Lens calibration


C cube

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Nov 23, 2011
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#1
Hi all,

What is lens calibration? How do we know if our lens need one? Thanks.
 

Csboi

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Jul 18, 2011
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#2
Hi all,

What is lens calibration? How do we know if our lens need one? Thanks.
Occasionally a lens comes with a faulty internal control unit that causes mis focus.
However most people claiming they have a focus or soft focus issue do not. They use AF targets where AF does not work well and then blame the camera or lens instead of themselves. Not using cameras and lenses as the manufacturers intended on the basis of recent threads seems to outnumber camera faults by around 100 to 1.
If a lens is built of good components correctly assembled it works - apart from adjusting the infinity and minimum focus points it cannot be relcalibrated.
So what happens to all the lenses and camera bodies that go back for recalibration that in most cases probably is not needed? Generally it is cheaper for the manufacturer to check it out and maybe put a new part in than risk a law suite for telling the owner they ought to improve their photographic ability.
 

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rhino123

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Sep 1, 2006
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#4
Hi all,

What is lens calibration? How do we know if our lens need one? Thanks.
Well... you need calibration when your autofocus was out. Meaning, when you focus on something and that subject that had already achieve a focus lock, but when you took the picture, the focus was not there. Most common error is front and back focusing, whereby your focus was actually at something behind or infront of the focus point.

One easy way to see was to take a photo and see if the subject or area where you have focus on was actually focused (meaning sharp) or another subject beside, behind or infront of it was actually the sharp one.

Many of the modern DSLR came with micro-adjustment capability so it is easy to do your own calibration. Another alternative would be to sent your camera and lens down to respective service center to do calibration for you.
 

daredevil123

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Oct 25, 2005
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lil red dot
#5
Occasionally a lens comes with a faulty internal control unit that causes mis focus.
However most people claiming they have a focus or soft focus issue do not. They use AF targets where AF does not work well and then blame the camera or lens instead of themselves. Not using cameras and lenses as the manufacturers intended on the basis of recent threads seems to outnumber camera faults by around 100 to 1.
If a lens is built of good components correctly assembled it works - apart from adjusting the infinity and minimum focus points it cannot be relcalibrated.
So what happens to all the lenses and camera bodies that go back for recalibration that in most cases probably is not needed? Generally it is cheaper for the manufacturer to check it out and maybe put a new part in than risk a law suite for telling the owner they ought to improve their photographic ability.
I think you what you said is a bunch of misconceptions and untruths.
 

Dec 29, 2010
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#6
Just sent my lens for calibration to correct the back focus issue.

Came back a tad bit better but still a little back focus present. Read up a little and some website say the 24-70 has a little back focusing issue at 70mm.

Should i send it back to CSC for re-calibration since its still under the 3 months warranty?
 

Fezqu

New Member
May 9, 2011
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#7
Occasionally a lens comes with a faulty internal control unit that causes mis focus.
However most people claiming they have a focus or soft focus issue do not. They use AF targets where AF does not work well and then blame the camera or lens instead of themselves. Not using cameras and lenses as the manufacturers intended on the basis of recent threads seems to outnumber camera faults by around 100 to 1.
If a lens is built of good components correctly assembled it works - apart from adjusting the infinity and minimum focus points it cannot be relcalibrated.
So what happens to all the lenses and camera bodies that go back for recalibration that in most cases probably is not needed? Generally it is cheaper for the manufacturer to check it out and maybe put a new part in than risk a law suite for telling the owner they ought to improve their photographic ability.
Loads of crap.
 

Fezqu

New Member
May 9, 2011
251
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#8
Just sent my lens for calibration to correct the back focus issue.

Came back a tad bit better but still a little back focus present. Read up a little and some website say the 24-70 has a little back focusing issue at 70mm.

Should i send it back to CSC for re-calibration since its still under the 3 months warranty?
I think zoom lens is harder to calibrate? It might need certain adjustment at different range. Best to use manual focus.
 

rhino123

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Sep 1, 2006
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#9
Just sent my lens for calibration to correct the back focus issue.

Came back a tad bit better but still a little back focus present. Read up a little and some website say the 24-70 has a little back focusing issue at 70mm.

Should i send it back to CSC for re-calibration since its still under the 3 months warranty?
Might help. But what is your camera model anyway, some of the newer model could let you do some micro-adjustment to your lens too. So you can actually do your own lens calibration.
 

Dec 29, 2010
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#10
Might help. But what is your camera model anyway, some of the newer model could let you do some micro-adjustment to your lens too. So you can actually do your own lens calibration.
I'm using a 7D. There's micro adjustment but since its still free to send back to canon for re-calibration I'll just do that, if time permits hehe.
 

kei1309

Senior Member
Apr 12, 2010
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#11
I think zoom lens is harder to calibrate? It might need certain adjustment at different range. Best to use manual focus.
if you bought the Lens because of its ability to AF...then what's the point of telling the bro to use MF? and if you bring the lens and body to CSC for calibration, they ARE supposed to do it for you.
 

daredevil123

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Oct 25, 2005
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lil red dot
#12
I think zoom lens is harder to calibrate? It might need certain adjustment at different range. Best to use manual focus.
Hope you can explain, how using manual focus will improve the situation of AF accuracy. How do you determine if something is in focus or out of focus when doing manual focus?
 

