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Tagged Questions

Autofocus is the ability of a camera/lens system to automatically adjust the focus of the lens via a motor attached to the focus group of the lens. Contrast with manual focus.

learn more… | top users | synonyms

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4answers
475 views

Autofocus performance of different brands at night

Are there huge differences in the ability to focus in low light between different brands and models? I have a Pentax Kx with a Sigma 30mm 1.4. My problem is, that the camera's autofocus does not work ...
4
votes
3answers
3k views

How do I keep my Nikon D5100 from attempting to autofocus with every shutter press?

I have a Nikon D5100 and the auto focus works fairly well most of the time. But there are times when I have a subject in focus and want to fire off multiple shots fairly quickly. I do not need to ...
1
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1answer
310 views

Why does the Fujifilm X-Pro 1 have fewer AF points in optical viewfinder mode?

From the Fujifilm X-Pro 1 manual: When AREA is selected for AF MODE in the shooting menu and S is selected for focus mode, the electronic viewfinder and LCD monitor offer a choice of 49 focus ...
3
votes
2answers
1k views

Is it really better to not half-press to focus with the Fujifilm X-Pro 1?

Fujifilm's new camera uses contrast-detect autofocus, and the current Internet hand-wringing is over whether this is a horrible critical flaw or not. As often happens in such discussion, a bit of ...
2
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2answers
394 views

Is there a secret way to make the Fujifilm X-Pro 1's autofocus point selection faster?

I think the answer to this is "no", but it may actually be available and I'm just not figuring out how to toggle the setting. The X-Pro 1 has a wealth of AF points — 49 in EVF mode and 25 in OVF ...
19
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3answers
3k views

What is the advantage of the huge number of AF points?

If the camera has only 1 central AF point, it is difficult to focus on an off-center subject ( without recomposing after autofocus ) so having 3 AF points seems really useful. Similarly I understand ...
6
votes
4answers
927 views

How important is auto-focus with a 50mm lens?

I have a Nikon D5000. I have wanted the 50mm AF-S as a portrait lenses for a while, but it was sold out forever. I finally broke down and got the older 50mm AF. Good lens, but no auto-focus on my ...
2
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2answers
5k views

Why does my Nikon D3100 no longer auto-focus via the viewfinder?

My Nikon D3100 out of the blue cannot focus correctly. It seem the that the focus motor always stops at the end of the run (Infinity) and cannot lock on the target, thus cannot release the shutter. I ...
5
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1answer
881 views

When is it really necessary to use AF assist light?

I find the AF assist light to be distracting at times when I'm trying to take a candid shot without disturbing the human subjects or taking pictures of pets (they hate getting the AF light in their ...
8
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3answers
936 views

When a camera auto-focuses, is the current focus distance reported from the lens to the camera?

The question says it all -- does the camera "know" how far the subject is from the lens, i.e. what is the current exact focus distance set at the lens?
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2answers
218 views

What settings do I need for shooting a candid against the sky?

I have Canon 1000D. Most of the times I use canon 50MM F1.8. I use evaluative metering and single point (center) auto focus. What setting do I need to change to have metering of sky (say red of ...
2
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1answer
378 views

autofocus and maximum aperture of 60D [duplicate]

Possible Duplicate: What are the aperture limits for autofocus on Canon DSLR cameras? It is mentioned on page 79 of the EOS 60D manual that the center point AF is twice as accurate at ...
1
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2answers
367 views

How to verify that Nikon SB-28DX AF-assist is working?

I have a Nikon SB-28DX which I am using with an F5. I understand from the instructions how to turn the AF-assist illuminator off. But, how do I verify that it's working? Does it still work with ...
3
votes
3answers
2k views

Is the Canon 600D Al servo autofocus up to the task of following moving subjects?

Has anyone tried shooting fast moving subjects (birds, cars, running animals) with Canon EOS 600D using Al servo autofocus? I am thinking of getting this DSLR but the internet reviews are a bit ...
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4answers
16k views

What should I do when my Nikon AF-S lens won't auto focus?

I have a Nikon 35mm f/1.8G AF-S DX I bought for my Nikon D5100, it's only a couple months old, never been dropped or anything, and it all of a sudden won't auto focus. Anyone know if this is a simple ...
19
votes
6answers
16k views

What is the practical difference between phase-detect and contrast-based autofocus?

