Tag Archives: lens

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Testing, testing…. Canon 800/1600 mm lens on F3

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Canon 800mm lens on PMW-F3

In preparation for the big Duran Duran shoot in Berlin later in the week I was out with Den Lennie of F-Stop academy along with Duran Duran video producer Gavin Elder and James Tonkin of Hangman Studios testing the Canon 800/1600 f5.6 lens on my F3. This is an adapted DSLR lens fitted with a PL mount. What a lens! The bokeh was simply gorgeous from this lens and I’m really excited about putting it to use in Berlin on Thursday night. Keep tuned for more info on this BIG project shooting with F3’s, FS100’s and SRW9000PL’s. We’re even throwing in a VG10 or 2 for good measure! Nine cameras in total, ultra shallow DoF is the goal, gonna be hard to do, but it should look awesome.

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

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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/

 

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

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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/

 

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Lens Tests at F3 Dubai Workshop.

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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.

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PMW-F3 and Stills Glass, some observations.

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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.

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

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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.

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

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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.

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MTF services to produce Nikon adapter for F3

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Well no surprises here to be honest but Mike Tapa of MTF has already finalised the design of an adapter that will allow users of Sony’s still to be released PMW-F3 to use low cost (compared to PL) Nikon DSLR lenses. This open up a huge range of lens options and I’m quite sure that with good high end lenses the results will be very good. It’s certainly the way  I will be going.

http://www.lensadaptor.com/

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Lens Choices for the PMW-F3

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The PMW-F3 has two lens mounts out of the box. The PL mount (via a supplied adapter) and the new F mount. PL mount lenses were developed by Arriflex for use with movie cameras, so PL mount lenses are an obvious choice. You used to be able to pick up older PL mount lenses quite cheaply, but when RED came along most of these got snapped up, so now PL mount lenses tend to be expensive. Sony will be producing a low cost three lens kit comprising of 35mm, 50mm and 85mm lightweight PL mount lenses. If you want top quality then Zeiss or Cooke lenses are the obvious choice. If your budget won’t stretch that far there are a number of 35mm SLR lenses that have been converted to PL mount.

PL  mount lenses often have witness marks for focus. This are factory engraved markings, individual to that lens for exact focus distances. They also often feature T stops instead of F stops for aperture. An F stop is the ratio of the iris opening to the focal length of the lens and gives the theoretical  amount of light that will pass through the lens if it was 100% efficient. A T stop on the other hand is the actual amount of light passing through the lens taking into account aperture size and transmission losses through the lens. A prime lens with an f1.4 aperture may only be a T2 lens after loss through the glass elements is taken into account. A multi element zoom lens will have higher losses, so a f2.8 lens may have a T stop of T4. However it is the iris size and thus the f stop that determines the Depth of Field.

But what about the F mount on the F3. What will that let you use? well right now there are no F mount lenses, but Sony are planning on a motorised zoom for next year. I am expecting a range of F mount to DSLR mount adapters to become available when the camera is released. These adapters will allow you to use DSLR lenses. The best mount IMHO is the Nikon mount. Why? Well most modern DSLR lenses don’t have iris controls. The iris is controlled by the camera. Nikon are the only manufacturer that has kept manual control of the iris on the lens body. When choosing a lens you want to look for fast lenses, f2.8 or faster  (f1.8, f1.4) to allow you to get shallow Depth of Field. You want a lens designed for a full frame 35mm sensor to avoid problems with vignetting or light loss in the corners of the image. You want a large manual focus ring to make focus control easy. Prime lenses (non zoom) with their simpler design with fewer lens elements normally produce the best results, but a zoom might be handy for it’s quick focal length changes. Do be aware however that zooms designed for stills photography normally don’t hold constant focus through the zoom range like a video lens so you may need to re-focus as you zoom. I have a nice Mk1 Tokina 28 to 70mm f2.6 Pro zoom. The optics in this lens are based on the Angineux 28 to 70mm and it’s a great all round lens. I also have a Nikkor 50mm f1.8, Pentax 58mm f1.4 and a few others. Of course you can also hire in lenses (DSLR and PL) as you need them.

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Lens Choices for the PMW-F3

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The PMW-F3 has two lens mounts out of the box. The PL mount (via a supplied adapter) and the new F mount. PL mount lenses were developed by Arriflex for use with movie cameras, so PL mount lenses are an obvious choice. You used to be able to pick up older PL mount lenses quite cheaply, but when RED came along most of these got snapped up, so now PL mount lenses tend to be expensive. Sony will be producing a low cost three lens kit comprising of 35mm, 50mm and 85mm lightweight PL mount lenses. If you want top quality then Zeiss or Cooke lenses are the obvious choice. If your budget won’t stretch that far there are a number of 35mm SLR lenses that have been converted to PL mount.

PL  mount lenses often have witness marks for focus. This are factory engraved markings, individual to that lens for exact focus distances. They also often feature T stops instead of F stops for aperture. An F stop is the ratio of the iris opening to the focal length of the lens and gives the theoretical  amount of light that will pass through the lens if it was 100% efficient. A T stop on the other hand is the actual amount of light passing through the lens taking into account aperture size and transmission losses through the lens. A prime lens with an f1.4 aperture may only be a T2 lens after loss through the glass elements is taken into account. A multi element zoom lens will have higher losses, so a f2.8 lens may have a T stop of T4. However it is the iris size and thus the f stop that determines the Depth of Field.

But what about the F mount on the F3. What will that let you use? well right now there are no F mount lenses, but Sony are planning on a motorised zoom for next year. I am expecting a range of F mount to DSLR mount adapters to become available when the camera is released. These adapters will allow you to use DSLR lenses. The best mount IMHO is the Nikon mount. Why? Well most modern DSLR lenses don’t have iris controls. The iris is controlled by the camera. Nikon are the only manufacturer that has kept manual control of the iris on the lens body. When choosing a lens you want to look for fast lenses, f2.8 or faster  (f1.8, f1.4) to allow you to get shallow Depth of Field. You want a lens designed for a full frame 35mm sensor to avoid problems with vignetting or light loss in the corners of the image. You want a large manual focus ring to make focus control easy. Prime lenses (non zoom) with their simpler design with fewer lens elements normally produce the best results, but a zoom might be handy for it’s quick focal length changes. Do be aware however that zooms designed for stills photography normally don’t hold constant focus through the zoom range like a video lens so you may need to re-focus as you zoom. I have a nice Mk1 Tokina 28 to 70mm f2.6 Pro zoom. The optics in this lens are based on the Angineux 28 to 70mm and it’s a great all round lens. I also have a Nikkor 50mm f1.8, Pentax 58mm f1.4 and a few others. Of course you can also hire in lenses (DSLR and PL) as you need them.