Is this far enough off to send in to Canon for calibration?

[james_taylor11]

I was reading some post about lens calibration and decided to use Bob Atkins

test sheet to see how a few of my lenses were doing. I recently purchased the

24-105 lens and haven?t been extremely happy with how sharp it is. I thought

this might tell me if it is possibly a calibration issue or not. I set my

tripod up and used the following lenses: 85 F1.8, 24-105 F4, 17-40 F4, and 70-

200 F4. The results seem to show the 24-105 as being the furthest out of

alignment (I think). I then decided to put up a book and shoot all four lenses

to see if I could tell a difference in sharpness. Once again, the 24-105 was

the least sharp. So, what does all this mean? It looks like the 24-105 could

use a calibration, but would that make a difference when shooting a flat book?

Also, if you lined up those four lenses, would you expect to see one of them

less sharp then the others, or should they be too close to tell. I did compare

the 24-105 against my 18-55 kit lens and the 24-105 was easy to pick out as I

would expect.

 

Thanks for any input,

 

James<div></div>

[calebcondit]

It's just not as sharp. That lens is touted by some as the best thing since sliced bread since it has IS and is versatile in its focal lengths. But it is bagged on by many as not performing up to snuff when compared to other L zooms. That's what you're experiencing. It's just not as sharp as your other lenses (especially the high quality 70-200). If it's that big of a deal, try out a 24-70 2.8 L and see if you see a difference in sharpness/distortion. It may be heavier but it does perform better.

[dcheung]

It looks fine. All three looks like it's within the DOF.

[bobatkins]

It's probably OK. One of your L lenses has to be the least sharp! If you look closely enough you'll find faults with all of them.

 

I'd say that you'd be unlikely to gain much (if anything) by sending it to Canon.

[beauh44]

Hi James, Great songs, btw! ;-) Just curious but you didn't mention what aperture you were using. You might try stopping down your 24-105 to ~f/8 or so and see if things don't tighten up a bit. I'm very happy with mine. Good luck!

[dan_roche]

Your lenses look pretty good to me, but alas, another case of the 24-105 being less than what it's cracked up to be. The more I read about this lens the less inclined I am to buy one. You might want to send it to Canon for calibration. I had my 17-40 calibrated a couple of weeks ago and it made a noticable difference in sharpness.

[mormegil]

Canon can't make the lens any sharper, but it can make the lens/body focus more precisely.

 

It looks like there's a slight backfocus on the 24-105. I don't know if it's within factory specs.

 

I did some tests with my 5D and several of the same lenses as you. I found it was front focusing by about 4mm (reproducable on all lenses). I figured that's enough off when I'm trying to get eye lashes in focus, so I sent everything in (actually drove everything).

 

Came back perfect.

[eric_lawson1]

You did a good job with this. Mine was the same and for $1,300.00 I wasn't happy so I sent it off to Canon for calibration. It came back SHARP AS A TACK @ F4. It is sharper than my Tamron 28-75 which is a very sharp lens. The thing is the Tamron doesn't get that sharp till F5.6 so I never used it anything less than that, now I shoot wide open whenever I want with no concerns at all. Also don't buy into folks who say "it is bagged on by many as not performing up to snuff when compared to other L zooms" and then suggest a 24-70 L. Lots of folks swear by the F2.8 of the 24-70 and bag "so to speak" on the 24-105 because it's ONLY F4. Lots of other folks love the IS and extended reach of the 24-105 and bag on the 24-70 for not having those things. Somebody usually throws out the supposed fact that one is sharper than the other "depending on what camp you are in" I have had both and when properly calibrated THERE IS NO DIFFERENCE IN SHARPNESS.

 

Also Canon themselves will tell you "as they did me in person" that if all your lenses work fine except one then the body does not need calibrating, just the lens.

[jim_simon3]

I did the same test and I found that I could rely upon getting the focus on the correct spot better if I drew a tiny line perpendicularly through the line you focus on (a cross). I also defocused the camera and retook the shots a few times. Manually focusing on the line and seeing how it looks when it is perfect is a good comparison to see what the lines should look like. Your post is about sharpness, but the test is about focusing, so I'm not sure which is your concern, but my suggestion is about focus.

[james_taylor11]

Thanks for the responses,

 

Caleb

?If it's that big of a deal, try out a 24-70 2.8 L?

 

I took your advice and went into my local camera shop. I put my 20D on a tripod and took shots at F4, F5.6, and F8 with my 24-105 and a 24-70 (also 2.8) at 50mm. The 24-70 was slightly sharper at F4, but I couldn?t tell a difference at F5.6 or F8. I then put both lenses on a 5D they had in the store and the results were basically the same. So, I?m not sure the slightly better sharpness at F4 is worth the reduction in reach. I was really hoping this lens would be on my camera for 80% of the time. I have the 70-200 for sports and the 17-40 for landscapes. I really wanted a zoom between those two lenses that I could use most of the time. That leaves the 24-70 or the 24-105 ? both of which do not appear to be as sharp as the other two.

 

Bob

?It's probably OK. One of your L lenses has to be the least sharp!?

 

I guess you are right. I sometimes wish I hadn?t purchased the 70-200 F4L as my first lens. No other lens seems to give me the same results. When I pick up that lens I am confident I will get great shots my clients will love. I want that felling with a mid range zoom like the 24-70 or 24-105.

 

Beau

 

?Just curious but you didn't mention what aperture you were using. You might try stopping down your 24-105 to ~f/8?

 

I was at F4 and F5.6. By F8 I would expect most lenses to be fairly good. There seems to be a different look to shots out of some of the L lenses that look better to me. Even as much as I like my 85mm (1.8) it doesn?t have the same look that I get with my 70-200 at 85mm.

 

Dan,

 

?I had my 17-40 calibrated a couple of weeks ago and it made a noticeable difference in sharpness.?

 

This was my original reason for testing the focus. My thought was that if the lens was front focusing I could have problems with sharpness. If my auto focus accidentally locked on the nose and things were slightly out of focus behind then the eyes would be soft. My test did show my lens goes out of focus faster behind the focus point, but I?m not sure it is that far out. I thought that shooting a flat page with letters would get rid of any focusing issues and give me a true idea of the sharpness. As the text wasn't as sharp, It seems the lens is just softer. Am I right in thinking that a calibration won?t help sharpness in this case?

 

 

 

Jose,

 

?Came back perfect.?

 

The focus result came back perfect? Did the lens look sharper in photos after this?

 

Eric,

 

?SHARP AS A TACK @ F4?

 

This is what I was hoping for!

 

Jim,

 

?Your post is about sharpness, but the test is about focusing so I'm not sure which is your concern?

 

I was thinking that if there was a focusing problem it would be affecting sharpness.

 

Thanks again,

 

James

[mormegil]

I wasn't testing sharpness, I was testing Autofocus Accuracy. I thought that's what you were looking for, since you posted pictures of focus tests.

 

So I don't really know if it came back any sharper, but it definately came back with better Autofocus Accuracy. It went from 4mm off to spot on with all lenses.

 

 

So just to clarify, the chart at 45 degrees with the parallel lines tests for focus accuracy. You focus on the middle line that goes across both groups, and check where the point of sharpest focus is on the outer lines. That won't tell you how sharp the lens is, only where it's focusing. Obviously if it's not focusing properly, you will have an unsharp intended target, but a sharper unintended target.