70-200f2.8 mk.II vs 70-300L sharpness test

[K-amps]

Did some tests as a result of a discussion on another thread. Comparing the sharpness of the 2 great lenses with the following test conditions: Subject shot = a Ruler placed 45 degrees on the wall and focused on the 12" mark.

Attached are 3 shots; 2 of the 70-200mk.ii (I have 2 copies, the old one is a refurb unit and the new one is a new unit bought from adorama) and the last 1 of the 70-300L

1) ISO = 100
2) F5.6 (favors the 70-200 slightly since it is natively larger aperture)
3) 5D mounted on tripod
4) camera jpeg used: zero PP done except 100% crop .
5) Spot AF at the 12" Mark. Did not MF since I seldom use MF with these 2 lenses; Spot AF relevant for my use.
6) Used various focal lengths but the attachments are for all 3 at 200mm
7) Ruler was vertically placed with top = higher numbers on scale. After cropped I turned the crops 90 degrees clockwise for better viewing.

Conclusion:

1) The 2 copies of the 70-200mk.II are very similar in sharpness and focal length
2) The 70-300L set at 200mm shows a smaller frame compared to the 70-200's not sure which one is accurate the 200's or the 300.
3) The 300 seems slightly sharper than both (though it is a toss) and has a greater DoF at f5.6 than the 200's.

Hope this helps people who are considering both:

[JR]

The 70-300L does seem like a great lens.  I have been thinking about it as a walkaround lens for a while.

"2) The 70-300L set at 200mm shows a smaller frame compared to the 70-200's not sure which one is accurate the 200's or the 300."

I think this could be caused by the fact the lenght of each zoom at 200 could be different and therefore not exactly at the same distance from your subject

[K-amps]

The camera did not move from the tripod, I switched lenses while the camera was latched on to the tripod. I know it did not move. While I can understand what you are referring to, I would like to think that the focal lengths are referenced to the sensor, again which did not change in distance to the ruler.

If you check the exif information in each jpeg, it shows 200mm for each shot (if you care to download the attachments).

[neuroanatomist]

Thanks for the tests!  I will reiterate that using autofocus is not the best way to test lens sharpness, since you're not testing just the lens, but how well the lens is matched to the camera's AF.  Also, an angled ruler is a challenging target for the AF system. So, while I appreciate the efforts, and acknowledge this test has meaning for your camera+lenses, I don't believe the results can be generalized to these lenses as a group, due to the confound of using AF (with no ability to calibrate it).

[JR]

The camera did not move from the tripod, I switched lenses while the camera was latched on to the tripod. I know it did not move. While I can understand what you are referring to, I would like to think that the focal lengths are referenced to the sensor, again which did not change in distance to the ruler.

If you check the exif information in each jpeg, it shows 200mm for each shot (if you care to download the attachments).

I could very well be mistaken on this one and maybe Neuro knows this technical aspect but I was referring to the fact that while the camera did not move, if once zoomed at 200mm the 70-300mm is not as extended as the 70-200mm, then the lens is actually further away from the target compared to the 70-300mm.  Again I could be mistaken but I thought I had seen this described in one post somewhere...

So say the 70-300mm when focused at 200m extend from your camera (total physical lenght of the lens) by 7 inches (I am just making these numbers up for illustration) and say the 70-200 is always 8 inches long, then are you not relatively speaking closer to your target by 1 inche with the 70-200?

You are right that both gives you 200mm at the sensors, but with the 70-300mm in my example, you could approach your target by another inche and still be at 200mm.

Does this make any sense?  In any case it does not take away anything from your test I think...cheers.

[neuroanatomist]

@JR - focal length is measured from the sensor, so lens length isn't relevant. Still, lenses don't always deliver the indicated focal length, and at closer distances focus breathing can affect apparent focal length (for example, at 1:1 magnification, the 100L Macro IS is delivering something like a 67mm angle of view).  Even ignoring focus breathing, lenses differ - I once tested an EF-S 18-200mm against my 70-200mm II, and compared to the L zoom, the 18-200 @ 200mm was giving an AoV equivalent to about 154mm (assuming the 70-200 was 'correct').

[K-amps]

Thanks for the tests!  I will reiterate that using autofocus is not the best way to test lens sharpness, since you're not testing just the lens, but how well the lens is matched to the camera's AF.  Also, an angled ruler is a challenging target for the AF system. So, while I appreciate the efforts, and acknowledge this test has meaning for your camera+lenses, I don't believe the results can be generalized to these lenses as a group, due to the confound of using AF (with no ability to calibrate it).

I understand about generalizing the tests for all lenses.

However, grant me this... if I saw the numbers sharper at the higher or lower end of the scale (lets say 13" or 11" etc, then it would indicated forward or back focus, this is not the case, the lens is correctly focusing at 12"
 
The older 70-200 (1st pic) has a slight back focus, however it is still withing the dof and captures 12" at good sharpness.  The second is centered at 12" meaning it is optimally focussed.

Given that the slanted ruler, an inaccurate focus would be visible either up or below (instead of 12"), thus I still believe, this test is valid for this set of 3 lenses.

The proof is that maximal sharpness is visible between 11.5" to 12" for all lenses.

[JR]

@JR - focal length is measured from the sensor, so lens length isn't relevant. Still, lenses don't always deliver the indicated focal length, and at closer distances focus breathing can affect apparent focal length (for example, at 1:1 magnification, the 100L Macro IS is delivering something like a 67mm angle of view).  Even ignoring focus breathing, lenses differ - I once tested an EF-S 18-200mm against my 70-200mm II, and compared to the L zoom, the 18-200 @ 200mm was giving an AoV equivalent to about 154mm (assuming the 70-200 was 'correct').

Thanks for the clarification...my bad!  I knew I would learn something new everyday with this website 

As for your test between your 18-200 and 70-200, wow the delta in AoV equivalent is really huge!

However, grant me this... if I saw the numbers sharper at the higher or lower end of the scale (lets say 13" or 11" etc, then it would indicated forward or back focus, this is not the case, the lens is correctly focusing at 12"

One thing is for sure the 70-300L has a lot of potential!

[bchernicoff]

If I remember correctly, focal length is measured at infinity focus and depending on the lens can change with focus.