Tag Archives: 2/3″

Will My B4 Lens Cover The FX9’s 2K S16 Scan Mode?

This has cropped up a few times in the comments and in various user groups so I thought I would go through what you need to do to use a B4 2/3″ lens with the FX9’s S16 2K scan mode.

Not all B4 2/3″ lenses will directly cover the FX9’s Super 16mm sized 2K scan mode as 2/3″ is smaller than S16. 2/3″ lenses are designed to cover 8.8 x 6.6mm and S16 is 12.5 x 7mm. Some lenses might just about cover this as is, with minor vignetting, but most won’t.

The Sony LA-EB1 includes an optical expander that compensates for this (I think it’s about a 1.35x). With the LA-EB1 all B4 2/3″ lenses should work without vignetting and in addition when an ALAC compatible lens is connected to the LA-EB1 the camera will support the ALAC function which reduces many of the aberrations typically seen with B4 lenses. The LA-EB1 needs a power feed (14.4v) to work correctly and to power the lens. It is supplied with a 4 pin hirose cable that is designed to be plugged into the 4 pin hirose power socket on the XDCA-FX9. This also provides the record trigger signal to the camera. If you don’t have an XDCA-FX9 then you will need to source a 4 pin hirose to D-Tap or similar power cable.


If you have a mount adapter that does not have any optical expansion such as the cheaper MTF B4 to E-Mount adapter (MTB4SEM approx $400), if the lens has a 2x extender you can use the lenses extender if the lens doesn’t cover without it. The more expensive MTF MTB4SEMP (approx $1,200) includes an optical expander and with this adapter all B4 lenses should cover the S16 area without needing to use the lenses extender. To get the zoom servo working you will need an adapter that can provide 12v to the lenses 12pin connector.

Whatever lens or adapter you choose, the lens needs to be an HD lens. The better the lens the better the end result, I know that may seem obvious but when you are using either an adapter with an included optical expander or having to use the lenses 2x extender to eliminate vignetting  with a straight through adapter any imperfections in the lens and any softness becomes quite obvious. Get a really good lens on a good adapter and the images are perfectly respectable, but a poor lens on an adapter will probably dissapoint.

Image quality with B4 ENG lenses on large sensor cameras.

DSC02056 Image quality with B4 ENG lenses on large sensor cameras.
2/3″ B4 lens on the FS700via the MTF adapter.

This is something that comes up a lot and I get many questions about. In part because I designed the MTF B4 to Canon, FZ and E-Mount adapters. Budget adapters that allow you to use a 2/3″ B4 ENG lens on a Super 35mm sensor by using the lenses 2x extender or on a center crop sensor without the 2x.

The question is… what will the pictures look like?

The answer is… it depends on the lens.

Not a very helpful answer perhaps, but that’s the truth of it. Different lenses perform very differently. For a start I would say forget 4K. At best these lenses are suitable for HD and you want to have a great HD lens if you want good HD pictures.

But what about the “look” of the images? My experience is that if you put a wide range ENG zoom on a S35mm camera the look that you get can be best described as “2/3″ ENG look with maybe shallow depth of field”. Lets face it, ENG lenses are full of compromises. To get those great big zoom ranges with par-focal focus there are a lot of glass elements in those lenses. Lot’s of elements means lots of places where CA and flare can occur. The end result is often a lowering of contrast and color fringing on hard edges, the very same look that we are used to seeing on 2/3″ cameras.  Typical cine or DSLR lenses tend to have simpler optical designs. Prime lenses are normally sharper and show better contrast with less flare than zooms due to there simpler internal design.

So don’t expect to put a typical B4 ENG lens on your S35mm camcorder and still have that crisp, high contrast digital cinema look. Of course B4 zooms are handy for the ability to zoom in and out through huge ranges while holding focus. So an adapter and lens may well make your S35mm camera more versatile. But if you want the best possible images stick to cine style lenses, DSLR lenses or zooms designed for S35.

 

Sensor sizes, where do the imperial sizes like 2/3″ or 4/3″ come from?

Video sensor size measurement originates from the first tube cameras where the size designation would have related to the outside diameter of the glass tube. The area of the face of the tube used to create the actual image would have been much smaller, typically about 2/3rds of the tubes outside diameter. So a 1″ tube would give a 2/3″ diameter active area, within which you would have a 4:3 frame with a 16mm diagonal.

An old 2/3″ Tube camera would have had a 4:3 active area of about 8.8mm x 6.6mm giving an 11mm diagonal. This 4:3 11mm diagonal is the size now used to denote a modern 2/3″ sensor. A 1/2″ sensor has a 8mm diagonal and a 1″ sensor a 16mm diagonal.

Yes, it’s confusing, but the same 2/3″ lenses as designed for tube cameras in the 1950’s can still be used today on a modern 2/3″ video camera and will give the same field of view today as they did back then. So the sizes have stuck, even though they have little relationship with the physical size of a modern sensor. A modern 2/3″ sensor is nowhere near 2/3 of an inch across the diagonal.

This is why some manufacturers are now using the term “1 inch type”, as this is the active area that would be the equivalent to the active area of an old 1″ diameter Vidicon/Saticon/Plumbicon Tube from the 1950’s.

For comparison:

1/3″ = 6mm diag.
1/2″ = 8mm
2/3″ = 11mm
1″ = 16mm
4/3″ = 22mm

A camera with a Super35mm sensor would be the equivalent of approx 35-40mm
APS-C would be approx 30mm

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

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.

Low Cost 2/3? HD Lenses.

OK, here’s my take on the situation.

If money is no problem then the safest bet is to purchase a good quality HD lens, expect to spend at least £8k.

If you budget is restricted then the situation is much less clear. There are now several low cost 2/3? HD lenses designed for cameras such as the Panasonic HPX500. In my opinion these lenses are just not worth the money. They might be cheap (£4k ish) but the one’s I’ve played with have been pretty grim, suffering from lots of CA and soft corners.

If your on a tight budget the best thing you can do is take your camera to a good dealer and go through their second hand lenses, trying them on the camera. Check for resolution (use a chart), corner softness, CA and contrast. I did this and ended up with a Canon 16x8x2 IF lens. I found that lenses with lower zoom ratios tended to be better than those with higher ratios. I’m really pleased with my lens and when compared to the latest HD equivalents I can not tell the difference in real world use. It certainly outperforms all the budget HD lenses I’ve tried.

One interesting thing that I have discovered in my research into this subject is that Contrast is what makes the biggest difference in lens performance, not simply resolution as one might expect. Visually the next thing you notice is CA. This is a tough one as when you increase the resolution or sharpness of a lens you also tend to increase the CA.

Until lens manufacturers start to release MTF curves for their lenses the only thing we have as buyers to go on is the advertising blurb. It’s easy for a manufacturer to claim improved performance or new glass or other technology, but without accurate MTF curves it’s all pretty meaningless. You would only need the tiniest resolution improvement to be able to claim that you new HD lens range is sharper than your SD range, it could just be a fraction of a percent difference.