Does this projector cut it/Standards for low budget projections

[ishboo]

I am working a production with a very low budget and we want to do projections onto a screen roughly 18'x15' where we only have a 20' throw for the projector. I am looking at the BENQ MP515. Here are the specs:
rightness (Lumens) : 2500 ANSI
Contrast (Full On/Off) : 2600:1
Variable Iris: **
Audible Noise: 32.0 dB
Eco-Mode: 26.0 dB
Weight: 5.3 lbs
Size (inches) (HxWxD) : 3.5 x 10.0 x 8.4
Std. Lens: Focus:
Manual
Zoom: Manual, 1.20:1
Throw Dist (feet) : 2.0 - 21.7
Image Size (inches) : 27.5 - 363.0

It can produce an image of the desired size with the available throw but I am worried about the lumens. It says it is 2500 lumens but I don't know at what distance that is measured from. If it is projected onto and actual projection screen and not just a white surface and light doesn't spill directly onto it would 2500 lumens cut it and would I be able to do projections with the projector?

 

[JohnHartman]

It really comes down to what is the director looking for... I have done something similar with a 2K projector on a larger screen area, I work with the lighting to stay off of the scrim, and we try to time the "background" changes with blackouts, hold the black-out long enough for the audience to get an idea of where we are. You can still see the projections in the back, but they are not prominent once the lights are up. If your Director wants the projection to stand out full time, you are going to need alot more lumens to throw at the screen.

Try and find a similar projector to borrow and see if you can get the look you want.



-Anything is possible given enough time, motivation and money

 

[ruinexplorer]

I assume that even though you are asking advice about a standard projection surface with no ambient light that you may not have this in practicality. Remember, what is actually present and what we see is not always the same, humans have the (dis)advantage of perception. So, as with what JohnHartman suggests, you would probably be able to pass as acceptable during blackouts, but even with light shuttered off the screen, the amount of bounce you will get will probably make that projector too dim. So, there is some level of what is acceptable since this is not being used exclusively as a movie projection or conference set-up. If you are unsure as to what you will be projecting on, you will likely want to go brighter depending on your content.

When you ask about how the lumens are measured, it isn't about distance from the source that is the issue, but the size of the image. Here's how it was explained in an Electrohome technical bulletin entitled The ANSI method of light output measurement (File No. TBC93-2).

The projector must be optically and electrically setup/focussed for optimum performance over the entire screen area. Projector must be allowed to stabilize for 15 minutes before measurement can be taken. Room ambient temperature of 25 degrees Centigrade should be used. No other light source should exist in the room. Any light falling on the screen as a result of reflections and or refractions should be less than 1% of the main incident light. Aspect ration of 4:3 should be used unless projector is specifically designed for some other ratio.
The test pattern ... was developed by ANSI to be used to setup a projector and prepare it for ANSI measurements. It is made up of a full white field with 6 blocks. Each block is sized to represent 5% of the total area. The projector's Brightness control is adjusted so that the 5% block is clearly distinguishable between the 0% and 10% block. The Contrast of the projector is increased until the 95% block is still distinguishable between the 90% and 100% block. Both the Brightness and Contrast is adjusted back and forth until the above conditions are obtained.
Once the projector is adjusted and stable, a full white field similar to figure 1 but without the 6 blocks, is used for the actual light measurements. Light output is measured at 9 places on the screen. Location of these 9 spots are ... the circles in the middle of each block. The 9 measurements are then averaged and screen size is factored in to give a Lumens reading.

 

[ishboo]

I've been working with a projector in the space that is 3,500 lumens and it is bright enough on the same screen I would be using with similar ambiant light. Obviously there is a difference between 2,500 lumens and 3,500, would it be a proportional difference, 5/7ths of the brightness or what?

 

[ishboo]

Ok this is making sense now, by my calculations (done with a projection calculator) with the proposed projector I will get 8fL where as I am getting 58fL right now so that would be a huge difference. What unit is an fL exactly?

 

[museav]

To start, the BenQ MP515 is a native 800x600 resolution, a 4:3 format. An 18'x15' image is not 4:3, so the projector would actually be creating either a 20'x15' or 18'x13.5' image. You could certainly mask off part of the projected image to get the desired size but it is the projected image area over which the projector's output is distributed. For 2,500 lumens that is 8.3 to 10.3 ftL hitting the screen. The actual perceived brightness will be dependent upon the screen and the location of the viewer as the screen reflects the projected image and thus affects the actual brightness a viewer perceives. Also, consider that 2,500 lumens is probably a maximized output; new lamp, lens at optimal operation, etc. and that factors such a lens operating at its extremes or a lamp with some hours on it could result in lower actual output.

The BenQ MP515 also does not have lens shift, so if you are not at the desired location vertically or horizontally the offset would have to be addressed via keystone correction. This is less than ideal so it would be important to try to get the projector as close as possible to the desired location (on the horizontal centerline of the screen and slightly above the top of the image for ceiling mount or below the bottom of the image for tabletop mount).

I'm also not sure about the 800x600 resolution with that large an image size. That is a fairly low resolution for the image sizes being discussed, however it may be just fine depending on the application and what you are projecting.

But perhaps the biggest problem I see is that I am not sure where you got the impression that the MP515 could support the desired image size with the 20' throw distance noted. According to the MP515 Owner's Manual, an 18'x13.5' image would require a minimum 33.4' throw distance and a 20'x15' image a minimum 39' throw distance, both quite a bit longer than the 20' distance you noted. According to that same document, a 20' throw distance would equate to a maximum image size of about 161.55" diagonal or 10'-9" wide by 8'-1" high. So apparently you'd either need to almost double the throw distance or work with a much smaller image.

If the projector is actually the BenQ MP515 ST or 'Short Throw' version rather than the standard MP515 noted, then the throw distance would appear to work. If that is actually what you have then you can ignore the throw distance comments as I just wasted a bunch of my time analyzing the wrong projector.

 

[headcrab]

I have used 2500 lumen projectors at that throw for about those dimensions of projected image, and it is somewhat dim, even when our house is dark. Our main projector is 4700 lumens, and can be seen when the stage is lit, even though the screen is upstage.
Look at Newegg.com - Computer Parts, PC Components, Laptop Computers, LED LCD TV, Digital Cameras and more! for this sort of projector. For under $2000 I found a 4200 lumen projector that has a native XGA resolution. (It was the 3M DX70I)