What true zoom for Pentax video?

dominikkolendo · 05-22-2012, 10:29 PM

@reivax
i just encountered this problem recently, after going from making stop-motion video to my first film video, and shooting a scene where the camera zooms in on someone's shocked face, i learned that i needed a parfocal lens.
eventually i went to my local vintage camera store and tried out a couple lenses while in video mode live view.
almost all the older manual lenses i tried were parfocal, i haven't bought one yet but i'll let you know when i do how it goes.
also, when shooting video, autofocus is usually a hindrance, not a help, so keep that in mind.

sjwaldron · 05-22-2012, 10:44 PM

Originally posted by eurostar

I am starting to make video with my k-5, and I have found one problem with my lenses (DA* 16-50 and 60-250): they are variofocal lenses that when you zoom, focus is not kept, and you have too refocus. This make impossimple to zoom during shooting. What options exists among older lenses for Pentax? In the past I had A35-105 and F70-210, but don't remember if they kept focus during zooming.

I did a pretty unscientific check with the DA 50-200mm WR and it seems pretty close (the camera did re-focus, but it was slight adjustment). There was some variation, but I think it might work. This sounds like good article material, but that's the only zoom lens I have these days!

twitch · 05-22-2012, 10:58 PM

DA 50-135 is parafocal

FullertonImages · 05-23-2012, 09:59 PM

Originally posted by twitch

DA 50-135 is parafocal

I you sure about that? From my experience, it's very close, much closer than most lenses, but it does stil seem to have a small shift in focus. Depending on whether you are going tele->wide or wide->tele, and what you're aperture is, you can still make it work for zooming in video, but it was my feeling that there was still some small change in focus. The Tamron 28-75 is also very very close to Parfocal.

Anvh · 05-24-2012, 09:17 AM

Originally posted by FullertonImages

I you sure about that? From my experience, it's very close, much closer than most lenses, but it does stil seem to have a small shift in focus. Depending on whether you are going tele->wide or wide->tele, and what you're aperture is, you can still make it work for zooming in video, but it was my feeling that there was still some small change in focus. The Tamron 28-75 is also very very close to Parfocal.

That's also my experience, it might be good enough if you use f/5.6 but at f/2.8 there is a shift noticable.

**mgvh** · 10-08-2012, 05:47 PM

Sorry to revive an old thread but no use starting a new one...
I also have been checking some zoom lenses to use for video on my K-x. As noted above, the K-x like the K-5 does not have autofocus once you start shooting video.
I did some checking and can add the following notes:

My beautiful little Pentax F 35-70 is parfocal.
The Pentax DA 16-45 is parfocal.
The Pentax DA 18-135, DAL 18-55, and Pentax DAL 55-300 are NOT parfocal.
I have a very nice older lens, the Tamron SP AF 24-135mm F/3.5-5.6 AD Aspherical [IF] and it is parfocal.
The Sigma EX 10-20 f4-5.6 is parfocal. (Since it's so wide, you have lots of room for error, but basically if you focus at 20mm, it will still be good at 10mm. If you focus at 10mm, it may be a bit off at 20mm.)

Maybe others can continue to add to this list. It would also be nice if this detail was included in the lens database summaries.

BTW, I see that the K-30 does allow you to readjust focusing while shooting video, but it does not offer continuous autofocus.
The initial report on the K-5 II is that it does not allow autofocus while shooting video.

kadajawi · 11-08-2012, 09:34 PM

Yes, the 18-55 kit lens will work (at least the old DA L).

TomGarn · 10-27-2013, 07:23 AM

Yes, parfocal lenses are a must for manual video !

You may try the Tamron 17-50 / 2.8 for Pentax
It is parfocal and well done anyway.

About old Pentax power-zooms with that high quality ...
it would be great to find them for sale ... or being revived.

Panasonic allready did that anew, but those "power-zoom" lenses
don't have the contious same aperture through all the focal length.

