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Author Topic: How do I know I have a bad lens?  (Read 1775 times)

TC1006

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How do I know I have a bad lens?
« on: July 06, 2012, 11:24:19 PM »
Hello All,
I just received my 5D3 a couple of weeks ago and with that I purchased the kit lens, 135L, and the 50 1.4. I just opened the 50 1.4 today and tried to take some test shots. I noticed that there was a significant vignette on the corners. How do i know that the lens is bad? I took a picture of a plain wall and the vignette was even more visible.

Should i just get it exchanged? Or should i do some more tests? Please advise.

Thanks

« Last Edit: July 06, 2012, 11:26:36 PM by TC1006 »

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How do I know I have a bad lens?
« on: July 06, 2012, 11:24:19 PM »

Mt Spokane Photography

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Re: How do I know I have a bad lens?
« Reply #1 on: July 06, 2012, 11:35:54 PM »
All wide aperture lenses viginette at larger apertures, its just part of the package.  DPP, Adobe, and most other editing software (even in camera jpegs) can be set to lighten the corners to reduce it.
Here is a link to some lens reviews.  Check out reviews and measurements for your lenses.  Most have both a FF and a crop measurement.  they will always be different.
http://www.photozone.de/

DJL329

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Re: How do I know I have a bad lens?
« Reply #2 on: July 06, 2012, 11:39:10 PM »
Did you by chance disable Peripheral Illumination Correction?  I believe it's enabled by default; see page 147 in the manual for instructions on checking it.  Are you using any filters or a third-party hood?
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RLPhoto

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Re: How do I know I have a bad lens?
« Reply #3 on: July 06, 2012, 11:44:52 PM »
Wide aperture lenses vignette more, its the nature of the beast.

They will vignette less on EOS film cameras though due to sensor design. 8)

TC1006

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Re: How do I know I have a bad lens?
« Reply #4 on: July 06, 2012, 11:59:08 PM »
Thanks for such prompt replies.

All wide aperture lenses viginette at larger apertures, its just part of the package.  DPP, Adobe, and most other editing software (even in camera jpegs) can be set to lighten the corners to reduce it.

How can I set this in LR?


Did you by chance disable Peripheral Illumination Correction?  I believe it's enabled by default; see page 147 in the manual for instructions on checking it.  Are you using any filters or a third-party hood?

DJL329 - how does this setting affect the vignetting and what would be the disadvantage of disabling the PIC?

Thank you

DJL329

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Re: How do I know I have a bad lens?
« Reply #5 on: July 07, 2012, 01:14:03 AM »
Did you by chance disable Peripheral Illumination Correction?  I believe it's enabled by default; see page 147 in the manual for instructions on checking it.  Are you using any filters or a third-party hood?

DJL329 - how does this setting affect the vignetting and what would be the disadvantage of disabling the PIC?

Thank you

PIC helps to brighten the corners on lenses that you have configured in order to reduce vignetting.  The corners should appear darker when that setting is disabled.  You can test it out by setting up on a tripod and take 2 identical shots -- 1 with it enabled, 1 with it disabled -- to see the difference.  Note:  it is a per lens setting, so turning it on or off for your 50mm lens, would not affect whether or not it is enabled for your 135mm.

I'm fairly certain that the EF 50mm f/1.4 is one of the lenses that is ON by default.  I thought that perhaps you had disabled PIC for that lens, which could have caused the vignetting that you are seeing.  If you have not disabled it (you need to attach the lens to the camera to check), then that's probably not the issue.

Try uploading (or posting a link) to a couple of sample images, so we can check it out.
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neuroanatomist

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Re: How do I know I have a bad lens?
« Reply #6 on: July 07, 2012, 06:26:16 AM »
Note that PIC applies to in-camera jpg images only, not RAW (although as stated, DPP, LR, DxO, etc., all offer a similar correction for RAW images).
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Re: How do I know I have a bad lens?
« Reply #6 on: July 07, 2012, 06:26:16 AM »

Marsu42

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Re: How do I know I have a bad lens?
« Reply #7 on: July 07, 2012, 01:03:28 PM »
Note that PIC applies to in-camera jpg images only, not RAW

... and rightly so - with an overexposed shot, the vignetted corners will be brightened in jpeg with in-camera correction though they are exposed correctly. And then the exposure of the whole thing is lowered in postprocessing resulting in a loss of dynamic range in the corners.

If shooting jpeg, I'd still turn off in-camera processing unless I want the shots to be used out of the box - postprocessing with dpp, acr and the like won't be worse and adds more flexibility. The only reason to turn on in-camera processing is with small jpeg+raw to quickly see what the camera would have done as a reference for raw conversion.

TC1006

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Re: How do I know I have a bad lens?
« Reply #8 on: July 08, 2012, 09:28:10 PM »
Hello,
So I validated that the PIC setting is enabled. Here is a test shot I took of a wall where the vignetting is really visible. Please advise.


TC1006

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Re: How do I know I have a bad lens?
« Reply #9 on: July 08, 2012, 09:34:38 PM »
So, i was just playing around in LR and found the Lens correction settings in the Develop module. All I did was check the option and it was able to identify the lens. That seems to clear up all the vignetting and any CA that were there.

Should you use this as part of workflow for every image imported?

Random Orbits

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Re: How do I know I have a bad lens?
« Reply #10 on: July 08, 2012, 09:47:08 PM »
So, i was just playing around in LR and found the Lens correction settings in the Develop module. All I did was check the option and it was able to identify the lens. That seems to clear up all the vignetting and any CA that were there.

Should you use this as part of workflow for every image imported?

I typically do apply the lens correction to all the photos are part of the workflow, but when I go through them one by one for cropping/adjustment purposes, I might turn it off for individual photos.  The ones I tend to turn it off for are those that I increase fill light significantly because it brings out the noise in the formerly dark areas that also tend to be in the corners. 

Mt Spokane Photography

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Re: How do I know I have a bad lens?
« Reply #11 on: July 08, 2012, 10:24:59 PM »
Hello,
So I validated that the PIC setting is enabled. Here is a test shot I took of a wall where the vignetting is really visible. Please advise.
The exposure makes it look terrible.  Try using the correct exposure.
Here is a image recently taken with my 5D MK II and the 50mm f/1.4 at f/1.4 with no lens corrections.  Viginetting is hardly a big deal, but its there.
 
If you can't get a similar image, then yes, your lens has some issue.
 

 
 

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Re: How do I know I have a bad lens?
« Reply #11 on: July 08, 2012, 10:24:59 PM »