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Phil
04-30-2012, 02:15 AM
Has anyone seen how you can adjust the iris aperture of a Canon EF lens on a BMC? I see in one of Johns clips that it looked like you could set a fixed F stop with a rather sudden jump but is there a way to smoothly adjust the iris? On the SI2K we use a follow focus for this. I just wondered what kind of lens control there would be & if we need to look for EF lenses with manual iris control.

Steve Wake
04-30-2012, 09:03 AM
The clip (from NAB, not JB) I remember with a jump used the auto-iris button. In one of the other NAB clips they used the Play/Rewind buttons to open and close iris. I don't know if steps were adjustable in 1/2 stops, 1/3 or smaller. Also don't know if there is a press-hold and ramp function (doubtful). I also remember from discussions on REDuser that Nikon G lenses are built with finer steps (8 I believe) between full stops, but Canon had fewer steps.

So if you want a smooth iris ramp, I think your best bet is manual iris control. I shoot Nikon so what I really want is a m4/3 adapter with a manual iris control that uses internal cams or levers to increase the throw of an iris ring (and for this you'd need a m4/3 mount BMC). There are EF - F adapters with iris control for G-lenses, but the throw is only 10-15 degrees and probably too cramped to add internal linkage and a ring.

John Brawley
04-30-2012, 09:12 AM
Has anyone seen how you can adjust the iris aperture of a Canon EF lens on a BMC? I see in one of Johns clips that it looked like you could set a fixed F stop with a rather sudden jump but is there a way to smoothly adjust the iris? On the SI2K we use a follow focus for this. I just wondered what kind of lens control there would be & if we need to look for EF lenses with manual iris control.

I think you're referring to my clip, Dusk ? In this i used a non declicked R series leica lens. You can get manual lens "declicked" so that you don't have the obvious stops.

If you're using EF mount lenses, this is very difficult to avoid, because the IRIS is electronic. There aren't the little steps in-between. The moron is in the lens and the cameras sends a command that tells the lens what aperture to be.

jb

Steve4505
04-30-2012, 11:40 AM
Dont forget there is the Remote Control 1 x 2.5mm LANC for Rec Start/Stop, Iris Control and Focus Control Thought I've not quickly found one that I like the shape of or has all the options. I am thinking something like the Zucato rig they just introduced. Another option for studio use could be a tablet/laptop. There is already one available for Canon DSLRs and Android.

Phil
04-30-2012, 12:15 PM
I have a few EF lenses including a 16-35mm L series that I would love to use. So control on the camera for the iris will go up & down in steps by pushing a couple of buttons, then there is a auto iris option also.

I would need to use a Lanc in this case, just did a google & it seems to be a huge choice of affordable controls. Would the iris control knob on the lanc work just the same with a EF lens as on say a Sony camcorder?

Is this what I need?
http://www.abelcine.com/store/VariZoom-VZ-PFI-Focus-Iris-Control-for-Panasonic-Compact-HD-Cameras/

John Brawley
04-30-2012, 05:49 PM
I have a few EF lenses including a 16-35mm L series that I would love to use. So control on the camera for the iris will go up & down in steps by pushing a couple of buttons, then there is a auto iris option also.

I would need to use a Lanc in this case, just did a google & it seems to be a huge choice of affordable controls. Would the iris control knob on the lanc work just the same with a EF lens as on say a Sony camcorder?

Is this what I need?
http://www.abelcine.com/store/VariZoom-VZ-PFI-Focus-Iris-Control-for-Panasonic-Compact-HD-Cameras/

Thta's the main reason for including LANC. ;-)

jb

Steve4505
05-01-2012, 12:26 AM
Like I was saying about activating the camera with an Ipod/Laptop etc see this Triggertrap: nine ways to activate your DSLR with an iOS device, choose one (http://www.engadget.com/2012/04/30/triggertrap-remote-activated-dslr-iOS-app/#continued) as an example of what is coming.

Steve Wake
05-01-2012, 02:35 AM
Is this what I need?
http://www.abelcine.com/store/VariZoom-VZ-PFI-Focus-Iris-Control-for-Panasonic-Compact-HD-Cameras/

No. That is for Panasonic. They use a different control protocol. It is not interchangeable with LANC, which is used on Canon and Sony. Go back to the LANC controllers you googled. JB seems to indicate the BMC will allow iris control through the LANC. I have no idea what else BMC will enable, though record/pause is a given.

However, a LANC won't get around the limit I and John pointed out - that the electronic aperture of the Canon lenses change in fixed steps. Whether those steps are fine enough to do a smooth iris ramp with a LANC will be up to your personal taste. Don't assume it will ramp as smoothly as a camcorder - it probably won't.

Just FYI - the only Nikon lenses with electronic aperture are the PC-E tilt/shift lenses. Even the G lenses with no aperture ring have a mechanical lever connecter to the iris. The camera body has a motor that moves the lever. Even that motor moves in steps, but as I said above, the steps are finer than Canon. Nikon also has the advantage that a mechanical linkage can be made to move the lens aperture lever smoothly (RED's prototype Nikon mount apparently has a smooth operating step-less motor). And of course Nikon lenses with aperture rings can be declicked (though the AI, AIS, D and AF-S non-G also have the lever and can be operated via any mechanical linkage that works with a G lens).