Keystone Artifacting with Rosco ImagePro

[Chris Chapman]

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]

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]

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]

Thanks guys, that is a HUGE help. ;>

The rental houses may hate me, but if I can spend the same $$$ on lighting hardware that I get to keep vs. the cost of rental drops, I think I know where my buck is going.

Thanks again,

-Chris

[Console1]

Originally Posted by Chris Chapman

Thanks guys, that is a HUGE help. ;>

The rental houses may hate me, but if I can spend the same $$$ on lighting hardware that I get to keep vs. the cost of rental drops, I think I know where my buck is going.

Chris,

Be careful here or you might hate yourself along with the rental guys that hate you. What I am getting at is you might not like I pros over a drop. They are nice but may wash out under front light. Especially if you fan them out of 90 degrees.

I think you need to budget time to experiment with keystone correction. That is accomplished by making your own slides in Photoshop and disorting the perspective. Keystone correction from stock slide is not possible. Otherwise you must have a strait shot at the drop. Not always easy to do.

If you dont use the two sided tape from the Rosco slide kit you can pop the frame apart and reuse it this saves a lot of money on the do it yourself kits.

Second these are not super bright video projectors. They look good but not as good as a drop.

Also carefully align the S4 to a flat field.

Spec the 750 watt lamp from the rental house.

Spec ETC's new sharper image lenses for an even better image.

And make sure the cooling fans are in a Non dim that stays energized until you pull the power. Otherwise the first time your helper does light check and calls lamp intensity before I Pro fan power say bye-bye to your slide.

Have fun and Good Luck!

[moojoe]

i personally would go with glass gobos instead of the image pro, image pros dont have a great lifetime, and they arnt very bright.
console1's ideas are pretty good, though a 750 lamp would kill a gobo. and just wondering, but arnt the sharper image lenses from etc like $400?

[Chris Chapman]

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]

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.