Photography Thailand Forum

[Marc Schultz]

I was shooting some textures with the Canon EF 24-105mm f/4 L IS USM Lens at F/16 when I discovered a sharpness problem on the attached shot, as well as many others taken under the same shooting conditions that day.



The image below shows some close-up sections of the above shot. The left is taken from the very upper most left hand corner of the photo. The section on the right is taken from the very middle of the image. As you can see, there is a huge difference in sharpness from within the same shot from left to center. The section from the left corner is completely unacceptable and unusable as such and I will need to reshoot these shots. The same goes for all corners and most areas outside of the center of the lens area.



Considering that I shot this image at F/16 you would expect the shot to be pin sharp throughout. Sometimes people talk about a drop in sharpness on zoom lenses when fully zoomed, but the focal length on this shot was 65mm, which is the middle of the zoom range of this lens and which should actually be the sharpest part of the focal length range of the lens.

I am so surprised considering the lens is an L Series lens and not an inexpensive lens for that matter.

I will obviously switch lenses on the reshoot and am starting to question the quality of Canon lenses all together.

[bkkdave]

Marc your observation is very interesting as I have four L lenses and the 24-105 is the one that stays attached to my camera the most. Of the four lenses I own; three are zoom's and one is a prime that is a  85 F/1.2 L which I find to be very sharp.

I have not been happy with the sharpness from the 24-105 L because it seems to be hit and miss and not at all consistent. As  matter of fact I was at the Canon repair center recently to ask about a OC-E3 Off Camera Shoe Cord that broke the very first time I used it and I did ask the technician about the sharpness problem I am having with the 24-105 L. He said it could be caused by a sensor that needs cleaning and there are no known problems with the lens. However as you have pointed out more than once there is a vignetting problem that is annoying.

On my trip Wednesday to see the seated Phra Buddha CENSORED WORD Nawamin statue located at Wat Muang in Ang Thong Province; it was the same thing with some of the photos very sharp and others soft using the 24-105 L. In fact when my friend who has a Canon Powershot S 90 emailed some of his images and also others taken with a Panasonic LX3 all I could think is WTF; why even bother with a 5D Mk II and all the heavy L lenses?

I will be watching this thread and thanks for posting.

[Marc Schultz]

Thanks Dave. Yes, there are also the vignetting problems with this lens too as we noted before. In terms of your sharpness problems with the lens too, are they problems throughout the entire picture or just in specific areas like the issue I posted? If the sharpness problem is throughout, then it could just be a focus problem where you might have back focused or something.

[bkkdave]

Marc attached are a few images all shot RAW with the 5D Mk II, 24-105 L at f/8 and the last one shot at f/6.3. They are right out of the camera with no post processing sharpening added. A few others do seem to have a back focusing issue and I will get that checked out. Thanks.

[Marc Schultz]

Thanks for posting Dave. To me they look relatively sharp, but I can't see the pixels close up so hard to comment. I am also wondering if the particular lens itself is having a focus problem and if the focus is not calibrated correctly.

The shot below I took where I am showing the problem was actually shot with the 5D Mark II as well. So the same exact equipment as used in your shots. Normally I shoot with an older 1DS Mark II, but for this shot I was using the 5D as I said.

I am not sure, but I remember something about there being a way to calibrate lenses with the camera on some of the newer Canon DSLR models. Is there a setting somewhere on the 5D Mark II which would allow you to calibrate the focus of the 24-105mm lens with the camera?

I think there is possibly a simpler explanation for what is happening with your pictures whereas the issue I had seems a lot more peculiar since the sharpness problems seem more specific to an isolated area of the photo and not the whole frame.

I may even take the lens to Canon and show them the problem and see what they say. It is hard to dispute the fact something is wrong with the sharpness of that photo and that the lens has either some sort of defect or shortcoming.

It will be interesting to see what the Canon technicians would have to say about it after they are done scratching their heads :)

[FrePe]

Yo Marco!

Shooting @ f16 is something i would only recommend if you really need the depth of field it renders, f 16 is small enough to
give you difraktion problems that has negativ impact on the sharpness of the shot. Im not sure about the lens you used but a safe
aperture is always (almost) f 8 on most lenses you get the most out @ f 8-11, though there is lenses that stride from thees "rules"
for example i have an 50mm/f1.4 that is at its best from f 2-f 4, that one is designed for low f shooting though.

So dail down the flashes and don't use an f higher than 11 if you dont have to.

Best regards,

Fredrik Persson
www.studiotva.se

[bkkdave]

Yes Marc I believe you are referring to 'C. Fn III-7 AF point expansion area' on the 5d Mk II. Before I change anything I am not 100 percent positive I had the focus set to 'ONE SHOT' or 'AL FOCUS' which are the only settings that allow recomposing after the shutter button is pressed half way down on the point of focus. Using 'AL SERVO' for still subjects is something I know not to do but it could be that I did not check the setting before shooting.
Thank you and also to Fredrik for your input as well.

