Are lenses using Focus by Wire to fake being Parfocal?

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#photography #videography #parfocal #focusbywire

Опубликовано:

30 сен 2024

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Комментарии : 20

@TVe200 2 года назад

I have tried two of my Zoom lenses (on an a7m4). The Tamron 70-180 works just as your 28-75. My Sigma 28-70 loose focus either I zoom fast or slow. (I can not test my 100-400 GM, because I am on a 10 days trip and the 100-400 rest at home).

@alberte6109 2 месяца назад

Wow, this made me realize that when I was using my dad's Nikon D80 and the 18-200 (I think, it's been quite some time since I used it), I often half press while zooming in or out and I didn't notice it before but the subject usually stays in focus when I do that... Maybe.

@networm64 2 года назад

Just tried the new kit lens Sony 28-60 on an old A6000 and surprise! It's parfocal! Even if it's only parfocal electronically and not optically. I couldn't get it out out focus for a second as fast as I could zoom in or out.

@TimvanderLeeuw 2 года назад

On my Fuji lenses, I see that when I zoom in or out the lens goes out of focus, then the focus “catches up”… 😁 Same as what you noticed. I think however that the same can be achieved with DSLR lenses that have AF, since they do also have focus motors. So I don’t know why the camera does this. I haven’t yet tested this with my adapted DSLR lenses, if I do I’ll add a comment with the results!

@DenBlendaman 2 года назад

Ok, what about parafocality varying, depending on zoom direction? Sigma Art DG HSM 18-35 F/1.8 is parafocal, while zooming from 35 to 18, but varifocal while unzooming from 18 to 35. Does it in any way connected to Focus by Wire? Because I genuenly have no idea. BTW kudos from Kiev, Ukraine, and keep up awesome work!

@DaveMcKeegan 2 года назад

I believe those are mechanically linked although not sure why it's one way, it could be an aspect of how it's linked makes it behave slightly different

@nightdonutstudio 9 месяцев назад

I find pretty much all my lens behavior like this. Focus on long end first and zoom out everything remain focus. But focus on wide end and then zoom in, not remain focus. I tested all my lens, they all behave this way. I doubt this is consider parfocal.

@nightdonutstudio 9 месяцев назад

Parfocal means focus on wide end and retain focus while zoom in, right? I find all my lens if focus at long end and zoom out, everything remain focus. and from that point I can keep zoom in and out everything in focus. But if I focus at wide end and zoom in it is not remain focus.

@RealCrashNG 2 года назад

I noticed the exact same thing in my 18-135 STM by Canon, when turned off the lens would just go out of focus Meanwhile when the camera was on and i moved it quickly it did the same thing as the lens in this video

@Anco 2 года назад

It seems like the canon EF-s 55-250 does the same trick (adapted to m50). So doesn´t seem to be only lenses for mirrorless cameras

@guyjordan8201 2 года назад

That’s clever and welcome behavior. A lot like automatic lens correction for aberrations and for focus breathing.

@noahfletcher3019 10 месяцев назад

I noticed this on my lumix s5 with the kit lens. Thanks for the explanation cuz I was very confused.

@panagiotistsiverdis 2 года назад

How on earth your channel does not have 200K plus subs, I don’t get it…

@carlmcneill1139 2 года назад

This is interesting. I will have to try this out on my z6 II and see how it works. I only have one native mount that is a zoom lens. The other two lenses are f mount but I believe they are focus by wire. Nikon is making all of their z lenses with video in mind. They all have silent motors and have very little, if any, focus breathing.

@tricamel 2 года назад

Hi Dave. It does make sense with a powered lens that the parfocal nature is digital. I have 3 zooms, all Sony, 24-70MkII, 70-200MkI and the 18-105 apsc power zoom. If you fancy a look, dm me as I am quite local to you.

@chryseass.5143 Год назад

Good boy, Rusty, and great explanation , Dave!

@lanegenovese 10 месяцев назад

Just tested my Sigma 24-70mm for Sony E mount, and it's only electronically parfocal. It's VERY non-parfocal when it's disconnected. This is a fascinating topic!

@tomkent4656 5 месяцев назад

If you focus at the telephoto end of the lens, you should be in focus for the whole zoom range.

@navidan2093 2 года назад

I noticed this on Fuji lenses a while ago, but it isn't as good as you have shown. When I zoom in too quickly my 18-55, things sometimes fall out of focus and stay that way. Therefore I always refocus to make sure I won't have blurred images