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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.

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3
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2answers
64 views

Why are phase detect lenses adapted onto contrast detect bodies so much slower?

The Sony A7 is able to adapt almost any type of auto-focus lens (Canon/Nikon/etc) and use autofocusing, but the auto-focusing is much slower than the same focal lengths native for the A7. Why would ...
2
votes
2answers
139 views

Why does my Nikon D5100 suddenly have a 30-60 seconds delay before auto focus starts working?

I have a Nikon D5100 with the 18-55 kit lens. It was working fine till a few days ago. The auto focus used to work from the very next second after turning ON the camera. But now the auto focus does ...
2
votes
5answers
223 views

Which one is better - more cross-type sensor or better sensitiveness of cross-type sensors?

What makes better sense for situations like: low light, sports/action, wild life? More cross-type sensor on AF (like Canon does) Or more sensitive cross-type sensors (like Nikon does)
2
votes
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 ...
0
votes
1answer
77 views

What to do when autofocus on Canon 85mm f/1.8 not working?

My Canon 85mm's AF isn't working. But here's the thing, it recognizes there's a lens mounted, it gives focus confirmation, and I can even set the aperture, but it does NOT recognize that it's an AF ...
11
votes
3answers
15k views

Will the Nikon D3100 autofocus with the 50mm f/1.8D lens?

I have the Nikon D3100 and was wondering if the autofocus on the Nikon 50mm f/1.8D lens would work with it. I've read that the AF is not compatible with the D5000, and that the AF is rather slow in ...
0
votes
0answers
31 views

Help is needed in Fixing Canon lenses USM's focus motor [duplicate]

I have the Canon EF lens, but the USM motor looks dead. I need help in order to get it fixed so I can use this lens again. Unfortunately a "focus by wire" system is used in this lens and I have no ...
0
votes
1answer
69 views

Why doesn't my Sigma lens autofocus if the subject is initially way out-of-focus?

I have a Sigma 150mm F2.8 EX DG OS HSM APO Macro lens mounted on my Canon 6D. Even if AF mode is set to minimum-to-infinity range, if my subject is way out of focus (too far or too near), like, say, ...
2
votes
5answers
9k 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 ...
17
votes
3answers
912 views

Why don't cameras have autofocus points in the edges and corners?

On all the DSLRs I've used, there are never any autofocus points near the edges and corners. Why is that?
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 -- ...
1
vote
1answer
3k views

Why isn't my Canon 70D autofocus accurate in manual zone AF mode with a 50mm f/1.8 lens?

I recently purchased a Canon 70D for its dual pixel autofocusing system and ISO performance. I am in love with this feature rich-camera; however I found the camera's autofocus fails to function ...
3
votes
1answer
54 views

How to test the autofocus system before asking for support?

For outdoor usage I got an Olympus TG-2 compact camera. Various tests claimed autofocus: 'quick and mostly accurate' - at least I could not find any that described problems. Now, I know that I cannot ...
1
vote
3answers
153 views

canon 6d or 5d II for macro?

At the mo I have a 550d and a 60d. my lenses are 17-35 2,8L, 24-80 2,8L, 70-200 2,8L, 100-400 4,5-5,4L sigma 150 2,8 and looking for the canon 50 1,2. The obvious next step is a FF Body. My main ...
3
votes
3answers
100 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 ...
0
votes
2answers
64 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 ...
6
votes
2answers
1k views

If the focal plane is curved, should the outer AF points work correctly or front-focus?

Many (all?) lenses have a (slightly) curved focal plane. In general it's close enough to flat that you don't really notice it, but under certain conditions it may become apparent. As I understand it ...
3
votes
1answer
125 views

Do mirrorless cameras focus less or more accurately than SLRs under low light?

How do the following compare in terms of autofocus accuracy for night photography: Mirrorless cameras like the Sony NEX-5R, in hybrid autofocus mode. The NEX-5R, in contrast-only autofocus mode. A ...
7
votes
1answer
378 views

What are the differences between AF/metering chips for M42 lens Canon DSLR adapter?

I'm looking for an adapter to use an M42 lens on a Canon DSLR. I was wondering if anyone knows the difference between the following types of chips : 2nd generation AF 3rd generation AF EMF AF ...
1
vote
6answers
235 views

What would be the right way to shoot a portrait in a very dark room with flash?

I have several flash units. Both the shoe-mount type and the "studio" type. The portrait has to be taken in a room that happens to not have windows. It is always dark in there. I can bring a light ...
1
vote
1answer
115 views

What can I do about Pentax superzoom 18-270 autofocus problems?

I use a Pentax K200 and have been satisfied with the original Pentax 18-250 superzoom, for travelling, outdoors, family types of use. However the autofocus gradually failed, the motor going to and fro ...
2
votes
4answers
276 views

How to take a photo of defects on a mirror?

