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Planar 85 focus trouble (message to Conurus)

 
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doc



Joined: 23 Feb 2008
Posts: 26

PostPosted: Fri Mar 21, 2008 3:23 pm    Post subject: Planar 85 focus trouble (message to Conurus) Reply with quote

Hello Bo-Ming! (hope the name is correct...)
I've got a converted Planar 85 (15148805); your job is great, the lens works correctly, but when shooting @ wide apertures and long distances, I've noticed front focus; if I manually correct the focus distance toward infinity just a little, I get the correct focus. This doesn't seem to happen at medium and short distance. I've try to correct with your AF adjustment feature, but, while there's a little improvement at long distance, I get back focus at short. With the adjustment set to "zero", shooting to a focus test chart at about 1 meter, the focus looks perfect.
The camera I'm using is a 1Ds2; never had similar problem with other lens, expecially with Canon 85L I'm comparing to the Planar.
So I don't know where is the problem: the lens, the convertion, the camera or what else...
Any idea?
Thanks
doc



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EXIF Information  Details
Camera make  Canon Camera model  Canon EOS-1Ds Mark II
ISO  50 Focal length  86mm
Shutter speed  1/2500 seconds Aperture  f/1.4
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conurus
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Joined: 15 Aug 2006
Posts: 795
Location: Vancouver, Canada

PostPosted: Sat Mar 22, 2008 9:24 pm    Post subject: Reply with quote

Hi doc,

Thank you for your problem report and your patronage. While I spent a significant amount of effort particularly on the 85/1.4, it is possible that my reference camera, a 1Ds mark I, may not be accurate or may behave differently from your 1Ds mark II.

Your lens, modified in July 2007, is equipped with firmware version 2.8, which has significantly extended adjustment capabilities, in addition to what I previously posted in the instructions.

To enter a value,

  1. manually focus to minimum focusing distance.
  2. Set camera's aperture and the lens' aperture ring according to the table.

    If minimum aperture is f/16,

    cam\lensf/2.8f/4f/5.6f/8f/11f/16
    f/2.8212019181716
    f/4 151413121110
    f/5.6987654
    f/83210-1-2
    f/11-3-4-5-6-7-8
    f/16-9-10-11-12-13-14

  3. Press DOF preview, and release it.

Each adjustment requires entering 5 values.

  1. -11
  2. 12
  3. choose the item to adjust ( new in v2.8 )

    • 4: fixed AF adjustment for standard precision
    • -5: zooming/focusing AF adjustment for standard precision
    • 0: fixed AF adjustment for high precision
    • -9: zooming/focusing AF adjustment for high precision
    • -1: erase all settings and restore to factory default (skip step 4 and jump to step 5)

    The "ONE SHOT", "AI SERVO" or "MF" indicator of your camera will start blinking. The number of times it blinks is the previous adjustment value you stored. If the previous value stored is negative, it will flash 31 times for -1, 30 times for -2, and so on. If the previously stored value is zero, or there is no previous value set, the MF indicator of the camera will not blink.
  4. Set desired adjustment value. The "ONE SHOT", "AI SERVO" or "MF" indicator of your camera will flash the same number of times as step 3, the adjustment item you have choosen.
  5. value 9 confirms and stores adjustment value in non-volatile memory. Your camera will display "f/1.2" and the aperture will not open. Remove the lens from the camera body.

For fixed AF adjustments, a positive value causes the point of focus to move away from you, curing a front-focus issue. A negative value causes the point of focus to move towards you, curing a back-focus issue.

For zooming/focusing AF adjustments, a positive value causes bigger differences between infinity and closest focusing distance, and a negative value causes smaller differences between infinity and closest focusing distance.

High precision AF and standard precision AF have separate settings. Please refer to this guide for more information: http://eosdoc.com/manuals/?q=AFCompat

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doc



Joined: 23 Feb 2008
Posts: 26

PostPosted: Sun Mar 23, 2008 1:01 pm    Post subject: Reply with quote

Hi! Thank you for your reply...
Actually, after a few more test shots, it looks like the problem is somehow in dialog between lens and camera or in lens AF-motor; in fact, shooting several photos, each time refocusing, some are sharp, some out of focus.
Shooting with 85L @1,2 every frame looks sharp.
Your useful and sofisticated AF adjustment feature cannot help me, I'm afraid...
Anyway I love this lens, so I'll get used to shoot 2-3 frame for every subject... wish my Canon had the focus-bracketing of my N1! Laughing
Happy Easter!
Doc
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jjlphoto



Joined: 17 Jan 2007
Posts: 102

PostPosted: Mon Apr 21, 2008 2:17 pm    Post subject: Reply with quote

Quote:
Each adjustment requires entering 5 values.
[list=1]
[*]-11
[*]12
[*]choose the item to adjust ( new in v2.8 )

  • 4: fixed AF adjustment for standard precision
  • -5: zooming/focusing AF adjustment for standard precision
  • 0: fixed AF adjustment for high precision
  • -9: zooming/focusing AF adjustment for high precision
  • -1: erase all settings and restore to factory default (skip step 4 and jump to step 5)


For fixed AF adjustments, a positive value causes the point of focus to move away from you, curing a front-focus issue. A negative value causes the point of focus to move towards you, curing a back-focus issue.

