How Accurate are Canon MTF Charts?

[darth mollusk]

I find it interesting that some people remain unconvinced that the new 400mm DO ii will be an exceptionally sharp lens. The MTF charts for the DO ii look amazing. In contrast I also find it interesting that many who own the 400mm 5.6L claim that this lens delivers impressive image quality, while the MTF charts look rather unimpressive.

Can Canon's MTF charts be used as an accurate prediction of lens sharpness and contrast, or are there cases where real world image quality and their MTF charts vary significantly?

For example: based on the Canon MTF charts alone, could one accurately predict a significant difference in image quality (sharpness and contrast) between the 400mm DO ii and the 100-400 4.5-5.6L ii at 400mm?

 

[Khalai]

MTF won't show out-of-focus rendering, colour rendering, colour fidelity and microcontrast. But 400 DO II should be sharp as a razor, rivaling 400 2.8 II and besting 400 5.6 and 100-400 (either I or II). Otherwise, what would be the point of such lens? It's MTF charts are astonishing as you stated.

 

[takesome1]

First keep in mind you should only be comparing Canon MTF with Canon MTF.

What I have noticed in the past is that it gives me an indication to what I might expect.
If the MTF chart appears about the same or better than a different lens it will perform the same or better.

Looking at the 100-400mm II it is very comparable to the 70-200mm II at their longest length, of course different focal lengths but it would be my guess they will perform very similar.

The 400mm F/4 MTF isn't as good as the 500mm F/4 but it isn't that far behind. Compare it to the 200-400mm F/4 and it looks better than it. I think we will see good things out of the new 400mm DO II.

 

[Lurker]

What's your reference? 400 5.6 is sharper than most of the 400 options unless you want to pay for, and lug around, the 2.8. Sure, it's not as sharp as the Canon "A" listers but it's a lot older. It's also cheaper and lighter which make it doable for many people. The new 100-400 is probably sharper too but more $.

Also keep in mind when comments are made. 400 f5.6 has been around a long time and is in a lot of kits. Same can't be said for the newer tech with higher price tags. In a few years you won't hear as much about the 400 5.6 but then again we may be talking about the 400 5.6 II which will once again best the 100-400.

I think most expect the 400 DO II to be sharp but maybe lacking in contrast or other qualities. A lot of people just have a wait-and-see attitude right now on new technology that is going to set them back several thousand dollars.

 

[NancyP]

I will go further and state that you should only compare Canon MTFs at a given focal length with other Canon MTFs at that focal length.

400 f/5.6L gets you 95% of the way to incredibly sharp. The 400 f/2.8L IS II gets you the rest of the way. Translated, that means that for people printing 13" x 19", the f/5.6 lens will do very well. If you want to print at 60" and crop, then you might appreciate that extra 5% from the f/2.8 lens.

Another way to compare is to look for MTF curves with Canon teleconverters added. Some lenses take teleconverters better than other lenses. I can see a definite hit in pixel-peeping sharpness with the 1.4X v.II TC on my copy of the 400mm f/5.6L under ideal conditions (on tripod, remote release, multiple manual refocusings) - but I still get very pleasing images from this combo. I wouldn't try the 2X TC - but who wants to look at an effective f/11 lens anyway? The 400 f/2.8 and other big big lenses get good TC performance (degradation is less).

 

[Mt Spokane Photography]

I find it interesting that some people remain unconvinced that the new 400mm DO ii will be an exceptionally sharp lens. The MTF charts for the DO ii look amazing. In contrast I also find it interesting that many who own the 400mm 5.6L claim that this lens delivers impressive image quality, while the MTF charts look rather unimpressive.

Can Canon's MTF charts be used as an accurate prediction of lens sharpness and contrast, or are there cases where real world image quality and their MTF charts vary significantly?

For example: based on the Canon MTF charts alone, could one accurately predict a significant difference in image quality (sharpness and contrast) between the 400mm DO ii and the 100-400 4.5-5.6L ii at 400mm?

The MTF Charts basically represent a perfect lens that has been properly assembled, calibrated, and as good as it can be.

As noted, MTF does not tell you everything, far from it.

The 400mm f/5.6L has been tested by many lens testers. Its a good lens, but nothing exceptional about it. For the price, its hard to beat. Its very close to the 100-400mm MK I, but has no IS and has faster autofocus. I preferred my 100-400L due to

1. IS
2. MFD
3. Same sharpness and reasonably fast AF.