Tag Archives: zoom

How big a compromise is using a DSLR zoom on a 4K camera?

This came up as a question in response to the post about my prototype lens adapter. The adapter is based around an electronic Canon EF mount and the question was, what do I think about DSLR zooms?

There is a lot of variation between lenses when it comes to sharpness, contrast and distortions. A zoom will always be a compromise compared to a prime lens. DSLR lenses are designed to work with 24MP sensors. A 4K camera only has around 9MP, so your working well within the design limits of the lens even at 4K. While a dedicated PL mount zoom like an Angenieux Optimo will most likely out perform a similar DSLR zoom. The difference at like for like apertures will not be huge when using smaller zoom ratios (say 4x). But 10x and 14x zooms make more compromises in image quality, perhaps a bit of corner softness or more CA and these imperfections will be better or worse at different focal lengths and apertures. At the end of the day zooms are compromises but for many shoots it may simply be that it is only by accepting some small compromises that you will get the shots you want. Take my storm chasing shoots. I could use primes and get better image quality, but when you only have 90 seconds to get a shot there simply isn’t time to swap lenses, so if you end up with a wide on the camera when a long lens is what is really needed, your just not going to get the shot. Using a zoom means I will get the shot. It might not be the very best quality possible but it will look good. It is going to be better than I could get with an HD camera and a very slightly compromised shot is better than no shot at all.
If the budget would allow I would have a couple of cameras with different prime lenses ready to go. Or I would use a big, heavy and expensive PL zoom and have an assistant or team tasked solely with getting the tripod set up and ready asap. But my budget isn’t that big. I could spend weeks out storm chasing before I get a decent shot, so anything I can do to minimise costs is important.
It’s all about checks and balances. It is a compromise, but a necessary one. It’s not a huge compromise as I suspect the end viewer is not going to look at the shot and say “why is that so soft” unless they have a side by side, like for like shot to compare. DSLR zooms are not that bad! So yes, using a DSLR zoom is not going to deliver quality to match that of a similar dedicated PL zoom in most cases, but the difference is likely to be so small that the end viewer will never notice and thats a compromise I’m prepared to accept in order to get a portable camera that shoots 4K with a 14x zoom lens.

What about DSLR primes and why have I chosen the Canon Mount?

This is where the image performance gap gets even narrower. A high quality DSLR prime can perform just as well as many much more expensive PL mount lenses. The difference here is more about the usability of the lens. Some DSLR lenses can be tiny and this makes them fiddly to use. They are all All sorts of sizes, so swapping lenses may mean swapping Matte boxes or follow focus positions etc. Talking of focus, very often the focus travel on a DSLR lens is very, very short so focussing is fiddly. If the lens has an aperture ring it will probably have click stops making smooth aperture changes mid shot difficult. My prime lenses are de-clicked or never had clicks in the first place (like the Samyang Cine Primes). It’s not so much the issue of requiring a finer step than the one stop click, but more the ability to pull aperture during the shot. It’s not something I need to do often, but if I suddenly find I need to do it, I want a smooth aperture change. That being said, one of the issues with using Canon EF lenses with their electronic iris is that they operate in 1/8th stop steps and this is visible in any footage. Ultimately I am still committed to using the Canon mount lenses simply because there are so many to choose from and they focus in the right direction unlike Nikon lenses which focus back to front. For primes I’m using the excellent and fully manual Samyang T1.5 Cine Primes. I really like these lenses and they produce beautiful images at a fraction of the price of a PL mount lens. My zoom selection is a bit of a mish-mash. One thing about having a Canon mount on the camera is that I can still use Nikon lenses if I fit the lens with a low cost Nikon to Canon adapter ring. If you do this you can only use lenses with an actual iris ring, so generally these are slightly older lenses, but for example I have a nice Sigma 24-70mm f2.8 with a manual iris ring (and it focusses the RIGHT way, like most Sigmas but unlike most Nikon mount lenses). In addition I have a 70-300mm f4 Nikon mount Sigma as well as an Old Tokina 28-70mm f2.6 (lovely lens, a little soft but very nice warm colour). One thing I have found is that most of the Nikon to Canon adapter rings are little bit on the thin side. This prevents any zooms from being Parfocal as it puts the back focus out. Most of the adpaters are made in two parts and it’s quite easy to take the front and back parts apart and add shims made out of of thin plastic sheet or even card between the two halves to correct the back focus distance.

