lördag 26 februari 2011

PL-glass or still lenses for Sony F3

I'm writing this post in English since I know there is a lot of interest in this subject in the video community outside of Sweden as well. Bear with me - it’s not my first language.

One of the interesting things with the Sony PMW-F3 is that it is a camera that unites two different areas of shooting. A lot of people buying it (like me) come from a broadcast background and are looking for a more exclusive and creative look for documentaries and current affairs. Some of us have struggled with DOP-adapters and DSLR:s for the last few years to achieve this.
The other group is coming from the film and commercial area. They are used to big chunky camera setups, focus pullers and lots of time to setup shots. These two areas have very different criteria for what is important in a good camera setup. I’m stating this to underline that the purpose of this post is not to give any generic answers to what lenses to choose for the F3, only to share what my conclusions are after some research and a week of using the camera.

I’m mostly shooting documentaries and current affairs. This means shooting interviews, some run-and-gun style work and shooting B-roll using a tripod. Therefore I am very curious to see what the coming Sony ENG-lens for the F3 will be like. Hopefully it will transform my F3 to something that is almost as easy to handle as my EX1. But that lens is almost a year away and in the meantime I need a collection of glass that will let me do my work. Also – it will be a slow lens which will possibly give it a look more like a traditional ENG-lens when it comes to depth of field.
For me there are three important criteria when choosing what path I should take.

1. Ergonomics
2. Image quality
3. Price

There is no doubt that PL-lenses offer another level of ergonomics than still lenses. They have long focus paths, manual aperture without clicks, no moving front lenses and smooth action. Compared to cheap plastic modern still lenses they are a dream to handle.
However choosing the right still lenses you can sometime come pretty close. The new Zeiss Distagon lenses and older Nikon still lenses are very well built, smooth and usually have relatively long focus paths. The problem is that they are small and fiddly to handle. However, if you are using a good follow focus and get used to finding the small aperture ring quickly with your hand they are not that far from using a prime. Of course you have to get rid of the aperture clicks. I own six Nikon Nikkor primes and I had them all declicked at a local Nikon repair shop for €190 including cleaning.
I found cheap focus gears from Dfocus systems that work well. I’d also like to try the ones from Half inch rails that look good.

Another problem with still lenses is that the front element can move a lot, especially on zooms. This sometimes makes it hard to use a matte box and you can’t use donuts very well either. On some lenses, like my 55 mm Nikkor macro, the focus ring moves when focusing so it is impossible to use a follow focus.
I am using Mike Tapas MTF-adapter with my Nikon lenses. It works well but when using lenses without aperture you are left with a very small knob on the adapter to change aperture. This is not as good as using the aperture ring on the lens. There is no way to see what f-stop you are at and the knob is really hard to reach. I am planning a small mod to make it longer. Hopefully that will eliminate the problem.

My conclusion when it comes to ergonomics is that PL-lenses win, hands down. But in a lot of situations you can come reasonably close with a good still lens.

Image quality
When I started to research what lenses I should get for my F3 I was under the delusion that PL-lenses were superior in all senses, particularly when it came to image quality. This is not the case. In fact modern still lenses can outperform older PL-lenses many times more expensive.
A couple of days ago I performed an unscientific test of a kit of older Zeiss PL-lenses compared to my old Nikons and the new cheap Sigma 18-50 f2.8 zoom. To top it all off I tested a Zeiss Master prime 50 mm t1.3 costing as much as the camera. The results surprised me!
Have a look at the still grabs below. I’m afraid I was a little sloppy setting up the shots and the framing is not identical so take it for what it is. It gives a hint on what the differences between the lenses are though.

Nikon 50 mm f1.4

Sigma zoom @50 mm f2.8

Arri Master Prime 50 mm t1.3

Nikon 50 mm f5.6

The three first images above show the lenses wide open. The Master Prime is of course sharpest. The Nikon is very soft at the edges but stopped down a little it is actually sharper then the Master Prime wide open and the Sigma is not bad at all @2.8.

Sigma zoom @18 mm f2.8

Arri 16 mm T2.1

The two pictures above show the Sigma zoom wide open and the Arri 16 mm wide open. The Sigma is better in every sense. The Arri is vignetting heavily and is very soft at the edges. Taken into consideration that the Sigma is a zoom, I was impressed.
Now – PL-lenses have other optical advantages. The Sigma zoom breathes a lot and it is not very good at holding focus through the zoom. But my conclusion is that when it comes to actual image quality a good still lens can absolutely match a good PL-lens. Especially if stopped down a few steps.

There are reasons why PL-lenses are many times as expensive as still lenses but there is no absolute correlation between price and what you get, especially not if you only look at image quality. The market for still lenses is sooo much larger than that for PL-lenses so you can count on a lot of the cost of PL-lenses being down to small series rather than exceptional quality. It is also not uncommon that PL-lenses and still lenses share the same glass. The Red 18-50 zoom supposedly uses the same glass as the Sigma zoom that I have tested. The Red zoom is a cheap PL-mount at $4000. The same glass in the shape of a Nikon mount Sigma is available for $400. That’s a big premium for better ergonomics.

Without a doubt still lenses are the winners when you consider price. Now – after the release of the Panasonic AG-AF101 and the PMW-F3 the demand for PL-lenses is seeing a dramatic increase. Hopefully the lens manufacturers are working right now on cheaper PL-lenses for this market. In the long run there is no way the price difference can stay this big. Only high end cinema and commercials can justify the cost. Hopefully by the time Sony release their ENG-lens for the F3 there will be a whole lot more cheap PL-lenses on the market as an alternative. Who knows what will make most sense to buy then, until then – I will stick with my still lenses.

Check out my first test shoot with my F3 and cheap still lenses. Klick the link above to see it in HD.

8 kommentarer:

  1. Thanks for the test Ola! It's great to get another guide in the giant djungle of leses, cameras and video formats. Have you noticed any back focus problems with your stuff? That you'll loose focus by zooming. I've spoke to a guy at SVT who had experienced that problem testing a AF 101.

  2. Hi Andreas!

    This is not the cameras fault. Most, if not all, still zoom lenses will be bad at keeping focus while zooming. They are not designed to do that and if that is important to you, PL-glass is the way to go. My only zoom lens - the Sigma 18-50 f2.8 is ok at holding focus though. However, you should look at still zooms as variable primes, not as ENG-lenses that you can use to zoom in and out while filming. But who wants to zoom anyway?

  3. Thanks for this, very well written and informative.

  4. I've been following Alister Chapmans development of an adapter so the F3 can take a 2/3 ENG zoom. He hopes it'll be available shortly and while I'm not madly enthusiastic about dealing with another adapter again, it will give the camera far greater range for quick documentary shooting.

    Have you had to adjust the back focus on your F3 at all?


  5. No, never changed it. The back focus seems to be fairly constant on all my Nikons. Infinity is where it should be. However, I got a loaner camera from Sony a couple of weeks ago with a backfocus that was way off. I fiddled with it a lot before I managed to get it right.

  6. Thx for sharing your experiences. One important thing about the test is that the framing of the chart should have been exactly the same for all lenses, then the comparison would have been more accurate

  7. camera lenses are very good and its a great concept

  8. Thanks for review, it was excellent and very informative.