# EF 300mm f/2.8L IS II USM and DXOMARK.COM



## Panurus (Feb 22, 2012)

I post this on rumors because DXO has created a rumor.

I find a test of the new EF300mmf/2.8LISIIUSM on:

http://www.dxomark.com/index.php/News/DxOMark-news/A-good-if-heavy-and-expensive-lens-the-Canon-EF-300-f-2.8L-II-USM 

Who can explain that DXO find the resolution of the old EF300mmf/4.0LISUSM is better? 

Why Canon don't react at this point? 

Are the FTM curve of CANON a joke? 

If on dxomark, you compare the EF300mmf/2.8LISIIUSM with a zoom like the 24-105L, you can observe that the resolution of the zoom is also better. Very strange ;D.

What is your opinion?


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## briansquibb (Feb 22, 2012)

Panurus said:


> I post this on canonrumors because DXO has created a rumor.
> 
> I find a test of the new EF300mmf/2.8LISIIUSM on:
> 
> ...



I think DxO have got something wrong - I would wait until other reviews are done.

I dont remember the 300F4 being that good - in fact I sold it after I found the 70-300L gave me better pictures


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## KeithR (Feb 22, 2012)

briansquibb said:


> I think DxO have got something wrong - I would wait until other reviews are done.



Like this one...


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## weixing (Feb 22, 2012)

Hi,


Panurus said:


> I post this on rumors because DXO has created a rumor.
> 
> I find a test of the new EF300mmf/2.8LISIIUSM on:
> 
> ...


 IMHO, it's quite normal... if you look at most review website, wide to standard lenses usually had a higher measured resolution than a super telephoto lenses. The main factor is distance... when shooting at the same test chart, super telephoto lenses need to be a lot further away to achieve the same field. The increased distance mean more air in between the lenses and that'll reduced the measured resolution.

As for EF 300mm F4L IS USM vs EF 300mm F2.8L IS II USM, The DxOMark wesite state that: *"The DxOMark resolution score shows resolution performance of a lens-camera combination averaged over its entire focal length and aperture ranges."* EF 300mm F2.8L IS II USM might have a slight "disadvantage" since it start the measurement at F2.8. Anyway, I look at the DxOMark MTF chart, EF 300mm F2.8L IS II USM is still perform better than EF 300mm F4L IS USM at F4.0.

Just my $0.02.

Have a nice day.


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## neuroanatomist (Feb 22, 2012)

Panurus said:


> Who can explain that DXO find the resolution of the old EF300mmf/4.0LISUSM is better?



DxO can, and they do. Do you define a 3 lp/mm difference as 'better'? DxO states, "_Differences below 5lp/mm are usually not noticeable._" Also, it's not unreasonable that the 300/4 might have slightly higher resolution in the center, and if that's the case, it would have a higher maximal resolution score on DxOMark. 

They go on to state, "_As noted above, the f/2.8’s resolution is homogenous across the field - rather more than for the f/4L, even though the f/4L has a slightly higher score for resolution._"



Panurus said:


> Why Canon don't react at this point?



Why would they?



Panurus said:


> Are the FTM curve of CANON a joke?



No, they're not a joke. What they are is _theoretical_ curves, generated by a computer from a computer model of the lens design, which assumes perfect execution on production and assembly. Further, those theoretical curves top out at 30 lp/mm, which is less than the spatial resolution of currently available dSLR sensors. DxOMark is generating real MTF data from a real lens, with a real camera. Of lens manufacturers, only Zeiss empirically determines lens MTF curves using real lenses (all others use the same type of theoretical curves that Canon uses), and even then it's different, since Zeiss is measuring the lens itself, whereas DxOMark is using a camera to test the lens, so the camera affects the data.


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## Axilrod (Feb 22, 2012)

Lenstip said this about the resolution: _"What can be said, just one word comes to your mind – a revelation! Already at the maximum relative aperture the lens gets to simply brilliant level of 43 lpmm. It’s worth emphasizing that this value is more or less the same as the maximum results of such classic instruments like the 135L or 200L, mentioned before. What’s more, the maximum value, reached by f/4.0, amounts to as much as 45.0 ± 0.7 lpmm. It is a bit lower than in the case of the EF 100L Macro but you should remember that those two results overlap each other within the margin of error. What’s more, “telephoto” lenses usually have a bit lower MTFs than lenses with shorter focal lengths because of a bigger distance from a testing chart and their greater susceptibility to interferences. Taking all those into account you can boldly say that the resolution values of the Canon 2.8/300 are on a level which is very close to records."_

So not everyone thinks it's bad


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## Panurus (Feb 22, 2012)

Thank you NEUROANATOMIST

"DxO can, and they do. Do you define a 3 lp/mm difference as 'better'? DxO states, "Differences below 5lp/mm are usually not noticeable." 

I come back for difference between EF 24-105mm f/4L IS USM : 60lp/mm
and EF 300mm f/2.8L IS II USM : 49lp/mm
and EF 100mm f/2.8L Macro IS USM 57lp/mm

When a surfer read dxo infos, has he to understand that the 100mm is good like the 24-105 and the 300 so bad?



Thank you keythR for your post :

On the site : lenstip.com, I find some very good informations about tests for the 300mm and the 100mm.
So still now, i will recommand it without restriction.


On this site :
http://www.the-digital-picture.com/Reviews/Canon-EF-300mm-f-2.8-L-IS-II-USM-Lens-Review.aspx
I find also realistic informations.

Is there another good place to consult?


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## OlAf (Feb 22, 2012)

Panurus said:


> Who can explain that DXO find the resolution of the old EF300mmf/4.0LISUSM is better?


I can explain - their statement is not true. I have both lenses and 300/2.8LIS II much better and sharper even with Canon Extender 2x III 8)


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## kubelik (Feb 22, 2012)

there was a thread a month or so back on this forum about DXOmark lens testing. regardless of how you feel regarding their sensor testing (I personally think it's utter trash), I think everyone is near unanimous in the fact that their lens testing is far more worthless.

please check Bryan's ISO charts on The Digital Picture, I've found those to be excellent examples of a lens' expected performance in the field. both 300mm f/2.8 lenses from Canon are amazingly sharp.


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## LetTheRightLensIn (Feb 23, 2012)

They also said 70-300 IS at 300 f/5.6 is better than 70-300 L and 300 f/4 IS L !?!?!
And that 70-200 2.8 IS at 200mm 2.8 is better than the 70-200 2.8 non-IS is better than the 70-200 2.8 IS II!?!
And that the 16-35 II has better corner performance at f/2.8 than at f/5.6!?!!!

And now having the 300 2.8 IS II losing to the 300 f/4 IS?!????

Seriously, their lens tests are wack. For sensors they do some good work, but for lenses, whoa.


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