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MTF of 18-55 EF-S

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edtang

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Actually seems to look not bad! :)





I also noticed that they changed the range of the x-axis to 13mm for the non-full frame lens. But even so, when compared to a lens like the 20-35, it seems a bit better I think.
 
edtang said:
I also noticed that they changed the range of the x-axis to 13mm
for the non-full frame lens. But even so, when compared to a lens
like the 20-35, it seems a bit better I think.
Click to expand...
...the kit lens is, IMHO, only usable from F8 to F11, and wide open it's very soft. The 17-40 F4 L is capable of producing a sharp image at nearly all aperatures, and some claim that it's best at F4...
 
Hi,

Could you give a legenda for the 8-lines I see (I think that are the aperatures?? correct??)
So flatter is better!?

Regards, Arno
-----------------------------------------------
edtang said:
Actually seems to look not bad! :)





I also noticed that they changed the range of the x-axis to 13mm
for the non-full frame lens. But even so, when compared to a lens
like the 20-35, it seems a bit better I think.
Click to expand...
 
AHB said:
Hi,
Could you give a legenda for the 8-lines I see (I think that are
the aperatures?? correct??)
So flatter is better!?
Click to expand...
See http://luminous-landscape.com/tutorials/understanding-series/understanding-mtf.shtml

quotes:

the higher a point is on the chart the higher the contrast transfer capability, and the further to the right one is the further from the center of the image.

The thick lines are measurements taken at 10 LP/mm (low spatial frequency, or low resolution) and the thin lines are at 30 LP/mm, at higher frequency / higher resolution.

The black lines are measurements taken with the lens wide open, and the blue lines are with the lens at f/8.

The solid lines are meridonial while the dotted lines represent sagittal measurements.

— the higher up the chart the 10 LP/mm line is (the thick lines), the higher the contrast reproduction capability of the lens will be.

— the higher up the chart the 30 LP/mm line is (the thin lines), the higher the resolving power and thus subjective sharpness of the lens will be.

— keep in mind that the black lines show the lens wide open while the blue lines show the lens stopped down to f/8, so the closer these sets of lines are to each other the better the performance of the lens when used wide open. The very best lenses will have the black and the blue lines close together.
 
It appears that the 55mm chart includes two sets of data, one of which looks suspiciously like the 18mm dataset. Is this just a flub, or am I missing something (or both!)?

--John
 
Yes, that's what it looks like to me.

Assuming that's true, let's compare the MTF charts for the 18-55 with the 17-40L at the center, edge and corner. The 17-40L chart is only for 10 lp/mm, so that's all we can compare. (I hope everyone sees this in the same font so that it lines up OK.)

Widest Angle (17/18 mm)

open~ Center...Edge....Corner
-------~----------------------------------
18-55 ~ .92/.92 .87/.78 .61/.50
17-40 ~ .75/.75 .75/.62 .71/.45

f/8 ~ Center....Edge.....Corner
---------~-----------------------------------
18-55 ~ .97/.97 .92/.80 .85/.55
17-40 ~ .97/.97 .97/.91 .97/.87

Longest Telephoto (40/55 mm)

open~ Center...Edge....Corner
-------~----------------------------------
18-55 ~ .88/.88 .91/.80 .92/.70
17-40 ~ .75/.75 .67/.50 .61/.40

f/8 ~ Center...Edge....Corner
-------~----------------------------------
18-55 ~ .95/.95 .95/.80 .95/.72
17-40 ~ .92/.92 .90/.80 .86/.76

Or putting it in words, which lens is better?
(Parentheses means they're close.)

Widest Angle (17/18 mm)

open ~ Center.Edge..Corner
------~------------------------------
lens ~ 18-55 18-55 (17-40)

f/8 Center.Edge.Corner
------~---------------------------
lens ~ same 17-40 17-40

Longest Telephoto (40/55 mm)

open ~ Center.Edge..Corner
-------~-----------------------------
lens ~ 18-55 18-55 18-55

f/8 ~ Center....Edge....Corner
------~----------------------------------
lens ~ (18-55) (18-55) (18-55)

Make the 18-55 look like a good deal for $100?
(The 17-40L costs $800 at B&H.) You bet.

