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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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4answers
685 views

Pictures coming blurry when trying to take a picture of myself using self-timer

I have a Nikon Coolpix S9100 camera I am trying to take few self-portraits by setting the self-timer and then going in front of the camera, however all the pictures come out very blurry. I am aware ...
3
votes
2answers
567 views

Why is the AF confirmation chip needed?

I've read that adapter rings for manual lenses in Canon and Nikon might incorporate an Autofocus Confirmation chip... With my old Pentax K10D all manual Pentax-K lenses had AF confirmation, and they ...
3
votes
2answers
2k views

What is a Dual pixel autofocus?

I have seen the term "Dual Pixel CMOS autofocus" used by Canon (specifically in relation to the 70D). What is it? Is this Canon specific technology? Are there equivalents in other manufacturer's ...
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1answer
237 views

Finding the distance of object from camera to the point of autofocus

Is it possible to find the distance to which the camera is auto focussing ? Camera auto focuses itself to view a particular plane in the real world in front of it. Is it possible to estimate the ...
1
vote
2answers
537 views

How to achieve auto focusing with a non-TTL flash (YN-560 II) in low light situation?

I recently bought a new YN-560 II hotshoe flash but found that it has neither TTL nor assist beam for focusing in low light situations. The problem now is that I'm starting my career as a night ...
2
votes
2answers
206 views

In which situtations are cross-type autofocus points better?

I understand that the difference between "regular" autofocus points and cross-type ones is that the latter consist of two diagonal "regular" ones. I also understand that this is better. But what are ...
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3answers
388 views

Canon 70-200mm F4 L USM IS Focus Issues Photo All Soft?

Focus Issues Bought myself a used Canon 70-200mm F4 L USM IS Lens but as yet I've not achieved a single Sharp image list of various settings tried attempts so far and still no joy very frustrating. I ...
3
votes
1answer
1k views

What happens to a lens when you turn the focus ring during AF mode?

What happens to a lens when you turn the focus ring during AF mode? I have read that this causes damage, or can cause damage. But what is actually happening? I've done this recently with my Canon EF ...
2
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3answers
258 views

How to correctly focus on the background person in a shot?

I tried to take some portraits of my sister-in and her fiance earlier in a sunny, green park. I took a few pictures where the fiance is closest to me but turning to look at his wife-to-be who is ...
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2answers
138 views

Understanding Auto focus capability with examples

There are lot of explanations/comparisons of auto focus capability of different cameras available. Canon 5D Mark III has been termed as a superior camera for this feature in the semi-pro range. In ...
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vote
3answers
4k views

What does infinity focus mean and when should I use it?

All my lens have focus ring where at the end there's an infinity symbol. What does that mean? If I'm taking landscape shot and what everything from near to far to be in focus, do I use infinity? Or am ...
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vote
2answers
256 views

What might be causing my AF system to misfocus?

I have a Canon Rebel T1i with the default Canon lens. When I shoot with it, I use Auto Focus and get the red dot indicators in the viewfinder as expected. But even though it looks like the camera is ...
2
votes
1answer
109 views

Circular Polarization and Passive autofocus [duplicate]

Couple of weeks ago, I was assigned a homework in one of my Applied Physics master's course. My professor asked to explain why passive autofocus works only with circular polarizers. I am not a very ...
6
votes
2answers
234 views

How does contrast detection autofocus choose its targets?

If I understand correctly the difference between CDAF and PDAF, CDAF basically does not have knowledge of distance while PDAF does. CDAF simply maximizes contrast. So if that is the case how does it ...
11
votes
4answers
549 views

Why aren't lenses designed with extra large apertures for autofocus beyond what's used for imaging?

Historically, designing large-aperture lenses has been difficult because correcting the optical aberrations that arise from large apertures requires complex designs and very large amounts of glass. ...
3
votes
2answers
1k views

Why is on sensor PDAF drastically slower than traditional PDAF?

Why is on sensor PDAF drastically slower than traditional PDAF? I assume the technology is the same, doesn't matter if the module is on the sensor or located behind a mirror. But the performance is ...
2
votes
1answer
101 views

Does using multiple batteries (via grip) improve AF speed?

I want to say I read somewhere that, particularly with heavier lenses (such as the 70-200 F/2.8), having two batteries in the portrait grip would provide extra juice to the AF motor and help it ...
3
votes
3answers
531 views

Is focus hunting “normal behavior” for the Sony SEL18200SE?

