Tag Archives: PL

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.

Triad PL to E-Mount Adapter. A PL adapter for the FS100 and FS700.

Triad E-Mount to PL adapter

A little while back I was loaned a Triad PL to E-Mount adapter for review. E-Mount is the Sony mount used on the NEX-FS100, NEX-FS700 as well as The VG10, VG20 and NEX stills cameras. While more and more E-Mount lenses are becoming available from Sony and other DSLR lens manufacturers there will be many times when something more suitable for video work might be needed. One of the big issues with DSLR lenses is the very small amount of rotation on the focus ring to go from near to far, often only 45 degrees which makes accurate focus tricky. A good PL mount lens will have over 180 degrees of rotation. PL has been the industry standard for movie cameras for years and most rental companies have large ranges of PL lenses to choose from. So the ability to be able to use a PL lens on any super 35mm camcorder is always welcome. While I use DSLR lenses on my cameras for my day to day shoots, if I am doing a high end production such as a commercial then I will hire in the appropriate PL lenses for the job. Sony’s soon to be released FS700 is a camera that will, I’m sure end up getting used for many commercials as slow motion is a technique widely used to show off new products or ideas. As a result there will be many time in the future where I will need a PL adapter.

The Triad adapter showing the Flange Back adjustment ring.

The Triad adapter is very solidly made, machined from high grade alloy with stainless steel and chrome plated steel inserts. One of the very nice features is that the adapter has a built in adjustment for the back focus distance. A locking outer ring on the adapter can be rotated to alter the physical distance between the PL receptor and the E-Mount bayonet. This will allow the user to calibrate the back focus or flange back distance so that the focus witness marks on any PL lenses will be 100% accurate. It will also ensure that PL zooms will track focus correctly through the entire zoom range. As the FS100 and FS700 don’t have built in back focus adjustments this really is a vital thing to have. The Sony E-mount was only designed to support the weight of light weight DSLR type lenses so the Triad adapter has a support post that can be attached to 15mm or 19mm rails (via a suitable bracket) to help carry the weight of heavy PL lenses without over-stressing the cameras E-Mount. One note from Triad is that the Sony PL lenses supplied with the kit that comes with the PMW-F3 do not fit this adapter. There are quite a few PL mounts that don’t accept the Sony PL lenses without shaving a bit of metal from the Sony lenses mount. So this isn’t a flaw with the Triad adapter, it’s a non standard quirk of the Sony PL lenses.
There’s really not much more to say about this mount. It’s well made and does what it designed to do.

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.

New Canon C300 and C300PL cameras and 4k lenses.

Canon C300 cameras and PL mount lenses

So, I might be a little late on this announcement as I’m currently working in Taiwan, but yesterday Canon released information on two new video cameras and 4 new zooms plus 3 cinematography prime lenses. The press information from Canon is below. Reading between the lines and picking out some of the key points this is a very significant announcement. The cameras have a new 8.29 mega pixel sensor recording to compact flash cards at 1920 x 1080, 4:2:2 at 50Mb/s. The sensor uses a bayer type pattern, but due to the very large pixel count it has a Red and Blue pixel  for each sample in the 1920×1080 frame as well as two Green pixels. This should lead to very good colorimetry, but is a little odd considering that the camera only has a single HDSDi output, which I assume would just be 1.5G 4:2:2, so much of the 4:4:4 data derived from the sensor goes to waste unless it can output 4:4:4 10 bit over HDMI. The higher pixel count and thus smaller pixels than F3/Alexa could have an impact on dynamic range sensitivity and noise, but until I see some raw footage or get my grubby hands on one, who knows? The Laforet video “Mobius” http://vimeo.com/30215350 has quite a “video” look to it, but that might just be the online compression. The camera has a built in Log Curve that is said to offer improved dynamic range. Clearly Canon have some of the F3 market in their sights.

There are HDMI and HDSDi outputs so recording to an external device to improve image quality should not be an issue, 8 bit, 4:2:2 is a bit of a shame on a camera with a sensor spec like this, at least it’s an improvement over the Sony F3’s 8 bit 4:2:0 at 35MB/s. If your going to use the Log curve then you defiantly want to record to a higher quality, preferably 10 bit codec (I am assuming the HDSDi output is 10 bit). UPDATE: I am reading many reports of the HDSDI out only being 8 bit. I hope this is not the case!!!

It does tick many professional feature boxes with XLR audio in, Genlock and even a sync output. This would make it well suited to 3D applications. It looks kind of like a DSLR and has a removable handgrip, a rear mounted EVF as well as a removable smallish LCD panel. One mistake I think Canon have made is that you have to choose between the EOS lens mount and PL mount versions of the camera. Why could they have not made a camera body with a removable mount that would allow you to choose between PL or DSLR glass without having to change the entire camera body, or use an EOS to PL lens adapter with it’s extra optical elements?

