Lens Focus / Sharpness - 24-70 f/2.8 L

lensworx

lensworx

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Mark
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Hi all,

First of all Happy Christmas to everyone and I hope you all have a great new year.

After more than enough problems with my Sigma 24-70 I returned it and got the Canon L version instead. When I got it the 70 end seemed fine but the wide end seems soft wide open but tack sharp at the zoom end.
can some of you with this lens please post up examples so I can see just how bad (if so) my copy is or if its just me pixel peeping too much.

Thanks in advance

Mark
 
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That's interesting. Well how did you do the 4s exposures? Was there any chance any camera movement, etc? I'd try to keep it < 1/200s. Then what was the method of focusing? Can you improve it by manual focusing in Liveview?

24mm does look pretty poor and that is probably due to a severe back focus (considering the focus was on the box).

48mm looks OK, and if anything there may be very slight front focus of a couple mm.

Things to try may involve upgrading 7D firmware or trying another copy of the lens or camera.

Failing that I'd suggest 24-105mm IS.
 
thanks for the reply.

I did in fact change the question slightly After some further tests and reading a number of reviews etc. I had posted up the original shots with the MA but I have now removed them as I did not think that they gave a good representation of the lens after further tests. I have changed the MA back to 0 as it had degraded the zoom end too much, 50-70 is sharp and from what I can tell seems fine. the wide end (will check how far across the zoom better tomorrow) however as you can see is really soft.

I have uploaded three new raw files with the camera MA set at 0, all are taken on a tripod with a release cable using liveview (quick mode) and the centre focus point. the three shots are taken at 24mm,50mm and 70mm.

http://www.lensworx.co.uk/wp-content/uploads/IMG_3441.CR2
http://www.lensworx.co.uk/wp-content/uploads/IMG_3442.CR2
http://www.lensworx.co.uk/wp-content/uploads/IMG_3443.CR2

If anyone would prefer JPEGS without any sharpening then please let me know but I thought that the RAW Files would be better

Thanks in advance
 
out of interest which sigma 24-70 did you have? I had the HSM version on my 5D2 and it was fine.

it could be you've been unlucky and got a poor quality lens. it's not unknown for the 24-70 L to have sharpness and focus issues.
 
Thanks for the reply,

The sigma I had was the 24-70 f/2.8 EX DG MACRO (Non HSM).
I had took the first copy back and then ended up sending the second copy to sigma. After them having it for three weeks and replacing the circuitry it still was really soft below about f/4 and only just become usable at around f/8.
In the end I took that once back and decided to get the Canon L version as I thought it would be a better option.

Looking at the last set of images that I took, there seems to be some major back focusing at 24mm, but I try and correct this it sends the rest of lens out.
I think I may end up sending it back to canon for investigation.

Can anyone recommend me a good service centre to sent it to?
 
I bought a Canon 24-70mm just before Christmas.

So far I'm not happy with mine either, seems very soft. Hopefully tomorrow, I'm going to do some proper test to see what's up with it.

I had just been ready through Marcel's thread. This might be handy for tests http://www.focustestchart.com/
 
Very interesting to hear 24-70L doesn't like 7D's.

My experience so far was excellent on 1D mkIII w/o any adjustment, but not as good with 1Ds mkII (back focus at ~50mm), and 40D / 30D (70mm was way out, 28-50mm excellent, 24mm was sorted after new firmware). This is all with the single copy and I am yet to service it. It needs a general tidy-up so I will ask them to look at it.

It suggests me this could well be camera and lens firmware issue, since 1DIII works fine with it.

I would be happy to quickly test other samples on my 1D if anyone is interested.
 
Thanks for the replies.

I have started wondering if it could in fact be the body at fault.
I have a mate just up the road that also has a 7D and a 24-70L. I have asked him to come around tommorow and we are going to try my lens on his body and my body on his lens etc...

I am hoping that we can come to some better Idea of the source of the problem.

I will be sending the culprit back to canon come the new year for investigation. Who would you recommend I send it too and what are their turn around times?

I have had nothing but problems since the day I decided to buy BETTER kit.

thanks in advance.
 
well im waiting for my mate to come around this afternoon with his kit so that we can do some comparisons but I did manage to go out yesterday afternoon for some "Real World" Testing.

Here are two shots that I took and to me they look soft. I have converted the RAWs to JPEGS without any sharpening but even with sharpening they look soft to me.

http://www.lensworx.co.uk/wp-content/uploads/lenstest-1.jpg


http://www.lensworx.co.uk/wp-content/uploads/lenstest-2.jpg

Could some please have a look at these and see what you think.These are both shot at F18 using a single focus point on a tripod using a release cable.

Thanks in advance
 
what is your shutter speed?

r they hand held/tirpod?

looks way 2 low as the birds have got movement blur.
 
