Orquid "Phoenix"

Orquid "Phoenix"

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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

9
votes
1answer
3k 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 ...
21
votes
7answers
6k views

How to nail focus for DSLR astrophotography?

I've been doing a bit of astrophotography and the problem that I almost always have is nailing focus. I'll manually focus on a bright star or the moon (which hopefully isn't an option!) by magnifying ...
2
votes
2answers
992 views

Is there a way to do focus bracketing on Nikon D90 with Nikkor 105mm f/2.8?

One feature I loved in my old Canon G6 was the ability to do focus bracketing in macro photography. Any hope of focus bracketing using my Nikkor 105mm f/2.8 macro lens on my D90 body?
15
votes
4answers
1k 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 ...
21
votes
9answers
3k views

Why would I want to select an autofocus point?

I'm trying to understand why I would ever want to select an auto focus point other then the center point. I have a Canon XTI Rebel DSLR which has 9 auto-focus points, but I'm also looking into getting ...
7
votes
2answers
2k views

How can a prime lens focus on more than one plane?

By definition, a prime lens is a fixed lens system with a fixed focal length. Then, simple physics tells us that it should be able to focus only on one plane (at a fixed distance) in front of it. But ...
16
votes
3answers
1k views

How can I get better focus when a subject is moving towards or away from the camera?

When shooting events or action photos, engaging people, I often find that frontal (or rear) perspective may be very expressive, but my problem is focusing when the subject moves towards the camera (or ...
23
votes
3answers
2k views

Does changing the focal length change focus?

When using manual focus or back focus on D60, I sometimes zoom in the lens, set the focus, and then zoom out. Does changing the focal length (zooming out), also change the focus? In case the answer ...
5
votes
1answer
16k views

What is the difference between Al Focus and Al Servo autofocus modes?

Recently I bought a Canon 60D and I am uncertain about when and how to use/activate the Al Focus and Al Servo functions. I understand the One Shot autofocus function for still subjects. You press ...
7
votes
4answers
698 views

Which is better - autofocus and recompose vs. manual focus?

In some occasions autofocus doesn't focus what I intend it to. What is the better option - to use autofocus, focus what I want and recompose, or use manual focus in that situation?
7
votes
5answers
2k views

Can more than one focus points be selected?

Now a days, almost every DSLR camera comes with many focal points 9, 11, 22 etc. Many of them provide us with settings to chose manual focus point while shooting images, apart from the auto-selection ...
7
votes
1answer
2k views

How do you trap focus on DSLRs without native support for it?

I came across the term trap focus on the autofocus page of wikipedia, and it seems to be a very handy feature that triggers the shutter release when a subject moves into the focal plane. This feature ...
8
votes
4answers
2k views

How can I get maximum DoF with no distance markers?

I am aware of what hyperfocal distance is and the general principles behind it. However, most of the tutorials I have seen and read regarding it make use of lenses with focus distance indicators. ...
13
votes
7answers
947 views

How can I improve focus using both manual and auto on a candle flame?

I got my new tripod and 50mm F/1.4 sigma on my Nikon D7000 and was testing it out doing some shots of a flame on a candle. The below image is the sharpest i was able to produce. In review of my 50+ ...
1
vote
0answers
377 views

How do you focus in the dark? [duplicate]

Possible Duplicate: How to focus in complete darkness When I take a photo of landscape (or something beyond the range of the focus assistance lamp) at night, it's hard to see when the ...
27
votes
8answers
3k views

What is the advantage to back-button autofocus?

I've heard some advanced photographers talk about using back-button autofocus. As I understand it, this involves changing one of the camera's custom setting to engage the AF when a button on the rear ...
12
votes
2answers
701 views

Does a crop sensor affect closest focusing distance? Why does it not affect focal length in EXIF data?

Since I am considering to buy the Nikkor 105mm micro VR, I wondered if the cropped sensor does affect the closest focusing distance of 0.31m? Thinking about this, the following additional (and ...
14
votes
3answers
3k views

Can software auto-detect image focus?

I was wondering if there was any photo management software out there that could auto detect and "rate" images on how in focus they are. This comes up for me quite commonly when i am looking through a ...
11
votes
1answer
4k views

What is a focus limiter?

What is a focus limiter and how does it work? What is the advantage of it? For instance Tamron 90/2.8 Macro has a focus limiter. According to the documentation: In the limit position, the Tamron ...
6
votes
2answers
175 views

Fisheye Image Quality: Improves with Price?

Using a little Opteka fish attachment, I've gotten some very cool shots. The problem is that all shots get, of course, progressively less sharp as you move out from the center. I know that this is to ...
5
votes
3answers
1k views

Are there advantages to using a viewfinder for focusing instead of using a camera's rear LCD screen?

Are there any particular advantages to using the viewfinder for focusing instead of the LCD?
12
votes
4answers
761 views

How close can a lens focus?

From my understanding, if you want to do some macro photography it is better to have a lens that can focus when it is really close to the subject. Sometimes people buy extension tubes to help them ...
3
votes
4answers
1k views

How to avoid soft image at longest focal length with telephoto zoom lens?

I have a Tamron 70 - 300mm lens. I have noticed that the best focus I can achieve at the 300mm setting is not as sharp as the focus I usually get at a lower setting. Is this a common problem? Is there ...
10
votes
6answers
1k views

How to micro-adjust distance for focusing in macro photography?

I'd like to take macro photos, but I have a problem with the focus. I put the object on a (light) table, I put my camera on my tripod and take a few shots. Since the depth of field is very small ...
19
votes
8answers
3k views

How do I focus in low light for long exposures?