Still I do like the thought of a stripped down EOS mount version (C300) with a nice L series zoom on it for shooting on the road or covert filming. However even the use of the EOS mount is a little strange as there is no provision for Auto Focus or Auto Iris, something that you would have thought would be easy to implement. This is a fully manual camera.  I’d really like auto iris you know, if only for tricky time-lapse sequences. Iris control is on the camera body. According to Andy Shipsides of Abel Cine the iris steps slightly as you adjust it when using EOS lenses, what a shame. Makes PL sound like a better option for serious productions.

Having a s35mm sized sensor and the 50Mb/s 4:2:2 codec does meant that it ticks all of the BBC’s approval boxes, so you should be able to use it on most broadcast projects. But it is a strange beast on paper. A DSLR-ish form factor, EOS lens mount without focus or iris control, a 4:4:4 ready sensor but only 4:2:2 recording. Hmmm, you know what, I have to wonder if that sensor isn’t going to appear in another camera with RGB or Dual Link recording. Camera price is approx $20k USD, available in January.

As an F3 owner the new Canon PL mount lenses look ver interesting indeed. The 30-300mm T2.9 – T3.7 would be a great lens for shooting music concerts and other similar events, while the 14.5-60mm T2.5 would be a fantastic all round zoom covering the most commonly used focal lengths that I use.

Canon Press Release:

Lights! Camera! Action! Canon Launches Cinema EOS System

 

All-New Cinema Lens Line-up & Digital Video Camcorders to Leave No Story Untold

Canon today announced its full-fledged entry into the motion picture production industry with the launch of the Cinema EOS System. Canon’s new professional digital cinematography system spans the lens, digital video camcorder and digital SLR camera product categories.

 

The Cinema EOS System targets a new area of imaging and builds on a 74-year history of innovation and expertise in the field of optical and imaging technology.

 

The new Cinema EOS System, offers compatibility with Canon’s wide array of high-performance EF lenses, provides cinematographers with a range of unprecedented creative possibilities to ensure that no story is left untold.

 

With the debut of the Cinema EOS System, Canon today introduced seven new 4K EF Cinema Lenses, four zoom lenses and three single-focal-length models, which complement the current diverse line-up of interchangeable EF lenses for EOS SLR cameras.

 

4K EF Cinema Lens Line up

The seven new 4K EF Cinema Lens models include  four zoom lenses covering a wide zoom range from 14.5 mm to 300 mm, two models each for EF and PL lens mounts, and three single-focal-length lenses for EF mounts.   All seven new lenses deliver exceptional 4K (4096 x 2160 pixels) optical performance and offer compatibility with Super 35 mm-equivalent sensors.

 

EOS C300/C300 PL Interchangeable-Lens Digital Video Camcorder

The Canon EOS C300/C300 PL is an all new digital video camcorder available in two models: the EOS C300, equipped with an EF lens mount which is compatibility with the wide array of Canon EF interchangeable lenses; and the EOS C300 PL, offering a PL lens mount for use with industry-standard PL lenses. The camcorder features a Super 35 mm, 8.29-megapixel CMOS sensor ideally suited for digital cinematography. 

 

Cinema EOS System: Product Overview

7 New EF Cinema lenses:

CN-E14.5–60mm T2.6 L S – (EF Mount)

CN-E14.5–60mm T2.6 L SP – (PL Mount)

CN-E30–300mm T2.95–3.7 L S – (EF Mount)

CN-E30–300mm T2.95–3.7 L SP – (PL Mount)

CN-E24mm T1.5 L F – (EF Mount)  

CN-E50mm T1.3 L F – (EF Mount)

CN-E85mm T1.3 L F – (EF Mount)

 

2 New Digital Video Camcorders:

EOS C300 – (EF Mount)

EOSC300 PL – (PL Mount)


Focal length conversion factor should apply to the camera not the lens.

I was asked in some post comments whether the a 50mm PL mount lens would give a wider picture than a 50mm DSLR lens. This confusion comes about I believe because of all the talk about focal length conversion factors. I don’t think this concept is well understood by some people as the implication is that somehow the lens is changing when its used on different cameras, when in fact it’s the camera that is different, not the lens.

It is important to understand that a 50mm lens will always be a 50mm lens. That is it’s focal length. It is determined by the shape of the glass elements and no matter what camera you put it on it will still be a 50mm lens. A 50mm DSLR lens has the same focal length as a 50mm PL mount and as a 50mm 2/3″ broadcast lens. In addition the lens focuses a set distance behind the rear element, agin the distance between the rear element and where it focuses does not change when it’s put on different cameras, so an adapter or spacer must be used to keep the designed distance between the lens and sensor, this distance is called the “flange back”.