So there you have it. Overall DSLR lenses are not a huge compromise. Of course I would love to own a flight case full of good quality PL mount, 4K ready, glass. Perhaps one day I will, but it’s a serious investment. Currently I use DSLR lenses for my own projects and then hire in better glass where the budget will allow. For any commercials or features this normally means renting in a set of Ultra Primes or similar.  I am keeping a close eye on the developments from Zunow. I like their 16-28mm f2.8 and the prototype PL primes I saw at NAB look very good. I also like the look of the Zeiss 15.5 to 45 light weight zoom. Then of course there is the excellent Fujinon 19-90mm Cabrio servo zoom, but these are all big bucks. Hopefully I’ll get some nice big projects to work on this year that will allow me to invest in some top end lenses.

Fujinon Cabrio 19-90mm T2.9 PL Mount Zoom Lens.

Fujinon Cabrio PL Zomm

This is a new lens announced today by Fujinon. It’s a 19-90mm T2.9 PL mount zoom lens, which in itself isn’t particularly interesting, there are plenty of similar lenses on the market. What is very interesting is that this lens has a removable hand grip that contains motors for the zoom and iris. So this lens bridges the gap between a traditional 2/3″ ENG style lens and a PL cine lens. If you don’t need the servo functions you can remove the hand grip. The lens has standard 0.8mod gears on the focus, zoom and iris rings so conventional follow focus motors can be used. In addition the lens is very lightweight for a PL zoom. Clearly this lens is in response to the growing use of Super 35mm camcorders in documentaries, news and other similar applications.

Frame Grabs from MTF B4 2/3″ to Canon C300, 7D, 550D, Sony F3, FS100 etc adapter.

Canon J16 SD 2/3" lens on a Canon C300, Wide.

I’ve been asked a couple of times for some frame grabs shot with one of the MTF B4 to super 35MM adapters that I designed. Well, here they are. Shot on a Canon C300 fitted with the adapter and an old standard definition Canon J16 zoom lens. It was late in the day when I shot this so it’s not showing the adapter in its best light and of course an HD lens would be even better.

 

Canon J16 2/3" SD zoom on a Canon C300, Tele.

Click on the thumbnails to view a larger image or the full resolution image. I love the fact that even when using a super35mm sensor you can still have this great par-focal zoom range. Put a 20x ENG zoom and you can get both wider and closer!

http://www.mtfservices.com/home.html?page=shop.product_details&flypage=flypage.tpl&product_id=110&category_id=2

Playing with lenses: 2/3″ Broadcast lens on PMW-F3.

OK folks. I wanted to see just how well a 2/3″ broadcast lens would work on an F3, but don’t have $5.5k to fork out on one of the Abel adapters. So with a bit of head scratching, a few, lowish cost lens purchases and a few hours in the workshop I cobbled together my own adapter. At first I tried a 2x magnifier but this didn’t quite give me full sensor coverage and was soft out in the corners. With a little more work I took the magnification up to 2.5x and I have clean corners. I’m really pleased with the performance, although one lens element needs changing for a higher quality element to combat some softness when the iris is fully open.

My old Canon J16x8 f1.8 becomes a 24 to 320mm f4(ish) par-focal lens which is actually quite handy. Next step is to make up a power cable for the lens so I can use the zoom servo.

I’m considering trying to find a manufacturer that can make these up for me properly, the converter should cost a lot less than $5.5k

Playing with lenses: 2/3″ Broadcast lens on PMW-F3.

OK folks. I wanted to see just how well a 2/3″ broadcast lens would work on an F3, but don’t have $5.5k to fork out on one of the Abel adapters. So with a bit of head scratching, a few, lowish cost lens purchases and a few hours in the workshop I cobbled together my own adapter. At first I tried a 2x magnifier but this didn’t quite give me full sensor coverage and was soft out in the corners. With a little more work I took the magnification up to 2.5x and I have clean corners. I’m really pleased with the performance, although one lens element needs changing for a higher quality element to combat some softness when the iris is fully open.

My old Canon J16x8 f1.8 becomes a 24 to 320mm f4(ish) par-focal lens which is actually quite handy. Next step is to make up a power cable for the lens so I can use the zoom servo.