I've been trying to take some long exposure shots at night with my Canon 450D. The problem I'm having is that I can't seem to get a shot in focus. The low light conditions prevent AF from working at ...
11
votes
6answers
6k views

How can I get everything in focus?

I have a Canon 550D with 70-200 f4 and 50mm prime lenses. Although the camera has built-in 9 focal points, I sometimes face a strange problem. Here's a sample photo: In reference to the above pic, ...
6
votes
2answers
205 views

Can a hard impact foul up a lens' focus?

Recently, a camera with lens attached got knocked off a chair and hit the floor (not my gear, fortunately!). Following that, the lens would not focus properly, either with manual focus or auto. The ...
5
votes
3answers
1k views

What's that sign with a dot and a number in the view-finder?

I have a Canon 550D and when I look through my view-finder to take photographs, it displays all the current settings inside the view-finder itself like aperture value, shutter speed, ISO etc. ...
16
votes
5answers
1k views

How to improve focus accuracy?

I've noticed that quite a few of my photos aren't terribly well-focused. This particularly happens at long focal lengths. I'm using a Canon 500D and (mostly) a Tamron 18-270mm f/3.5-6.3 lens. I find ...
23
votes
3answers
2k views

What tips and advice do you have for photographing the Aurora Borealis?

A friend has been kind enough to lend me a DSLR for a few months. It's my first foray into DSLR photography, or indeed any kind of photography beyond simply aiming my Canon IXUS at something and ...
6
votes
4answers
842 views

How can I get sharp images using optical zoom function on a point-and-shoot?

We’ve got a point-and-shoot (Canon A590 IS), and it seems that the zoom function is completely useless because it is always blurry, even in broad daylight. For example, I tried to take a picture of a ...
21
votes
3answers
5k views

How can a 18-55mm lens focus on objects beyond 55mm?

I guess this is a total noob question, but doesn't 18-55mm mean that it can focus only up to 55mm?
15
votes
1answer
2k views

What is focus throw?

This answer to an earlier question of mine about manual focus lenses uses the term "focus throw". Exactly what does that mean? Why do manual focus lenses have more of it than auto focus lenses?
92
votes
7answers
7k views

What is bokeh, exactly?

I understand that "bokeh" refers to out-of-focus areas of an image — but there is obviously more to it than that. What does the term mean exactly? How well is bokeh really understood? Is it purely ...
9
votes
1answer
249 views

How can I achieve an effect in still photography that's analogous to a cinematographic effect?

I don't know how it's achieved or what it's called, but occasionally in a movie I see an effect in which the perspective of the scene is modified in such a way that the objects that are further away ...
19
votes
2answers
1k views

Why am I allowed to turn my focusing ring beyond infinity?

Is there a good reason why I can turn the focusing ring on my lenses beyond infinity mark on focusing scale? Following recent questions here and here, it sounds like a real usability issue. ...
12
votes
7answers
600 views

How do I get proper focus when photographing lightning strikes?

I've been lucky to have the opportunity to photograph several large thunderstorms in Colorado recently, however I ran into a couple issues. The first issue I've run into is getting proper focus. As a ...
25
votes
13answers
6k views

How does one get manual focus right with a fast-aperture lens?

I have got an old lens (f1.4) that I have to use only with manual focus on a DSLR. Well, it is difficult for me to get the subject on focus. Although on focus according to the viewfinder, the actual ...
11
votes
4answers
982 views

How do you manually focus accurately without a focusing screen?

I have a Canon 1000D and it doesn't come with a focusing screen. Sometimes my camera cannot focus in low-light. I'd like to manually focus, but without a focusing screen I haven't been able to do it ...
9
votes
7answers
418 views

Focusing an entry-level DSLR

I like really really sharp photos. Even with a prime lens, I seem to be able to do noticeably better with my 450D by manually focusing using live view at maximum zoom than by using auto focus (even ...
56
votes
15answers
7k 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 ...
4
votes
4answers
1k views

Why does my Nikon D90 autofocus not work in rapid succession?

When photographing candid shots of my children at play with a Nikon D90, I have trouble with the autofocus system. I focus and shoot one shot, great. But a second later another shot opportunity ...
27
votes
4answers
36k views

What is back-focusing?

What is back-focusing? Is it something I need to be worried about, or can I just live with it? How can I tell if my camera/lens is sufferring from it?
6
votes
5answers
2k views

Why is my Nikon 18-200 lens not focusing at higher focal lengths?

My Nikon 18-200 lens on a D300 camera will not focus when it is zoomed between 135mm and 200mm. Is there any tips on how to solve this besides handing it in to a photo store?
16
votes
1answer
531 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?
23
votes
5answers
1k 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?
24
votes
6answers
4k views

Can I damage the focus system by turning the focus ring when the lens isn't mounted?

I have a couple lenses that don't have an internal focusing system, and whenever I want to put them back in my bag, I turn the focus ring to make the lens shorter. I noticed that when the lens is set ...
23
votes
18answers
2k views

What are some techniques for hand-held image stabilization?

My zoom lens (75-300mm) is fairly slow: 5.6 at its farthest point. (I think it's 3.5-5.6, and it's not image stabilizing. I'm on a budget, sadly!) Unfortunately, my primary use for it is hand-held ...
32
votes
7answers
1k views

What is “Hyperfocal Distance”?

I'd like a clear & easy-to-understand (especially for non-physics-types) explanation of what Hyperfocal Distance is, how it affects photographs, and what determines its value.
13
votes
4answers
3k 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 ...