Of course, MTFs aren't the full story about lens performance, but they certainly are a large part of it. If someone wishes to show "the rest of the story" with matched tripod mounted shots, 100% crops, from the 18-55 and 17-40L, I'd love to see them. The only set I've seen so far at this site, taken at the wide angle end, confirmed the above in the center and did not resolve the question at the corner because the crop was so far away from the focal plane. Wide angles are notorious for non-planar focus. Their field of focus curvature may help for objects closer than the "focus distance (at the center of the image)" and hurt for objects farther away, or vice versa. A real comparison needs to make sure the objects in the center, edge and corner are all in the same plane perpendicular to the camera.
 
Please note, that the 17-40 charts are wrong on Canon USA's site. In fact there are so many errors on Canon USA's site I'd recommend not going there at all for data.

Here are the correct 17-40 charts from Canon Japan:



Jason
edtang said:
Actually seems to look not bad! :)





I also noticed that they changed the range of the x-axis to 13mm
for the non-full frame lens. But even so, when compared to a lens
like the 20-35, it seems a bit better I think.
Click to expand...
 
Thanks Jason. Here are revised tables and summaries based upon Canon Japan's MTF charts.

Since the 10 lp/mm number is representative of contrast, and the 30 lp/mm number is representative of resolution, we can summarize the lenses from the tables below as follows:

CENTER:
The 2 lenses are very close in contrast and resolution.

EDGES - wide angle:
18-55 has slightly better resolution, almost the same contrast.
EDGES - telephoto:
17-40L is a bit better

CORNERS - wide angle:
17-40L is better
CORNERS (telephoto):
About the same resolution. 17-40L has better contrast.

So $800 for the 17-40L (compared to $100 for the 18-55) basically gets you the following:
1-Slightly worse wide angle edges, slightly better telephoto edges
2-Better wide angle corners, slightly better telephoto corners

Except for the corners,the 2 lenses are about a toss-up. $700 buys you better corners. Those are awfully expensive corners! You probably can't see the difference until you get to larger prints.

But if you get standard enlargement sizes (8x10, 11x14,16x20) and you're cropping is centered in the image, the corners didn't make it into the print and the worst you'll see is what we've got for the edes. So if you bought the 17-40L, you better be making large full frame prints to get your money's worth!

I took values from the chart at 0, 10 and 13mm for the 17-40L; 0, 10 and the edge of the graph for the 18-55. Afterwards, I calcuated the diagonal of the sensor size - the corner is really at 13.63 mm, so the 17-40L corner numbers should be slightly lower than in the tables below. And the very edge (long ways) is really a little over 11.35 mm from the center, but at least I did both lenses the same. So read those as "Near the Edge" and "Near the Corner". (Oh well, I've spent too much time doing this already!)

First, the 10 lp/mm MTFs:

Widest Angle (17/18 mm)

open.. ~ Center.. Edge... Corner
----------~--------------------------
18-55 ~ .92/.92 .92/.78 .61/.52
17-40 ~ .95/.95 .94/.80 .90/.76

f/8.... ~ Center.. Edge... Corner
-----------~--------------------------
18-55 ~ .97/.97 .92/.80 .75/.55
17-40 ~ .98/.98 .98/.83 1.0/.79

Longest Telephoto (40/55 mm)

open. ~ Center.. Edge... Corner
--------~--------------------------
18-55 ~ .88/.88 .91/.81 .92/.69
17-40 ~ .94/.94 .94/.94 .92/.92

f/8.... ~ Center.. Edge... Corner
-------~--------------------------
18-55 ~ .96/.96 .95/.81 .95/.72
17-40 ~ 1.0/1.0 .98/.98 .94/.96

Now the 30 lp/mm MTFs:

Widest Angle (17/18 mm)

open.. ~ Center.. Edge... Corner
--------~--------------------------
18-55 ~ .78/.78 .68/.52 .32/.24
17-40 ~ .77/.77 .70/.46 .65/.36

f/8.... ~ Center.. Edge... Corner
---------~--------------------------
18-55 ~ .86/.86 .77/.56 .40/.25
17-40 ~ .88/.88 .81/.49 .88/.40

