Stay Away From Cheap Glass

I learned a lesson in lenses yesterday. I'd just received my Canon 100-400mm f/4-5.6 L USM Zoom lens and was gagging to get it out and do some shooting with it. Of course, before I could, I had to burn the packaging and bury the courier's body in the back yard before Mrs C found out about my second big purchase in one week.

The evidence taken care of, I leapt in my truck under the pretense of going out for cigarettes, and headed down to the local bird roost. I was a little worried about the deception because Mrs C is an amateur detective and I've never smoked cigarettes in my life before, but like many photogs I'm not that rational when I've got a new piece of gear to play with. Anyway, after a breakneck drive down to the inlet, I started shooting some pictures of some royal spoonbills and shags, but was immediately underwhelmed by the zoom's performance.

I couldn't believe how soft the images in the review screen were, even in the 100-200 range, and at all f-stops. I expected to get some joy at f/8 or f/11, but saw no improvement whatsoever. I put my 70-200 on the 5DII to check, and sure enough, even blown up, shots from the 70-200 at 200mm look better than the 100-400.

Here's a shag with the 10-400.



...and here he is with the 70-200. Even zoomed in, the image is sharper.



I was starting to feel a bit gutted, having shelled out a reasonable amount of money for this lens. Had it had a bad knock and needed the elements realigning? Was it just a dud? This is a lens with a great reputation and I really expected better, especially after considering the much cheaper Sigma 150-500 which has some very good reviews. I was having another look at the Canon when I got home and duh - I realised it had a Kenko lens protect filter on... Could that be it?

Here's another shot, this time of a wild lawn sprinkler from my back yard - same lens, 400mm.



And now here's the same lens, same focal length, same wildlife, with the filter off.



I felt a flood of relief (and just a little embarrassment) at this discovery. I'd always heard that cheap filters degrade your images, but I didn't think the effect was this pronounced. I like to use Circular Polarising Filters (CPL's) for a lot of my shooting, and was immediately worried that I should've gotten the $400 ones instead of the sub-$100 that I do have, that everything I've done so far could have been much, much sharper. I checked them out, and thank goodness they're okay. But boy, the whole experience will make me a lot more careful about choosing filters in future.

So I tried my 2x extender on, just for good measure. As I expected, you lose some sharpness with it, as well as half your speed - at maximum focal length, you go from a max aperture of 5.6 to 11. Even more challenging is the fact that you lose autofocus. But frankly, the results are still better than with that crappy filter.

I was so relieved I had to tell somebody. The good news is: Mrs C didn't bat an eyelid when I confessed about the new purchase. That woman is an angel. Of course as soon she's out of the house I'm going to be checking her wardrobe for the new dress or pair of knee-high leather boots that must be there.

So now I'm free to fall in love with my new lens but what I really need is a subject worthy of it. The local Yellow - eyed penguins are all hiding in their burrows and moulting at the moment and frankly, 400mm is overkill for sea lions. Luckily, I've got a project coming up that is the main reason I got this lens.

Stay tuned for that adventure.