm 1.8D

I have been using this lens for a while, mostly for portraits and have noticed that for some reason the outdoor pictures where I most likely had to quickly compose and take the shot have had something ...
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3answers
7k views

What is the technical difference between focus and zooming?

This may look like a silly question but I don't know what the difference between zooming and focusing is. Zooming in will usually let me have fewer subjects in the scene while zooming out will allow ...
2
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3answers
181 views

Precise focus information in metadata

I am trying to get the precise focal length used for a stack of photographs taken with various focal length. See the following link. My problem is that even if the photographs are obviously focusing ...
2
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2answers
188 views

What determines the sharp parts in an image: the DoF or the focus point?

I am a little bit confused between depth of field (DoF) and focus points. Which of them is responsible for making part of the image sharp?
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0answers
58 views

How to get accurate focus at night? [duplicate]

I've tried focusing shots at night, but never get a perfect click. Are there any tips that might help?
4
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2answers
154 views

Light-field shots entirely in focus?

A light field camera can be used to make shots which can be truly refocused after the shot, however if I understand the technology correctly it would be just as easy to process the "image data" in ...
0
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2answers
162 views

Wide aperture in low-light results in muddy image on Powershot G16?

I have a Powershot G16 that I'd like to use as my standard camera for its light weight. It takes amazing photos in the day, but I'm having some problems with handheld at night. I'm still a photography ...
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3answers
270 views

Why can't I get a sharp macro image when shooting handheld, even with IS?

These days I shoot macro handheld, using the focus and recompose technique. I used AF-one shot. I used a Canon 100mm 2.8 on my Canon 550D. My shutter speed was 1/100s, but it was quite frustrating ...
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1answer
364 views

How can i get AF confirmation working with Samyang 500mm f/6.3 with dandelion chip?

I've put a dandelion chip (4th gen) on my Samyang 500mm f/6.3. I shoot a Canon 6D by the way. So, that's cool now I've set the chip to return f/6.3 and I can get a correctly exposed LiveView, EXIF ...
3
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3answers
442 views

Do focus area modes matter if shooting in manual focus?

It seems my camera lets me change the focus area modes (e.g wide, center or spot) even when I am shooting in manual focus so I am trying to understand if area modes matter even if the camera is in ...
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2answers
2k views

Nikon d7000 will not auto focus

Nikon D7000: When I press down on the shutter release my camera does not auto focus with any lens. I have checked and it's NOT on manual I have tried resetting my camera I want to shoot nightlife so ...
1
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1answer
85 views

Is there a way to avoid focus searching? [duplicate]

While using my camera in a relatively low light scenario I noticed some shots I missed because my camera was struggling to focus. I use a Nikon D7100 and noticed that the AF assist light only came on ...
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2answers
1k views

Why does my Samsung NX1000 zoom way in when manually focusing?

I bought a Samsung NX1000 this week, and I have the 20-50mm lens. However when I put it on manual focus, the picture keeps jumping from standard zoom to "mega zoom" — it zooms a lot further in then ...
2
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2answers
1k views

What is the difference Focus mode and AF-Area mode?

I am using Nikon D5100. To shoot a subject which is: Stationary: we can set AF-area mode to Single Point AF we can set Focus mode to AF-S Moving: we can set AF-area mode to Dynamic-Area AF we can ...
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1answer
719 views

What is the purpose of Quick Mode focusing in live view?

What is the purpose of Quick Mode (found on some Canon DSLRs) focusing in live view? To me it seems like a bad blend between live view and viewfinder mode that really doesn't cut it. Of course it's a ...
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3answers
710 views

How does autofocus point selection relate to manual focus?

Every lens I have comes with an auto-focus / manual focus switch. How should it be used if I am shooting on AV mode? If I were to select one of the focus points, do I need to have the lens on ...
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4answers
2k views

Why can't my DSLR with kit lens focus on objects close to the lens?

I have a Nikon D5200 with the 18-105 kit lens. I cannot focus the objects which are 15-20 cm away from the lens. Can anyone tell me how to manipulate the settings so that i can focus those objects? ...
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1answer
324 views

Why do I see different focuspoint in my DSLR's viewfinder and screen with old lenses?

I've had an old completely analog Praktika SLR with a set of lenses for a few years now. The camera and lenses are still quite good but I wanted to go digital. Having recently acquired a Nikon D5200, ...
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1answer
176 views

Which lenses show focus shift?

Some lenses, because of a design that includes uncorrected spherical aberration, shift their plane of focus backwards as the aperture is narrowed. This is most apparent at close focusing distances and ...
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1answer
111 views

Compensating for Focus Shift?

Some lenses, because of a design that includes uncorrected spherical aberration, shift their plane of focus backwards as the aperture is narrowed. This is most apparent at close focusing distances and ...
17
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2answers
2k views

What makes the focus ring on a lens go smoothly?

