Question HDR and projector to screen distance?

Luminated67

Distinguished Member
Hi guys, quick question.

Is there a benefit to have the projector as close as possible to the screen to improving HDR ability?
 

Peter Parker

Distinguished Member
Most projectors produce more lumens when they are zoomed for a larger image (with the downside of less on/off contrast), and less lumens (and more contrast) when zoomed to their smallest. From min to max zoom that can be a 25% increase in lumen output with some projectors.

If your pj is already somewhere in the middle of it's zoom range, then you will probably get maybe 10 to 15% more lumens by moving it closer, so not a big difference and probably not that noticeable.
 

Luminated67

Distinguished Member
Not sure what the distance to screen ratio is on the Epson TW9400 but my ceiling mount has the Sony at approximately 3.5M from my 100" screen.
 

Peter Parker

Distinguished Member
If you want to maximise the lumen output at the expense of contrast and black levels, try and get it as close as you can while still filling the screen.

You might want to try experimenting with the pj on a temp floor mount (like a small coffee table or something) and move it closer and further back to see if you can see improvements in brightness over reductions in black levels, and see what suits you most for HDR.
 

THX1138UK

Well-known Member
Hi guys, quick question.

Is there a benefit to have the projector as close as possible to the screen to improving HDR ability?
It’s not the distance that affects brightness, but the size of the image projected. A smaller image will always produce a brighter image.

(Moving the projector forwards/backwards or zooming the image using a lens has exactly the same results).

The inverse-square law of physics applies: An image twice as big is half as dim.
It always applies and is impossible to avoid.

I’m projecting a 92” diagonal 16:9 image using a JVC440 and I get fantastic results from HDR content - it will never be anywhere near as bright as a flat panel display, but with the right-tone mapping results can be superb.

Regards,
James.
 

Peter Parker

Distinguished Member
It’s not the distance that affects brightness, but the size of the image projected. A smaller image will always produce a brighter image.

(Moving the projector forwards/backwards or zooming the image using a lens has exactly the same results).

The inverse-square law of physics applies: An image twice as big is half as dim.
It always applies and is impossible to avoid.

I’m projecting a 92” diagonal 16:9 image using a JVC440 and I get fantastic results from HDR content - it will never be anywhere near as bright as a flat panel display, but with the right-tone mapping results can be superb.

Regards,
James.
While that is true, because of the F-stop of the lens, you will find that on a fixed screen size, if you have the pj as close as possible zoomed as large as possible to fill the screen, it will be brighter than if you have it as far back as it can go but zoomed as small as it can go while still filling the same screen. So you might get 1000 lumens when close to the screen, but only 750 when far back from the screen.
 

KelvinS1965

Distinguished Member
The only thing that does tend to get glossed over in this quest for short throw/brightest image is that it can mean that the image isn't as sharp because it's using a larger area of the whole lens.

Projectors: Chose your poison and chose your compromise. ;)
 

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