What are the main differences in field use between phase detect AF and contrast based AF? I understand the technical differences, but I am not sure what the implications from a photographer ...
0
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2answers
746 views

Auto-focusing problem on a Canon 500D with a EF-S 18-55mm 1:3.5-5.6 IS(standard kit lens)

I'm having problems with the lens. I've tried auto-focusing with my other lenses, and it works fine. It can only auto-focus one way, i.e. the focusing ring is still able to move, but only able to turn ...
4
votes
1answer
544 views

What is an auto-focus motor?

I recently bought a Canon 550D, and I read it has an auto-focus motor, which not all cameras possess. I'd like to know what it is, and what I can do to keep it running smoothly; AFAIK the manual ...
7
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4answers
731 views

Why does my lens focus better/faster with a speedlight attached to the camera?

I have a Nikon d90 and have often found that the camera reaches focus faster, with less re-adjusting and missing the focus, when I have a speedlight (the Nikon sb-600 in my case) attached. Why is ...
3
votes
3answers
1k views

Is focusing problems on Sigma lenses still a problem on a Canon body?

I am considering purchasing the Sigma 70-200mm f/2.8 EX DG HSM II Macro Lens. The problem is that many reviews point out that the lens has front focus problems, at least on a Canon mount. But those ...
7
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3answers
1k views

What causes auto focus to misfocus?

If I understand correctly, autofocus works with contrast detection or phase detection, and both of these systems are in the camera rather than the lens. Surely then, the camera just needs to control ...
2
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2answers
581 views

How important is auto focus and aperture control in a macro setup?

I'm thinking of starting some amateur macro photography, and I'm not sure I want to go with macro lenses, due to their price. I currently have the following lenses: Canon EF 50mm f/1.8 II Canon EF ...
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2answers
925 views

'Bokeh' effect with autofocus switched off in manual mode (Nikon-D90)

I want to understand how focusing works in Manual mode in my D90. I switched off the autofocus buttons in the Kit lens and the camera body. I have changed to the manual mode. Now, when I try to ...
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2answers
852 views

Where can I find advice on using an advanced AF system for wildlife and bird photography?

I recently purchased a Canon 7D, as my previous 450D had become a severely limiting factor in my endeavors to wildlife and bird photography (particularly bird photography, which I LOVE, but for which ...
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1answer
326 views

What happens when a Sony SLT camera is operated with mirror up?

What happens if you attempt to operate a Sony SLT (pellicle mirror) camera with the mirror up? Does the camera detect this condition? Will the camera shoot? What happens to autofocus--can the ...
6
votes
3answers
5k views

Why does my Nikon D5000's AF Assist only turn on in some automatic modes?

I am using a Nikon D5000 with a 50mm f/1.4 with autofocus. When I try to use manual mode (or aperture priority, or shutter priority), my AF assist beam does not light, which makes it hard for my ...
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votes
3answers
843 views

How does color affect auto-focus?

I've noticed that the subject color seems to affect auto-focus, and am curious if I am just imagining this, or if there is a reason for it. For instance, I shoot a lot of figure skaters, and ...
2
votes
1answer
1k views

Is back-button autofocus possible on the Nikon D7000?

A while back I asked about the purpose of back-button autofocus and got several answers. The Nikon D7000 lacks the "AF ON" button that's present in some higher-end cameras. Is it possible to use ...
5
votes
8answers
12k views

How can I focus in very low light with my Canon 60D?

I'm using a Canon 60D and would like to focus in low light. I know Canons — in fact, all cameras — can struggle here with auto focus, but I'm talking about light so low that I wouldn't be able to see ...
5
votes
2answers
363 views

What is the reason to use fewer points than the maximum available for the autofocus?

According to the manual, Nikon D7000 has three options for the number of autofocus points: 9, 21 and 39 points. The manual explains that less points may be used when the subject is moving ...
2
votes
2answers
355 views

How can I find which lenses have “Continuous manual focus”?

Canon lenses with USM auto focus can be called "continuous manual focus" (at least some). By this I mean that you can override the AF without switching it off. I've found this very handy, and I often ...
2
votes
2answers
485 views

Why is AF performance different in automatic and selective mode?

How often do you use AF in selective (SEL) mode? The reason why I'm asking is that I've noticed that on a Pentax body (K10D and K-5) the AF is a lot more accurate when in AUTO mode than in SEL mode. ...
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2answers
2k views

Is it possible to measure distance to an object by adjusting the focus?

This is maybe not a 100% on topic photography, but I couldn't find a better stackexchange site to post this on and maybe you guys can help me out. I have a camera that takes pictures of a production ...
2
votes
1answer
356 views

Is Sigma 50-500mm EX DG HSM lens compatible with a Nikon D90 body?