I recently bought an NEX-6, the 24mm F1.8 (SEL24F18Z) lens, and the black 18-200mm F3.5-6.3 (SEL18200LE) lens. I love the 24mm lens, but I'm having a what I believe one would call a "focus hunting" ...
2
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3answers
254 views

What can I do when autofocus suddenly starts blocking at around 2m on a Nikkor AF-S 28-70mm 1:2.8 D?

I had this lens for quite a few years now, it used to work as expected. I didn't use my stuff for a few months, maybe 6-8 months. I just bought a D600 and tried to use them. The AF does not work as it ...
1
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1answer
3k views

How to troubleshoot a Nikon D5100 that will not autofocus at all?

A good friend of mine has a d5100, which was working perfectly fine yesterday. Today, however, it refuses to autofocus at all - it makes no effort to move the focusing ring etc. I have tried ...
3
votes
1answer
999 views

What settings affect how the focus points are displayed for my 7D?

My Canon 7d is about 2 months old. I used it for a shoot in DC, and it just isn't behaving as expected. When I try to focus, I get little black boxes in the focus frame. They used to be black, with ...
6
votes
1answer
4k views

Why isn't the focus indicator light showing when focused on my Canon 5D Mark III?

I've been working with two different Canon EOS 5D mark III cameras, and had the same problem with both. When auto-focusing I have two kind of indicators when the image is focused on a certain point. ...
3
votes
3answers
2k views

Missing focus with Canon 50mm 1.8 lens - is it the lens or me?

I purchased a Canon EOS 650D and EF 50mm f/1.8 II lens. Unfortunately, the auto-focus seems to miss focus at f/1.8. I've tried setting it to single-point auto-focus: it is better, but still not good ...
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votes
2answers
2k views

Do I use the camera or lens switch to change between auto and manual focus?

I own Nikon D7000 with 18-105mm lens. I am bit confused how the auto focus and manual focus switching works, particularly with my gear. The confusing part is both the camera and lens have an A-M ...
2
votes
2answers
567 views

Nikon D5100 intermittent focusing problem

I'm having this intermittent problem that the camera does not want to focus in auto-focus. When this happens I try to switch to manual on the lens, (both 300mm, and 55mm) but the toggle button will ...
4
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2answers
2k views

What is the effect of the number of cross-type focus points on sharp focus?

Canon claims that EOS 6D has special capability to focus in low light, but it has only one cross-type sensor and overall only 11 focus points. Does only one cross-type focus point in the Canon EOS 6D ...
6
votes
1answer
555 views

What do orange AF points mean on a Canon DSLR?

I recently bought a Canon 7D and Ive noticed that occasionally the AF points are orange. What conditions cause this? It seems like it is a warning of some sort. Usually when the camera focuses on a ...
2
votes
2answers
245 views

Should Canon 5D mk II autofocus be accurate enough for a f/1.2 lens?

What autofocus accuracy can be expected from an EOS 5DII or EOS 5DIII camera? I have an EOS 5DII with f/1.2 and f/1.4 lenses. I have a lot of problems getting consistent autofocus with these lenses. ...
4
votes
1answer
233 views

Why isn't the gain on phase-detect autofocus sensors increased in low light?

Modern phase-detect sensors can focus in pretty low light. However, the limit for low light focusing tends to be reached much before the camera can no longer capture images using a high imaging sensor ...
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2answers
2k views

Why are images with my Nikon D7000 and 70-200mm lens soft?

I'm having trouble getting sharp pictures with my D7000. I've tried it with a 70-200 and 18-70 and produce the same results. I've tried AF Fine Tune with one of those focus charts, but the value of 0 ...
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6answers
450 views

Why is the main sensor not used instead of the separate AF sensor to focus a DSLR?

From this answer I understand that the reflex mirror of a DSLR is actually not reflecting all the light, but it passes a certain amount on to the AF sensor. So if the reflex mirror can pass light, ...
6
votes
1answer
365 views

Where is the AF sensor located in a DSLR?

As I understand every DSLR has a separate, smaller sensor that handles phase detection focusing. Where is it located? If this location is different for every DSLR, and therefore this broad question ...
5
votes
1answer
1k views

Why does the IR-Assist beam of Canon Speedlites not get used in AI Servo AF mode?

The IR AF-assist beam on the Canon Speedlites (I have a 430 EX II) doesn't seem to come on when the DSLR (I have the EOS 7D) is in 'AI Servo' AF-mode. It works fine if I'm in one-shot mode (comes on ...
3
votes
2answers
3k views

Do the issues with sharpness I am seeing require AF fine-tuning?

