Lens focus speeds and scripting

[garry23]

A1ex/David

One thing I have noticed in running my auto focus bracketing scripts on a 5D3 and a 50D, is that the 5D3 zips along, whereas the 50D is relatively sluggish in driving the lens.

Am I right in assuming this is simply a reflection of the different chip sets used in the two cameras and their relative clock cycles etc.

Cheers

Garry

[nikfreak]

Focusing with a sigma lens (50-150OS) I am noticing quite the opposite.
The 100D is focusing faster and also hunting less through the viewfinder compared to the 70D. Though I din't compare it w/o ML and it may be also related to the sigma being used. Another theory I have is that 100d is using the old focus module with a single cross center focus point and due to this fact the DIGIC5 may help it to perform really better. Like old stuff on steroids.

[garry23]

@nikfreak

The issue I see is not related to focusing, but driving the focus motor from a Lua script.

With an  indentical lens on my 5D3 and 50D, the Lua script drives the lens about tenth of the speed of the 5D3.

As I say, I guess this reflects the different chip sets in these two cameras.

Or is there a bug in the 50D code ;-)

Cheers

Garry

[a1ex]

How does the follow focus function from ML behave on the two cameras? They both use the same backend.

I expect minor differences between them, but certainly not one being 10x slower than the other.

[garry23]

@Alex

I use the same script, ie driving the lens, and use the same lens.

On the 5D3 the lens moves 'quickly' and the 50D the same script drives the same lens about 5-10 slower.

Cheers

Garry

PS For interest here is the relevant bit of my script that drives the lens:

Code Select Expand

if lens.focus_distance < inf and no_tv_error then
repeat
a1=a2
b1=b2
repeat
lens.focus(-1,1)
b2 = lens.dof_far
a2 = lens.dof_near
fp = lens.focus_distance
until a2 > b1 or fp >= inf
lens.focus(1,1) -- move back one step for focus bracket overlap
take_brackets()
until fp >= inf
end