# Keystone Artifacting with Rosco ImagePro

#### Chris Chapman

##### Active Member
I'm looking at picking up some Rosco Imagepros to do some projection work to replace flown drops. I plan on using ETC Source 4 70 or 90 degree units (the new ones) and I need to figure out how to manipulate the images to prevent keystoning with the projection.

Can anybody point me in the right direction for the math to calculate defelections so oI can hopefully change the pics in Photoshop?

-Chris

#### JP12687

##### Active Member
Chris,

I would actually recomend the Selecon 70 or 90deg units with the Image Pros.

They offer better beam cooling, and hence offer longer life on the image slides, which get expensive.

as for "keystone" correction, i would recomend squaring the image using the shutters, if you plan on losing some of the edge of each slide, you can square into it, using the shutters.

Josh

#### Chaos is Born

##### Active Member
1. plot out your throw distance in cad (top of the drop and bottom of the drop)
2. add in the beam and feild angles of the light
3. take and fit your image to that shape in reverse (small part of image ends up being the bottom)

#### Chris Chapman

##### Active Member
Thanks guys, that is a HUGE help. ;>

#### Chris Chapman

##### Active Member
The throw isn't going to be that far so I doubt there will be any front light on the Cyclorama. I wasn't planning on using the stock images because of the keystone manipulation. We're looking at like a 16-18 foot horizontal throw, I haven't had the time to do the true throw distance to the cyc.

It's for a musical with a 4 show run and one week of tech. I'm looking at the ImagePros as a cost effective item to add to the inventory because we do a LOT of gobo and projection effects here.

That's also the reason glass gobos are out of the question the one off cost to make the gobos eliminates the cost benefit.

I'm still toying with the idea and haven't commited 100% to it yet.

Thanks for the input again, guys.

-Chris

#### moojoe

##### Active Member
ah, ok. for some reason i thought this was for a perminent/semiperminent rig, so then it would make sense to use glass gobos, but for one show, yea, imagepro all the way.

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