mgunduz

Richard and Alistair, thanks a lot for your comments and I was in doubt myself but had no

first hand experience like yours with 17-40L and consequently I'll keep 20-35and skip

upgrading for future alternatives (if ever).

Thanks for your advice, Yakim. I am going to use with a 20D mainly and 300X(Rebel T2).

I'd like hear photo.net member experiences/comments as well.

Regards,

As far as optical qualities(sharpness, colour and contrast ec.) concerned what conclusion

can be drawn when comparing Canon 20-35mm F3.5/4.5 to a Canon 17-40mm F4L lens?

Would it be sensible upgrade or the differences are minimal and not worth upgrading?

Your comments/help all are wellcome unlike 17-40mm F4L there are too few comments on

Canon 20-35mm F3.5/4.5 lens on forums..

Bob,

Here is an excerpt on 17-40mm f4L from the article;

"A significant drop-off in resolution and increase in chromatic aberration was revealed

when the lens was tested on the EOS 300D. Here the uncorrected MTF50 figure dropped to

an average of 878.5line widths per pixel height, while chromatic aberration averaged

0.086%, which is just into the'moderate' range(visible at high print magnifications). These

results are not surprising but they confirm the fact that lenses designed for 35mm

cameras cannot perform at their best on DSLR cameras with the sensors smaller than

24*36 mm."

Thanks for everyone response.

A Photography magazine in Australia claims EF lenses would yield poorer results(lower

resolution and chromatic aberration increase) when used on Canon DSLRs with sensors

smaller than full frame.

They claim to have tested two popular L- lenses( 17-40mm f4L and 70-200mm f4L) to prove

and recommend them to be used on full frame DSLRs or film bodies for peak performance.

As a newcomer to Canon range of lenses I find their claims surprising and find forum

discussions(especially Bob Atkins responses) quite useful.

Any input to above will be appreciated.

This is my first forum posting to photo.net.

Digital Photographic Output by Duncan Evans has now become available by AVA Publishing

SA.

The author, writer of numerous books and articles as well as a freelance photographer/

photojournalist, has used two of my pictures in my portfolio Monorail and Steps in this book.

I'd like to express my gratitude/thank him and Picture Researcher Sarah Jameson giving me

the opportunity .