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Author Topic: 6d, canon refurb issues, and AFMA results  (Read 2033 times)

ashmadux

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6d, canon refurb issues, and AFMA results
« on: November 28, 2013, 11:11:44 AM »
I recently purchase a 6d from canon refurb sale. Tested it out, image quality sucked. AF was totally off, even after focal and hand AFMA. I compared shots taken from a bh demo unit, with no edited settings besides raw. Immediately noticeably better. I prepare a whole folder for canon repair to look at.

The choice was to send it back or have them fix it. I've need a replacement for my junked 7d I sold a while ago. I chose to fix it. Jus got it back, took some shots, then focal. Here are the results.

Minimal info on the repair sheet - AF adjustments.

These are twice as good as the blur city it was originally. But it doesn't look great, especially not full frame great. Admittedly, the pictures do look a lot better and it harder to argue it, but look at those results...like soft. To less soft. In comparison, before it went back the settings came back -9 -9 for this sharp copy of 24-105.

I will not an do not conduct image quality test after image processing, so no I won't be running them through lightroom or dpp to see how much better they can get. I expect good images out of camera.

Lastly, every image I work with is viewed at 100 percent and similar settings, so there is no deviation.

What do you guys think? More details to come.

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6d, canon refurb issues, and AFMA results
« on: November 28, 2013, 11:11:44 AM »

dcm

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Re: 6d, canon refurb issues, and AFMA results
« Reply #1 on: November 28, 2013, 04:16:38 PM »
It's hard to say.  I suggest you rerun the tests and follow the setup guidelines a bit more closely to improve your results.  Your light levels are below the 8ev minimum recommended.  I typically calibrate with light in the 10ev to 11ev range.  Your target isn't level in the tests either - it helps to level both the target and camera.  Your target distances are also outside the recommended ranges.  Suggested distance for calibration is 50x focal length, or in a range from 25x-50x.  You are a bit long on the 24mm side - 1.6m vs 0.6m - 1.2m recommended and short on 105mm side - 2.0m vs 2.6m to 5.2m recommended.  I also find that target print quality can greatly affect the results.  I've tried a few different papers and ink settings to get the highest contrast targets.

Using the recommended setup I achieve excellent result confidence with both a new 6D and refurb 6D on the 24-105L and several other lenses.  The results are pretty consistent on both bodies, within 1 AFMA at both 24mm (1,2) and 105mm (0,1). I also verify the autofocus with a LensAlign tool that I got before FoCal.   
« Last Edit: November 28, 2013, 04:19:05 PM by dcm »
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ashmadux

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Re: 6d, canon refurb issues, and AFMA results
« Reply #2 on: November 29, 2013, 02:17:12 PM »
It's hard to say.  I suggest you rerun the tests and follow the setup guidelines a bit more closely to improve your results.  Your light levels are below the 8ev minimum recommended.  I typically calibrate with light in the 10ev to 11ev range.  Your target isn't level in the tests either - it helps to level both the target and camera.  Your target distances are also outside the recommended ranges.  Suggested distance for calibration is 50x focal length, or in a range from 25x-50x.  You are a bit long on the 24mm side - 1.6m vs 0.6m - 1.2m recommended and short on 105mm side - 2.0m vs 2.6m to 5.2m recommended.  I also find that target print quality can greatly affect the results.  I've tried a few different papers and ink settings to get the highest contrast targets.

Using the recommended setup I achieve excellent result confidence with both a new 6D and refurb 6D on the 24-105L and several other lenses.  The results are pretty consistent on both bodies, within 1 AFMA at both 24mm (1,2) and 105mm (0,1). I also verify the autofocus with a LensAlign tool that I got before FoCal.   



Ive basically done the best that i could with the usb length that i have. its not that long at all. That would be quite a bit of light to hit ev10- and im in a white walled room with windows to the right of the target setup- how did you manage to achieve that level of light? (at night i blast the target with a small flashlight).

It was pretty disheartening to look at the raws from a demo 6d and find the images were immediately noticeably better.

Im takign it around the block to see what i get form some real world sceneariosn

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dcm

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Re: 6d, canon refurb issues, and AFMA results
« Reply #3 on: November 29, 2013, 05:22:29 PM »
I use a pretty simple rig in my office for a 15' range shown in first image.  The target is taped to the closet door at one end of the room, checked for plumb/level.  The tape measure on the floor let's me easily adjust target distance.  The target was printed at 150% to fill the page.  You just need to remember to modify the "large target width" on the Tests Preferences to the size of the target if you choose to do this since the target width increases from 128mm to 192mm.