The key thing is that it’s not the lens or it’s focal length that changes when you swap between different cameras. It is the size of the sensor that changes.

Imagine a projector shining an image on a screen so that the picture fills the screen. The projector is our “lens”. Without changing anything on the projector what happens if you move the screen closer or further away from the projector? The image projected on the screen will go in and out of focus, so that’s not good, we must keep the projector to screen distance constant, just like the lens to sensor distance (flange back) for any given lens remains constant.

What happens if we make the screen smaller? Well the image remains the same size but we see less of it as some of the image falls of the edge of the screen. If our projected picture was that of a wide landscape then on the reduced screen size what would now be seen would not appear less wide as we are now only seeing the middle part of the picture. The width of the view would be decreased, in other words the FIELD OF VIEW HAS NARROWED. The focal length has not changed.

This is what is happening inside cameras with different size sensors, the lens isn’t changing, just how much of the lenses projected image is falling on or off the sensor.

So the multiplication factor should be considered more accurately as being applied to the camera, not the lens and the multiplication factor changes the field of view, not the focal length.

So whether it is a PL mount lens, a Nikon or Canon DSLR lens or a Fujinon video lens, if it’s a 50mm lens then it’s a 50mm lens and the focal length is the same for all. However the field of view (width and height of the viewed image) will depend on the size of the sensor. So a 50mm PL lens will give the same field of view as a 50mm DSLR lens (no matter what camera the lens was designed for) on the same video camera.

The only other thing to consider is that lenses are designed to work with certain sizes of sensor. A lens designed for a full frame 35mm sensor will completely cover that size of sensor as well as any sensor smaller than that. On the other hand a 2/3? broadcast lens will only cover a 2/3? sensor, so if you try to use it on a larger sensor the image will not fill the frame.
The sensors in the Sony F3 and FS100 are “Super 35mm”. That is about the same size as APS-C. So lenses designed for Full frame 35mm can be used as well as lenses designed for 35mm cine film (35mm PL) and lenses designed for APS-C DSLR’s such as the Nikon DX series and Canon EF-S.

See also http://www.abelcine.com/fov/

 

Focal length conversion factor should apply to the camera not the lens.

I was asked in some post comments whether the a 50mm PL mount lens would give a wider picture than a 50mm DSLR lens. This confusion comes about I believe because of all the talk about focal length conversion factors. I don’t think this concept is well understood by some people as the implication is that somehow the lens is changing when its used on different cameras, when in fact it’s the camera that is different, not the lens.

It is important to understand that a 50mm lens will always be a 50mm lens. That is it’s focal length. It is determined by the shape of the glass elements and no matter what camera you put it on it will still be a 50mm lens. A 50mm DSLR lens has the same focal length as a 50mm PL mount and as a 50mm 2/3″ broadcast lens. In addition the lens focuses a set distance behind the rear element, agin the distance between the rear element and where it focuses does not change when it’s put on different cameras, so an adapter or spacer must be used to keep the designed distance between the lens and sensor, this distance is called the “flange back”.

The key thing is that it’s not the lens or it’s focal length that changes when you swap between different cameras. It is the size of the sensor that changes.

Imagine a projector shining an image on a screen so that the picture fills the screen. The projector is our “lens”. Without changing anything on the projector what happens if you move the screen closer or further away from the projector? The image projected on the screen will go in and out of focus, so that’s not good, we must keep the projector to screen distance constant, just like the lens to sensor distance (flange back) for any given lens remains constant.

What happens if we make the screen smaller? Well the image remains the same size but we see less of it as some of the image falls of the edge of the screen. If our projected picture was that of a wide landscape then on the reduced screen size what would now be seen would not appear less wide as we are now only seeing the middle part of the picture. The width of the view would be decreased, in other words the FIELD OF VIEW HAS NARROWED. The focal length has not changed.

This is what is happening inside cameras with different size sensors, the lens isn’t changing, just how much of the lenses projected image is falling on or off the sensor.

So the multiplication factor should be considered more accurately as being applied to the camera, not the lens and the multiplication factor changes the field of view, not the focal length.

So whether it is a PL mount lens, a Nikon or Canon DSLR lens or a Fujinon video lens, if it’s a 50mm lens then it’s a 50mm lens and the focal length is the same for all. However the field of view (width and height of the viewed image) will depend on the size of the sensor. So a 50mm PL lens will give the same field of view as a 50mm DSLR lens (no matter what camera the lens was designed for) on the same video camera.

