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Old Nov 1, 2006, 9:49 PM   #11
NHL
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eric s wrote:
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I would also throw out there that I would be suspect of MTF charts.
For example, from what I've read the ones on http://www.canoneos.com are calculated and not "real world". In other words, they are the best the lens can perform in theory, and not what an actual instance of the lens does (or even an average lens would do.)
The MTF's from both Photozone and Photodo are actual results measured from real lens samples (unlike the MTF's provided by Canon!). They both use Imatest with pictures results taken from standard ISO-12233 resolution chart. With a 'real-world' image it's more subjective than objective data...

Regardless: really can't anyone see the difference? - The prime is clearly much better here and a standardize chart will clearly pin-point theses areas of differences:






-> An ISO-12233 resolution chart will clearly show where those separate lines joined into one as illustrated below (same as the areas I highlighted above):




A real-world picture (especially wildlife) will not show the distortion figures as graphed by the chart @ Photozone unless one shoots a picture of a brick wall with clear horizontal and vertical lines (but again how do one ensure that the bricks are placed straight?)

CA (fringing) are also plotted @ Photozone, and unless one shoots a some high contrast scene, no one will observe this phenomenom either... in a real-world image

Can all theses people be wrong then? http://www.i3a.org/downloads_iso_tools.html
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Old Nov 2, 2006, 8:38 AM   #12
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I tend to hear this a lot as well:
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I know people who like the 50-500 quite a lot. I wouldn't want to hand-hold it, which you can do with the others you listed... but if you have enough light it does work well.
Well think about the focal lenght that the Bigma cover... You'll need three lenses for that (or two lenses + a TC), what about their dead weight (and a bag that you need to carry)?
F/6.3 is only a 1/3 stop down from f/5.6 which is barely noticeable, but you're gaining a full 100mm :idea:
(putting on a 1.4x TC costs a full f-stop i.e. f/8, but no one seems to complain!)


-> This is why I mention the Tamron 200-500mm it's MTF is higher than the Bigma (which already exceeds the 100-400L) and matches the 400L at 400mm and is also lighter... than the prime! :-)

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Old Nov 2, 2006, 10:05 AM   #13
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NHL - I agree zoom is softer at f5.6 than the prime but the results I posted are without any pp. Apply a tiny bit more USM to the zoom picture and it will look same to the one with the prime. And these are 100% crops. Print at regular sizes and then tell which came from which lens. I usually use my zoom at f6.7 not f5.6. Prime I shoot at f5.6 all the time.

If tamron 200-500 was same notch as 400mm f5.6 then a lot more birders would be using that.

There is a big variance in lenses. It shouldn't be but it is. And lot depends on the body being used. Don't know how many combinations of lens/body that your chart people use but I bet it is not more than 5.

You yourself say that sigma 100-300 f4 is sharper than sigma 120-300 f2.8. So after one puts 2x on sigma 120-300 f2.8, the quality is going to suffer more. Not to mention the AF. I did try 2x on canon 300 f2.8 IS and even though that lens is one of the best lenses out there, you could still see huge difference that 2x made to that glass.

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Old Nov 2, 2006, 12:36 PM   #14
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thanks for the replies guys. A friend of mine has a bigma and 100-400 and he is letting me use both to find which one would be comfortable for me.

As everyone pointed i am trying to see how real life image comes out when shooting with these lens. I dont want to restrict myself to 400mm/5.6 prime since i would like to have the zoom to get either closer or far. When spending aorund a 1000buck i am also looking at the versatality of these lens.

Thanks for the patience and will let you guys know which one will suit my needs.

Vj
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Old Nov 2, 2006, 4:20 PM   #15
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bobbyz wrote:
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You yourself say that sigma 100-300 f4 is sharper than sigma 120-300 f2.8
I've (many times) strongly advised the Sigma 100-300 f/4 for anyone who does not need the f/2.8 - In fact I've always strived to recommend people to get something better that the lenses I already owned and have experienced with, the EF 100-400L included!
No problem with that at all... Ditto with the 85 f1/8 and 55 f/1.8 (vs the 85 f/1.2 and 55 f/1.4)



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NHL - I agree zoom is softer at f5.6 than the prime but the results I posted are without any pp. Apply a tiny bit more USM to the zoom picture and it will look same to the one with the prime. And these are 100% crops. Print at regular sizes and then tell which came from which lens. I usually use my zoom at f6.7 not f5.6. Prime I shoot at f5.6 all the time.
-> which is all the more reason to check the MTF - as the subject(s) change (or get smaller) with even more details than your current test image you will see the difference as the 100-400L always trails the 400L in resolution no matter what the f-stop. From Photozone (MTF results from Photodo sample are no better...):

100-400L f5.6 f/8 f/11
Center 1488 1549 1508
Border 1489 1539 1512

EF 400L f5.6 f/8 f/11
Center 1657 1767 1768
Border 1655 1767 1738

As a reference:
Tamron f5.6 f/8 f/11 - 200-500 (@400mm)
Center 1651 1749 1730
Border 1631 1711 1695

or the 100-300 f/4 EX with a 1.4x on:
Sigma f5.6 f/8 f/11 - 100-300 (@420mm)
Center 1655 1750 1631
Border 1505 1587 1510
You can definetly see the differences if the pictures are enlarged for wall-mount :idea:



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If tamron 200-500 was same notch as 400mm f5.6 then a lot more birders would be using that
Bear in mind too that the the 400L has been around a long time, whereas the Tamron is brand new so it'll take some time to get the word around... It's been only a few months since it was released...

MTF don't lie - I see it here too:
How can you USM something that is not there??? (i.e the lines are merged into a solid black)


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