[Marc Schultz]

Thanks Frepe. You may have a point about shooting the lens stopped down too much. But this lens is actually designed to focus at close range in order to act partially as a macro lens. This means Canon would expect people to be using the lens at the higher F-Stops for more DOF on close-up photography.

I hate to come right out and say this, but in conclusion, this expensive Canon professional level lens is pretty much complete junk. It has vignetting problems at F/4, F/5.6 and F/8 and it is has a sharpness problem at F/16 and above. So maybe the only decent F-Stop on the lens is F/11.

I should show some of my RAW files to Canon.

[Ray Evans]

I upgraded from a Canon 5D MK1 to the MKII earlier this year.

My initial reaction was shock - overall nowhere near as sharp as I was led to believe, BUT some shots were enough to make your eyes bleed!

But only on certain lenses. Micro adjustment came to mind.

I then purchased this item http://www.lensalign.com/

A lot of my lenses needed adjustment and now all is fine.

I have:-

17-40 L -          spot on
70-200 F4 L is - spot on
85mm F1.8 -     spot on
50mm F1.4 -     spot on
100mm macro - way out
24mm F1.4 L  -  way out
Sigma 12-24  -   way out - and I mean waaaaaay out!

The higher resolution of the MKII certainly does show up any glass abnormalities - ironically the 50 and 85mm lenses I've had for some 20 years. Clearly the QC was a lot more stringent in those days!

I deliberately avoided the 24-105 due to mixed reports. Seems this is THE lens that suffers the most from poor QC. I have a friend who's 24-105 on my MKII is awesome BUT he admits that it took 4 changes to get a good one!

p.s. Take a look at this thread :- http://forum.getdpi.com/forum/showthread.php?t=8982

[bkkdave]

Marc I will be very interested in hearing anymore that you may find out in connection with your discovery about the sharpness problem associated with the 24-105 L.
Thank you and also to Ray for the LensAlign information.

[Ray Evans]

On my trip Wednesday to see the seated Phra Buddha CENSORED WORD Nawamin statue located at Wat Muang in Ang Thong Province; it was the same thing with some of the photos very sharp and others soft using the 24-105 L. In fact when my friend who has a Canon Powershot S 90 emailed some of his images and also others taken with a Panasonic LX3 all I could think is WTF; why even bother with a 5D Mk II and all the heavy L lenses?

I use a Panasonic GF1 with Contax G Zeiss lenses 35mm 45mm and 90mm. I also have a Kern-Switar 75mm C mount. All these lenses are donkeys years old and absolutely blow my MKII away. I'm not over-reacting here either. Using the Canon lower RAW settings to acquire a similar 12megapixels as a fair comparison the Canon is destroyed. Sharpness, contrast, colour is far superior on the GF1.

I need the Canon for it's superior action, cropping and high ISO ability but for any other purposes, especially weight and discretion, the GF1 is the tool.

I shot side by side comparisons using my GF1 and Contax 45mm planar against a visiting friends Leica M9 and 35mm pre - asph.

The only difference, and we both agreed, was the Leica bokeh looked a little sweeter. Other than that IQ was comparable.

p.s. Oh and my set-up was c$8,000 less!  


Here's a link to my Flickr site and a GF1/45mm Planar comparison (no artistic intent)

http://www.flickr.com/photos/f4foto_grafs/4289461659/sizes/o/in/set-72157623122625175/

and here's the 100% crop

http://www.flickr.com/photos/f4foto_grafs/4290201474/sizes/o/in/set-72157623122625175/

This was shot the first day I had the camera and I hadn't found the RAW mode - it's a Jpeg from the camera - and was hand held also.

[bkkdave]

Ray the links you posted say:
This page is private.

Oops! You don't have permission to view this page.

[Ray Evans]

Oh, sorry about that

Is this any better?

http://www.flickr.com/photos/f4foto_grafs/sets/72157623122625175/

Hope so

Ray

[bkkdave]

Yes Ray it works now and very impressive images!

[Marc Schultz]

Ray, that thread was interesting about others who bought the lens and how that one guy had to take his back 2-3 times before getting a good one.

In my case, there is no real way of knowing if I got a dud or if those problems are just the short comings of the lens' optics itself. I tend to think it is the latter though. The truth is though it will go from being one of my most frequently used lenses to one of my least frequently used lenses after all the things I have learned about it recently.

Its a shame really because the 24-70mm lens is just a bit short for most things and the 70-200 is a bit long and heavy for most things too. So the 24-105mm lens was a great mid range focal length lens, light weight, and has the IS.