NEW 50mmf1.2 MTF charts v 1.4

http://www.usa.canon.c​om …egoryid=152&mod​elid=14259

can someone who understands MTF charts explain what the differences in the 1.2 and the 1.4 MTfs mean?

I tried reading the explantaio on Luminous landscape and thought I had understood until he said 'this shows why such and such a lens does such and such' and I realised I hadn't understood at all!

the way i'm reading that, assuming both charts are correct is that the 1.4 has "better" bokeh and just as good of IQ as the 1.2. So i would gather from that, save your money unless you need that extra stop and weathersealing, plus most likely faster AF. is that worth 1000 bucks more? that's up to you.

deadpass wrote in post #2225051
unless you need that extra stop

It's not even a stop, it's only half of a stop.

Remember, these MTF charts that Canon puts up are preliminary, they're not "real". However, those show that the 1.2 is sharper than the 1.4, even if it's not a LOT sharper. Edge sharpness is noticeably better on the L as well.

adas wrote in post #2225096
It's not even a stop, it's only half of a stop.

touche! and yes I should've mentioned the sharpeness fall off as well. For me, at this point, it's not worth the upgrade, my 50 1.4 does me well. I thought all MTF charts weren't real, but merely estimations by the company that makes them.

Ronald S. Jr. wrote in post #2225134
Remember, these MTF charts that Canon puts up are preliminary, they're not "real". However, those show that the 1.2 is sharper than the 1.4, even if it's not a LOT sharper. Edge sharpness is noticeably better on the L as well.

How can you tel that from the MTFs I just cannot work it out! Drives me crazee!

You must understand what the two axis of the diagram mean:

Horizontal axis: Distance from center of sensor (or film) in milimetres. (Left side is the center).
Vertical axis: Detail rendition percent, (usually in the center is better and drops to the margins).

They usually measure this at 3 frequencies: 10, 20 and 40lp/mm. So there are three base lines (or group of lines) on the same chart.

For easy comparison...

First, the 1.4 - then the 1.2:

I Simonius wrote in post #2224989
http://www.usa.canon.c​om …egoryid=152&mod​elid=14259

can someone who understands MTF charts explain what the differences in the 1.2 and the 1.4 MTfs mean?

I tried reading the explantaio on Luminous landscape and thought I had understood until he said 'this shows why such and such a lens does such and such' and I realised I hadn't understood at all!

Easier to see if you have overlay plots of the average of S and M.

http://www.zen20934.ze​n.co.uk …s/50mm_Region_A​/index.htm

deadpass wrote in post #2225051
the way i'm reading that, assuming both charts are correct is that the 1.4 has "better" bokeh and just as good of IQ as the 1.2...

how could you tell of a better bokeh by looking at MTF? please enlighten me. -alex

Lester Wareham wrote in post #2225790
Easier to see if you have overlay plots of the average of S and M.

http://www.zen20934.ze​n.co.uk …s/50mm_Region_A​/index.htm

from that it looks like te 1.2 performs worse than the 1.4 - is that right?

adas wrote in post #2225220
You must understand what the two axis of the diagram mean:

Horizontal axis: Distance from center of sensor (or film) in milimetres. (Left side is the center).
Vertical axis: Detail rendition percent, (usually in the center is better and drops to the margins).

They usually measure this at 3 frequencies: 10, 20 and 40lp/mm. So there are three base lines (or group of lines) on the same chart.

yeah I get it that far - then which is which?

Double Negative wrote in post #2225634
For easy comparison...

First, the 1.4 - then the 1.2:

[GIFS ARE NOT RENDERED IN QUOTES]

[GIFS ARE NOT RENDERED IN QUOTES]

This should keep the peepers busy.

can't see any real differences - are there any?

Hi I Simonius,

have a look at the following link Canons MTF info, higher up the graph is better.

Bold lines = contrast (using 10 lines/mm)
Fine lines = resolution (using 30 lines/mm)

Solid lines = sagital lines (the lines they are trying to view were drawn parallel to a line drawn from the center of the image to a corner)
Dashed lines = meridional lines (the lines they are trying to view were drawn perpendicular to a line drawn from the center of the image to a corner)

Black lines = wide open
Blue lines = f8

Hope that helps

BearSummer

BearSummer wrote in post #2226311
Hi I Simonius,

have a look at the following link Canons MTF info, higher up the graph is better.

Bold lines = contrast (using 10 lines/mm)
Fine lines = resolution (using 30 lines/mm)

Solid lines = sagital lines (the lines they are trying to view were drawn parallel to a line drawn from the center of the image to a corner)
Dashed lines = meridional lines (the lines they are trying to view were drawn perpendicular to a line drawn from the center of the image to a corner)

Black lines = wide open
Blue lines = f8

Hope that helps

BearSummer

thanks for the link and it sort of helps , only somewhere i also read that black lines = resolution + Blue lines = contrast.........???

Okay Let me try
Left is center, Right side is the edges of the image. The higher the lines the better the resolution.

As far as Bokeh is concerned the object should be to have the matching dashed lines and the solid lines almost right on top of each other (perfect would be I seem to remember the dashed line parrallelling the solid line just below it. There is obviously more to it then that, but that would be what you would look for on the MTF chart as far as Bokeh is concerned in terms of having the out of focus circle of a point of light be even with soft edges. This and aperture blades are about the limits of technical characteristics you can look for in figuring out good or bad bokeh.

Black lines are wide open so the F1.2 is at F1.2 and the F1.4 is at F1.4. (this means the wide open are not directly comparable as you would need to have the F1.2 lens at F1.4, but you can extrapolate a touch.

As mentioned the numbers along the bottom are distance from center, some where around 15 is where the APS-C sensor (1.6X ) would cut out so if you have for example a 30D no point in looking beyond the 15mm point.

So first look at the Blue lines (F8) and compare how the lines go accross the top. You should be able to note that the F1.2 lens continues across, while the F1.4 starts dropping off at about the 15mm mark (meaning no difference on an APS-C camera between the two lenses at F8 (or close enough to not matter)

Then Look at the Black lines or wide open. Now taking into account F1.2 versus F1.4, consider that the F1.2 does almost as good as the F1.4, but definately better at the edges of the image beyond the APS-C sensor area.

So the F1.2 should be a better lens overall then the F1.4 if you have a 35mm FF camera and no real difference based on MTF if on an APS-C camera.

At least I gave it a try,