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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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308 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 ...
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3answers
4k 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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3answers
802 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
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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 ...
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8answers
11k 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 ...
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2answers
348 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 ...
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2answers
328 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 ...
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2answers
443 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 ...
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1answer
344 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 ...
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1answer
203 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 ...
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3answers
672 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 ...
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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 ...
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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 ...
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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 ...
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6answers
14k 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 ...
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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 ...
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3answers
168 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 ...
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1answer
288 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 ? ...
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1answer
665 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.
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3answers
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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
178 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 ...
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2answers
5k 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 ...
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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 ...
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4answers
302 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 ...
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1answer
5k 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 ...
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1answer
2k views

How do I fix a lens with a problem returning to autofocus mode?

I bought a Canon EF 28-105mm f/3.5-4.5 II USM lens for my Canon 350D. It works mostly fine, except after switching from AF to MF, I can't return to AF mode. After I switch MF->AF, the lens doesn't ...
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2answers
327 views

Control and option comparison between the Nikon D7000 and the D300s?

I'm looking to purchase a new camera for both photoshoots and videos. I know all the technical differences like resolution, speed,...and all that. But I went to a shop where the sales lady told me ...
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1answer
422 views

Is continuous autofocus in video a software or hardware function?

My camera (Sony alpha A580) does not natively support video autofocusing. When I was buying camera, I didn't think that was such important feature for me. Now I want my camera to be able to autofocus ...
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1answer
455 views

Why doesn't the focus assist light get triggered on a flash connected via a Pocket Wizard TT1?

I have a Pocket Wizard TT1 and TT5 which work fine. I mount the TT1 on the camera shoe and the TT5 fires my remote flash ETTL fine. I now want a focus assist light, so I set a flash (580, 430 or ...
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1answer
6k views

Can I fine tune the autofocus on my Canon 60D to be more accurate?

I noticed that some of my lenses auto-focus more accurately then others. (Assume perfect light conditions and fast shutter speed) Zooming-in on say the center focus point (if only the center focus ...
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1answer
395 views

Why is my Canon Powershot A1100 focusing only on the bottom part of scenes?

I've been using a Canon PowerShot A1100 IS camera for the past year and it had been working just fine until I decided to change its settings. After I had serious trouble with it, I reset the settings ...
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4answers
2k views

Why can't I take a photo in dark with auto focus, manual mode?

I'm dorking around with a Nikon D80 and I am a total beginner. I am trying to shoot some light trails but the darn thing doesn't even take a picture. I am in manual mode with the bulb setting. For ...
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2answers
503 views

What is being set with Micro Focus Adjustment?

An autofocus system is system based on a feedback loop, where the AF sensor error reading if fed back to the lens focus motor. Being a closed loop, then theoretically there should be no focusing ...
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3answers
3k views

What do the AF-A, AF-C, and AF-S autofocus settings mean?

My camera has these settings for autofocus, and I don't know what they mean. I suspect "A" is "Auto", and "C" is "continuous", but I have no idea what "S" is.
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2answers
574 views

What does this switch do on my macro lens?

There is a switch on my Canon 100mm USM Autofocus Macro Lens that switches between 0.32 mm and 0.48 mm (I think those are the numbers I dont have my camera near me). What do these numbers mean and in ...
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3answers
2k views

Why is AF slow in Live View on DSLRs?

Why is AF so slow in Live View on SLRs ? On compacts, the AF works very smoothly and quickly.
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3answers
2k views

Are there cheap or DIY focus assist solutions for the Canon 5D?

I want a better autofocus system for low light. Low light auto focus is my biggest bane. I use a 5D so the options are AF on a flash like the 430 or 580. I happen to use the Pocket Wizard TT1 so I ...
0
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1answer
378 views

Is there a way to make auto-focus more smooth while filming with Sony A55?

Wondering if anyone can help with this. I have a Sony SLT-A55, and when in video recording mode it is able to auto focus. My issue is that it does this "too quickly". For example, if I'm shooting ...
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3answers
2k views

How can I get better focus results with my Nikon D90 at a fashion show?

I shot at a fashion show last week, and had focus problems. I used my Nikon D90 with a Sigma 70-200mm f/2.8, with no flash. I tried many autofocus settings but none of them worked. I also tried ...
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4answers
2k views

What is the best camera for concert photography?

I am interested in camera recommendations with a fast shutter and which are able to focus well in low light. The camera will be used for indoor concert photography where no flash is allowed.
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4answers
818 views

How to speed up autofocus on moving subjects under low-light conditions?

Since I am usually taking pictures under low light ambient conditions I have discovered the nifty 1.4 lenses (such as the Sigma 30mm/1.4 or the Canon 50mm/1.4 or also the Canon 85mm/1.8) for my Canon ...
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2answers
1k views

AF-D vs AF-G: is the aperture ring necessary?

I just purchased a Nikon D7000 with an 18-105 f/3.5-5.6 AF-S lens. I'm also looking at purchasing a lens around the 200-300mm focal length range, and I found the 70-300mm f/4-5.6 AF lens. As far as I ...
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5answers
3k views

Why am I getting poor AF results with my Pentax K10D?

I've been using Pentax K10D for a while and I'm a bit frustrated with performance of auto focus on that camera. Very often the images are not sharp enough despite taken in with decent lens (e.g. ...
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3answers
1k views

Is the color of the AF assist light important?

What are the differences between white and this darkroom red/orange active autofocus assistance lights?
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1answer
7k views

Sony 18-250 or new Tamron 18-270 lens? Which has better autofocus?

I want to buy either Sony 18-250 F3.5-6.3 or the new Tamron 18-270 F3.5-6.3 as a travel lens for Sony A55. I have found good reviews that told me quite something about image quality of these lens. ...
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2answers
305 views

What's a Typical “In-Focus” Rate for Portraits with an 85mm?

I have a lot of experience doing travel, landscape, product, ... in short, things that don't move much. Models? Not so much. I have a beautiful 85mm portrait lens for my Canon 1Ds Mk III DSLR, and at ...
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2answers
1k views

Why is my Canon 500D with kit lens having trouble focusing at higher focal lengths?

I have a Canon 500D with the kit lens. Recently I have observed that its not able to focus at higher zooms but it works at min zoom. To get it to focus, I have to zoom out or recompose and it works. ...
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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 ...
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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 ...