To evaluate the suitability of some projectors for our planetarium theatre, calculated some numbers based on projectorcentral's calculator.
Our existing projector,
at
0.15 m, output = 0 cm vertical offset, 8 cm x 5 cm image.
20.0 m, output = 0 cm vertical offset, 1049x656 cm image = 1229 cm diagonal
28 nits brightness @ 20 m.
15.0 m, output = 0 cm vertical offset, 1037x648 cm image = 1229 cm diagonal
50 nits brightness @ 15 m. for wide angle
15.0 m, output = 0 offset, 658x411 = 776 cm diagonal
65 nits @ 1.0x telephoto zoom.
Highlights page shows 2.0 to 10.8 m Throw Range.
With that throw range, only NEC projector with zoom lens can fit @ 10k lumens.
with NP19ZL lens
15.0 m, output = 115 offset, 409x230 = 469 cm diagonal
243 nits @ 1.0x telephoto zoom.
If non-4K
Sony VPL-FHZ65B - 6000 lumens
@zoom = 1.0x
15.0 m, output = 0 offset, 650x406 = 766 cm diagonal
57 nits @ 1.0x telephoto zoom.
7300 lumens
66 nits.
$7000
Barco F80 4K12
via paulbourke
$26,000
w GLD Zoom R9801721 lens
@15 m
141 cm offset, 556 cm diag im, 176 nits.
0.15 m, output = 0 cm vertical offset, 9 cm x 5 cm image.
20.0 m, output = 0 cm vertical offset, 950x535 cm image = 1083 cm diagonal
26 nits brightness @ 20 m. @zoom=1.05
20.0 m, output = 0 cm vertical offset, 901x507 cm image = 1033 cm diagonal
28 nits brightness @ 20 m. @zoom=1.0
15.0 m, output = 0 cm vertical offset, 1037x583 cm image = 1190 cm diagonal
26 nits brightness @ 15 m. for wide angle @zoom=1.53x
15.0 m, output = 0 offset, 676x380 = 775 cm diagonal
49 nits @ 1.0x telephoto zoom.
TODO: check zoom on current position, distance to mirror and size on mirror. (noted below)
Current setup:
Distance to mirror centre ~ 80 cm
Width of image ~41 cm
Corresponding values on
= 1.16x zoom
@1.16x zoom, distance of 15.0 metres
== 760 x 427 cm, 872 diag, for 16x9, 52 nits.
Corresponding values on
= 1.14x zoom
@1.14x zoom, distance of 15.0 metres
== 768 x 432 cm, 881 diag, for 16x9, 40 nits.
If we adjust for a slightly smaller 871 diag as for the mitsubishi,
@1.12x zoom, distance of 15.0 metres
== 759 x 427 cm, 871 diag, for 16x9, still 40 nits.
(52-40)/52 = 23% dimmer.
But we can get 23% dimmer/brighter just by changing modes from theatre to custom etc, and also when the lamp age increases. So, probably this projector may be OK. https://www.projectorcentral.com/Optoma-ZK507-W.htm
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