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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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3answers
1k 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
8k 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
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 ...
1
vote
1answer
83 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 ...
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6answers
296 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 ...
-1
votes
1answer
168 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 ...
1
vote
1answer
7k 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
402 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 ...
31
votes
3answers
186k 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
389 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
81 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 ...
0
votes
1answer
497 views

Has D600 AF fine tune option? Can I fix backfocus of my lens on D600?

I know that the D800 has an option to tune AF. Does the D600 have this option, and does it work as well as it works on the D800? Can I fix a back-focus issue with my lens on a D600 without sending it ...
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vote
2answers
115 views

How does aperture/DOF affect continuous autofocus?

When the autofocus system is deciding to adjust the focus, say in a situation of the subject getting closer to or farther from the lens, does it take into consideration the current depth of field, ...
0
votes
2answers
50 views

Superzoom unable to autofocus at infinity at mid-zoom focal lengths

I have an inexpensive "superzoom" camera that functions properly and fills my needs but has one problem I seem unable to resolve. It is a GE Power PRO X500 camera with which I have taken several ...
3
votes
3answers
192 views

Why won't Nikon V1 autofocus with a close up filter attached?

I have a Nikon V1 with a 10-30 mm lens and recently purchased a +10 filter for close up work, but the camera won't focus when i use the filter. Am I doing anything wrong or is this a limitation of the ...
4
votes
2answers
329 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.
1
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1answer
325 views

What is broken on my Canon 450D? Edit: Missing focusing screen and submirror: fixable?

I recently aquired a used Canon 450D, which the previous owner said was broken. I'm new to photography and SLRs so please excuse some of the ignorance following. After digging a bit around the last ...
2
votes
3answers
284 views

How to take clear photographs with DSLR

I just bought a Nikon D5200 with the 18-105mm lens and I have taken this flamingo photograph but can't see their faces properly and If I zoom in a little bit the image is pixelated. I have tried ...
1
vote
1answer
302 views

What Ever Happened to Hologram AF?

I'm currently using it in my Sony DSC-F828 and I think works very well especially in low light condition. I've read a lot of hypothesis about it but anyone know for sure why modern cameras don't use ...
1
vote
2answers
1k views

Using old, manual focus lenses with a new Pentax DSLR

I have an old Pentax ME SUPER with three lenses, all of which have manual focus rings and no autofocus motors. Do new Pentax DSLRs have built-in focus motors that can deal with old lenses? FYI, ...
18
votes
4answers
9k views

How do camera body motors compare to in-lens motors for focusing?

What is the difference between using a motor on the camera body and the motor built into lenses? Aside from how both compare in terms of speed, what differences would I notice if I use a body with a ...
2
votes
1answer
153 views

A recently acquired lens will focus automatically, but won't manually, why?

I have recently acquired a Sigma 70-200mm f/2.8 (Canon mount, relatively old), and it focuses perfectly in auto mode, but in manual mode the focus ring simply won't budge at all. What could be causing ...
0
votes
1answer
125 views

Canon camera DIY repair

I have a digital rebel XT, an 18-55mm, and 75-300mm lens, all by Canon. Everything has saltwater damage. I'm aware that it's cheaper to just replace it all, but I was fiddling around with it, testing ...
12
votes
5answers
1k views

Why don't most cameras use infrared for focusing?

All auto focus assist lights are either red or white. Why do DSLRs not use infrared instead? It seems it would be beneficial to a photographer to not blind their subject before taking a picture. ...
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votes
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 ...
0
votes
1answer
414 views

Nikon AF-S Nikkor 70-300mm 1:4.5-5.6 G ED Lens will not autofocus

I have a Nikon AF-S Nikkor 70-300mm 1:4.5-5.6 G ED Lens that I purchased in Feb of 2013. I have been using this lens with my Nikon D3200. Up until this point my lens and camera have been completely ...
0
votes
1answer
3k views

How to fix inoperative autofocus in Canon 70-200 F4 L USM?

This lens has been sitting on the shelf for years and I recently hauled out my DSLR to play with it. Turns out the autofocus no longer works. I'm wondering if there's any kind of remedy for this short ...
8
votes
2answers
5k views

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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vote
2answers
140 views

Quiet video autofocus on a consumer level SLR? [closed]

I bought a Canon Rebel T3 a while back before doing my homework on the features. The video quality looks very good to me. However, I have to hold down the shutter button to keep focus. The auto-focus ...
4
votes
0answers
113 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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4answers
779 views

Will the Canon 5D MK II with 100-400 1:4.5-5.6 work properly with Kenko 1.4 converter?

I'm using 5D MKII body and 100-400 f/4.5-5.6 lens. I want to use a 1.4 converter; will the Kenko converter work and autofocus properly?
6
votes
1answer
892 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 ...
15
votes
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 ...
1
vote
1answer
297 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 ...
4
votes
2answers
986 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
3k 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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2answers
1k 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 ...
5
votes
3answers
1k views

Enable Auto focus after timer on Nikon D800?

I'll start with an apology if everyone knows this but me. I bought a Nikon D800 about a month ago (adore), but the wireless remote I used for the D7000 is not compatible. No worries, I'll just ...
30
votes
3answers
3k views

How does autofocus work?

How does auto focus work on modern cameras? How accurate is it?
2
votes
2answers
273 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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votes
3answers
606 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
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 ...
2
votes
3answers
359 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 ...
1
vote
2answers
665 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 ...
1
vote
2answers
427 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 ...
-3
votes
2answers
144 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 ...
2
votes
2answers
5k views

Why does my Nikon D3100 no longer auto-focus via the viewfinder?

My Nikon D3100 out of the blue cannot focus correctly. It seem the that the focus motor always stops at the end of the run (Infinity) and cannot lock on the target, thus cannot release the shutter. I ...
1
vote
3answers
7k 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 ...
2
votes
1answer
160 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 ...