Is Panasonic 12-35mm II parfocal?

I was wondering if Panasonic 12-35mm II is parfocal? i mean the focus won't change if i zoom in or out. I just acquired a used GH5 and the only lens i have right now is 42.5mm f/1.7

First I thought I want fix manual lens, something like Rokinon 12mm, but then I decide to get zoom first  and save $ to get Voightlander 17.5mm in the future.

Thanks.

I don't know about the 12-35 per se but it would be exceptional for it to be parfocal.

However, many newer camera-lens combinations are able to apply focus correction as you zoom, giving you the (false) impression that the lens is parfocal whereas instead of the focus not changing as you zoom it deliberately changes to compensate for the lens not being parfocal.

You can hear this actually: half-press to achieve focus. Then let go of the shutter button (so as to not refocus deliberately), zoom in and out and listen carefully to the lens. When you hear something moving (as in driven by a motor) it is the focus mechanism changing focus so as to keep actual focus constant. So for all practical purposes it is as if the better modern zoom lenses are parfocal: you can change the zoom to some extent and more or less retain focus.

What Paul said. All current panasonic zooms I've tried have exhibited parfocal behavior by electronic compensation. Would expect the 12-35ii to do the same.

Holistic Photog wrote:

It's not important in stills to have true parfocal behavior, but if you do manual focus in video, AF to give the illusion of parfocality obviously won't help. Even if you do AF in video, there might still be a difference between true parfocality and mimicked.

The electronic compensation for native zooms is just the same whether you're doing auto or manual focus; doesn't really matter who's moving the elements around.

Both the 14-140ii and the 100-300ii that I use regularly display perfectly parfocal behavior in manual focus.

Curious if it compensates for Olympus zooms too actually. Any 12-40 users on panasonic bodies care to chime in?

hindesite wrote:  I personally think you asked the wrong question - because nobody cares if the lens is parfocal these days; it is almost certainly electronically adjusted so the effect for the end user is the same.

I disagree, if you ever shoot SPORTS, that total 3 ~ 6 seconds lost due to camera re-focusing after changing zoom range is DEADLY.  Its the difference between "getting the shot" versus losing all the shots.

A true parfocal zoom can

• Retain AF (no need to refocus) while changing Zoom from 70mm to 200mm back to 70mm. 
• Parfocal zoom makes them excellent of TRACKING, fellow focus, and mostly for shooting sports when you need to Zoom Out to wider 70mm then zoom into tigher 200mm head shots

Versus cheaper Non-Par-Focal

• cannot retain AF when you change your zoom range
• every change in zoom ring will require another Focus Readjustment
• more you Zoom In/Out, more Lost Time in Refocusing is required and is costly in sports shoooting.

AFAIK, Panasonic 12-32 II isn't parfocal, so changing from 12mm to 32mm will induce a camera to refocus.  One solution is to buy the Sigma 18-35/1.8 HSM (canon version) and used a $600 Magic Lantern adapter.

Having said that, In Real Life, I find PARFOCAL rather meaningless in the WIDE-to-Normal zoom because camera can focus so fast that losing refousing and refocusing isn't as costly as it is in Telephoto Zoom with heavy lens elements.

007peter wrote:

hindesite wrote: I personally think you asked the wrong question - because nobody cares if the lens is parfocal these days; it is almost certainly electronically adjusted so the effect for the end user is the same.

I disagree, if you ever shoot SPORTS, that total 3 ~ 6 seconds lost due to camera re-focusing after changing zoom range is DEADLY. Its the difference between "getting the shot" versus losing all the shots.

I don't know where you're getting this figure. The adjustment happens pretty much instantaneously as you're turning the zoom ring. I can't feel any delay.

Unless you're pressing the shutter button quite literally as you're turning the zoom to get some special effect, it doesn't make any difference.

Lucas Jarvis wrote:

Stejo wrote:

Curious if it compensates for Olympus zooms too actually. Any 12-40 users on panasonic bodies care to chime in?

I noticed that the G9 and the Olly 40-150 2.8 Pro combo is not parfocal and does not use any compensation to overcome it.

Interesting, thanks. So, one more reason to stick with same brand lenses for zooms.

Now the question remains if Oly bodies do any sort of compensation for zooms of either brand.

andyus08 wrote:

I was wondering if Panasonic 12-35mm II is parfocal? i mean the focus won't change if i zoom in or out. I just acquired a used GH5 and the only lens i have right now is 42.5mm f/1.7

First I thought I want fix manual lens, something like Rokinon 12mm, but then I decide to get zoom first and save $ to get Voightlander 17.5mm in the future.

Thanks.

I have the first generation and it is not corrected to parfocality (by the focusing mechanism, as already discussed) at the wide end. It is ok between 18-35mm. As always with these  corrections, focus has to be locked at the long end and the correction while zooming can be noticed.

hindesite wrote:

Stejo wrote:

Lucas Jarvis wrote:

Stejo wrote:

Curious if it compensates for Olympus zooms too actually. Any 12-40 users on panasonic bodies care to chime in?

I noticed that the G9 and the Olly 40-150 2.8 Pro combo is not parfocal and does not use any compensation to overcome it.

Interesting, thanks. So, one more reason to stick with same brand lenses for zooms.

Now the question remains if Oly bodies do any sort of compensation for zooms of either brand.

Why?

Doesn't the example show the possibility (which is my assumption) that the lens manages it own corrections of focus to maintain parfocality; after all, these lens know their own characteristics and could adjust accordingly (just as they used to do using mechanical designs in the past).

Nothing to do with the camera body for this function; AF is not involved.

Exactly, the lens is doing the correction by itself, nothing to do with the body. For example, the 9-18mm and 12-50mm Oly lenses I own are correcting themselves as expected on my Panasonic bodies.

hindesite wrote:

Why?

Doesn't the example show the possibility (which is my assumption) that the lens manages it own corrections of focus to maintain parfocality; after all, these lens know their own characteristics and could adjust accordingly (just as they used to do using mechanical designs in the past).

Nothing to do with the camera body for this function; AF is not involved.

The lens can't power its AF motor by itself. Nor does it have an advanced processing engine on board typically. In order to keep shifting the elements around to maintain parfocality, somebody has to apply precise amounts of electrical current at specific moments. It seems unlikely that a lens would be allowed access to power on demand without the body provisioning for it.

Furthermore, the more likely scenario is that the amount of current required has to be judged on the basis of the projected image rather than focal length change. Seems reasonable to assume that as you're zooming in and out the body adjusts focus accordingly to maintain maximum contrast at the original focus plane.

After all, if manufacturing tolerances were so precise that all copies of the same model lens have the exact same focus drift when zooming in and out that the same preset amount of power could fix it, they might as well be truly parfocal in the first place.

But this is all conjecture. If somebody knows what's the actual inner workings of the system, I'm all ears. And the speed at which the adjustment happens also had me wondering if it's a DFD thing. Not sure if it's full on CDAF happening at that moment, fast as it might be. If Oly bodies do it too, then it's obviously not DFD. Might be the lens by itself too, as you say. Really don't know.