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Author Topic: Canon EF-S 10-22mm f/3.5-4.5 USM - SEEMS SOFT  (Read 4966 times)

nworbmit

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Canon EF-S 10-22mm f/3.5-4.5 USM - SEEMS SOFT
« on: August 07, 2011, 03:06:56 pm »

I recently traded with someone for a Canon EF-S 10-22mm f/3.5-4.5 USM

When manually focusing (this is not an autofocus microfocus adjustment issue) I am getting pretty soft images at 10mm (it's still annoyingly soft, but better at 22mm)
I'm not attaching images..... trust me.

My question is whether correcting resolution problems is something that CAN  BE CORRECTED by the Canon service center?
I am just unfamiliar with what is possible.
Do lenses GO OUT OF PRECISION?
Do photographers send their lenses in to be tweeked for sharpness/resolution?
Has anyone sent in a soft lens and had a corrected, sharper lens returned to them?

Again, I'm not talking about Electronic or Autofocus fixes as I am testing this lens at f/8 and manually focusing.
The test images are being made at the lenses optimum focus - manually.
Testing on a Canon 50D

Thanks
Tim

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kaelaria

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Re: Canon EF-S 10-22mm f/3.5-4.5 USM - SEEMS SOFT
« Reply #1 on: August 07, 2011, 05:21:37 pm »

How about a sample?  ;D
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nworbmit

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Re: Canon EF-S 10-22mm f/3.5-4.5 USM - SEEMS SOFT
« Reply #2 on: August 07, 2011, 05:33:21 pm »

Not posting a sample.
I'm not near the camera, (different city) at the moment, to do so.
I'm interested in answers about what camera repairs that are possible and the Canon repair center in particular.
Thanks
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Ken Bennett

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Re: Canon EF-S 10-22mm f/3.5-4.5 USM - SEEMS SOFT
« Reply #3 on: August 08, 2011, 12:55:44 pm »

Yes, I have sent lenses to Canon Professional Services for tweaking of the focus. They can get out of adjustment.
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nworbmit

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Re: Canon EF-S 10-22mm f/3.5-4.5 USM - SEEMS SOFT
« Reply #4 on: August 08, 2011, 01:52:14 pm »

It's not the Focus that needs tweeking.

I very carefully manually focused on a card, perpendicular to the film plane.
The card displayed a bunch of resolution charts.

It's focused at the best lens will focus.

But the images are soft.
It's not the autofocus that needs adjusting - as I know camera repair can tweek.
I was not using autofocus.

I'm wondering if lens elements creep out of alignment and
then the lens essentially can not resolve as designed.
Can not resolve, when it is focused.
And CAN THIS BE REPAIRED?  :P

I found one other post on this forum about this lens being soft.

It's Monday now. So I will call Canon.
But if anyone can answer this , let me know.

Thanks again
Tim
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feppe

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Re: Canon EF-S 10-22mm f/3.5-4.5 USM - SEEMS SOFT
« Reply #5 on: August 08, 2011, 02:24:17 pm »

Test the softness by using LV focus if your camera has it. Your AF/MF might be off. Just because you used MF via viewfinder doesn't necessarily fix misaligned focus, for example if you focus and recompose.

Zoom lenses are generally softer than primes. I had Sigma's 10-20mm for Canon, and it was a bit soft - the Canon is supposed to be marginally better. I wouldn't be surprised if it's soft, given their 24-105mm L lens is soft as well.
« Last Edit: August 08, 2011, 02:26:29 pm by feppe »
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nworbmit

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Re: Canon EF-S 10-22mm f/3.5-4.5 USM - SEEMS SOFT
« Reply #6 on: August 08, 2011, 02:43:52 pm »

This softness problem is not related to an autofocus issue.
I am aware of the camera's microfocus adjustment in matching camera/lens combos.

I do not set it, as I am a product photographer and need absolute control of focus, manually.

I do not use VF autofocus or LV autofocusing.
I am manually focusing.
I am not focusing and recomposing.
I'm doing a test of a resolution chart.
Camera on tripod.
Camera positioned in center relative to target.
Film plane is parallel to target.
Sorry I can not provide a sample , I am currently in a different city than the camera/lens.

Again, my question is not about repairing the focus.
I am asking about whether the resolving power of a lens can creep out of alignment.
Not the focusing ability.
The tests are focused correctly, manually.

And specifically my question is whether 'resolving issues' are something that can be tweeked or repaired.

Thanks
Tim
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feppe

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Re: Canon EF-S 10-22mm f/3.5-4.5 USM - SEEMS SOFT
« Reply #7 on: August 08, 2011, 04:29:12 pm »

Again, MF via VF doesn't guarantee accurate focusing. LV does.

nworbmit

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Re: Canon EF-S 10-22mm f/3.5-4.5 USM - SEEMS SOFT
« Reply #8 on: August 08, 2011, 05:04:39 pm »

But my question is about lens resolution, not focusing?
And what is possible in lens repair.

I was not looking for advice in how to set up any testing.

I called Canon a few hours ago and they verified that indeed
lens elements drift and that repairs regarding resolution, not focusing, are done at the center.

But
I would be interested in learning more about LV focusing.
Do you have any articles you could reference regarding it being more reliable than View finder Auto focus?