Longest Telephoto (40/55 mm)

open. ~ Center.. Edge... Corner
---------~--------------------------
18-55 ~ .72/.72 .70/.56 .69/.40
17-40 ~ .78/.78 .70/.70 .54/.56

f/8.... ~ Center.. Edge... Corner
---------~--------------------------
18-55 ~ .85/.85 .80/.56 .79/.40
17-40 ~ .98/.98 .81/.87 .55/.75
 
Sometimes.. mathematics really is beautiful. :)

I'm using a modified 18-55mm on my 10D and the results are quite pleasing. This little lens is impressive for it's cost and build.

edtang
Leonard Richmond said:
Thanks Jason. Here are revised tables and summaries based upon
Canon Japan's MTF charts.

Since the 10 lp/mm number is representative of contrast, and the 30
lp/mm number is representative of resolution, we can summarize the
lenses from the tables below as follows:

CENTER:
The 2 lenses are very close in contrast and resolution.

EDGES - wide angle:
18-55 has slightly better resolution, almost the same contrast.
EDGES - telephoto:
17-40L is a bit better

CORNERS - wide angle:
17-40L is better
CORNERS (telephoto):
About the same resolution. 17-40L has better contrast.

So $800 for the 17-40L (compared to $100 for the 18-55) basically
gets you the following:
1-Slightly worse wide angle edges, slightly better telephoto edges
2-Better wide angle corners, slightly better telephoto corners

Except for the corners,the 2 lenses are about a toss-up. $700 buys
you better corners. Those are awfully expensive corners! You
probably can't see the difference until you get to larger prints.

But if you get standard enlargement sizes (8x10, 11x14,16x20) and
you're cropping is centered in the image, the corners didn't make
it into the print and the worst you'll see is what we've got for
the edes. So if you bought the 17-40L, you better be making large
full frame prints to get your money's worth!

I took values from the chart at 0, 10 and 13mm for the 17-40L; 0,
10 and the edge of the graph for the 18-55. Afterwards, I
calcuated the diagonal of the sensor size - the corner is really at
13.63 mm, so the 17-40L corner numbers should be slightly lower
than in the tables below. And the very edge (long ways) is really a
little over 11.35 mm from the center, but at least I did both
lenses the same. So read those as "Near the Edge" and "Near the
Corner". (Oh well, I've spent too much time doing this already!)

First, the 10 lp/mm MTFs:

Widest Angle (17/18 mm)

open.. ~ Center.. Edge... Corner
----------~--------------------------
18-55 ~ .92/.92 .92/.78 .61/.52
17-40 ~ .95/.95 .94/.80 .90/.76

f/8.... ~ Center.. Edge... Corner
-----------~--------------------------
18-55 ~ .97/.97 .92/.80 .75/.55
17-40 ~ .98/.98 .98/.83 1.0/.79

Longest Telephoto (40/55 mm)

open. ~ Center.. Edge... Corner
--------~--------------------------
18-55 ~ .88/.88 .91/.81 .92/.69
17-40 ~ .94/.94 .94/.94 .92/.92

f/8.... ~ Center.. Edge... Corner
-------~--------------------------
18-55 ~ .96/.96 .95/.81 .95/.72
17-40 ~ 1.0/1.0 .98/.98 .94/.96

Now the 30 lp/mm MTFs:

Widest Angle (17/18 mm)

open.. ~ Center.. Edge... Corner
--------~--------------------------
18-55 ~ .78/.78 .68/.52 .32/.24
17-40 ~ .77/.77 .70/.46 .65/.36

f/8.... ~ Center.. Edge... Corner
---------~--------------------------
18-55 ~ .86/.86 .77/.56 .40/.25
17-40 ~ .88/.88 .81/.49 .88/.40

Longest Telephoto (40/55 mm)

open. ~ Center.. Edge... Corner
---------~--------------------------
18-55 ~ .72/.72 .70/.56 .69/.40
17-40 ~ .78/.78 .70/.70 .54/.56

f/8.... ~ Center.. Edge... Corner
---------~--------------------------
18-55 ~ .85/.85 .80/.56 .79/.40
17-40 ~ .98/.98 .81/.87 .55/.75
Click to expand...
 
edtang said:
I'm using a modified 18-55mm on my 10D and the results are quite
pleasing. This little lens is impressive for it's cost and build.

edtang
Leonard Richmond said:
Thanks Jason. Here are revised tables and summaries based upon
Canon Japan's MTF charts.

