General Image sharpenness:definition in video

M

mat321$

New member
Hi,

My questions concern the sharpenness (i talk about the definition on the image) in video.

On my old canon xha1, i have a really good sharpeness that i can't have the same on dslr, so i want to understand how it works.

First, is it correct that in video the optical quality of a lens is not as important as on photo ? i want to say that a really good lens could not "express" completely in video mode....

Second, on the dslr like 7d, the image is not quite sharp, all people know that. Can you explain me why ? It's due to the large sensor definition and downscaling ? I try to make some test and sometimes i see no difference between very expensive lens, are you able to see real difference between L lens and normal lens.

I want to know that because i have dslr and i'm going to have the fs700 or c100 soon so i want to know if with the same lens i'm going to have difference between those cameras and the dslr ?

I saw some footage about fs700 and c300 and the image is more sharper that on the dslr.

Is the crop factor of the aps-c or super 35 sensor affect the sharpeness ? is it better to have a full frame to have good sharpeness ?

So finally, i want to propose some good lens to buy for filmaker, can you advice me on some two lens like :

- Is the tokkina 11-16 v2 is really better thant the v1 for vidéo
- for the 24-70, do you test and see difference between tamron 24-70, canon 24-70 v1 and canon 24-70 v2

or do you have other good lens to advice me ?

Thanks a lot and sorry for takinf your time
 
First off, the full frame vs APS C vs 1/3" vs anything else doesn't change sharpness. The reason the 7D and Canon DSLRs aren't sharp is because they are using a poor method to downscale to 1080P out of their high MP (18 and up) sensors. They throw away information during this process. The FS100 and the C100/300 are much sharper because their sensors are designed for video only...using only 8MP to start with and excellent methods to get HD signals from that starting point.
Lenses are a bit tougher to answer on...because pretty much any photo lens is up to the task of resolving the 1080p signal....they are designed to handle much more. BUT...different lenses have different quality glass and will reveal subjects in different ways. Your lenses should look beautiful on the C100/Fs100...because they will not be hampered by the soft image fed by a DSLR.
 
Sharpness is a vague term with different meaning to different people with different needs.
It does matter even for 1080p video (a lot), but in a different way than for, say, 24 Mpix stills (6K).

For 1080p, the aspect of "sharpness" that you care about is "acutance". For 24 Mpix stills, it is "resolution".

Read about them here:
http://www.lensrentals.com/blog/2009/06/have-you-seen-my-acutance
And see my tests here:
resolution: http://www.similaar.com/foto/lenstests/lenstestsa.html
acutance: http://www.similaar.com/foto/lenstests/lenstestsv.html
 
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