Aloha, Can anyone tell me if the Sigma 50-500mm EX DG HSM lens (non OS model) is compatible with a Nikon D90 body? I recently purchased this lens on eBay but it seems that the lens will not ...
3
votes
1answer
225 views

How can one measure the autofocus performance of a lens?

Many of the lens reviews tend to comment on their autofocus performance, but they seem to be mostly subjective in nature (fast, slow, hunts around etc). I understand that the autofocus performance is ...
5
votes
3answers
715 views

Is there a way to make the Canon 7D warn when a lens is not in Auto Focus mode?

I pretty much shoot all the time in manual focus mode. I often borrow my girlfriend's most excellent Sigma 8-16mm ultra wide angle lens. She almost always shoots in Auto Focus mode. When I return it ...
3
votes
4answers
2k views

Which lenses typically don't focus properly on the Canon 60D?

I currently have the 18-200mm kit lens for my canon 60D. I am thinking of getting the 10-22mm wide angle lens as a second lens. So far with my kit lens I havent experienced any focusing problems or ...
6
votes
3answers
16k views

Is the lack of AF Motor on the Nikon D5100 an important factor?

I had made up mind on purchasing a Nikon D5100 during the holidays but only yesterday I realized that it doesn't have a AF motor with it. This is forcing me to change to Canon 550D which is in the ...
6
votes
6answers
1k views

Is it important that the Canon 1DX isn't specified to autofocus with lenses slower than f/5.6? [closed]

Seeking the lens market AND the related info WRT Canon 1D X, I found some things which seems concerning: 1st, a note from Canon's Chuck Westerfall (see here) saying: “AF is unavailable on the ...
5
votes
6answers
16k views

Why does my Nikon D3100 no longer auto-focus correctly?

I bought my camera on January 2011. Since a few months ago, I'm facing a problem with the autofocus. It happens with my two lenses 18/55mm and 55/200mm. I noticed that the focus light doesn't turn on ...
5
votes
1answer
1k views

What does the mirror do when shooting in Nikon Live View tripod mode?

When shooting with Nikon's Live View in tripod mode, the camera uses contrast detection to focus. It does this by using the sensor, which it would seem would raise the mirror similar to mirror lock ...
8
votes
3answers
169 views

Is there a rating, spec or measurement that a buyer can use to compare how fast cameras can autofocus?

I know that Phase Detection autofocus is faster than Contrast Measurement autofocus. Is there a spec that can tell me whether one DSLR or compact camera can achieve autofocus on a subject faster ...
2
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1answer
306 views

Do AF-S lenses work with bodies with in-built motors?

I have D-5000 body (without AF motor in the body) and two AF-S lenses. If I upgrade my body to more expensive body one with built-in AF motors, will AF-S lenses work (do autofocus) with new body ? ...
7
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1answer
2k views

What is EOS iTR AF?

I have read references to this feature on some Canon DSLR cameras and am wondering what benefits or uses it has.
37
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4answers
13k views

What apertures are required to enable autofocus, including cross-type or high-precision focusing, on Canon DSLR cameras?

This is a follow-up to Why does Canon and Nikon limit or disable autofocus beyond certain f-numbers? I'm doing this to separate the AF aperture requirements from the linked question above. My goal ...
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3answers
183 views

Why does my autofocus fail in windy conditions?

When I say windy, I mean inside 100+mph prop-wash, shooting from an open cockpit aircraft. The camera is an Olympus C-765 UltraZoom, which features a retracting zoom lens. It may be that manually ...
11
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2answers
6k views

Why does Canon and Nikon limit or disable autofocus beyond certain f-numbers?

One thing that I've noticed with Canon DSLR camera is they will disable or limit autofocus when the lens is below certain aperture values, which are specified in my answer to What are the aperture ...
0
votes
4answers
3k views

Which DSLR other than Sony A55 has best video capabilities with autofocus?

I've bought an Sony A55 camera for home use. Recording video is very important for me. Fortunately this camera is very good in video recording. It records 1080 HD and more important than that it does ...
2
votes
4answers
322 views

Will the Nikkor 85mm f/1.4D be a good fit with the D60, even though it doesn't autofocus?

I've been using a Nikon D60 for over a year now, and thinking about upgrading the stock lens. I am thinking about this lens: Nikon Telephoto AF Nikkor 85mm f/1.4D IF Autofocus Lens But on the page ...
7
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1answer
6k views

What are the AF-A, AF-C and AF-S autofocus modes, and how and when should I use each one?

I have seen these autofocus options on all my Nikon DSLR cameras (D50, D80, D90) but I have never really used them. There is the AF button on top. What are AF-A, AF-C, and AF-S ? How do I use ...