The only other thing to consider is that lenses are designed to work with certain sizes of sensor. A lens designed for a full frame 35mm sensor will completely cover that size of sensor as well as any sensor smaller than that. On the other hand a 2/3? broadcast lens will only cover a 2/3? sensor, so if you try to use it on a larger sensor the image will not fill the frame.
The sensors in the Sony F3 and FS100 are “Super 35mm”. That is about the same size as APS-C. So lenses designed for Full frame 35mm can be used as well as lenses designed for 35mm cine film (35mm PL) and lenses designed for APS-C DSLR’s such as the Nikon DX series and Canon EF-S.

See also http://www.abelcine.com/fov/

 

Lens Tests at F3 Dubai Workshop.

Off to the airport to fly home in a minute, but I thought I would jot down some notes about the various lenses we were able to look at during the F3 workshop I ran here in Dubai. We had a set of the Sony PL primes, a Zeiss CP2, some Zeiss ZF.2 stills lenses, a Nikon 50mm and a Tokina 28-70mm ATX pro zoom. The stills lenses were all attached to the F3 using an MTF to Nikon adapter.

It was hard to see any difference between the Sony primes and the CP2, this was kind of expected. When comapring the PL’s to the Tokina zoom, the zoom was a little soft wide open at f2.6. Stopped down half a stop and it looked much better, but it needed to go down to f4 before it came close to matching the PL’s. Even then the PL’s had the edge, but then this is comparing a zoom to a prime. I would certainly have no hesitation over using the Tokina at f4 or more closed. The Nikon 50mm pancake, f1.8 was surprisingly good. Even wide open it produced a respectable image, stopped down to f2.8 it was a very close match to the PL’s. The Zeiss ZF.2’s were the budget stars of the show as even wide open these produced sharp, clean images with very similar bokeh and flare performance to the primes, very impressive performance.

Of course ergonomically the PL’s were better. Bigger focus rings, bigger iris rings and better focus scales. The CP2 impressed with it’s near 360 degrees rotation of the focus ring with very clear and accurate witness marks and wide distance spacing even approaching infinity. If I could afford a set of CP2’s that’s what I would buy, but I can’t. The Sony PL’s are good lenses, they don’t quite have the build quality of the CP2’s but they do represent excellent value for the money. If your budget won’t stretch to PL glass then the Zeiss ZF.2’s are about as close as you’ll get to a PL lens, but do watch out for the amount of telescoping when you focus the longer focal length ones. That can make using a matte box very tricky. I know my Nikon 50mm and Tokina 28mm primes work well. The Tokina 28-70 while not as sharp as the primes will still make a good all-round lens. All I need now is to get a nice 85mm and 135mm and I’ll be happy. Maybe a couple of ZF’s.

PMW-F3 and Stills Glass, some observations.

I have been using my F3 with a range of stills lenses via the MTF F3 to Nikon adapter. Overall everything works very well and I am pleased with the quality of the images I have been getting. However the use of stills glass is not as easy as using dedicated PL lenses. The main issue for me is iris control. With a PL mount lens you have a nice big iris ring so you know exactly where your exposure is. With some of my stills lenses I do have a traditional iris ring and with these lenses all is good. But as so many DSLR’s these days have electronic iris control many of the lenses I have don’t have an iris control ring. Mike Tapa’s adapter can control the iris of a Nikon DSLR lens by moving the blade that controls the shutter on the rear of the lens, but there are no markings or any way way of knowing what the iris is set to. This makes judging when to use more ND or where you are regarding DoF impossible to judge other than via a monitor. You can’t tell whether you are operating the lens at it’s optimum settings. In addition many of the Nikon DX lenses don’t have calibrated focus scales, so again it all comes down to guess work and the monitor.

With well designed stills glass things work well. My older Tokina 28-70 AT-X pro works very well with an accurate focus scale and proper iris control. My Nikon 50mm f1.8 manual lens and Tokina 28mm f2.8 lens also work nicely, but the Nikon DX lenses I have are far from ideal. I’m considering getting a set of Zeiss ZF.2 stills lenses as these appear to be very good lenses. I really need a prime in the 85mm range for interviews and portrait type shots.

The focal lengths I use the most are: 28mm, 50mm and  70mm. I would use a bit longer if I had the right lens. I don’t use the 18mm very often except for panoramas and landscapes.

So…. PL would be nice, but at the moment my budget won’t stretch to that. The Sony kit lenses are certainly great value for the money, but really 35mm isn’t wide enough so I would have to add a wider lens anyway. Stills glass can produce great results, but is not quite so user friendly.