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February 11, 2012, 11:43:05 AM
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Offline Colyn Serfontein

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When your brain and your camera conflicts
« on: February 11, 2012, 11:43:05 AM »
I am sure many of us have been in this position ...

You set the shot up, concentrate on all the technical things you can think of ... double check ... press the shutter for Auto-focus ... hear the assuring BEEP and you fire the shot. With great anticipation you download the image onto you PC and then ... :o

To your utter dismay you find the shot is not crystal clear.  :'(

With muttered words that is not appropriate to verbalize here you go back ... this time you take the tripod ... almost possessed you take the shot again.  >:(

You open the shot on your PC ... confident that you have nailed it this time ... WTF !!!!!  ;ticked

Same story ... now you are beginning to doubt everything, your eyesight, your PC, your sanity, your ability, your ancestry and you are even beginning to think that the moon landing was a fake.

You go back and now you are swearing, sweating and is hyper focused. You go for the last thing you can think of and set the shutter release at 2sec. delay just to ensure there is no camera shake. You even lock the mirror up. With mutterings that resembles far off thunder you take the shot ... just for luck you take one more ... this time even holding your breath.  ^-^

Now here comes my additional action ... the action that was born out of frustration and more out of desperation than anything else. I changed the camera to manual and did a manual focus ... click ... shot is in the can.  ;idiot2

Back to the PC ... holy cow ... same story with the first two shots but then ... lo and behold :o ... the manual shot is crystal clear.  :D

I lean back in my chair and stare at the images on the screen ... years of indoctrination by the media makes my brain refuse to accept the facts ... it just cannot be ... how the hell can manual focus be sharper than AUTO-FOCUS ... this is just not right !

Another long pull on my cigarette and while the blue smoke curls slowly into the air sanity came to me as my eyes convinced my brain that they are more trustworthy than the flashy advertising posters.

The rest of the day I struggled with this reality and my mind spun around and around. It was hard to accept that this camera and lens was basically flawed. 7D with 70-200 L f2.8 ... my word ... it is generally accepted as excellent kit.

Going through the archives of the 7D I began to realize that basically every shot where focus was critical did come out soft. I was ready to toss that camera into a dark cupboard.

I shared my frustration with my brother and with my friend Pierre. Both were a bit skeptical and I shared the images with Pierre. He has the same kit except his lense is not the f2.8.

Two days later he passed me a link to an article on the flaws in AUTO-FOCUS and he pointed me to a piece of equipment that is used to test exactly this. It was a Friday and the tool was not in Nelspruit. Me being a fairly impatient man I took another look at the fancy tool on the internet and then decided to improvise.


This is what I did ... the calendar is fixed in such a way that the face is 90 degrees on the tabletop. The ruler is supported at the back with a small glass to sit at an angle as in the image. I then lined the rule up to the edge of the calendar to touch exactly at the 140mm mark. This meant that the writing on the calendar and the 140mm mark were basically on exactly the same vertical plane.

This is the result ... camera 100% level and set as close to the object as what the minimum focus distance would allow, max zoom and and widest f-stop.


From this shot it is clear that the actual AUTO-FOCUS point is more in the region of 170mm than on 140mm.

This is actually such a common occurrence that there is even a term for it ... BACK FOCUS :o

I started to abuse GOOGLE and pretty soon it became clear that this problem is more common than we realise.

Fortunately in the Canon range the 50D, 5D, 1D and 7D there is a menu option that takes you to a place where you can rectify this yourself. On the xxxD and the other xxD Canons you need to send it to a Technical workshop to fix.

Under the CF settings there is a setting for the AUTO FOCUS correction. You have the ability to correct GLOBALLY or per specific lens. In my case a GLOBAL +3 solved my problem but for Pierre he had to do it per lens.


The following two images will show clearly what the true effect of this BACK FOCUS syndrome is ...


Here it is clear that the intended focus was on the center of the flower but the actual focus is on the petals in the back.


Here the intended focus point is actually in FOCUS !

After taking the time to do this experiment and take the steps needed to rectify it, I am for the first time really smitten with my 7D and now I am shooting with renewed energy.

So ... the moral of the story ... DO NOT ACCEPT that technology is always better than your brain :D

If you have found value in this article, please post it here.
Capture it when you see it ... it is a mere moment in time and will never come by again.
LPSSA

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February 11, 2012, 11:52:13 AM
Reply #1

Offline Colyn Serfontein

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Re: When your brain and your camera conflicts
« Reply #1 on: February 11, 2012, 11:52:13 AM »
Here are the results for Daleen's 400D with 17-85 on and my 550D with 18-200 on ...


400D


550D

They are fine and that is fortunate because if there is problem then the lens and camera must be sent to Canon. That could be while for you without the kit.

Personally, I will be very sceptical in future to buy a camera that does not allow you to custom fix the problem of AUTO-FOCUS that is screwed.
Capture it when you see it ... it is a mere moment in time and will never come by again.
LPSSA

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February 13, 2012, 08:54:00 AM
Reply #2

Offline Lucia Streuderst

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Re: When your brain and your camera conflicts
« Reply #2 on: February 13, 2012, 08:54:00 AM »
Colyn,
Baie insiggewend, dankie dat jy dit deel! Ek bÍre die inligting vir 'n 'rainyday'.

February 13, 2012, 09:25:57 AM
Reply #3

Offline Colyn Serfontein

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Re: When your brain and your camera conflicts
« Reply #3 on: February 13, 2012, 09:25:57 AM »
Dis a plesier Lucia. Bly iemand vind dit insiggewend.
Capture it when you see it ... it is a mere moment in time and will never come by again.
LPSSA

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