TELE LENS MAPPING

[labridis]

Hi folks,
I have a very interesting upcoming mapping project but there are some serious technical downsides on it. The mapping is supposed to take place on a castle which is on a hill. There is no clean view of the castle or anywhere i could place the projectors close to it. So the only solution is to go far away. But seriously far. The only spot i can put the projectors are at the rooftop of a hotel which is 530m far. The barco calculator gives me a lens (xld 5.5-8.5) which is supposed to be ok with this distance. The projectors i want to use is a double stack of BARCO HDQ 4K35. Has anyone tried this distance before? Is seems a bit scary...

I am attaching the view to the castle from the rooftop i believe is ideal for the mapping which is 530m away.

Thanks in advance,
Giorgos

[Oaktown]

530m is a lot of distance to cover and you'll be dealing with a lot of adverse environmental factors that will work against you. How big is your resulting image?

Since you're using two BARCO HDQ 4K35 projectors, it seems that you have access to gear and funds, right? Have you thought about going the opposite direction and using ultra short throw lenses such as the Panasonic ET D75LE90 and using more smaller projectors mounted super close to the castle?

[drazkers]

Your going to have a hard time with two 35k projectors on such a large structure with ambient light.

At blizzcon we're a fraction of that size and use thirty 30k barcos because of lighting.

Do you have permits to shut down all city lighting?

[Oaktown]

Take a look at this calculator I made a while back to calculate brightness. https://drive.google.com/open?id=1PnFSo ... Qofx0SfDOA

You can download it and change the parameters to figure out what projector and lens will work for you. Since you're projecting on an old castle from a long distance, I would probably adjust the gain to 0.3. This is all theoretical but it's worked for me on countless projects so I hope it works for you as well.

[labridis]

Thanks Oaktown, I will try the calculator.
It is not possible to go with the UST lens because there is no space between the castle wall and the closer buildings. The ground also is very steep. Scaffolding will raise the budget a lot and the same will happen with multiple UST. The closer buildings are in different hight levels and most of them don't have flat rooftop. Even if we used scaffolding for those that are flat it is impossible to go that high from the buildings roofs.
It would be ideal if i could project on this castle from the rooftop which is 530m away and i could use only one head with the 2 barcos stacked. Do you thing there is any other alternative that could do the job???

Thanks again,

[Oaktown]

How high and wide is the castle?

[labridis]

The castle is 80m wide and 12m high.

[labridis]

Hey drazkers, thanks you for replying,
i guess the town hall will do their best in order to make ambient light less because they are the ones organizing the event.

[Oaktown]

Because of the inverse square law of light, your best approach would be to blend the two 35K HD projectors side by side rather than stacking the but the BARCO's wouldn't have the right lenses. 35K over 40m will be twice as bright as 70K over 80m.

How about using 2 stacks of 2 or 3 Panasonic PT-DZ21KU (yielding a theoritical 40K or 60K per side) with the ET-D75LE8 Zoom Lens 7.30:1-13.80:1?

Keep in mind that lining up two projectors at 530m will be a daunting task!