October 25, 2014, 05:39:52 AM

Author Topic: Need some advice - lens calibration  (Read 1157 times)

DRR

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Need some advice - lens calibration
« on: September 02, 2014, 08:52:03 AM »
I recently bought a used 35L, and I am convinced it's out of calibration.

I've seen a bunch of 100% crops from this lens online and I'm 99% sure my copy is just soft. It doesn't begin to get sharp until about f/2.8.  F/1.4 is unusable. It's actually quite similar to the images in this FM thread:

http://www.fredmiranda.com/forum/topic/922937/0

Ultimate sharpness is not critical to me. If it had been, I likely would have purchased a different lens. I've used different copies of the 35L in the past and they neither behaved like this.

I've done a couple of AFMA and it's not any better. From my understanding AFMA will correct front focus and back focus, but FF/BF is not my issue. Even with manual focus, I cannot achieve anywhere near the level of sharpness I should be able to. I was expecting a little soft at f/1.4, and then approximately as sharp at f/2 as my old 35mm f/2 non-IS. I did a "manual" AFMA and got a setting of -8. I then tried the DotTune method and got a similar result, landing at -10 (-17, +3).  FWIW, my 6 other lenses are all within +/- 2  of zero, so I have a fair amount of confidence that my camera is at or near zero. This 35L appears to be the outlier, my other lenses perform similarly on other bodies as well.

So where do I go from here? It's a used lens, presumably out of warranty. If I send to Canon, what exactly am I asking for, a "calibration?"

On a side note, I do have enough points for CPS Gold, would that be a better way to go about fixing this? Would this be covered under their standard 11-point inspection for lenses, or would this type of repair be separate?

(http://www.usa.canon.com/CUSA/assets/app/html/Support/11point.html)

Can probably post some pictures later tonight but looking for advice in the mean time.


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Need some advice - lens calibration
« on: September 02, 2014, 08:52:03 AM »

Random Orbits

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Re: Need some advice - lens calibration
« Reply #1 on: September 02, 2014, 09:25:40 AM »
How does it look when you use LiveView to focus?  Using manual focus without a focus screen made for it will be difficult to get consistent results with fast lenses.

If the LiveView images look good, and your AFMA attempts do not seem to fix the issue, the lens may need to be calibrated by Canon.  I had a similar issue with my 24L II, and I took a series of pictures of an object at f/1.4, f/2, f/2.8, f/4, f/5.6 and sent the images with the lens to Canon explaining that the AF accuracy was not nearly as good as the LiveView images taken at the same images (also included those images).  The service sheet stated they they adjusted the focusing board on the lens, but did not go into details.  No parts needed to be replaced, it was an adjustment only, so hopefully, it won't be very expensive.  Mine was under warranty at the time...

Mt Spokane Photography

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Re: Need some advice - lens calibration
« Reply #2 on: September 02, 2014, 09:39:03 AM »
A calibration is adjustment of the autofocus.  You can check the autofocus by photographing a flat surface like a brick wall making sure that you are square to the surface.

Put the camera on a tripod and use live view and live autofocus.  The camera with a 35l should be about 5 ft or more from the wall.  If its not sharp, your lens is likely damaged, and needs repair.  When you purchase a used lens, its a good idea to allow for a $350 trip to Canon in your purchase price.

I'd return the lens if you can.  Someone knew of the issue.

My new 35mmL was sharp, but needed a lot of AFMA.  Canon adjusted it under warranty, and it was excellent from then on.

I found myself in a indoor arena photographing a friends Monster Truck.  I only expected to photograph it up close while on display, but he wanted motion shots during the performance.  All I had with me was my 35mmL, so I cropped the images a lot.  They were still sharp enough to print 8X10 and larger.


DRR

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Re: Need some advice - lens calibration
« Reply #3 on: September 02, 2014, 10:31:46 AM »

Unless I am doing something seriously wrong, it's not a focus issue. I can't get it to focus sharp in Live view at 10x. It's "cloudy" looking, "hazy," like I'm shooting with a plastic lens.

I checked The-digital-picture's lens test here

http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=121&Sample=0&FLI=0&API=0&LensComp=0&CameraComp=0&SampleComp=0&FLIComp=0&APIComp=0

...and it's nothing like that. At 1.4, my center sharpness is worse than this test in the corner. Even if I was at 2.2-2.5 my center sharpness would be worse than Brian's test at 1.4 corner.

My AFMA I believe, was set up correctly, 25x focal length, which worked out to about 3 feet from sensor. Focal plane aligned with subject plane. Shot at 1.4, good light, live view, tripod, tethered.


andrewflo

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Re: Need some advice - lens calibration
« Reply #4 on: September 03, 2014, 08:15:47 PM »
If you're manual focusing and have tested this out in Live View @ 10x it doesn't sound at all like an AFMA issue to me.