A light stand holds a PAR30 5K 15 watt 800 lumen LED reflector bulb in a Manfrotto Double Super Clamp at a 30-45 degree angle from target to minimize reflections. It's a bit close to the target now to accentuate the effect.  I usually kill other lights in the room and close the blinds (even during the day) to minimize reflections/interference and shoot with spot metering on the target.

The LensAlign tool is mounted atop the stand at eye-level so I can easily verify AFMA after FoCal.  It is also a good way to practice holding the camera still/steady when shooting with narrow DOF. You'd be surprised how much sway you can impart to camera between focus and capture.  Shooting continuously can give you some idea.

I use a three axis level in the camera hot shoe once mounted on the tripod and measure distance from floor and side wall to camera and target centers to ensure it's square.  You can also verify with a mirror taped in front of target if you aren't sure.  I verified the setup with a mirror the first few times, now I don't bother.

A cheap, powered USB hub hanging on the tripod doubles the distance from my Mac which is on the side wall, allowing me to move the camera from end to end in the room.  The Mac is near to door so its easy to setup in the hallway for longer lenses.  I've also got a laptop if I need a longer test range.

I just calibrated a refurb 85f1.8 on both bodies using this setup with raw image captures.  I use a Normal amount of test points for the first pass, then run it again with Many test points.  I also run an aperture sharpness test to see how the lens performs.  Then I hand hold a series of shots at the LensAlign target from various distances.  Results for this lens on the refurb 6D are shown in the last three images. 

Even with a calibrated lens setup, I find there is still a need for some post processing of RAW files.  You can't really use RAW files asis from the camera.  I used Aperture's auto enhancement when I got started.  The resulting jpgs were often better than the  out of camera jpgs.  I now use some custom presets on DxO Optics Pro 9 and make adjustments if needed, particularly when I'm shooting in low light without flash.

AFMA does vary lens to lens and body to body.  I have a 35f2 that requires AFMA -10 - it was noticeably soft wide open on both the 6d and my old 550D.  You may still have a bum 6D, but its hard to tell from the tests you posted.
« Last Edit: November 29, 2013, 06:48:17 PM by dcm »
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Re: 6d, canon refurb issues, and AFMA results
« Reply #4 on: November 29, 2013, 06:32:04 PM »
As noted, you are using too little light, and the shutter speed is very slow as a result.  This will give erratic test results, and as a result, the test is invalid.
Get the light level up to EV 12 preferably more.  Then you will start to see some better results.  10 or 15 foot USB cables can be had from Amazon for $5-7, so they are not expensive.
 
You spent a lot of $$ on the camera, use a bright set of lights.  I use 12 32 watt fluorescent lights when I'm stuck indoors, and more would be better.
 

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Re: 6d, canon refurb issues, and AFMA results
« Reply #5 on: November 29, 2013, 09:02:12 PM »
It's important that the setup be stable. Solid tripod on a firm surface. I first set up for FoCal on the main floor of my house, which has hardwood flooring. Results were sometimes erratic, especially if anyone was walking around. I moved to the basement, with a concrete slab floor, and get good results.

A definite +1 on more light.  I use the same three gooseneck lamps I used with my LensAlign Pro setup, placed ~18" from the target, which is taped to a wall.  FoCal reports EVs in the 11-12 range.

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ashmadux

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Re: 6d, canon refurb issues, and AFMA results
« Reply #6 on: November 30, 2013, 02:30:48 PM »
Unfortunately i dont have any lamps that could get me that kind of setup- so ill have to go purchase one from home depot  and ive ordered a much longer usb cable.

However i also made the decision to send the body back- canon will swap it ( after a 30 minute long tirade to sales and tech.) The insanity i went through with the 7d, i cant go through that again.

ill update when i get the new body in, likely by next weekend, an ill resume testing.

I appreciate the assist guys.
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Re: 6d, canon refurb issues, and AFMA results
« Reply #6 on: November 30, 2013, 02:30:48 PM »

dcm

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Re: 6d, canon refurb issues, and AFMA results
« Reply #7 on: December 03, 2013, 03:46:25 PM »
Forgot to mention that with a second similar light I easily get 12+ ev without putting them too close to the target.  Depending on the lens (f1.4), this pushed the shutter speed to less than 1/4000.  The extra light can be helpful with the aperture sharpness test to help overcome slow shutter speeds at small apertures (f22+).
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Re: 6d, canon refurb issues, and AFMA results
« Reply #7 on: December 03, 2013, 03:46:25 PM »