70mm is not the same for Canon 24-70 f2 8 II & 70-200 f2.8 II?

Hi!

Any of you noticed a difference in the framing using the 24-70 f2 8 II & 70-200 f2.8 II?

I was doing some tests (on a tripod) and it looks like 70mm is not the same for both lenses. (on a 7D mark II) .... is it a known fact or there is something wrong on my side?

Manufacturers tend round-up or round down to the nearest whole value when they label lenses.
You will probably find that in reality of them is 68mm and the other is 72mm or something similar, this is quite normal and there is nothing wrong with your lenses.

Agreed, also with lenses that focus internally, you lose some focal length when the zoom is racked out(eg. your 24-70) as opposed to being racked in(eg. your 70-200)

Focal lengths are only accurate when the lens is focused at infinity. I suspect if you check the two lenses against each other while focusing at infinity, you will find they are very close.

JeffreyG wrote in post #18194958
Focal lengths are only accurate when the lens is focused at infinity. I suspect if you check the two lenses against each other while focusing at infinity, you will find they are very close.

Agree. As a result of focus breathing images from two different lenses set at the same focal length result in images of different sizes when shooting closer in than infinity. This difference will likely also change as you vary the distance to the subject. When shooting at infinity at the same focal length, the two lenses should result in images of equal or almost equal size. It is true that the actual focal length and the stated focal length of a lens may differ slightly, but it would not account for a significant difference in image size between two lenses.

Your two posted examples are consistent with focus breathing. Here are several links. There are hundreds of others.

https://www.slrlounge.​com/focuslens-breathing-matter/

http://www.bobatkins.c​om …focal_length_ch​anges.html

https://northrup.photo …features/focus-breathing/

JeffreyG wrote in post #18194958
Focal lengths are only accurate when the lens is focused at infinity. I suspect if you check the two lenses against each other while focusing at infinity, you will find they are very close.

This. The 70-200 II is known to increase in focal length on shorter focus distance. Until about a week ago, I had no clue about this. Learned it right here on POTN.