Parfocal lens for FS700 ?

J

jodyjody11

Member
I am using Sony NEX-FS700 and the SELP18105G lens. That lens is a parfocal lens so that there is no hunting or re-focusing when zooming. However, when I try to use the latest Tamron 70-200 lens (A009), the focus point is changed significantly when zooming in or out. It's definitely not a parfocal lens, and it's unusable for videography. Is there any parfocal lens in the 200mm range? On B&H, I find one made by Zeiss. It's a 70-200mm cine lens with T2.9 aperture, but listed as US$19,900. That's even more expensive than a Honda Civic.
 
It seems there's a whole slew of non parfocal lenses on the market, these days. Maybe it's because using a DSLR lens on a video camera has become so popular. Unfortunately, as you've pointed out, a non-parfocal lens is pretty much useless for video work, unless you're ready for some keyframing in post. There are a few parfocal lenses in the lot of DSLR lenses. The two that come to mind are the canon 70-200 2.8 L lens, and the 24-105 canon f4. If you want to spend a little more, step out of those DSLR lenses and look at used Red lenses. You can get a PL to e-mount adapter to use these cine lenses on the FS700.
 
Parfocal Zoom Lens I had used and tested:
RED 18-50/3
Minolta 35-70/3.5
Canon 24-105/4

Other known or stated Parfocal lens:
Sony FE 28-135/4
RED 17-50/3
RED 50-150/3
Tokina Cine Lens (Not the DSLR lens)
11-16/3, 16-28/3, 50-135/3
http://www.tokinacinema.com
GL optic 18-35/1.8
 
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The Sigma 50-150 (at least the old version) is parfocal. But that doesn't reach your desired 200mm. Cuervo
in a post above said the Canon 70-200 F2.8 was parfocal.....You could try renting a couple (maybe a Sigma or
Tamron 70-200 or a Nikon?) and testing them maybe? I usually get by with the Sigma 18-35 and 50-150 or
use the Sony 18-105 for R&G. Also have a old FD 50mm F1.4 so i have no experience with the 70-200mm lenses.
Good thing about the FS700 is that it can use so many lenses....but that means a lot of lenses to test out too....
 
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My copy of the new version of the Sigma 50-150 is also mostly parfocal. I think there's a fairly high chance of if varying from copy to copy, though.

I run the same sort of setup as alaskacameradude and love it.
 
I have a Nikon 18-200mm VR I (they came out with a new version that's exactly the same but has zoom lock, called VR II), which holds focus while zooming. It's really sharp for a zoom lens of this range, and you can use it with a Speedbooster to make it slightly faster. Of course, you don't get the VR (IS), nor any auto functions, and you need an adapter that allows you to control the Iris. It doesn't have an Iris ring.

I find this to be a really fun lens!
 
I also use the A009 but haven't really noticed that it isn't parfocal it takes me less than 2 seconds to adjust my focus with peaking enabled (best feature ever). I just wanted to know do you use a lens support when using the lens or do you let the lens mount bear the weight of the lens as the downforce might interfere with the electronics moving the lens away from the contact pins so it can't communicate at 100% thus creating the illusion that it isn't parfocal. I will double check mine at some point today.
 
Sorenson said:
There is always this beauty Sony 18-200. not a horrible lens, not a good lens either... but not horrible. similar to what you're using.
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I used to have it, but sold it along with the EA50 it came with. Never expected I'd miss it so much.
Will probably end up picking up another at one point. Really rather useful lens with good auto focus and the active steady shot mode.
 
There's also the new sony 28-135 f4. I'm probably going to look into this when the budget allows. Anyone used it on the FS700? I know it's popular on the A7s and Fs7.
 
Sorenson said:
There's also the new sony 28-135 f4. I'm probably going to look into this when the budget allows. Anyone used it on the FS700? I know it's popular on the A7s and Fs7.
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The 28-135 F4 lens is so much more expensive than my 18-105mm F4 lens because the former is a full frame lens with more control functions, and the latter is a half frame lens with less control functions. Both are very popular power zoom lens. However, the sensor of FS700 is Super 35mm (very close to half frame) and it can't fully benefit from the 28-135mm full frame lens quality. Maybe using that lens on Sony A7 series would make more sense?
 
CinematicFanatic said:
I also use the A009 but haven't really noticed that it isn't parfocal it takes me less than 2 seconds to adjust my focus with peaking enabled (best feature ever). I just wanted to know do you use a lens support when using the lens or do you let the lens mount bear the weight of the lens as the downforce might interfere with the electronics moving the lens away from the contact pins so it can't communicate at 100% thus creating the illusion that it isn't parfocal. I will double check mine at some point today.
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I never let the lens mount bear the weight because it's too heavy, and I am afraid of damaging the mount. I use a lens support device on my 15mm rods. I bought it from China and it only costs less than $20. It looks exactly the same as this one:
http://store.redrockmicro.com/Catalog/microClamps/microLensSupport.html

With that support, the lens mount does not need to bear any weight.
 
Sorenson said:
There's also the new sony 28-135 f4. I'm probably going to look into this when the budget allows. Anyone used it on the FS700? I know it's popular on the A7s and Fs7.
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I rented one for a shoot. It was fine, but for that shoot, I feel I would have been better served by the 18-200 actually. But it was a well lit stage.
The only times I need power zooms is when I shoot live performances, and they never pay enough to justify a lens as expensive as the 28-135 ;)
The 18-105 is probably as cheap as it is because the optics needs fixing in software to be useful, which means they took some shortcuts to make it cheaper.
 
dmitrizigany said:
I rented one for a shoot. It was fine, but for that shoot, I feel I would have been better served by the 18-200 actually. But it was a well lit stage.
The only times I need power zooms is when I shoot live performances, and they never pay enough to justify a lens as expensive as the 28-135 ;)
The 18-105 is probably as cheap as it is because the optics needs fixing in software to be useful, which means they took some shortcuts to make it cheaper.
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I thought the 28-135 needed distortion correction in camera as well.....
 
dmitrizigany said:
Maybe it does!? I honestly don't know. Don't think its to the same extent as the 18-105 though.
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I haven't used it but pretty sure I saw a video with Juan Martinez from Sony
talking about the distortion correction needed for the 28-135. But it is quite possible
the 18-105 is more distorted.

However, the 28-135 is a full frame lens (instead of the Super 35 that the 18-105 is,
which means more glass) plus it is more of cinema lens (real iris ring for example.)
So several reasons it is more expensive than the 18-105. It sounds like Sony
is planning on making more 'cinema' lenses like the 28-135 which is nice.
 
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