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Thanks for the reply.

They are both shot on a tripod using a cable release. The Shutter speed was 1/30th at ISO 200 but on the tripod I would have thought this should not have been a issue. had not noticed the birds tho. Will wait until my mate gets here and do some better tests
 
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lensworx said:
Thanks for the reply.

They are both shot on a tripod using a cable release. The Shutter speed was 1/30th at ISO 200 but on the tripod I would have thought this should not have been a issue. had not noticed the birds tho. Will wait until my mate gets here and do some better tests
Click to expand...

It is very hard to tell if a lens of soft or not, just by looking at images in isolation. And the processing applied, in camera or in post, makes a huge difference. However, I can tell you that anything shot at f/18 will be very soft indeed due to diffraction. Your lens will be sharpest at around f/5.6. And 1/30sec is unlikely to show the lens at its best, tripod or otherwise.

There are two potential issues here - a poor copy of the lens, or misfocusing. Completely different things.

If you are concerned about sample variation, then shoot comparison images with your lens and another lens of the same focal length and of known good quality. All settings and processing identical and see what you think.

Misfocusing is something else - quite a few threads on testing that. Try this, at f/2.8 and 50mm, no closer than about five feet and set up square on a tripod. It should nail that. Use microadjust if necessary, then check at longer and wider focal lengths, but don't be tempted to go closer than 25x focal length as you may find very slight variations and if you correct for them you could then throw it out at normal shooting distances. Zooms are always a compromise in this respect, but an L-grade lens should be pretty damn good.

IMG_3381-1.jpg
 
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thanks for the reply.

My god that looks a lot better than mine.

Here are a few that I done this evening using a very simular test. all are done on a tripod using the timer and a shutter speed of 1/250 @ ISO 200
I have done no more sharpening to them than is done as standard when importing into lightroom (Set to default at 25 if im correct)

24mm @ f/2.8
lenstest2-4.jpg


24mm @ f/5.6
lenstest2-5.jpg


24mm @ f8
lenstest2-6.jpg




50mm @ f/2.8
lenstest2-1.jpg


50mm @ f/5.6
lenstest2-2.jpg


50mm @ f8
lenstest2-3.jpg


I really think that I may well send the lens back to canon or I may infact send the lens and body at the same time. what are their turn around times like?

any input would be great
 
What are you testing for there?

Where is the angled rule and the 100% crop of that? Can't see anything amiss at that size.

If a focus test, why did you shoot higher than f/2.8?

Are you married to Cheryl Cole?

You just need one shot, as described above, then zoom in on the LCD and see where the sharpest focus is on the rule, compared to where it should be.
 
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well here is one at 24mm @ f/2.8 cropped to 100%

24mmf2-8100.jpg


Hopefully you can now see what I was trying to get at, I dont think i need a ruler to tell me that this shot is oof.

I could see that this image was oof from the original shots but i am sorry if you could not.
no i am no married to Cheryl cole but if you want to arrange it I would be more than willing to go along with your plans :D

I will be making a few phone calls come wednesday and hopefully get this sorted, I will either take it back to the store (50 miles each way) or send the lens and body back to canon for further investigation.
 
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Hi, just out of interest how have you got the focus point set up,high sensitivity spot focus( the smaller spot within the spot)? The only reason I ask is that at 24 you seem to have picked up the filling draws behind. Either that or it's back focusing. Try prefocusing at 70mm, stick in manual AF then go wide, see what that gives .
 
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lensworx said:
well here is one at 24mm @ f/2.8 cropped to 100%

<snip>
Click to expand...

Ah right. Then, assuming you had centre point focus on the 24-70's box, then that's clearly about a mile back focused and summat is wrong for sure :(

If you can exchange it, then the chances of another lens being out have got to be very slim. Try it in the shop - you'll be able to see it zoomed in on the LCD - and if it's still out, then it's the camera.

Also, if it's the camera, other lenses will show a similar error.
 
well I spoke to canon @ elstree this morning.
I explained the issue I was having and they recommend that I take the lens back to store and ask for a replacement under their "14 Day Guarantee".

I followed this up with a telephone call to the camera shop. They do not have another one in stock and said that they would have to phone them to see how quick they can get me another one. I was supposed to hear something back from them by the end of the day but so far I have heard nothing.
 
right a quick update.

I telephoned to store again this morning to be told that I should ring back this after and they would be able to tell me more.

I have just rang them back to be told that they would not be able to get another replacement in until the middle of next month.
I will be going down there tommorow and getting a full refund.

I am going to have to wait for the refund to then clear on the card until I can get a replacement from elsewhere (and pay the extra in VAT).

thanks everyone for all your help and hopfully I can get a replacement that will work.
 
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