Help with Canon 100-400mm purchase

[KiwiExpat]

Hi everybody,  I have been following with interest the discussions about the Canon 100-400mm zoom lens, and how different examples seem to be softer at the edges, etc.

So now I am about to go out and buy one, but I need some guidance on exactly what to look for, and the best ways to make sure that I get a good one.

My initial thoughts are to take my camera and notebook computer along to the store and take some shots at various focal lengths (100, 200, 300, 400) and aperatures Wide open, f/11, f/22), then copy the images to my conputer, and look at them at 100-200%.   Them repeat with each example that the shop will let me work with.  

OK, so far, so good.    Sorry, this post is getting long...

Where i need help is in what is the best thing to take the photos of, and how best to exaluate the images.

Anybody care to offer their thoughts?

Many thanks,   ...David

[KiwiExpat]

Oh yes,  another question!!

Everybody seems to think that Canon should be thinking about producing a new version of this lens.

Does anybody know any more about this?

If there is a new long zoon about to hit the streets, I would rather wait for it.

David

[996sps]

David,

Consider this, if you are going to use the long end of the lens more than anything else have a look at the 400mm f5.6L instead. Check the test report and comparo between the zoom and prime in the Luminous Landscape under reviews. The 400mm prime is not only sharper but cheaper too.

Your testing method is long and labourious, one way of checking for a "sharp" copy is the paste a page from the newpaper on the wall and do what you have to and compare the sharpness of the print.

Good luck.
Phil

[svein]

Your method should work in theory, but I'm not sure how easy it is to actually do this. Of course if image quality varies a lot then it would be easy to pick the best, but comparing shots of general images is often difficult. The problem is to find a detail level in the shots that will show the differences. Guess that's why most review sites use testcharts with a lot of detail designed to do this task easier. A newspaper (like a previous poster suggested) could work, but again you have to find the correct distance/focal length to be able to compare.

[KiwiExpat]

Thanks for these two good responses.  You both seem to endorse the difficulty that prompted the original question.  :-(

What about this as a way around the problem?  Just buy the first example off the shelf, then take it (and the camera) to the local Canon servic centre and have them recalibrated?

Come to think about it, might as well get my other lenses calibration checked at the same time.  

Does this sound like a beter solution?

David

[svein]

Don't know how much calibration cost, but it's certainly an easier way out. Also don't know if variations can be corrected with calibration or if there are other issues as well.

You might try a combination by first check for obvious differneces without putting too much work into. Then check the lens at home/office and do a calibration or return if it seems necessary.

I've just been trying a friends 100-400mm and I'm impressed with the results, which at full aperture and 350mm is visibly more contrasty than my current 35-350mm. Neither lens is known for perfect optical characteristics (but both are good for other reasons), and for me it's difficult to know how good the example I'm looking at is without comparing to something of similar quality. Comparing with the 400mm 5.6 would be really interesting, but I don't have access to that lens.