Canon 17-55mm f2.8 IS and Canon 40D - expecting too much or what?

[ESP2008]

Hi, back in November of last year I splashed out on the above lens, quickly followed by a Canon 40D, believing it time to move up from the 400D and 17-85mm IS combo I had been using for over a year.  My aim was to improve on the quality of images I was providing for our local (wait for it) ferret welfare charity.  A faster and higher quality lens was intended to give greater chances of capturing good shots of our furry friends both in action and at rest, often in less than perfect lighting conditions.  Publicity is important and my pictures are doing a lot to help, but I believe they can be better (especially if they are to be decent poster size).

However, I have been increasingly convinced that maybe there is something not quite right.  The shots I have taken at close range seem to lack the resolution and sharpness I anticipated.  Though the autofocus latches on quickly enough, the images are somehow disappointing (to me anyway).  I am beginning to wonder whether I am doing something wrong, just expecting too much, or if the lens is focussing either just in front or just behind the expected focus point.

I swapped from the 40D back to the 400D and I am fairly sure there has been no change.  I have, within the last couple of days, swapped back to 400D and 17-85mm IS and think there may even be an improvement.  Next, I suppose I should try the 40D and 17-85mm to see what results.

However, I would welcome any thoughts and advice.  Should I send the lens off to Canon?  It is out of warranty (being second-hand) Are there any practical tests I can do to confirm the true situation?

General shots are great, but as soon as I do close-up work and zoom to 100% the results just don't seem to cut the mustard.  If it's me, I need to know what I am doing wrong.  I tend to use the centre focus point almost exclusively when zeroing in on my little fuzzy pals.

Your help and advice is appreciated.

[Bob Atkins]

Take a look at http://www.bobatkins.com/photography/technical/testing_lenses.html, especially the sections on focus and resolution testing.

You need to do the testing with a flat, stationary target (which is something ferrets certainlt aren't!), and with tha camera on a tripod or some other firm support.

It's possible the AF is slighly out of adjustment. If you're shooting the 17-55 wide open at f2.8 the depth of field is smaller than shooting the 17-85 since it's a stop (or more) slower.

Many (possibly most) lenses (other than macro lenses) will show a little less sharpness when focused really close. You might try shooting in RAW mode and boosting the sharpness setting in DPP.

[ESP2008]

Bob, thanks for your reply.  I will have a look at the link.  Actually, ferrets, once asleep, are very immobile (the term 'sleeping, not dead' has oft been applied  ) and even then, sadly, the images are not as sharp as I would like.  However, perhaps I should try experimenting with the depth of field.  Mind you, despite this, I did win the 'cute & cuddly' category at a fairly significant pet show recently (well, when I say I won it, I really mean that my picture of Thora the sleeping, not dead ferret won...  )

Anyway, moving on, I have, indeed, been shooting with RAW almost exclusively since mid 2008, but find it less than satisfactory to have to tweak each image for sharpness in DPP.  I would hope that the Canon kit with IS would be up to providing really good images without recourse to tripod or DPP post-processing at shutter speeds greater than 1/60.  So I value your advice and will take some time to check it out - many thanks.

[Bob Atkins]

There's no shame to sharpening in DPP. All digital images need to be sharpened or they will look soft. The camera setting apply some degree of sharpening by default and if you don't want to mess with DPP you can always dial up the sharpness setting in whatever picture style you are using.

Sharpness should increase (along with DOF) as you stop down of course.

Without testing it's really not possible to say whether or not you have a problem and if you do, whether is caused by focus issues or a soft lens.

[whizkid]

For sharpness there are two areas an image can invariably benefit.  Post image sharpening is one and using a tripod the other. Image stabilization is nothing I would count on for poster size prints for handheld shooting.  Why not give a tripod or solid support a workout with both those lenses and cameras  and instead of depressing the shutter button, use the self timer feature? IS off of course. That should give you an idea if you need persue other measures.

[ESP2008]

Thanks for taking the time to reply. I have had a go at tweaking the RAW images to sharpen them with encouraging results.  I also took advice from Bob elsewhere in the forums: try using f8 as your optimum setting - I'm now experimenting with the M position on the dial, rather than trusting solely to Tv.  Getting a better depth of field and slightly sharper images.  Still tempted to go for the 50D or 500D upgrade for some definition increase, though - the lure of the extra megapixies! 

As for the tripod...hmmmm, you've not tried photographing ferrets in the home and garden environment have you? 

However, I do take your point and will try this out on some less mobile subjects in due course.

Still, my fuzzie pictures are much admired, even if I remain ever critical.