17-40L, Sigma 10-20, Canon 17-85 rationalising?

[DrJon]

Re: 17-40L, Sigma 10-20, Canon 17-85 rationalising?

I think I mentioned that, part of my point is there are endless comparisons you can make and you need to know what you care about. My main point was these days there isn't a gulf from all other Canon lenses to L lenses, as people keep suggesting (especially on the APS bodies as Canon don't ever call an EFS lens a L, although the 15-85 and 17-55 are optically in the L ball-park). As I said to my friend (see elsewhere) the best walk-around lenses for an APS camera are IMHO:

15-85 if you don't shoot in low light, plus it's the lightest and cheapest of these three
24-105 if you like to go long and don't mind not having a wide end and especially if you might go full frame
17-55 if you don't want to go that long and want the best one otherwise

Spot the caveats - what there isn't is a right answer. I'd pick the 17-55 as it's a stop faster and probably the sharpest. (Then again while it appears to be sharper than my 24-105 there are reports it flares more, I mentioned "I could go on" I think...) I suspect she'll pick the 15-85 as the extra wide end can be very useful (still haven't found out what she got).

I would have mentioned more things, but the post was way, way, way too long and all I was doing is showing my previous comment had some factual backing, rather than actually comparing the lenses. I did slip in another point I like to make, that most of the Canon lenses are good enough for most pictures you'd want to take and there aren't big gaps in optical quality or lemons all over the place. I think the low end 18-55 IS and 55-250 are pretty good lenses and exceptional value.

John

[DrJon]

Re: 17-40L, Sigma 10-20, Canon 17-85 rationalising?

P.S. I'm not really enjoying quite so much facts and figures stuff, too dry, so will try to stay away from it for a little while...

P.P.S. it would be interesting if we had a thread... hang on...

[Wayne Els]

Re: 17-40L, Sigma 10-20, Canon 17-85 rationalising?

John,

Very interesting stuff. I think i will have a play with both lenses on my body but given the similarity in IQ I'm swinging back to the cheaper 15-85.

Cheers!

[DrJon]

Re: 17-40L, Sigma 10-20, Canon 17-85 rationalising?

I think if you can live with the f5.6 at the long end and a little bit of distortion at the very wide end it's a good choice...
Oh, but buy the optional lens hood if you do get one!
John

[EOS_Jim]

Re: 17-40L, Sigma 10-20, Canon 17-85 rationalising?

Like I always say it really depends what you want to use it for and how you shoot :)

[DrJon]

Re: 17-40L, Sigma 10-20, Canon 17-85 rationalising?

We agree on that...

[Woolley]

Re: 17-40L, Sigma 10-20, Canon 17-85 rationalising?

A very interesting set of results. What I do notice is that nearly all lens tests concentrate on sharpness as being the deciding factor. I'd suggest that if you compared contrast that is where the L lenses start to show their class. Colours tend to better too as all that glass, clever coatings and the larger object lenses pull in much more user friendly light. That in turn makes it slightly easier to get the basics of a good shot leaving you free to concentrate on the elements that will hopefully make it great.

[George Bear]

Re: 17-40L, Sigma 10-20, Canon 17-85 rationalising?

Then there is build quality, weatherproofness (sic), filter size, closest focus, AF speed, ... so it's been said before it's what you want the lens for, how you are going to use (abuse) it, how money you can justify .... actually the number of permutations our brains need to go through to get it right makes my brain hurt. Guess thats why we sometimes get choice wrong.

So who can really tell a lens that'll do 2400 at the centre from one that will do 2200 (say) ? I actually prefer a lens where the fall off is less marked as you get towards the edges. A sweet spot that scores high in resolution is one thing, but one that does it across the frame is another. Check the Zeiss lens or ask a Leica user ;-)

[DrJon]

Re: 17-40L, Sigma 10-20, Canon 17-85 rationalising?

MTF is actually measuring contrast and sharpness, where sharpness usually means MTF for fine lines and contrast means MFT for wider lines. Photozone (I believe) use it in an easier-to-digest way that you certainly could argue is sharpness-biased.