I’m curious about the smooth movement of the zoom or focus rings on a lens. How is the smooth movement done? Is there some kind of liquid with high viscosity? That doesn’t sound very probable. On the ...
16
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1answer
855 views

What is a focusing rail?

In What are the best practices for DOF stacking? I noticed a mention of a "focusing rail". I've never heard of such device. What is it, and in what circumstances is it useful?
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2answers
1k views

What might make focus points blurred/gone from viewfinder on Canon T2i after cleaning?

The red lights are all but lost in my T2i now....barely a haze of a blur. The focus points work fine, and I get the audible beep, but I have to check my focus point on the back before shooting and I'm ...
4
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2answers
324 views

What is the reference plane used when the minimum focus distance is measured?

Once you know the MFD (minimum focus distance) for a particular lens, is that the distance from the subject to the front of the lens or to the camera sensor?
7
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4answers
560 views

How much does a drop in temperature affect focus?

In an answer to question "What lens characteristics are important in astrophotography?" there was mentioned "If the temperature changes drastically, you may need to refocus as different materials in ...
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1answer
327 views

Canon 50mm F1.4 focus problems

I've had this lens for a couple of years, but am really struggling to get sharp pictures now. I've tried it on a 400D and a 7D and both show the same results. I had the problem with it getting stuck ...
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2answers
117 views

Science Fair Project Relating focus to pinhole size

I am doing a science fair project in which i want to see how the size of a pinhole effects the light diameter, and i would like to also relate this to focus and focal point. How would i do this?
61
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15answers
12k views

How does one focus for landscape photos in very dark conditions?

Tonight I tried my best to take some night landscapes in the darkest of dark conditions. Hoping for an epic composition of the Milky Way and a landmark. Of course, none of my glass could auto focus ...
2
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2answers
188 views

What would appear on polaroid film exposed without a lens?

I am trying to get a better understanding how lenses & focusing works. Let's say that I am standing in a completely dark room holding a unexposed polaroid film, and turn on a TV in the other ...
1
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1answer
107 views

Tricking compact's camera autofocus

I'm trying to get some bokeh using a compact (almost premium) camera, a Nikon Coolpix p300 (although the question is general). Since the camera hasn't got a manual focus option, I'm trying to use the ...
9
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1answer
258 views

Is the focus plane of a fisheye lens inherently curved?

After shooting of a fisheye lens earlier this week, I noticed that what is in focus does not seem to lie on a flat plane as it would for a rectilinear lens. Now, I am aware that lenses usually exhibit ...
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5answers
351 views
9
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1answer
5k views

What is the difference between depth of field and depth of focus?

Reading this answer I realized that I didn't know the difference between the two depths (of field and focus). Browsing related questions didn't reduce the blur (!) between the two... Wikipedia ...
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2answers
431 views

how to select a proper aperture for 50mm portrait lens? [duplicate]

I am using 50 mm 1.8 potrait lens with my canon 600D. But when i take a portrait with f1.8 on Av mode using autofocus, only subjects eyes are sharp and rest of the other face is slightly blurry. How ...
0
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2answers
67 views

What (and why) are the differences for AF between viewfinder and LiveView [duplicate]

I find that viewfinder never beeps to confirm focus. It also is much quicker (~0.5s) but sometimes jumps around constantly and never settles to a focus point. LiveView probably gets less light for ...
1
vote
2answers
417 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 ...
14
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4answers
6k views

How does changing focal length affect depth of field?

I'm curious about how my "area of acceptable focus" changes when the focal length of the lens I'm using changes as I zoom (or switch lenses). In particular, I'd like to know how the front & back ...
5
votes
3answers
483 views

How can I increase depth of field when photographing through a microscope?

I was photographing a small beetle and ran into the problem that it was just 0.5 inches long, and the macro setting on my camera failed to produce a sufficiently detailed and crisp image. Therefore I ...
0
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1answer
319 views

Canon lens FD 50mm 1:1.4 with Canon Rebel T3i - no focus

I am trying to use an old FD 50mm lens with my Rebel T3i camera but cant get focus. Is there any configuration on the camera I havo to make or it just don't work at all? Thanks!
4
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3answers
679 views

how to focus with a ND filter

I've just bought a ND3 filter (-10 stops) and was looking for recommendations on how to focus the camera. Basically many recommendations are around focusing WITHOUT the filter, then switch to manual ...
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4answers
2k views

Why can't my SLR autofocus on certain parts of a scene?

I had my Nikon D7000 on single-point auto focus and it just would not focus on the spots I wanted. I have marked the spots that could not be focused on with red circles, and the parts that could be ...
3
votes
4answers
54k views

How can I fix an out-of-focus blurred photo in Photoshop?

How can I fix this picture? Somebody else took this picture and well he wasn't able to do it very well, and it's blurred. I have photoshop
23
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5answers
2k views

What are the best practices for DOF stacking?

What are the best practices for DOF stacking? How do you get the frames with focus just right amount apart? How do you stack them in post processing?