I’m considering trying to find a manufacturer that can make these up for me properly, the converter should cost a lot less than $5.5k

Canon XF105, using OIS to correct zoom axis shift. (3D applications)

While I was in Singapore last week I got to play with a pair of Canon’s XF105’s on a Genus Hurricane 3D rig. We were able to use the programmable axis shift function to compensate for the way the zoom lenses don’t remain centred as you change focal length. Zooming in 3D with two cameras is very hard to do because of this shift, normally requiring very expensive matched lenses. With the 105’s and and a few minutes of adjusting we were able to do synchronised zooms (using the IR remote) that retained very good tracking and accuracy. This really is quite remarkable at this price point!

Can you use a 2/3″ Zoom on a 35mm camera??

Can you use a 2/3″ B4 broadcast zoom on a 35mm camera. Well yesterday I would have said “no”, but having seen this video on the AbelCine web site, now I’m not so sure. UPDATE: OK Should have read the specs…. it’s only suitable for smaller sensors as it has a 22mm image circle, the F3 has a 27mm diagonal. It’s still a viable option for the AF100 however.

http://blog.abelcine.com/2011/02/11/using-23-lenses-on-the-panasonic-af100/

The HDx2 adapter magnifies the image to fill a 35mm sensor, doubling the focal length at the same time. This is very intriguing as 35mm zooms are few and far between and very expensive. There is a 2 stop light loss (well if you expand the image 2 times that’s what happens) but most broadcast zooms are pretty fast lenses to start with. I can’t help but think that the pictures might be a little soft, but if you already have decent 2/3″ glass then the $5,500 for the adapter might make a lot of sense. Anyone out there with experience of one of these? I’d love to know how it performs.

Can you use a 2/3″ Zoom on a 35mm camera??

Can you use a 2/3″ B4 broadcast zoom on a 35mm camera. Well yesterday I would have said “no”, but having seen this video on the AbelCine web site, now I’m not so sure. UPDATE: OK Should have read the specs…. it’s only suitable for smaller sensors as it has a 22mm image circle, the F3 has a 27mm diagonal. It’s still a viable option for the AF100 however.

http://blog.abelcine.com/2011/02/11/using-23-lenses-on-the-panasonic-af100/

The HDx2 adapter magnifies the image to fill a 35mm sensor, doubling the focal length at the same time. This is very intriguing as 35mm zooms are few and far between and very expensive. There is a 2 stop light loss (well if you expand the image 2 times that’s what happens) but most broadcast zooms are pretty fast lenses to start with. I can’t help but think that the pictures might be a little soft, but if you already have decent 2/3″ glass then the $5,500 for the adapter might make a lot of sense. Anyone out there with experience of one of these? I’d love to know how it performs.

Chasing Vulcans.


Last weekend was the Royal International Air Tattoo. The largest military air show in the world. I’ve filmed this event many times and every year we try to do things a little differently to jazz things up. We have been shooting the show in HD for the past 3 years, this year it was entirely XDCAM with the exception of the minicams which were HXR-MC1P HD minicams. We had an EX1, EX3 and 3x PDW-700?s. As well as the usual extra long telephoto lenses we had a couple of gyro stabilized lenses including a schwem gyrozoom. While not an HD lens we found that the performance of the lens wasn’t too bad. There is no other lens that offers the degree of stabilization offered by the schwem so for the applications we were using it for we were happy to accept the slight softness in the corners. The application we had was to use it in one of the “Follow Me” vehicles used to marshall the aircraft around the airbase.

The high point of this was doing a tracking shot of the recently restored Vulcan bomber landing at Fairford. To do this we drove along the taxiway parallel to the runway at high speed as the Vulcan came into land. Once it had landed we got some impressive shots as it taxied right behind us. The Vulcan is a huge aircraft and to have this bearing down on you as it taxies with all four engines running (they normally use only 2) is quite a rush! The Schewm is a long lens so the Vulcan completely filled the frame, despite this the gyro stabilisation kept the images rock steady. Over the weekend I shot aircraft startups and GV’s using an EX3, then the follow me stuff with the schwem and PDW-70 as well as flying and display footage using a PDW-700 and 42x Fujinon lens. The most reassuring thing is that as these are all XDCAM cameras we know they will all cut together well in the final edit.