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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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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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104 views

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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6answers
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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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2answers
277 views

Why can't I access Single Point Spot AF even when it is enabled on my 5D Mark III?

I have been using Canon 5D Mark III since long but somehow never been able to get across this thing. With the advanced 61 point focus system which the Mark III has, I have always missed the ability to ...
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2k views

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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1answer
845 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 ...
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3answers
2k 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 ...
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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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104 views

Converting cameras for infrared use: When does the filter have to be replaced, and when is simply removing it ok?

When converting a digital camera for infrared use, the general approach is to remove any filters that limit its sensitivity to the visible range of light wavelengths. Some conversions replace the ...
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1answer
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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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213 views

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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175 views

At which lux level do the Nikon 1 cameras switch from PDAF to contrast-detection?

The Nikon 1 cameras are famous for being able to track focus with their on sensor PDAF. But the story goes that if light is low, it will switch to contrast-detect only and will not track focus as ...
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1answer
538 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 ...
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4answers
4k 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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4answers
1k views

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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2answers
268 views

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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2answers
630 views

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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3answers
857 views

Why are there no autofocus tilt-shift lenses? or, why do tilt-shift movements appear to be incompatible with phase-detection autofocus?

I have never seen or heard of an autofocus tilt-shift (perspective control) lens. It seems like perspective control movements prevent phase-detection autofocus from working correctly; for example ...
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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 ...
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1answer
261 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
1k 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 ...
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2answers
440 views

Does having the AF points bunched up in the middle make a big difference?

I was looking into the new Nikon D600, which looks like a pretty compelling camera. I however noticed that its 39 AF points though quite a lot are all bunched up in the middle. I am used to having AF ...
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2answers
328 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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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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EOS Rebel T3i 18-55mm lens won't take a picture - happened with two lenses

I'm a reporter for a small town paper - Early in 2012 we had a body of a T3i go bad and it was replaced new body and we used the old 18-55mm lens. It worked fine for 7-8 months. I do a lot of sports ...
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1answer
280 views

What autofocus zone selection mode should I use for action/event shooting?

I have a Canon 7D, and typically shoot everything I do in its single-point autofocus zone select mode, because I usually want fine control over exactly what the camera is focusing on and I often find ...
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2answers
143 views

What does it mean for a camera to be able to autofocus at EV 0 at f/2.8?

I know what it means for a camera to be able to autofocus at EV 0. As the answer to this question says, EV0 is the light level to achieve correct exposure with 1 second of exposure at F1 and ISO 100. ...
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2answers
462 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. ...
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What can I do if autofocus does not work but manual focus does?

Recently, the autofocus on my Nikon D3100 stopped working. The ring of the lens wouldn't even turn when I tried to focus. However, when switched to manual focus, the camera works fine. When I used a ...
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282 views

Are of cross-type focus points more accurate, or just faster?

Do cross type focus points achieve sharper photos than horizontal points or do they just grab focus faster.
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238 views

How much did the v2.0 firmware update improve the Fujifilm X-1 Pro's autofocus?

I really liked the Fujifilm X-1 Pro when I tried it for a couple of weeks — enough that it made me think seriously about switching from my much-loved DSLR about five years earlier than I thought the ...
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2answers
307 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
781 views

Force AF assist light on body / flash to come on with Nikon DSLRs?

I have a Nikon D-40 and D-90 with a wide assortment of prime lenses. I like fast primes for low light photography. Some of my lenses are sufficiently old that they do not auto focus at all. Others ...
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2answers
857 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 ...
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3k views

Could autofocus of the Canon t4i be improved with a firmware update?

I am trying to decide between the Canon t4i (650D) and the t3i (600D). Initially I was going for the t4i because of the autofocus. But the sample videos I have seen did not really impress me. Can I ...
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1answer
163 views

What factors influence whether a lens and camera combination front or back focus?

I know that sometimes a lens/body combo needs to be micro-adjusted to attain ideal focusing behavior, and that this is usually because of sample variation, but which parts of the lens and/or body are ...
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0answers
112 views

Halos on images taken with a Panasonic Lumix DMC-FS35 [closed]

Every image I take with my DMC-FS35 shows a halo around the subject. (See below) This is true in all light conditions with or without flash. INSERT IMAGE HERE
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346 views

Do all cameras with autofocus need motors?

Do all autofocus cameras need motors to drive the lens? I would have thought today's modern electronics rendered motors obsolete.
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4answers
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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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2answers
4k 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 ...
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1answer
2k 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 ...
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3answers
731 views

Is there a Canon equivalent for Nikon's AF-ON focus system?

I'm very new to photography, and have been reading a lot about concepts and techniques. Yesterday, my brother gave my kid a gift of a professional photography session. I saw the photographer had Nikon ...
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How can I make my Coolpix focus after I'm in place for a time-delayed self portrait?

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 ...
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2answers
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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 ...
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3answers
821 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" ...
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1answer
2k 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 ...
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2answers
636 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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1answer
257 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 ...
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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 -- ...
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613 views

How to improve the PowerShot G12 shooting speed?

I have been using a Canon PowerShot G12 for about a year, and find it incredibly slow. In full auto-mode, with good lighting conditions, I feel the G12 regularly takes close to 0.5 s between the time ...