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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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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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, ...
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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 ...
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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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Why the AF confirm lights won't blink when the spot is in-focus while using an all-manual lens with an adapter without any connectors?
I understand that my Canon 450D's (XSi/Kiss X2) passive autofocus system knows a spot in the view is in-focus when its nearby contrast is adequate. Then the camera blinks AF confirm lights to inform ...
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Precise focus in self-portraiture
I've been trying to take some self-portraits, but I often have to struggle with the auto/manual focus. I don't miss by a lot, but I really want sharp focus in the eyes. I'm using a 50mm/1.8 around ...
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543 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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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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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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How should I chose a manual focusing screen for my Pentax K10D?
I am considering buying a split focusing screen, replacing the original one. I would like to use some split/microprism screen to ease the focusing of the manual lenses. I own both kit lenses (18-55, ...
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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 ...
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How do I focus a Nikon 50mm f/1.8?
I recently bought this lens, but it seems to me that it hunts a lot in low(ish) light, and sometimes (often) does not achieve focus at all. I never had any problems with the kit lens.
Pointing the AF ...
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What technical reasons prevent Canon's new hybrid AF working with non-STM lenses?
Canon's new Rebel T4i (a.k.a. EOS 650D) has a new "hybrid AF" mode, which allows continuous AF during video, but only when used with one of the new STM lenses.
I've seen chatter on the web forums ...
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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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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 ...
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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?
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Why can't my camera autofocus in low light with a small aperture?
My question is not about "how to focus in the low light" or "how to focus a camera". The question is why the camera is unable to auto-focus in low light with high f numbers?
In these conditions, I ...
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How does the Nikon D40 decide which focus location to use?
How does the D40 decide which focus location to use? It always seems to choose the wrong focus area.
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How to enable Canon AF with teleconverter?
Canon DSLR bodies prevent poor auto-focus performance by disabling it completely when the lens reports maximum aperture at chosen focal length smaller than f/5.6. This implies that some lenses will ...
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Can I intercept and interpret the autofocus signals sent to the lens?
I would like to use a Nikon D80 body with a reflecting telescope as the lens to take pictures of bright/textured objects in the night sky (e.g. the moon). The D80 has autofocus capabilities; the ...
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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 ...
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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 ...
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Have I broken my Canon 28-135mm lens after DIY repair?
Last week I removed the front element from my Canon 28 - 135mm lens to remove a grain of sand from the lens. It was easy to remove the 4 screws, take of the top layer of glass and remove the grain.
I ...
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Why isn't there an adapter to make manual lenses autofocus?
I was wondering why nobody has come up with an adapter to autofocus lenses like 50 mm f1.8 on lower-end Nikons like the D60. I believe that the lens and the body lack a motor to autofocus. Why can't ...
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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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Will I regret buying an older lens that doesn't autofocus or have image stabilization with my Nikon D5000?
I am planning to buy a Nikon Normal AF Nikkor 50mm f/1.8D Autofocus Lens.
It doesn't autofocus on the D5000 but for the price, I think it's a good choice of lens for portrait.
What do you think? ...
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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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Replacing my XXD with a 7D?
My goto camera is still my 5D Mark II. As I primarily shoot landscape, I love Wide Angle on a Full Frame body.
That said, I do occasionally shoot animals and people running.
The 5D Mark II's AF ...
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199 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 ...
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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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Can't auto-focus at full zoom
I have a Canon 1000d, and the standard lens EF-S 18-55mm. Recently I was out taking photos and I've noticed that if I zoom in fully, the lens can't auto focus. I can still take shots using manual ...
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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 ...
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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 ...
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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 ...
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Does “the same” lens, with different autofocus systems, have the same optical quality?
I'll give examples with Nikon only, but the question is pretty general.
So, is this a fact or not?
Examples:
Nikkor 50/1.8G AF-S, Nikkor 50/1.8 AF-D and Nikkor 50/1.8 AF
70-300 AF and 70-300 AF-S
...
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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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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.
...
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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 ...
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Shutter half-press to focus possible in Live View mode on EOS 50D?
When not in Live View mode and when the lens is set to AF mode, when I press the shutter button half way on my Canon EOS 50D it causes the camera to auto-focus, as expected. In Live View mode, I have ...
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Sigma 70-200mm vs. Nikon 80-200mm auto-focus speed
I'm considering the newest Sigma 70-200mm F2.8 EX DG APO MACRO HSM II and comparing it against the older (but still for sale) Nikon AF 80-200mm F2.8 D ED.
These are roughly in the same price class, ...
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271 views
Which offers better results: FoCal or LensAlign Pro?
I am in need of microadjusting my autofocus for a couple of my lenses with my Canon 7D. Namely, I need to adjust the 100-400 L lens, which seems to consistently AF a bit softer than I've seen from ...
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747 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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How to Turn Off Custom Functions in Canon Film SLRs
So I adjusted the Custom Function settings in the dial, and then I noticed that my Autofocus is now controlled by the CF button. I am using a Canon EOS 50, a 1995 film camera (not 50D).
How do I turn ...
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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 ...
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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 ...
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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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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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Do point and shoot cameras have a metering sensor?
I have a Pentax point and shot camera and I tried to convert it to Infrared. I was successful to remove the front IR filter from CCD and then I had a 760 nm IR filter to kick start with the infrared ...
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Why does Nikon warn about banding at high ISOs when using autofocus on Nikon D4 or D800?
Nikon says that banding may occur at high ISO sensitivities with autofocus on the D4 or D800:
D800
Noise in the form of horizontal lines may appear in pictures taken with AF-S Zoom Nikkor 24-85 ...
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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 ...