Hate to say it, but maybe the copy you purchased wasn't the best :(

Any chance of getting your money back?
6D | 70-200mm f/2.8L IS II | Tamron 24-70mm f/2.8 VC | 100mm f/2.8L IS | 50mm f/1.8 II | Sigma 15mm f/2.8 Fisheye | 600EX-RT | EOS M | EF-M 22mm f/2 | Helios 44-2M 58mm f/2

Mt Spokane Photography

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Re: Need some advice - lens calibration
« Reply #5 on: September 03, 2014, 08:34:54 PM »

Unless I am doing something seriously wrong, it's not a focus issue. I can't get it to focus sharp in Live view at 10x. It's "cloudy" looking, "hazy," like I'm shooting with a plastic lens.

I checked The-digital-picture's lens test here

http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=121&Sample=0&FLI=0&API=0&LensComp=0&CameraComp=0&SampleComp=0&FLIComp=0&APIComp=0

...and it's nothing like that. At 1.4, my center sharpness is worse than this test in the corner. Even if I was at 2.2-2.5 my center sharpness would be worse than Brian's test at 1.4 corner.

My AFMA I believe, was set up correctly, 25x focal length, which worked out to about 3 feet from sensor. Focal plane aligned with subject plane. Shot at 1.4, good light, live view, tripod, tethered.

That sounds bad!  If you can't return it, send it in.  Canon can repair it, but until they determine the issue, the price is unknown.  The foggy part (If I understand it right) worries me.  Rather than give out opinions of the issue, just take it for repair.

DRR

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Re: Need some advice - lens calibration
« Reply #6 on: September 06, 2014, 05:48:22 PM »

Had a friend look at it. She thinks it's not that bad. I still think there's a problem. I'm basically second guessing myself at this point so I'll post some pics and hopefully you guys can tell me what you think and I can factor that into deciding what to do.

These are tripod, remote shutter release. Like I said earlier, I don't have a focus problem, focus has been AFMA'ed and this is as good as it gets.

Shot at f/1.4, f/2.0, f/2.8, f/4.0. (in order.)

Obviously it gets sharper as it's stopped down but tell me if you think there is an obvious problem here, or if the problem is my expectation.

Full shots:






100% crops:





Thoughts? If I'm making a newbie mistake here please let me know (nicely)  ;)




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Re: Need some advice - lens calibration
« Reply #6 on: September 06, 2014, 05:48:22 PM »

YuengLinger

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Re: Need some advice - lens calibration
« Reply #7 on: September 06, 2014, 08:25:46 PM »
Let Canon repair give you an estimate.  Useless wide open, as you said.

takesome1

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Re: Need some advice - lens calibration
« Reply #8 on: September 06, 2014, 09:13:11 PM »
Your pictures are worthless to comment on unless they were taken using manual focus.

The 35mm L is not sharp at 1.4, but by 1.8 you should be getting good results.
If your pictures are in manual ship it back to Canon.
A 35mm 1.4 L that isn't sharp at 2.0 is worthless IMO, that is the whole reason to own it.

takesome1

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Re: Need some advice - lens calibration
« Reply #9 on: September 06, 2014, 09:17:51 PM »
By the way it appears every one of the shots is focused on the left drawer not the battery.

unadog

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Re: Need some advice - lens calibration
« Reply #10 on: September 06, 2014, 10:30:49 PM »
Three things:

1.) > landing at -10 (-17, +3)

The center of-17, +3 is not -10. If you counted the spread as 20, it is -17+10 = -7. Very close to your previous -8.

2.) You can't test a lens using autofocus! You need to use Live View and manual focus:

From Roger Cicala:

http://www.lensrentals.com/blog/2014/02/why-you-cant-optically-test-your-lens-with-autofocus

3.) Also from Roger, "How to Test a Lens":

http://www.lensrentals.com/blog/2010/11/how-to-test-a-lens

Setting up an optical testing station:

http://www.lensrentals.com/blog/2014/02/setting-up-an-optical-testing-station

Examples using the optical testing station:

http://www.lensrentals.com/blog/2014/02/examples-using-an-optical-testing-station

Good luck!
Michael

YuengLinger

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Re: Need some advice - lens calibration
« Reply #11 on: September 07, 2014, 08:43:24 AM »
CPS is definitely great, but, no, this is not free maintenance.  My guess, from almost three years using them, $300-400 before 20% discount.  They'll let you decide before charging.

Only you can decide cost benefit.

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Re: Need some advice - lens calibration
« Reply #11 on: September 07, 2014, 08:43:24 AM »