Since the 10 lp/mm number is representative of contrast, and the 30
lp/mm number is representative of resolution, we can summarize the
lenses from the tables below as follows:

CENTER:
The 2 lenses are very close in contrast and resolution.

EDGES - wide angle:
18-55 has slightly better resolution, almost the same contrast.
EDGES - telephoto:
17-40L is a bit better

CORNERS - wide angle:
17-40L is better
CORNERS (telephoto):
About the same resolution. 17-40L has better contrast.

So $800 for the 17-40L (compared to $100 for the 18-55) basically
gets you the following:
1-Slightly worse wide angle edges, slightly better telephoto edges
2-Better wide angle corners, slightly better telephoto corners

Except for the corners,the 2 lenses are about a toss-up. $700 buys
you better corners. Those are awfully expensive corners! You
probably can't see the difference until you get to larger prints.

But if you get standard enlargement sizes (8x10, 11x14,16x20) and
you're cropping is centered in the image, the corners didn't make
it into the print and the worst you'll see is what we've got for
the edes. So if you bought the 17-40L, you better be making large
full frame prints to get your money's worth!

I took values from the chart at 0, 10 and 13mm for the 17-40L; 0,
10 and the edge of the graph for the 18-55. Afterwards, I
calcuated the diagonal of the sensor size - the corner is really at
13.63 mm, so the 17-40L corner numbers should be slightly lower
than in the tables below. And the very edge (long ways) is really a
little over 11.35 mm from the center, but at least I did both
lenses the same. So read those as "Near the Edge" and "Near the
Corner". (Oh well, I've spent too much time doing this already!)

First, the 10 lp/mm MTFs:

Widest Angle (17/18 mm)

open.. ~ Center.. Edge... Corner
----------~--------------------------
18-55 ~ .92/.92 .92/.78 .61/.52
17-40 ~ .95/.95 .94/.80 .90/.76

f/8.... ~ Center.. Edge... Corner
-----------~--------------------------
18-55 ~ .97/.97 .92/.80 .75/.55
17-40 ~ .98/.98 .98/.83 1.0/.79

Longest Telephoto (40/55 mm)

open. ~ Center.. Edge... Corner
--------~--------------------------
18-55 ~ .88/.88 .91/.81 .92/.69
17-40 ~ .94/.94 .94/.94 .92/.92

f/8.... ~ Center.. Edge... Corner
-------~--------------------------
18-55 ~ .96/.96 .95/.81 .95/.72
17-40 ~ 1.0/1.0 .98/.98 .94/.96

Now the 30 lp/mm MTFs:

Widest Angle (17/18 mm)

open.. ~ Center.. Edge... Corner
--------~--------------------------
18-55 ~ .78/.78 .68/.52 .32/.24
17-40 ~ .77/.77 .70/.46 .65/.36

f/8.... ~ Center.. Edge... Corner
---------~--------------------------
18-55 ~ .86/.86 .77/.56 .40/.25
17-40 ~ .88/.88 .81/.49 .88/.40

Longest Telephoto (40/55 mm)

open. ~ Center.. Edge... Corner
---------~--------------------------
18-55 ~ .72/.72 .70/.56 .69/.40
17-40 ~ .78/.78 .70/.70 .54/.56

f/8.... ~ Center.. Edge... Corner
---------~--------------------------
18-55 ~ .85/.85 .80/.56 .79/.40
17-40 ~ .98/.98 .81/.87 .55/.75
Click to expand...
Click to expand...
--
Arno
 
I'm very curious about this!!!

It seems that the back-lens is taken out and......?????????
What have they done........?

The pictures are tack-sharp with very little CA !!!!

Please ...edtang can you translate this for us or tell us what sort of modification we are talking about!!!

