# How to find out if lens is too soft/bad copy ???



## YoungRebel (Apr 13, 2008)

Hey guys...

In 2007 I bought the Canon EF 24-70 f/2.8 L.
As you know it's not a cheap one and so I am a little worried about the quality that it produces...

I researched online and so many shots from others (same lens) looked just way sharper at almost all f/stops as in the different focal-lenghts...

I'd like to know if there is a "best way to" to test a lens on softness!?

To just give you an example:
70mm - 1/400 - f/5 - ISO200

100% crop


I updated from a canon 28-105 $300 lens and I honestly gotta say that when I look at pictures like this I regret that I bought the L lens... 

That's why I posted this thread, maybe it's "just" a bad copy and I should send it in for recalibration....

Thanks for your time!

I appreciate every answer


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## KhronoS (Apr 13, 2008)

Well if you want to test the lens, try using an object  to take photos of, then a tripod, and double check the focus... might be a focus problem... try testing with a focus chart...


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## evo5gsr (Apr 13, 2008)

I'm curious, how often do people get bad copies?


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## JerryPH (Apr 13, 2008)

With Canon? Quite rare. With Sigma? It was a lot more common a year ago than it is now, and it was specific to only a few models (first and second generations of the 18-50mm, 30mm and a few others). It was not a softness issue, it was a front/back focus issue.

95% of the time, sharpness issues are related to poor shooting technique, poor understanding of the basics, poor post processing techniques or a combination of the three.

For the lens front/back focusing issues, you can google focus chart and use that. It's results are good ONLY if you use it following the instructions 100%.

In your case, Patrick, I am pretty confident that its a 75% post processing and 25% shooting technique issue and not the lens. If your picture had more EXIF camera related info, I could tell you a touch more.


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## Garbz (Apr 13, 2008)

evo5gsr said:


> I'm curious, how often do people get bad copies?



With every company it's quite rare. Some people will sware black and blue various things do this or that but they just forget basic laws of diffraction or it's outright user error that the image is backfocused.


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## soylentgreen (Apr 13, 2008)

Do a search for lens sharpness chart. Someone posted one a couple of months back. Print it out and follow the instructions. I used it for my 70-200 f/2.8L IS because I thought it was "soft". Way wrong on my part. Lens is ridiculously sharp. It was me. :mrgreen:


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## MX962 (Apr 13, 2008)

http://focustestchart.com/chart.html

Here is the focus test page it has a mixed review but may come in handy for you, also a simple ruler laid out flat and camera at a 45 degree angle works pretty well also .......Be sure to use alot of light ! and dont under expose its easier to see the results


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## CWA_JGEISINGER (Apr 13, 2008)

JerryPH said:


> In your case, Patrick, I am pretty confident that its a 75% post processing and 25% shooting technique issue and not the lens. If your picture had more EXIF camera related info, I could tell you a touch more.




How are you planning on making the image more sharp in post .....

The only way I know is to use smart sharpen or something like that in PS and with that you can only do so much before the image starts to distort.


Is there another way?


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## JerryPH (Apr 13, 2008)

CWA_JGEISINGER said:


> How are you planning on making the image more sharp in post .....
> Is there another way?


 
There are several ways.
- The basic sharpen in PS
- The smart sharpen in PS
- NIK software Pro sharpener
- In camera sharpening
- Adobe Camera RAW sharpener

I use three methods, dpending on the results I want:
- Camera RAW sharpening
- NIK Sharpener Pro v.2.0
- Smart Sharpening in Photoshop

Like everything else in life, too much of anything is not good.  It will not correct for a picture blured by bad technique.  It will sharpen a well focused picture for a nice improvement in crispness.


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## RyanLilly (Apr 13, 2008)

JerryPH said:


> There are several ways.
> - The basic sharpen in PS
> - The smart sharpen in PS
> - NIK software Pro sharpener
> ...




Plus, if you shoot raw, there is no in-camera sharpening applied sharpening(among other adjustments) is *required* in post.


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## YoungRebel (Apr 13, 2008)

Thanks guys! I will totally try it out with that chart....

Another question:
Under the same circumstances, just changing aperture-settings, f/4-f/5 is sharpest, everything else looks softer, even when shooting with tripod.
Isn't f/22 supposed to create an overall sharper image than f/4 ? Or at least the same sharpness on the focused spot? - looks way softer with mine....


