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17-35 AF inconsistency

 
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cjjmst



Joined: 14 May 2007
Posts: 9
Location: Washington, DC

PostPosted: Mon May 14, 2007 8:45 pm    Post subject: 17-35 AF inconsistency Reply with quote

I recently bought a used 17-35 previously modified for Canon.
I can't say I'm very happy with it as I notice some AF inconsistency. It sometimes focuses perfectly well, and then I get a great shot, but most often, I don't get the sharpness I would expect, (especially wide open of course).
I bought a split focusing screen to investigate the issue, and I can now confirm that the AF lacks accuracy. I considered giving the AF adjustment a try but my firmware doesn't seem to be compatible with it. Another point is that it sometimes back focuses (most often), but sometimes front focuses (especially when shooting at infinity).
If I manually correct the focus using the split screen, it works like a charm, but it's pretty frustrating.
Did anyone else face the same issue?
Thanks,
Jean-Jacques
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jjlphoto



Joined: 17 Jan 2007
Posts: 102

PostPosted: Tue May 15, 2007 3:40 am    Post subject: Reply with quote

No AF system is perfect. As I learn to better my AF skills, what I thought was convention is actually detrimental to AF. I use a Canon EcB Split-Image Screen in my 1Ds, and my conventional practice was to locate a pole, stripe, or other straight object near where I wanted to place focus, and align the halves. I am finding that AF doesn't like things like straight poles, stripes, or edges. AF prefers actual tones or scenes. I have better success with AF by selecting an AF zone where I want focus, and now avoiding things that I used to like with my split image screen. Sure, this is anecdotal data, but it seems to work for me.
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conurus
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Joined: 15 Aug 2006
Posts: 795
Location: Vancouver, Canada

PostPosted: Tue May 15, 2007 9:53 am    Post subject: Reply with quote

Hi cjjmst,

Did you get S/N 15130373? That is the only 17-35 still at firmware 1.0.5 level, not equipped with AF micro-adjustment. And that is the world's first VS17-35/2.8 converted to EF mount, if there is some collectible sentiment to it. Smile

My goal is to not fiddle with any adjustments at all, but it should work accurately right out of the box. As you can see with the samples of 24-85 and 70-300 I posted, this has been accomplished by firmware 2.0. You can clearly tell there are "different shades of infinity" when you pixel-peep those samples at 100%, and the AF got it right! Therefore, I would suggest you to upgrade the firmware to the latest version.

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I am a bird and I uncovered the E, EF and N-mount communication protocols!
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cjjmst



Joined: 14 May 2007
Posts: 9
Location: Washington, DC

PostPosted: Tue May 15, 2007 11:31 pm    Post subject: Reply with quote

Hi,
Thank you for your quick answer.
Just to illustrate the issue I've got, I attach 2 100% crops of pictures shot at 35 wide open, one in full AF made with the center sensor, one after manual correction. This is pretty representative of what I get in 95% of the cases. I'm really disappointed as none of my Canon lenses would perform so poorly.
My S/N is 15129704. So, according to your files, I should have the firmware 2.0.... However, when I apply the procedure for micro adjustment, at step 7, the indicators won't blink.
Thanks for advising.
Jean-Jacques



MF correction.jpg
 Description:
After slight MF adjustment relying on the split center focusng screen
 Filesize:  105.69 KB
 Viewed:  26914 Time(s)

MF correction.jpg

EXIF Information  Details
Camera make  Canon Camera model  Canon EOS-1Ds Mark II
ISO  100 Focal length  28mm
Shutter speed  1/125 seconds Aperture  f/2.8

AF center sensor.jpg
 Description:
Shot in AF mode using the center sensor.
 Filesize:  96.67 KB
 Viewed:  26914 Time(s)

AF center sensor.jpg

EXIF Information  Details
Camera make  Canon Camera model  Canon EOS-1Ds Mark II
ISO  100 Focal length  28mm
Shutter speed  1/125 seconds Aperture  f/2.8
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conurus
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Joined: 15 Aug 2006
Posts: 795
Location: Vancouver, Canada

PostPosted: Wed May 16, 2007 12:38 am    Post subject: Reply with quote

Jean-Jacques,

Did you set the lens' focusing ring to closest focusing distance before trying to enter AF micro-adjustment mode?

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cjjmst



Joined: 14 May 2007
Posts: 9
Location: Washington, DC

PostPosted: Wed May 16, 2007 1:28 am    Post subject: Reply with quote

Yes, I did, and I just gave another try to make sure. It doesn't blink...
Jean-Jacques
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conurus
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Joined: 15 Aug 2006
Posts: 795
Location: Vancouver, Canada

PostPosted: Wed May 16, 2007 2:59 am    Post subject: Reply with quote

Thank you! I just checked the records again and found that S/N 15129704 has firmware 1.1.0 installed. It has AF micro-adjustment, but nothing blinks on the top deck LCD. Visual confirmation that you entered AF micro-adjustment was added in v2.0.

I noticed that we drive the same car. So, let me take some pictures at the same angle. If I get the same results, I will figure out the proper adjustment values and post them.

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conurus
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Joined: 15 Aug 2006
Posts: 795
Location: Vancouver, Canada

PostPosted: Tue May 22, 2007 5:22 am    Post subject: Fixed in firmware v2.1 Reply with quote

Thank you for your problem report. This has been fixed and a new firmware version 2.1 will be released very shortly pending final testing. In the following test shots I was focusing on the hour of the clock.


394V4605.JPG
 Description:
original
 Filesize:  191.78 KB
 Viewed:  26816 Time(s)

394V4605.JPG

EXIF Information  Details
Camera make  Canon Camera model  Canon EOS-1DS
ISO  100 Focal length  28mm
Shutter speed  1/30 seconds Aperture  f/2.8

394V4605.JPG
 Description:
100%
 Filesize:  168.14 KB
 Viewed:  26816 Time(s)

394V4605.JPG

EXIF Information  Details
Camera make  Canon Camera model  Canon EOS-1DS
ISO  100 Focal length  28mm
Shutter speed  1/30 seconds Aperture  f/2.8

394V4604.JPG
 Description:
original
 Filesize:  195.45 KB
 Viewed:  26816 Time(s)

394V4604.JPG

EXIF Information  Details
Camera make  Canon Camera model  Canon EOS-1DS
ISO  100 Focal length  34mm
Shutter speed  1/30 seconds Aperture  f/2.8

394V4604.JPG
 Description:
100%
 Filesize:  189.17 KB
 Viewed:  26816 Time(s)

394V4604.JPG

EXIF Information  Details
Camera make  Canon Camera model  Canon EOS-1DS
ISO  100 Focal length  34mm
Shutter speed  1/30 seconds Aperture  f/2.8
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cjjmst



Joined: 14 May 2007
Posts: 9
Location: Washington, DC

PostPosted: Wed May 23, 2007 2:04 am    Post subject: Reply with quote

Bo-Ming,
It's great! Shocked
I'm looking forward to getting my lens upgraded...
By the way you're right, we not only have the same photographic stuff but also the same car.
Next time, I will perform focusing test on my microwave oven. Laughing
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