Regards, Arno
dejal said:
http://www.slrclub.com/bbs/view.php?id=user_review&page=1&sn1=&sid1=&divpage=1&sn=off&sid=off&ss=on&sc=off&select_arrange=headnum&desc=asc&no=4312

and

http://www.slrclub.com/bbs/view.php?id=user_review&page=1&sn1=&sid1=&divpage=1&sn=off&sid=off&ss=on&sc=off&select_arrange=headnum&desc=asc&no=4315
Click to expand...
 
Hi Edtang,

I'm very interested in your modification of the kit-lens.

Can you tell us, if you can do this modification yourself if you are a handy-person!!

Thanks,
Regards, Arno
edtang said:
Actually seems to look not bad! :)





I also noticed that they changed the range of the x-axis to 13mm
for the non-full frame lens. But even so, when compared to a lens
like the 20-35, it seems a bit better I think.
Click to expand...
 


I had my machinst modify the EF-S ring so the lens fits perfectly. I'll be writing up a "how-to" with plenty of pics soon for everyone. Look for it in the next few days.

edtang
edtang said:
Actually seems to look not bad! :)





I also noticed that they changed the range of the x-axis to 13mm
for the non-full frame lens. But even so, when compared to a lens
like the 20-35, it seems a bit better I think.
Click to expand...
 
Great initiative!
R. Arno
edtang said:


I had my machinst modify the EF-S ring so the lens fits perfectly.
I'll be writing up a "how-to" with plenty of pics soon for
everyone. Look for it in the next few days.

edtang
edtang said:
Actually seems to look not bad! :)





I also noticed that they changed the range of the x-axis to 13mm
for the non-full frame lens. But even so, when compared to a lens
like the 20-35, it seems a bit better I think.
Click to expand...
Click to expand...
 
Hi edtang,

How is your progress on this issue?
I'm very curious if I can do it myself!!!

I've seen two pictures of the modificated lens and they are very sharp indeed and -most important- no CA at all!!!
Regards, Arno
edtang said:


I had my machinst modify the EF-S ring so the lens fits perfectly.
I'll be writing up a "how-to" with plenty of pics soon for
everyone. Look for it in the next few days.

edtang
edtang said:
Actually seems to look not bad! :)





I also noticed that they changed the range of the x-axis to 13mm
for the non-full frame lens. But even so, when compared to a lens
like the 20-35, it seems a bit better I think.
Click to expand...
Click to expand...
 
I have both the 18-55 EF-S and the 17-40 F4L. You can believe what you want from the MTFs but the 17-40 is clearly superior in sharpness on both the edges and the corner. It is clearly superior in terms of flare, contrast, and CA as well.

These differences show up in prints, not just 100% crops.

The kit lens is a great lens for 100$. But a 17-40 F4L it isn't.

I'm not going to get into a debate about this. If you have access to both, simply shoot the same scene at F4 at 18mm. Print the results so they fit on a standard sheet of paper (8 1/2 x 11) and look at what you get.

--
If you are a new user chances are good your question is answered in the FAQ at:
http://www.marius.org/eos300dfaq.php

For a small gallery of my photographs, see:
http://ratphoto.home.comcast.net/
See my profile for my equipment
 
Of course you are right!
But I'm only curous about the modification of the 18-55 EF-S.

R. Arno
RATPhoto said:
I have both the 18-55 EF-S and the 17-40 F4L. You can believe what
you want from the MTFs but the 17-40 is clearly superior in
sharpness on both the edges and the corner. It is clearly superior
in terms of flare, contrast, and CA as well.

These differences show up in prints, not just 100% crops.

The kit lens is a great lens for 100$. But a 17-40 F4L it isn't.

I'm not going to get into a debate about this. If you have access
to both, simply shoot the same scene at F4 at 18mm. Print the
results so they fit on a standard sheet of paper (8 1/2 x 11) and
look at what you get.

--
If you are a new user chances are good your question is answered in
the FAQ at:
http://www.marius.org/eos300dfaq.php

For a small gallery of my photographs, see:
http://ratphoto.home.comcast.net/
See my profile for my equipment
Click to expand...
--
Arno
 
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