10-08-2012, 05:47 PM	#21
mgvh Site Supporter Join Date: Sep 2010 Location: MD Photos: Gallery \| Albums Posts: 1,029	More parfocal or not lenses Sorry to revive an old thread but no use starting a new one... I also have been checking some zoom lenses to use for video on my K-x. As noted above, the K-x like the K-5 does not have autofocus once you start shooting video. I did some checking and can add the following notes: My beautiful little Pentax F 35-70 is parfocal. The Pentax DA 16-45 is parfocal. The Pentax DA 18-135, DAL 18-55, and Pentax DAL 55-300 are NOT parfocal. I have a very nice older lens, the Tamron SP AF 24-135mm F/3.5-5.6 AD Aspherical [IF] and it is parfocal. The Sigma EX 10-20 f4-5.6 is parfocal. (Since it's so wide, you have lots of room for error, but basically if you focus at 20mm, it will still be good at 10mm. If you focus at 10mm, it may be a bit off at 20mm.) Maybe others can continue to add to this list. It would also be nice if this detail was included in the lens database summaries. BTW, I see that the K-30 does allow you to readjust focusing while shooting video, but it does not offer continuous autofocus. The initial report on the K-5 II is that it does not allow autofocus while shooting video. Last edited by mgvh; 10-09-2012 at 10:01 AM.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Little bird video made with Pentax KR and cheap zoom lens.	cbeeching	Pentax K-r	4	02-20-2012 03:30 AM
Pentax delivers the best TRUE PRO camera for both worlds ?	pTom	Pentax K-5 & K-5 II	42	04-02-2011 11:47 PM
Are old push/pull zoom lenses better for video?	jake14mw	Video Recording and Processing	3	01-16-2010 10:38 AM
K-7, First DSLR w/ True Aperture Control with Video!	HermanLee	Pentax News and Rumors	11	05-20-2009 06:59 PM
My First True Test Of k100d and Sigma Zoom	shutterpuppy	Pentax DSLR Discussion	12	04-01-2008 04:52 PM

05-22-2012, 10:29 PM	#16
dominikkolendo Site Supporter Join Date: Jan 2012 Location: portland, or Posts: 105	@reivax i just encountered this problem recently, after going from making stop-motion video to my first film video, and shooting a scene where the camera zooms in on someone's shocked face, i learned that i needed a parfocal lens. eventually i went to my local vintage camera store and tried out a couple lenses while in video mode live view. almost all the older manual lenses i tried were parfocal, i haven't bought one yet but i'll let you know when i do how it goes. also, when shooting video, autofocus is usually a hindrance, not a help, so keep that in mind.

05-22-2012, 10:44 PM	#17
sjwaldron Veteran Member Join Date: Aug 2009 Photos: Gallery Posts: 1,235	Originally posted by eurostar I am starting to make video with my k-5, and I have found one problem with my lenses (DA* 16-50 and 60-250): they are variofocal lenses that when you zoom, focus is not kept, and you have too refocus. This make impossimple to zoom during shooting. What options exists among older lenses for Pentax? In the past I had A35-105 and F70-210, but don't remember if they kept focus during zooming. I did a pretty unscientific check with the DA 50-200mm WR and it seems pretty close (the camera did re-focus, but it was slight adjustment). There was some variation, but I think it might work. This sounds like good article material, but that's the only zoom lens I have these days!

05-22-2012, 10:58 PM	#18
twitch Veteran Member Join Date: Nov 2009 Posts: 4,571	DA 50-135 is parafocal

05-23-2012, 09:59 PM	#19
FullertonImages Veteran Member Join Date: Apr 2009 Location: Boulder, CO Posts: 883	Originally posted by twitch DA 50-135 is parafocal I you sure about that? From my experience, it's very close, much closer than most lenses, but it does stil seem to have a small shift in focus. Depending on whether you are going tele->wide or wide->tele, and what you're aperture is, you can still make it work for zooming in video, but it was my feeling that there was still some small change in focus. The Tamron 28-75 is also very very close to Parfocal.

05-24-2012, 09:17 AM	#20
Anvh Veteran Member Join Date: Sep 2011 Posts: 4,616	Originally posted by FullertonImages I you sure about that? From my experience, it's very close, much closer than most lenses, but it does stil seem to have a small shift in focus. Depending on whether you are going tele->wide or wide->tele, and what you're aperture is, you can still make it work for zooming in video, but it was my feeling that there was still some small change in focus. The Tamron 28-75 is also very very close to Parfocal. That's also my experience, it might be good enough if you use f/5.6 but at f/2.8 there is a shift noticable.

11-08-2012, 09:34 PM	#22
kadajawi Veteran Member Join Date: Sep 2010 Posts: 2,799	Yes, the 18-55 kit lens will work (at least the old DA L).

10-27-2013, 07:23 AM	#23
TomGarn Veteran Member Join Date: Sep 2013 Location: Hamburg Posts: 339	Yes, parfocal lenses are a must for manual video ! You may try the Tamron 17-50 / 2.8 for Pentax It is parfocal and well done anyway. About old Pentax power-zooms with that high quality ... it would be great to find them for sale ... or being revived. Panasonic allready did that anew, but those "power-zoom" lenses don't have the contious same aperture through all the focal length.