Red One bridge plate + Shim plate on EPIC - alignment issue

[anneso_M]

French being my native language, I will try to be as clear as I can for those technical issues that hopefully some of you will be able to answer.

Here is my EPIC set-up :

-ronford head + legs 150mm bowl

-Red one bridge plate 15mm studio offset
http://files.indierents.com/1/photos/f/914809_238786_red arri 15mm copy.jpg

-ET shim plate
EL-ABPR-SP-E.png
http://www.radiantimages.com/media/package/416.jpg

ET calls it "Hybrid EPIC Shim Plate" and says "It also works with the 15mm Red Bridge Plate"

-Epic X



I couldn't spend any more money onto another bridge plate specifically design for the epic, which is why I decided to use the red one bridge plate that I already have and get a shim plate, which is what I thought was an efficient and cheap solution. When I was testing the alignment, it was fine. I put my cooke 15-40 with the lens support and it was perfectly fine.

BUT!

the day before we shoot, as I am checking the gears with the DOP's mattebox, it is just not aligned. The whole set-up seemed wrong.
His mattebox is perfectly fine, a normal 15mm studio offset that really should be aligned with the lens, NO ??
Me and the camera assitant tried to put our head around it, and our head is now frozen, and it seemed that I won't find the answer by myself.

Any thoughts about it ??

I really want to know what I am doing wrong

Thanks

 

[Andre W.]

With the Hybrid Plate, you have your offset screw holes so that your bridge plate can sit a little off center. It should be the first set of mounting holes to camera right that you use (power button side of camera). If the MB is close to alignment but just misses, then it could be a slight off angle issue with the Bridge plate. This can be solved by having your bridge plate screwed in, but not tightened all the way down (allow for a little twist left to right), then make sure that the MB will slide over the lens, then tighten the screws in your bridge plate.

I find a two person team on this works great. Setting the camera on a table with the back screw being over the edge of the table so that you can have access with a screw driver to tighten that screw once the MB is in place.

A very small angle difference on the plate, can mean an inch at the front of a lens

 

[anneso_M]

Hey Andre, thanks for that. The MB was indeed opposite to alignment. While the offset is on the left (from a camera perspective), the MB will be set on the right. Only way to work that out, is to turn the bridge plate around, so the screw that are naturally set on the right of the bridge plate are now on the left, meaning that now, everything is perfectly aligned. except that it feels a bit weird to work with a bridge plate in reverse...