I own a nikon D7000 with 18-105 lens. I am not happy with sharpness I get with autofocus in portraits. I read about front/back focusing, but I am not sure whether my gear has this issue. Is this issue ...
1
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2answers
3k views

Why does Nikon D3100 locks Shutter in Autofocus mode?

So I just got this Nikon D3100 Camera. And I am trying to take a picture using autofocus with the kit lens(18-55mm). The system is in Auto mode, AF-A, single frame and the lens A-M switch is on ...
2
votes
5answers
2k views

Why my “action” shots are blurry even shooting on AF-C, is this a lens or camera limitation?

I'm currently using a Nikon 28-200mm AF-D with my D7000. While trying to take action shots (e.g. my dog running or sports) none of the shots seem to be in focus even on AF-C mode. Would this be a ...
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2answers
1k views

What kind of AF-motor does a Nikon D7000 body have?

I am a novice in the SLR photography world and am going to buy my first camera. I intend to take occasional videos. I guess if the AF-motor is screw and gear type, the clicking noise will ruin the ...
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vote
2answers
538 views

How can I repair a kit lens with a stuck auto/manual focus mode switch?

Recently got a Nikon D5100. After a few days I realized that I can't focus in manual mode. The auto-manual (A-M) switch on the lens seems to be the issue (I have to press the switch hard to manually ...
0
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1answer
75 views

Will a shutter half-press perform an autofocus while shooting video on an EOS 650D?

Have Canon kept this feature or has it gone like the movie cropping mode?
2
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1answer
199 views

Why is my ISO so high in auto mode?

New user of a Canon 7D - less than 50 shots taken. Last night, I needed to take a quick picture of something that was on my cell phone with my Canon 7D I propped the phone up against a white pillow ...
11
votes
3answers
3k views

Why do mirrorless cameras have quicker autofocus than SLRs using live view?

With early 2013 cameras, it's generally accepted that using contrast detection autofocus on SLRs (ie live view on most SLRs) is something which is really suitable only for static, or close to static, ...
3
votes
2answers
1k views

Is it safe to manually-focus the Nikon 18-105 while in autofocus mode?

There are only A and M settings, no A/M. but I just noticed that Nikon website has mentioned three focus modes for this lens: Auto, Manual and Manual/Auto I'm confused if this is only a typo or is it ...
1
vote
1answer
129 views

Can I use a Cosina AF 28-300mm f/4-6.3 with a Nikon D5100 if I focus manually?

The Cosina AF 28-300mm is an autofocus zoom for Nikon F-mount (body must have AF motor). Can I still use it with the D5100, provide that I will have to manual focus?
5
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3answers
407 views

Do I need a better Camera or do I need to learn how to use the one I have?

Read some of the old questions. I figure that due to my wants you may be able to help me. Let me be clear about what I am doing, what I want to do, and see where we can go from there. I help run ...
4
votes
2answers
357 views

Can I control if the in-body AF motor is used instead of the lens AF motor on my Nikon?

I have Nikon D7000 with 18-105mm. I know that the camera body has the AF motor and the lens itself has the AF motor too. I was wondering can I control which AF motor should be used while autofocusing. ...
3
votes
2answers
1k views

Can a drop of a camera+lens cause AF calibration issues on either — or both — the lens and the body? What are the mechanics involved here?

My question is, if you drop a camera, and you think you might have an AF issue, what are the mechanics involved that might cause a mis-calibration? I can imagine that the lens has movable parts -- ...
4
votes
2answers
872 views

What is the “AF Stop” button on some Canon lenses?

When looking at custom functions in Canon camera manuals, I've come across mention of setting functionality to have happen when the "AF Stop" button is pressed - a button that, apparently, exists on ...
6
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2answers
968 views

How does the eye-controlled focussing of the Canon EOS 5 work?

I just read that the Canon EOS 5 had eye-controlled focussing. How does this work? In this short article I found that it had to do with the coupling of infrared eye-tracking and the AF-point choice, ...
3
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1answer
213 views

Why 5-50x focal length for autofocus micro-adjustment?

When we do an AutoFocus Micro Adjustment session, the general opinion is to set the focusing target at 25 x focal length (or somewhere in the range of 5-50 x focal length). Why is so? What happens if ...
3
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3answers
985 views

Where is Canon 1100D autofocussing in low light low contrast conditions?

It's obviously my fault for living in the UK and expecting to want to enjoy my bird photography in grey January afternoons, but, I would appreciate some opinions on the following. I took 150 shots ...