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rhino123

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#13
Hope you can explain, how using manual focus will improve the situation of AF accuracy. How do you determine if something is in focus or out of focus when doing manual focus?
Well... using manual focus could help if AF is not accurate... it would all be up to the photographer's own judgement then. Using the liveview, we could zoom in on the subject, then manually focus until the subject in question is sharp. This would be difficult I would admit, and need some time to get used to, but it can be done...






The above photos are taken using my 7D paired with my industar 50-2 50mm f3.5 lens (manual lens so there is no AF in this case)...
 

daredevil123

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Oct 25, 2005
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#14
Well... using manual focus could help if AF is not accurate... it would all be up to the photographer's own judgement then. Using the liveview, we could zoom in on the subject, then manually focus until the subject in question is sharp. This would be difficult I would admit, and need some time to get used to, but it can be done...

The above photos are taken using my 7D paired with my industar 50-2 50mm f3.5 lens (manual lens so there is no AF in this case)...
So when using manual focus, the only way to get accurate focus is to use Liveview. So what happens to times when one needs to capture moments, or shoot events or something that moves faster?
 

rhino123

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Sep 1, 2006
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#15
So when using manual focus, the only way to get accurate focus is to use Liveview. So what happens to times when one needs to capture moments, or shoot events or something that moves faster?
I never say the only way is to use liveview. But I find that liveview certainly help :)

And it is difficult, I admit for manual focusing... there are a couple of tricks that people had been using, one of them was to pre-focus on an area and if something walked into that area... 'click' and you got it. Use a deeper DOF for that...

In difficult lighting condition, you might want to use a flash.

I can see people using manual lens for birding, and before AF came into existence, people are using manual focus and still get good results. I believe that you can do it if you practiced enough.

(the undermentioned had been taken by my Sigma 28mm f2.8 Mini Wide II manual lens)

(no live view was used)

(this shot is done using live view)

(no live view was used here... in fact I prefocus in an entire area, then when the object came in, I shoot).

(here... I sneak up this aunty, who was too engross with her food, do some quick focusing and take the shot when I find the image relatively sharp in my viewfinder - using some more recognisable items like the wording on her chair as a focus point to check my focus, then use a deeper DOF and shoot, it was a hit or miss, because as soon as I took the shot, she noticed me and looked up at me crossly... hehehe)
 

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daredevil123

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Oct 25, 2005
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#16
I never say the only way is to use liveview. But I find that liveview certainly help :)

And it is difficult, I admit for manual focusing... there are a couple of tricks that people had been using, one of them was to pre-focus on an area and if something walked into that area... 'click' and you got it. Use a deeper DOF for that...

In difficult lighting condition, you might want to use a flash.

I can see people using manual lens for birding, and before AF came into existence, people are using manual focus and still get good results. I believe that you can do it if you practiced enough.

(the undermentioned had been taken by my Sigma 28mm f2.8 Mini Wide II manual lens)

(here... I sneak up this aunty, who was too engross with her food, do some quick focusing and take the shot when I find the image relatively sharp in my viewfinder - using some more recognisable items like the wording on her chair as a focus point to check my focus, then use a deeper DOF and shoot, it was a hit or miss, because as soon as I took the shot, she noticed me and looked up at me crossly... hehehe)
I know MF without LV is possible. But wouldn't that be dependent on having a correct frame of reference? If AF is off, it also means focus confirmation is also off. Only way is to install a split prism focusing screen, and even with that, you have to be sure that the focusing screen is installed correct (with shims in some instances), and/or the mirror angle is correct.

In the end, to use MF or AF, it is important to get your gears tuned/adjusted to get accuracy.

I think zoom lens is harder to calibrate? It might need certain adjustment at different range. Best to use manual focus.
That is my point from the beginning in response to the above statement. If your AF is off, and you want to use MF to get it spot on, you still need to get your AF tuned properly. If not, LV is usually your only option, and using LV is not the best in many situations. Or like you said, the way to get things in focus is to compromise, by stopping down or/and doing zone focusing. But if your AF is only slightly off, stopping down will also solve the problem, without having to switch to MF.
 

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Wizongod

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Nov 25, 2011
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#17
If you want to check for AF and calibration problems, I'd suggest this website (add the http in front of it cos I'm not allowed to post links yet): regex.info/blog/photo-tech/focus-chart
I personally think it's great for home testing, so you know if you need to go any further, or bring your lens + camera down to Canon Servicing Centre.

At first I thought my AF was off too, but after performing the tests there (with a good tripod of course), I found out, it's me that's at fault and not the AF, as most newbies will also discover =D
It's very simple to do, so if you're fretting over AF problems, go give it a try to help you sleep better at night haha!
 

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