For zooming/focusing AF adjustments, a positive value causes bigger differences between infinity and closest focusing distance, and a negative value causes smaller differences between infinity and closest focusing distance.

High precision AF and standard precision AF have separate settings. Please refer to this guide for more information: http://eosdoc.com/manuals/?q=AFCompat


I am confused. If I have a zoom lens, I do not select individual front or back focus cures like in my fixed lenses, I only can either widen or tighten the gap between close and infinity?

What is the High Precision adjustment? Is it only for the newer bodies that offer the micro-adjust feature?
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doc



Joined: 23 Feb 2008
Posts: 26

PostPosted: Mon Apr 21, 2008 4:44 pm    Post subject: Reply with quote

I guess "high precision" is referred to the high precision cross-type AF points of Canon cameras, "standard precision" to the AF assist points.
But I only use the central point... Very Happy
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conurus
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Joined: 15 Aug 2006
Posts: 795
Location: Vancouver, Canada

PostPosted: Mon Apr 21, 2008 5:44 pm    Post subject: Reply with quote

jjlphoto wrote:

I am confused. If I have a zoom lens, I do not select individual front or back focus cures like in my fixed lenses, I only can either widen or tighten the gap between close and infinity?

What is the High Precision adjustment? Is it only for the newer bodies that offer the micro-adjust feature?


If you have a zoom lens, such as a 17-35, different ranges of focal lengths are independently adjusted:
focal lengths around 20mm
focal lengths around 28mm
focal lengths around 35mm

A fixed adjustment may be applied to each of the focal length ranges. In addition, a variable adjustment which widens/narrows the gap between infinity and closest may be applied.

http://eosdoc.com/manuals/?q=AFCompat is really the best reference with regards to what is "high precision" and "standard precision". To give you an example, for 1-series up to mark II, high precision detects vertical detail, but horizontal detail is standard precision.

The complexity can be overwhelming at times, I will grant. Given Canon itself receives AF accuracy complaints all the time, including reports of inaccuracies only at certain focal lengths and certain focusing distances, a flexible adjustment system is required to address those kinds of issues.

We spent 3+ years fine tuning AF accuracy (but of course, nothing compared to 20+ years by Canon). It is supposed to be accurate out of the box. Adjust these parameters only if you encounter problems.

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jjlphoto



Joined: 17 Jan 2007
Posts: 102

PostPosted: Mon Apr 21, 2008 6:48 pm    Post subject: Reply with quote

[quote="conurus"]
jjlphoto wrote:

...It is supposed to be accurate out of the box. Adjust these parameters only if you encounter problems...


So if my lens has firmware v2.8, and am not happy with some of my adjustment values I've been messing around with, can I reset to your latest "default" position?
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conurus
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PostPosted: Mon Apr 21, 2008 10:16 pm    Post subject: Reply with quote

Yes, to reset everything to factory and nullify all adjustments, enter -1 in step 3 above, and skip step 4. The table for lenses with a f/22 minimum aperture is as follows.

cam\lensf/4f/5.6f/8f/11f/16f/22
f/4212019181716
f/5.6151413121110
f/8987654
f/113210-1-2
f/16-3-4-5-6-7-8
f/22-9-10-11-12-13-14

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jjlphoto



Joined: 17 Jan 2007
Posts: 102

PostPosted: Wed Apr 23, 2008 5:51 pm    Post subject: Reply with quote

So in doing "-1", and I go back to check its state at a later date, "One Shot" will flash 31 times, where-as an untouched lens fresh from you will have "One Shot" not flash at all because it has not ever been adjusted by the user? (even though it will perform the same as when it left you.)
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conurus
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PostPosted: Wed Apr 23, 2008 10:11 pm    Post subject: Reply with quote

The factory values are all zeros, so if you check the values again at a later date, they will be all zeros (no blink of ONE SHOT).
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jjlphoto



Joined: 17 Jan 2007
Posts: 102

PostPosted: Thu Apr 24, 2008 12:23 pm    Post subject: Reply with quote

Thanks! Found my flaw. I was doing the default reset properly, but when checking results at a later time, I should have been selecting in Step 3 item #4. (that's all was I ever adjusting). I was still selecting item #-1 in Step 3. When I select item #4 in Step 3, it does not flash at all.
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