Taking a picture of a reflected image of object is depicted in this image. Camera focus is on the image of a piece of paper. Besides the depth of field (cheap Panasonic DMC-FX8 in makro mode, ...
0
votes
2answers
61 views

Are extra auto focus points expensive for the manufacturer?

Having a lot of auto focus points is a feature associated with expensive camera bodies. There are of course different types of points like crosstypes and also different sensitivities, but lets ...
0
votes
1answer
69 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 ...
2
votes
1answer
107 views

How to get tack sharp portraits with shallow DOF when lacking an AF point where I want to focus?

What is the best way to get tack sharp portraits with shallow depth of field when lacking an auto focus point where I want to focus. I don't want to crop and "focus and recompose" is not an option ...
2
votes
3answers
161 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 ...
2
votes
2answers
123 views

How AF works with lenses f/2.8 vs f/4

I read following in a web site (http://realphototips.wordpress.com/tag/ai-servo/) Lenses with maximum apertures of f2.8 allow the camera to use all high precision sensors. In low light or other ...
0
votes
2answers
94 views

Should I always use point-autofocus and spot metering while shooting a small restless bird in a bush?

I am a beginner and I am finding more and more images to be out of focus or grainy when viewed on a computer screen, compared to the camera LCD. Could anyone give a step by step listing of the ...
1
vote
0answers
69 views

Nikon 300mm autofocus makes noise and stops working temporarily

I have a Nikon D5100 and a used Nikkor 300mm AF-S f/2.8D IF-ED II, where the two usually work great together. However, if I use autofocus a few times in a row (usually when the change in focus ...
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 ...
5
votes
5answers
2k 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. ...
1
vote
3answers
179 views

Why is micro 4/3 autofocus so much faster than DSLR live mode focus? [duplicate]

Both a DSLR in live view mode and a micro 4/3 system camera use the main sensor for autofocus. However, on a DSLR it's embarrassingly slow. This can't just be a software thing. How is it that one is ...
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 ...
3
votes
1answer
169 views

What does AF -0.5 EV sensitivity mean? Or -3EV in Canon 6D's case? [duplicate]

I know that it stands for Exposure Value, so my 6D focuses in 2.5EV worse light than a 600D. But it's relative to... what? What makes it meaningful? What's the "base unit" for AF sensitivity?
19
votes
6answers
12k 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 ...
17
votes
2answers
38k views

What's the difference between cross-type autofocus points and regular ones?

What's the difference between different autofocus point types (cross vs point and such)? Cross points seem to be a "feature" — why?
3
votes
1answer
1k views

Why is my Canon Rebel T3i delayed 10 seconds or more before image capture?

I am brand new to photography and this camera. Had the smaller lens on and the shutter seemed fine. Tried the larger lens (I bought a kit) which was 200M. Played around with settings, also tried the ...
3
votes
3answers
978 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 ...
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. ...
5
votes
3answers
1k views

What causes auto-focus “freezing”?

On occasion, the auto-focus system in my camera and/or lens just stops working. I'll be holding down the shutter release halfway and tracking a subject and I can feel/hear the auto-focus system ...
1
vote
1answer
58 views

Why are OVF and Liveview focus dots in different locations in my Nikon D800?

I put my camera (D800) on a tripod to check for any focusing issues ,and if I switch from OVF to Liveview the focus dot is in a different location.I tried two different lenses and they both give the ...
1
vote
6answers
208 views

Is it normal for autofocus to produce blurry photos under low light?

I use a Sony NEX-5R. I find that the autofocus often fails during low light, as in produces out of focus photos. Sometimes it's clearly out of focus, and I can see that on the LCD, in which case I ...
0
votes
1answer
107 views

Can I filter by autofocus in Lightroom?

Does Lightroom let me filter photos by whether they were manually focused? Or is this information not even stored in the ARW metadata? (I'm assuming they were not lost during DNG conversion in ...
5
votes
7answers
10k 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 ...
1
vote
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 ...
5
votes
5answers
251 views

With the advantages of an AF-ON button, why don't all DSLRs have one?

I've just updated my body from Nikon D40X to Nikon D300 and realized that the D300 has a AF-ON button on the rear of body. That button's feature do the same as half-pressing shutter button, which ...
26
votes
3answers
122k views

What does STM mean on a Canon lens?

The Canon EF 40mm f/2.8 has a designation of STM on the lens. What does this mean? What are the advantages of having it and does it replace an older technology? We have a terminology thread that ...
6
votes
2answers
214 views

When do you not want to use continuous autofocus (C-AF)?

This Nikon promotion website sums up when to use single autofocus and when to use continuous autofocus. (http://imaging.nikon.com/history/basics/16/03.htm) So, basically if you want to ...
2
votes
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 ...
1
vote
1answer
73 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 ...