Thanks









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ErikKaffehr

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Re: Canon EF-S 10-22mm f/3.5-4.5 USM - SEEMS SOFT
« Reply #9 on: August 08, 2011, 05:23:16 pm »

Hi,

You activate live view and there used to be a button so the LCD display shows image at actual pixels. The idea is to use the actual output from the sensor for focusing. There is no more exact method.

Best regards
Erik

But my question is about lens resolution, not focusing?
And what is possible in lens repair.

I was not looking for advice in how to set up any testing.

I called Canon a few hours ago and they verified that indeed
lens elements drift and that repairs regarding resolution, not focusing, are done at the center.

But
I would be interested in learning more about LV focusing.
Do you have any articles you could reference regarding it being more reliable than View finder Auto focus?

Thanks










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nworbmit

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Re: Canon EF-S 10-22mm f/3.5-4.5 USM - SEEMS SOFT
« Reply #10 on: August 08, 2011, 06:55:31 pm »

When you are using LV focusing, isn't it just another use of Autofocus?

And when using autofocus, there is a possible problem of front or back focusing.
(which can be corrected with the microfocus adjustments +1, +2, -1 -2 etc. etc.)

So this extra variable of a possible auto-focus mismatch is introduced.
So an auto-focus error is possibly introduced.

I do not want to test the focus.

I want to focus manually, and I am testing the resolving power of the lens.
The sharpness of the lens at proper focus.

So manually focusing eliminates the variable of an auto-focus lens/camera microfocus mismatch error.
I do not use auto-focus when shooting anyway.

Again, I'm curious if anyone has had a resolution problem (not an auto-focus error) - a soft lens - corrected by Canon?


Thanks

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feppe

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Re: Canon EF-S 10-22mm f/3.5-4.5 USM - SEEMS SOFT
« Reply #11 on: August 08, 2011, 07:21:36 pm »

When you are using LV focusing, isn't it just another use of Autofocus?

And when using autofocus, there is a possible problem of front or back focusing.
(which can be corrected with the microfocus adjustments +1, +2, -1 -2 etc. etc.)

So this extra variable of a possible auto-focus mismatch is introduced.
So an auto-focus error is possibly introduced.

I do not want to test the focus.

I want to focus manually, and I am testing the resolving power of the lens.
The sharpness of the lens at proper focus.

So manually focusing eliminates the variable of an auto-focus lens/camera microfocus mismatch error.
I do not use auto-focus when shooting anyway.

Again, I'm curious if anyone has had a resolution problem (not an auto-focus error) - a soft lens - corrected by Canon?

You keep saying you don't want to test focus, but you need to have accurate focus to be able to test resolving power of the lens, otherwise the test is pretty useless. Non-LV AF is not a reliable method unless you have calibrated the lens/camera combo.

LV focusing has the huge benefit in that it uses data from the sensor, and doesn't require calibration. There is no focus mismatch or front/back focusing issues with LF focus. Contrast detection focus (ie. LV focus), while slow (on DSLRs), is more accurate than non-LV AF or VF MF. Non-LV AF doesn't use use data from the sensor, but a different method similar to film SLR cameras, I believe it's called phase detection. MF through VF is not a reliable method for numerous reasons, from mirror mis-alignment, etc., and you need to have very good eyes and a bright VF, and/or a focusing screen.

So, to recap: test proper focus with LV AF or LV MF, and see if the images are as soft as non-LV AF or VF MF. If they are, it's unlikely you will get benefit from calibrating the lens. If they are sharper, calibrating the lens/camera will probably improve performance. But note that pictures done with LV AF/MF on a sturdy tripod and timer/remote release will show the best the lens can do, so that'll give you an idea of how soft the lens really is.

Much more about this here. There's also a brand new video advertised on LL front page addressing your questions.
« Last Edit: August 08, 2011, 07:24:24 pm by feppe »
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nworbmit

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Re: Canon EF-S 10-22mm f/3.5-4.5 USM - SEEMS SOFT
« Reply #12 on: August 08, 2011, 07:26:22 pm »

Ok thanks
I will read this stuff.
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Ken Bennett

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Re: Canon EF-S 10-22mm f/3.5-4.5 USM - SEEMS SOFT
« Reply #13 on: August 09, 2011, 08:26:19 am »

Turn on Live View. Hit the zoom button a couple of times to show the actual pixels. Use a loupe or a magnifier, put it up to the LCD screen, and use the manual focus ring to fine tune the focus. This is the most accurate method of focusing that I have found. (But of course the subject can't be moving very fast.)

Canon has fixed a lens for me that had uneven sharpness across the image, which is a lens element issue.
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David Eichler

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Re: Canon EF-S 10-22mm f/3.5-4.5 USM - SEEMS SOFT
« Reply #14 on: August 09, 2011, 06:21:39 pm »

And the answer is, of course lenses can go out of alignment in ways that affect the maximum resolution that a lens can deliver, especially complex lenses such as zooms. Frankly, I think that Canon's quality control is sometimes not that  good and that they all too often deliver brand new lenses that are out of alignment.
« Last Edit: August 13, 2011, 04:21:55 pm by David Eichler »
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sbay

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Re: Canon EF-S 10-22mm f/3.5-4.5 USM - SEEMS SOFT
« Reply #15 on: August 14, 2011, 11:40:17 am »

Agree with the other posters to use live view as manual focus is too often not accurate enough if you are examining 100% crops. Actually, even with live view I've had problems with some lenses getting perfect focus so if I am testing a lens, I'll refocus several times to make sure I get it right.
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