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## soylentgreen (Apr 13, 2008)

Not so. Almost all lenses will start to degrade past f/11 or so. With the higher quality of L lenses, they retain optimum performance from wide-open to 1-2 stops down. That's the premium you pay for such a lens. Your 24-70 should perform just as well at f/2.8 as f/4-5.6. My 70-200 is only slightly sharper at f/4 or f/5.6. Only major diference in the DOF. My 400 practically stays at f/2.8. I only stop down when the shutterspeed is too high for the camera to cope or the 1.4x TC is attached.


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## YoungRebel (Apr 13, 2008)

I tested the lens with the chart:
It a little weird 'cause depending on the focal-length I set it, it has either a little back- or front-focussing problems.

Not too extreme, but sometimes the text that's supposed to be in focus is almost out of it...

It also varies at different f-stops...


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## soylentgreen (Apr 14, 2008)

YoungRebel said:


> I tested the lens with the chart:
> It a little weird 'cause depending on the focal-length I set it, it has either a little back- or front-focussing problems.
> 
> Not too extreme, but sometimes the text that's supposed to be in focus is almost out of it...
> ...


 
At what ranges? The lens should be sharpest around the 50-55mm range. Try at diffrent ranges wide-open 24,50 & 70 f/2.8. Post some pics if you got them handy. Rarely there may be a problem.


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## K8-90 (Dec 20, 2010)

Going to resurrect this post 

I'm in the same situation, just ordered the Canon 24-70mm 2.8 lens. Should I test it once I get it? Is that common practice? I decided not to purchase the extended warranty, so I want to make sure it's a good copy asap.


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## KmH (Dec 21, 2010)

You should have just started your own thread.

Most people make some photos when a new lens they have just purchased arrives.

That is one way to test it.

The warranty is good for at least a year, if the lens is new.

Extended warranties are usually not a good buy.


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## Village Idiot (Dec 21, 2010)

I had to adjust my 24-70 almost all the way out to +20 because it's focus was off. That definitely helped with sharp photos.


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## Village Idiot (Dec 21, 2010)

erose86 said:


> Village Idiot said:
> 
> 
> > I had to adjust my 24-70 almost all the way out to +20 because it's focus was off. That definitely helped with sharp photos.
> ...


 
I know. I ****ing rock.


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## K8-90 (Dec 21, 2010)

KmH said:


> You should have just started your own thread.



LOL. I can never win! If I had started a new thread, I would have been told to use the search feature :er:

Thanks for the help, though. I'll obviously be taking some photos once I get it, but there are so many variables in what makes a lens soft! I thought there might be some method used to test them. Guess I'll try that focus chart mentioned in the initial posts.

...I'd also like to know what Village Idiot meant by the adjusting +20...


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## Village Idiot (Dec 21, 2010)

I know Canon has started including features with their newer cameras called micro adjust which lets you change the focusing range of your lenses +20 or -20 steps from it's stock setting. This way, you can adjust a lens that's front focusing or back focusing. I believe they started this with the 5D MKII.

Other manufactures may or may not include an option like this in their cameras. RTFM.


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## K8-90 (Dec 23, 2010)

Huh, cool. Will have to look into it...

PICKING LENS UP TODAY


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## pgriz (Dec 23, 2010)

It's never a bad idea to "calibrate" your gear.  Front-focus and back-focus issues are pretty easy to test.  Knowing your resolution (center and corners) at various f/stops for each of your lenses is also a good idea.  You don't even need a lens resolution chart (although it certainly helps) - a target with detail ranging from coarse to very fine will do.  The point is that each of us should take the time to work with our gear in a controlled and structured way to know what it can do.


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## RacePhoto (Mar 22, 2011)

Yes it's been a couple of months, but I couldn't find the thread asking about getting a "good copy" of the 100-400MM Canon zoom, this is the best one the search turned up.

Interesting viewpoint.

https://www.lensrentals.com/blog/2008/12/this-lens-is-soft-and-other-myths

Cameras vary, lenses vary if you get a camera that's -2 and a lens that's -2 you are going to see some focusing issues. And if you keep changing lenses until you get a nice set that matches your camera, and the camera is way to one direction, they may not match your next camera!

Thank you camera makers for adding micro adjustments.


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