Resolume Forum

Hello there.

I need some advice on how to work around not having lens shift on my projector. I recently purchased a Epson Powerlite 1985wu for use in medium to small scale projection mapping (mostly for a couple screens I have made out of coroplast).
I know it was a gamble when I purchased the projector, but its specs were so much better than the low cost alternative I could find which had lens shift (the Powerlite 4855wu)

Powerlite 1985wu specs:

Lumens - 4800
Contrast - 10,000:1
Native Resolution - 1920x1200

Powerlite 4855wu specs:

Lumens - 4000
Contrast - 5000:1 (Dynamic)
Native Resolution - 1920x1200

I use my old projector (an old Infocus LP810) for projection mapping at a couple medium sized indoor venues and outdoors for smaller stages (usually for about 1000 people or less). It worked well enough for the things that I was doing, but I now wanted to upgrade.
The 4855wu's Dynamic Contrast ratio is what really killed me. I know the dynamic contrast ratios are not nearly as on point as their static contrast ratings.

Is there any tools I can use to move my projector around, but still give it the flexibility to place it in different areas without having to Keystone too much? Someone mention using a custom setup with a Manfrotto Avenger Baby plate and swivel attached to a wooden anchor for stability. Not sure if this would work though.

Thanks in advance for the help!

You can't replace lens shift with pan-tilt heads.
lens shift moves the image around as like if you would move the projector to the side or up/down without introducing keystone, keeping the projection brightness pretty much constant across the image - pan-tilt does not.

If you have arena, then forget about in-projector keystone correction, do what you need to correct in resolume. (in-projector correction is also software and you don't need another step of that)

Having these said, if you can place your projector in the center line of the projection area, at least on one axis, you'll have enough resolution to achieve nice results without lens shift. And if you are doing projection mapping, then you won't have in-plane projection surfaces anyway, where lens shift would help out.
You'll have a bit darker image on farther surfaces, but I doubt that anyone besides you will notice that, unless you are projecting from extreme angles.
So don't worry.

I found out the hard way on a project years ago that cheap projectors are cheap for a reason and the lack of lens shift is one of them!

Unfortunately, there is not much you can do about it if your projector is a table-top model besides using the mapping ability of Resolume Arena to correct the geometry and wasting a lot of good pixels & lumens.

Oaktown wrote:I found out the hard way on a project years ago that cheap projectors are cheap for a reason and the lack of lens shift is one of them!

Unfortunately, there is not much you can do about it if your projector is a table-top model besides using the mapping ability of Resolume Arena to correct the geometry and wasting a lot of good pixels & lumens.

Well, I have the opportunity to return this projector still. Do you think the shitty contrast and the 800 lumens less would be worth the trade out for Lens Shift?

Slurpee wrote:

Oaktown wrote:I found out the hard way on a project years ago that cheap projectors are cheap for a reason and the lack of lens shift is one of them!
Unfortunately, there is not much you can do about it if your projector is a table-top model besides using the mapping ability of Resolume Arena to correct the geometry and wasting a lot of good pixels & lumens.

Well, I have the opportunity to return this projector still. Do you think the shitty contrast and the 800 lumens less would be worth the trade out for Lens Shift?

the one with the lens shift also has a bit wider throw range.

if it's worth the trade?
lens shift 4k lumens + 200USD more , vs no shift 4.8k lumens I would decide based on the work I'm going to do with it, placement and ambient light wise.
The brightness you gain with shifting 4k vs the loss when tilting 4.8k should be about the same.
Lens shift projectors are easier to set up, but there are crappy shift mechanics like the acer p7500 where moving on one axis manual control moves the other axis too...

how much do you need to tilt your old projector usually?

In reality lens shift only saves me from repositioning a projector. I suppose if i did more edge blending it might be useful

I would get the PowerLite 4855WU any day over the Powerlite 1985wu.You won't really notice the 800 lms of difference and the H/V lens shift will come handy all the time.

Assuming your biggest screen with 4,000 lms will be about 10ft with this type of projector, the 1.38:1 vs 1.5:1 throw means you'd have to locate your projector 1ft 10in further back assuming perfect placement

In addition, the 5000:1 contrast is more than enough. Take a look at this white paper on contract ratio and you'll understand how a jump from 5,000:1 to 10,000:1 is not quite the gain you think it is and mostly a marketing thing.