How To Focus Properly

[phantomi]

Hi! From what I have read then if you change to manual focus and hit the infinity icon at the bottom of the sliding bar, then it is like having a fixed focus like that of the Phantom 4. Then you can take pics and vids without worry about out of focus takes? Thanks.

 

[zanderlane]

...on my mavic, the problem with the focusing to infinity, is that it has the most annoying behavior of being able to go PAST INFINITY, where it starts to throw EVERYTHING out of focus...why would you let a camera focus past infinity DJI, why? - on the other hand, my p4p will let me slam the dial to infinity and it just stops at infinity like a good lens should! - go figure this company out, I sure can't!

 

[BossBob]

Why are you focusing on infinity? You need to focus on something at hyperfocal distance, which I believe is about 13m. This should give you acceptable focus from close up to infinity.

 

[zanderlane]

...yes, everyone knows hyperfocal distance is where to be for maximum depth of field - this does not change the fact that being able to focus past infinity so that NOTHING is in focus is just plain, what's the word...NEGLIGENT!? - silly ol' DJI...

 

[BossBob]

Silly old Nikon, Canon, Olympus etc. Every one of my dslr lenses has the ability to focus beyond infinity so I don't think that an el cheapo mobile phone lens that has been retasked into a drone is going to be any different. The ability is there to allow for thermal expansion of components. It would be even worse if they could only focus on infinity in specific conditions! I'd never be able to resolve a star as a point or the major moons of Jupiter.
And the hyperfocal distance of a lens alters with aperture, which we can't change, so the hyperfocal distance with a Mavic puts infinity at the far end of the field of acceptable focus and brings the near end of the field of acceptable focus as close to the Mavic as possible. On a manual slr this allowed you to shoot quickly without focusing or even bringing the camera up to your eye for candid or street photography.

 

[zanderlane]

...hmmm, so can you further explain why the p4p appears to nail focus every time with a quick roll of the dial to max infinity setting? shouldn't the mavic be capable of the same dependable focusing capability? or are you saying that the p4p's hard focus point for infinity is actually a bad thing cuz it'll be in focus at 72*F but soft at 85*F? and if this is the case, then does anyone know: what is the base temperature that is optimum for the infinity focus point to be correct with the p4p?

 

[BossBob]

I've no idea as I don't have a phantom and I'll only talk about things I know about. I do know that when I'm using a Canon 7d2 with a Canon 100-400 L to image stars or planets, which for our purposes are as close to infinity as we are going to get, there is still more movement available in the focussing ring so you cannot just turn it to the end of its movement and say that will be ok you actually have to focus, either automatically or more often, manually. Same for all lenses I've handled.

 

[zanderlane]

...FYI: ok, I asked the google and it says that only parfocal lenses have a hard stop for infinity focusing, whereas most lenses are varifocal and will require manual adjustment at the end of the focus range - for canon, the parfocals are mainly prime L glass and forward focusing zooms - so I believe bossbob is correct regarding wiggle room at end of focus range as I kinda doubt the "el cheapo" lenses in DJI's lower end drones are parfocal.

 

[geigy]

The Mavic's camera does not have a hardware infinity stop, and relies on software for focus.

There are two problems with continuous auto-focus that stem from the fact that the software can only tell it is in focus by shifting focus slightly, every few minutes. The first problem is that there will be a slight de-focusing every once in a while. The second problem is if the center of the field has no detail, this could cause loss of focus.

Setting the lens to infinity seems like a great idea, but since there is no hardware stop, this tactic has the problem once again of risking being always out of focus, for example a temperature change may change the focus. This is similar to the horizon tilt issue.

So, for now, manual focus is the solution and it needs to be part of your routine, even if you have AFC enabled.

 

[Blacksails]

I don't really see the issue to be honest... it doesn't take long really, considering.

Pop it up, focus on something in the distance with high contrast, the horizon usually works well, then set it to manual focus so it doesn't shift.
Having said that, I come from a camera background and the early drone days where we had to focus dslrs before attaching them to servo driven gimbals. That sucked.