there has been a few posts over the years on using the GH cameras with parfocal lenses - I came across this one recently but is anyone actually using a setup like this for indoor low light stuff like dance concerts??

https://www.localstage.video/single-post/2019/02/12/GH5s-B4-lens-The-Unbeatable-setup

I'm very skeptical that a B4 lens is going to look good on that camera. Did they post any actual video to show what the results look like? If not, enough said.

It’s amazing what you can do but unless you’re in search of a “man cave” project you’d be better off with an eng camera. The smaller sensor of an eng will help you keep everyone in focus on stage that are typically at least 20ft deep. They also sell remotes that make it easier to control the camera while filming.

Not that useful on a smaller sensor size camera apart from if it's a 2/3" type already with the B4 mount as on a 1/2 or 1/3" chip camera you also get a magnification factor removing much of the wide angle. They are great outside though. I use my B4 lens on my JVC 750 with it's 2X adaptor,which coupled with the magnification from the adaptor gives me a VERY long telephoto that stays perfectly in focus. At small or large f numbers it gets a bit soft but at f8-f11 it's very usable.

there has been a few posts over the years on using the GH cameras with parfocal lenses - I came across this one recently but is anyone actually using a setup like this for indoor low light stuff like dance concerts??

Frequently use B4 lenses on S35 sensors and even A7 FF with the necessary dumb and optical adapters. You can buy a solid B4 to M4/3 of eBay these days for around A$70.

https://bit.ly/2rCwnMQ

With the fact that they are parfocal and in 95% of cases are constant aperture of around F1.6 to F1.8 and have a beautifully controlled zoom servo and good focus and iris rings they make shooting events like concerts and sport far more practical. You can end up producing a much more fluid event. Especially single camera events when you have to change shot size and don't have the luxury of covering the move with a cut to a second or third camera. With the M4/3 sensors you will need to use a B4 with a 2 x doubler to get full coverage of the sensor as a B4 2/3" lens is only designed to cover an HD 11mm diagonal sensor. Most M43 sensors run out a around about 16.4mm on the diagonal.

Running a 2 x doubler is going to drop an F1.8 B4 lens down two stops to around F4.0. I've found with modern sensors and usually reasonably well lit concerts that this is not a problem. In fact often for a suitable DOF I'm shooting around F5.6 down to F8.0 at times to get the best results.

The following example is a single camera Fujinon 18 x B4 on a S35 sensor shot in Chatswood... a bit south of you in other words :)

https://youtu.be/hj3wOzL1Y-Q

Chris Young

I watched rather smugly the BBC in my theatre yesterday with one ENG camera and two 4/3 cameras with the usual grey Canon Zooms, and smiled at the constant refocussing required every time they zoomed. Mistake editing so hard as none of the zooms would be usable, and very clearly the shallow DoF was working against them, apart, of course, from the ENG cameraman who had perfectly sharp and solid shots with minimal focus input required. I shoot lots from his position and it's simple to get up and down stage sharpness by just selecting a mid-point. Sometimes, it's just having the right tool for the job. Any lens designed for still photography is a compromise for this kind of thing.

4/3 cameras can be wonderful things, but without a zoom designed for video, that's a big downside!

Frequently use B4 lenses on S35 sensors and even A7 FF with the necessary dumb and optical adapters. You can buy a solid B4 to M4/3 of eBay these days for around A$70.

https://bit.ly/2rCwnMQ

With the fact that they are parfocal and in 95% of cases are constant aperture of around F1.6 to F1.8 and have a beautifully controlled zoom servo and good focus and iris rings they make shooting events like concerts and sport far more practical. You can end up producing a much more fluid event. Especially single camera events when you have to change shot size and don't have the luxury of covering the move with a cut to a second or third camera. With the M4/3 sensors you will need to use a B4 with a 2 x doubler to get full coverage of the sensor as a B4 2/3" lens is only designed to cover an HD 11mm diagonal sensor. Most M43 sensors run out a around about 16.4mm on the diagonal.

Running a 2 x doubler is going to drop an F1.8 B4 lens down two stops to around F4.0. I've found with modern sensors and usually reasonably well lit concerts that this is not a problem. In fact often for a suitable DOF I'm shooting around F5.6 down to F8.0 at times to get the best results.

The following example is a single camera Fujinon 18 x B4 on a S35 sensor shot in Chatswood... a bit south of you in other words :)

https://youtu.be/hj3wOzL1Y-Q

Chris Young
That video is very soft. Imhop not worth the trouble for such a setup.
Here’s highlights of the Nutcracker I filmed with the Panasonic Ux90. This also has been recompressed a couple of times and the lighting wasn’t that bright.

https://vimeo.com/creationdream/btcnutrailer

Paul I wasn't referring to the video for sharpness but for the smooth movement of lens operation as that is what the OP was all about. The original video this clip came from was 1080i specifically commissioned for BD duplication. The Blu Rays produced are clean and sharp so I'm not concerned about what it looks like on YouTube. Also the post was to help explain not justify the use of B4 on bigger sensors just that it can be done if it's necessary. Many shooters don't have the luxury of having different types of cameras for different jobs. Paul was asking if it can be done. I was saying yes. I'm not saying it is a better solution to a dedicated camera designed for B4 glass. That's why for broadcast use I still retain two three chip B4 lens cameras and three lenses.

Re the Vimeo clip you refer to. Down here I'm not seeing it any sharper that the clip I referred to. Also I think Vimeo does a better job than the tube especially with 720p as opposed to 1080i on YouTube.

Chris Young

Seems like a complex setup that wouldn’t be cheap either. I wouldn’t recommend cobbling together old, used equipment just so you can film an event with a camera that it’s not intended for. I’m risk averse for paid live event work. Just because it can be done doesn’t mean it should be.

You see the art of experimentation is gone. Sure sometimes these things are dire, but if you have access to a lens and don’t mind the adapter and the hassle of supporting it physically and electrically you could be throwing away another bit of your arsenal. I now always take my old B4 lens because sometimes you can use it to advantage. In my case, can I live with the overall loss of sharpness and still fill the frame with an aircraft dropping parachutists from the ground? With the proper lens I’d have been left with a large magnification figure in the editor which would be far worse quality wise. I’m not saying she’ll put a grand but if it’s a hundred or two that’s worth trying?

Based on this setup he would need
https://www.localstage.video/single-post/2019/02/12/GH5s-B4-lens-The-Unbeatable-setup
B4 lens
2x adapter
remote control (if you can find one)
custom made lens support or rail system
power supply
necessary cables

zoom demands are often owned by the folk with B4 lenses - I've got three different types, and the 2X adaptor MUST be incorporated into the lens.They have this feature on most broadcast lenses - although the effects you get on the 1x setting is not really vignetting, it's simlly a hard edged circle!, However, as these lenses usually come in a minimum of 14X zoom (and often 17-20) you just zoom in till the corners are clear. The problem is the power supply - not somuch the actual power supply itself, but the connector. You can use them manually with no power by disengaging the servo. Power simply gives you the servo variable speed feature and teh rear remote demand. The lens in the clip also has the inserts to attach a focus demand too - so you can have rear operated focus, using a Bowden cable assembly. These, and the lens adaptor are far less common, and therefore expensive. What you don't get is the camera controlling the iris. That's a manual adjustment.

I actually did some tests last weekend with a 45-175 lumix power zoom on a gh5s and it looks pretty good - it's not a parfocal lens but with the wider depth of field I can keep most of the stage in focus - I'll do some more next weekend and load it up. I still think the B4 setup is worth playing around with and I'll get a lens and adapter to give it a go