Borrowing a quote "The MTF gives us a measurement of how much contrast remains between white and black lines after they have been projected through a lens. How big was the difference, or contrast, in the original? What percentage of the original contrast is left after projection? If the MTF for a particular line frequency is 0.85, that means that 85% of the original contrast remains after projection. "

Here are the charts for the 17-55 (I don't know if these are on the European site, I always go to the US as I know where to find them):

(Short explanation - the thick lines are contrast. Higher is better.)

http://usa.canon.com/cusa/consumer/products/cameras/ef_lens_lineup/ef_s_17_55_f_2_8_is_usm

(BTW the black lines are wide open, which is a stop more than the other two as not really a good comparison, blue will be f8 and the solid one is hard to see as it's nailed to the top of the chart.)

and the 24-105:
http://usa.canon.com/cusa/consumer/p...mm_f_4l_is_usm (for crop comparisons ignore the right third)

Summary - the 17-55 is a very impressive lens. Then again the 15-85 is not too shabby either:

http://usa.canon.com/cusa/consumer/products/cameras/ef_lens_lineup/ef_s_15_85mm_f_3_5_5_6_is_usm

I'm not going to explain these any more as MTF charts take a lot of explaining... plus I don't always remember all of it anyway...
Here: http://www.luminous-landscape.com/tu...ding-mtf.shtml
and here: http://www.punitsinha.com/resource/u...mtf_chart.html
will do it better than me.

Masochists can try my favorite link on the subject of sharpness: http://www.normankoren.com/Tutorials/MTF.html but don't say i didn't warn you.

BTW I'm not arguing about having to look at lots of things to pick a lens, and didn't cite Photozone in my original comment, merely adding a post later to say I thought (after it was introduced to the thread) that it didn't disagree with my comments (at arguably excessive length, but that's as I wasn't sure how to quickly knock up a table which would have made it 1/5 the length).

...and, as I said, I still love my 24-105, it's a great lens. Really not having a pop at it, just saying the other two are somewhere up there.

John

P.S. I don't recall a Zeiss MFT chart (and I think they actually measure them) that doesn't fall off somewhat to the right hand side, although comparing primes to zooms is a bit unfair.

[briansquibb]

Re: 17-40L, Sigma 10-20, Canon 17-85 rationalising?

Just did a wedding with the 24-105 plus flashes on the 5DII. IQ is excellent throughout.

The rest of my shots are with the 17-40 Marmite lens. Again excellent IQ.

This is a 1945 Churchill Tank, according to the plate on the turret.

Below is a picture with the marmite lens just to show how good they can be
5dII, 17-40@40, iso50, 1sec, f16,

[briansquibb]

Re: 17-40L, Sigma 10-20, Canon 17-85 rationalising?

Here is a picture with the 24-105 - not an exciting picture but shows the IQ capability (picture of the old lighthouse on Portland Bill)

I am not suggesting that these lens are better than the 15-85 but showing that both these lens give pin sharp quality. It is allright talking in theory - but here are some real life pictures. So the question now is - is this good enough? (and they are better at A3 size than on the web)

5dII, 24-105@92, iso 50, f13, 1/13

[MX5]

Re: 17-40L, Sigma 10-20, Canon 17-85 rationalising?

I think where premium glass generally scores in the optical area is in a lack of distortion, reduced flaring and minimal colour fringing (look at Brians' examples above on how good L glass can be). Although these 'errors' to some extent can be corrected in DPP/PS et al. Out and out resolution is just another factor. Naturally Canon will make consumer lenses that are very good and from time to time some L lenses that don't live up to expectations.

I'm happy with my Marmite 17-40L (apart from coverage it's as good [for me] as my 24-105L). I think we can get too hung up over lens optical quality. I'm thinking of getting a 55-250 EF-S to take on my walks ... not to replace the 17-40L ... but as a second lens when I need reach ... because it's not bad, its light and it doesn't cost much (all compared with the new 70-300L which would be a natural choice ... but it's just too big and heavy to carry around in my pocket 'just in case'). I'm not really a camera (or lens) snob per se ... it's more about getting stuff that's fit for purpose. The 40D can still bring home results with the 17-40L and that for me is what counts.

Never sure what it is about the 17-40L that folk don't like. But then I eat Marmite and even Marmite XO